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This paper investigates direct di-methyl ether (DME) production based on dry methane reforming (DMR-to-DME) and on bireforming (BiR-to-DME). Technically, DMR-to-DME is preferred to BiR-to-DME because the former produces synthesis gas (syngas) with a hydrogen to carbon monoxide molar ratio (H 2 /CO) of 1 which is the ideal ratio for DME synthesis. Whereas the latter produces a H 2 /CO close to 2 and consequently suffers from two apparent drawbacks: (1) lack of the so-called ‘synergy effect’ – a feature that enhances DME yield when operating at H 2 /CO close to 1, and (2) generation of a high heat capacity by-product (H 2 O) which makes DME recovery energy intensive. In this paper, we find that those two disadvantages actually enhance the performance of BiR compared to DMR across a range of performance metrics. Although the presence of water increases the cooling/heating duty and the distillation columns’ reboiler duty in the BiR route, more heat released from DME synthesis reactor can be utilized in the reboilers to make BiR techno-economically compatible. To assess the sustainability of DMR and BiR, evaluations are carried out against an existing industrial scale DME production route (auto-thermal-reforming (ATR)). By utilizing the carbon in the CO 2 from an attached post-combustion carbon capture plant, DMR and BiR can save 22.3% methane feed uptake on average compared to the ATR process, which results in the DMR and BiR reducing CO 2 emissions by at least 6.5% on average. [ABSTRACT FROM AUTHOR]

In buildings, occupant behaviour is recognised as a major contributing factor to energy demand and in particular to heating consumption. To achieve thermal comfort within the heating season, people report to use heat in very different ways; for example behaviours include switching on the heating system, putting on warm clothes, drawing curtains, changing rooms, making a hot drink and using a hot water bottle. While research has focused on subjective accounts using interviews, diaries and questionnaires, little is known about the frequency and probability of these behaviours. Using a mixed-method approach, this paper reports on the results of a field study in dwellings using wearable and environmental sensors. The analysis investigates the probability of these behavioural responses as a function of seven independent variables; (1) external and (2) internal monitored temperature, (3) probability of heating being on or off, (4) time of the week, (5) time of the day, (6) the three categories of the predictive thermal comfort model, and (7) the three categories of the adaptive thermal comfort model. Results show that participants were more likely to increase their clothing and activity level as internal temperature decreased, although there was no significant change in activity level throughout the course of a day. Methodologically, this paper demonstrates the effectiveness of different statistical tools in analysing occupants’ behaviours. Substantively, this paper emphasises the need for future research to gather objective data on what people do. [ABSTRACT FROM AUTHOR]

Gasification experiments were performed for several feedstocks alone (wastewater sludge, waste wood, reeds, olive pomace, solid recovered fuel, paper labels and plastic labels) using a fixed bed reactor operating in semi-batch conditions. In order to combine them in an optimal gasifying blend, the gasification behavior of each feedstock was compared with that of wastewater sludge through the following criteria: the raw feedstock proximate and ultimate composition, the solid conversion, the gas heating value, the pollutants release and the ashes melting. Operated alone, the conversion rate of the feedstocks after 58 min of solid residence time was over 77% of initial mass. The Syngas low heating value produced at 1123 K was in the range of 9.0 to 11.9 MJ m −3 . The major concerns regarding the wastewater sludge were the pollutants precursors' release (NH 3 , COS…) and the ash slagging and fouling. The calculated slagging and fouling indexes were high also for olive pomace and for waste wood. Finally, among the possible blends studied the paper labels and plastic labels can be co-gasified with secondary and digested wastewater sludge without any restriction, reeds and solid recovered fuel can be blinded with secondary wastewater sludge without any restriction, a specific attention have to be taken to fouling when they are blended with digested wastewater sludge. The blend based on waste wood and olives pomace should be avoided for instance due to their ash slagging and fouling tendency. [ABSTRACT FROM AUTHOR]

Resource accounting is widely practiced to identify opportunities for improving the sustainability of industrial systems. This paper presents a conceptual method for resource accounting in factories that is based on the fundamentals of thermodynamics. The approach uses exergy analysis and treats the factory as an integrated energy system comprising a building, its technical building services and manufacturing processes. The method is illustrated with a case study of an automotive cylinder head manufacturing line in which the resource efficiency of this part of the factory is analysed for different energy system options relating to heating ventilation and air conditioning. Firstly, the baseline is compared with the use of a solar photovoltaic array to generate electricity, and then a heat recovery unit is considered. Finally, both of these options are used together, and here it was found that the non-renewable exergy supply and exergy destruction are reduced by 51.6% and 49.2% respectively. Also, it was found that a conventional energy analysis would overestimate the resource savings from reducing the hot water supplied to the heating system, since energy analysis cannot account for energy quality. Since exergy analysis accounts for both energy quality and quantity it produces a different result. The scientific value of this paper is that it presents an exergy-based approach for factory resource accounting, which is illustrated through application to a real factory. The exergy-based approach is shown to be a valuable complement to energy analysis, which could lead to a more resource efficient system design than one based on energy analysis alone. [ABSTRACT FROM AUTHOR]

This paper presents an investigation of forced convection effects on transient boiling heat transfer of water on plate-type heaters, at atmospheric pressure, under exponentially escalating heat fluxes. It complements the work performed under pool boiling conditions presented in the companion paper (Part I). Infrared (IR) thermometry and high-speed video (HSV) were used to gain insight into the physical phenomena and generate data that can be used for development and validation of accurate models of transient flow boiling heat transfer. Exponential power escalations with periods in the range from 5 to 500 ms, and subcooling of 10, 25 and 75 K were explored. The Reynolds number was varied from 25,000 to 60,000, depending on the subcooling. Single-phase heat transfer, onset of the boiling driven (OBD) heat transfer regime and overshoot (OV) conditions were identified. The experimental data suggest that during the single-phase heat transfer regime, forced convection is the dominant heat transfer mechanism for long periods, whereas transient conduction is more important for short periods. A criterion based on the normalized time scale for turbulent heat transfer is shown to capture all single-phase heat transfer data on a single curve. At a given period, OBD heat flux and wall superheat, as well as OV wall superheat increase with increasing subcooling and increasing Reynolds number. For a given Reynolds number and a given subcooling, they decrease with increasing periods at short periods, when the dominant heat transfer mechanism is transient conduction, whereas they barely change for long periods, as the dominant single-phase heat transfer mechanism is forced convection. Once boiling is fully developed, the heat transfer coefficient is proportional to the wall superheat to the fourth power and increases with increasing subcooling. [ABSTRACT FROM AUTHOR]

Along with the development of Smart Energy System (SES), the advancing popularity of hybrid energy appliances, such as micro-combined heat and power (CHP) and electric heaters, requires an overall energy management strategy to optimize the energy using while guaranteeing energy supply for both the electricity and heat demand. This paper based on the concept of Multi-Commodity Smart Energy System (MC-SES) proposes a self-sufficient hybrid energy model to minimize the energy exchange with the external electricity grid. Next to the optimization solution for this hybrid energy management problem, a greedy algorithm has been proposed to alleviate the high computational complexity of optimization searching. The optimization, direct allocation and greedy-based methods will all be analyzed, simulated and compared in this paper. [ABSTRACT FROM AUTHOR]

This paper presents an approach to design robust fixed structure controllers for uncertain systems using a finite set of measurements in the frequency domain. In traditional control system design, usually, based on measurements, a model of the plant, which is only an approximation of the physical system, is first built, and then control approaches are used to design a controller based on the identified model. Errors associated with the identification process as well as the inevitable uncertainties associated with plant parameter variations, external disturbances, measurement noise, etc. are expected to all contribute to the degradation of the performance of such a scheme. In this paper, we propose a nonparametric method that uses frequency-domain data to directly design a robust controller, for a class of uncertainties, without the need for model identification. The proposed technique, which is based on interval analysis, allows us to take into account the plant uncertainties during the controller synthesis itself. The technique relies on computing the controller parameters for which the set of all possible frequency responses of the closed-loop system are included in the envelope of a desired frequency response. Such an inclusion problem can be solved using interval techniques. The main advantages of the proposed approach are: (1) the control design does not require any mathematical model, (2) the controller is robust with respect to plant uncertainties, and (3) the controller structure can be chosen a priori , which allows us to select low-order controllers. To illustrate the proposed method and demonstrate its efficacy, an application to an air flow heating system is presented. [ABSTRACT FROM AUTHOR]

The neutral beam test facility, which is under construction in Padova, Italy, is developing the ITER full-scale ion source for the ITER heating neutral beam injectors, referred to as the SPIDER experiment, and the full-size prototype injector, referred to as MITICA. The SPIDER control and data acquisition system (CODAS) has been developed and its construction will start in 2014. Slow control and data acquisition will be based on the ITER CODAC core system software suite that has been designed to facilitate the integration of ITER plant systems with CODAC. Fast control and data acquisition will use solutions specific to the test facility, as the corresponding concepts are not ready-to-use in the ITER design. The ITER hardware catalog for fast control has been taken into consideration. The software development will be based on the integration of MDSplus and MARTe, two framework software packages that are well known in the fusion community, targeting data organization and fast real-time control, respectively. The paper revises the system requirements and the system design and shows the results already achieved in terms of system integration. In addition, the paper will report the experience in the usage of different cooperating software frameworks and in the integration of industrial procured plant systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A whole system approach to studying a low-temperature HGSHP system. • 3D coupled TH model with realistic boundaries and dynamic heat pump COP. • Design of a HGSHP system to support a 5th generation DHC network. • Different factors on performance of the HGSHP system and ground thermal behaviour. • Ground moisture transfer, cooling process and buried depth are important. Exploitation of shallow ground and its low-grade heat potential is fundamental to designing 5th generation district heating and cooling (DHC) networks. Horizontal ground-source heat pump (HGSHP) systems are a common way to utilize shallow geothermal energy. Realistic estimation and prediction of performance of a HGSHP system and shallow ground thermal behaviour should consider the whole system including building heating and cooling load, heat pump and ground heat exchanger, and the ground. This should be accompanied by realistic atmospheric and ground conditions. In this paper, a three-dimensional coupled thermal–hydraulic model with realistic boundary conditions adopting a whole system approach is presented. Dynamic heat pump coefficient of performance (COP) that depends on seasonal variation of heating/cooling demand and ground conditions are also considered. Model validations are conducted against experimental and analytical results in literatures. The model is applied for evaluating a HGSHP system to support development of a 5th generation DHC network on a potential site in the UK. Several influencing factors, such as ground moisture transfer, building thermal load mode, buried depth of ground loops, and initial ground temperature profile are studied to assess performance efficiency of the HGSHP system and evolution of ground thermal behaviour in response to heat extraction or rejection into the ground. The results show that 5% of the monthly total heat demand of the site could be met by the designed HGSHP system, consisting of 200 U-shaped ground loops buried at the depth of 3 m and pure water as the heat carrier. Overlooking the ground moisture transfer or hyperbolizing the ground saturation would overestimate the load-carrying capacity of the HGSHP system. The HGSHP system is more efficient with a higher heat pump COP under the heating and cooling mode than under the heating-only mode. Predicted performance of the HGSHP system improves with buried depth of the ground loops. The results also show that a 1 ℃ increase in the undisturbed ground temperature could suffice up to 8% of the monthly total heat demand of the site. [ABSTRACT FROM AUTHOR]

The development of the combined radiant floor and fan coil heating (RF-FCH) systems have improved the energy efficiency. In this study, the heating capacity and system operation state of the combined heating system were analyzed by experiments. The heating influencing factors of the combined heating system were investigated by two-way analysis of variance (ANOVA) and the Pearson correlation coefficient. Based on the technique for order preference by similarity to ideal solution (TOPSIS) the optimal operation scheme was determined. The results show that during the operation of the combined heating system, the fan coil bears significant heating capacity. The fan coil heating capacity accounts for about 62.2%-70.4% of the total heating capacity. The radiant floor plays an increasingly important role in the combined heating system with the decreasing outdoor temperature. The radiant floor response time varies from 1.5 h to 5.4 h. The fan coil responds faster to outdoor temperature changes compared to the radiant floor. The control of the fan coil can be considered as the dominant factor for dealing with outdoor temperature changes. The operation status of the RF-FCH system is mainly affected by the outdoor temperature. The energy conversion efficiency of the RF-FCH system increases with the increase of outdoor temperature. The energy efficiency ratio (EER) of the RF-FCH system varies from 2.2 to 3.2. The Pearson correlation coefficient analysis results are consistent with two-way ANOVA. Compared with the radiant floor, the indoor temperature and system energy consumption were more influenced by fan coil supply water temperature. When the evaluation indexes of the TOPSIS method have the same weight, the scheme with the fan coil supply water temperature of 32 °C exhibits a better performance. The innovation of this paper is that the best water supply scheme of the combined system is determined by TOPSIS method, which provides guidance for engineering projects. [ABSTRACT FROM AUTHOR]

Assessment methods to assess smart ventilation, in most countries focus only on comfort as criteria for the indoor air quality (IAQ) (Guyot et al., 2019). This is an issue as in doing so, pollutants that are known to cause harm to the human health are not taken into consideration while the exposure to VOCs will be elevated if the smart ventilation system lowers the ventilation flowrates to save energy (De Jonge & Laverge, 2021). This research addresses the question of what the impact of changing family sizes would be on the individual exposure to unhealthy pollutants for a smart ventilation system that only uses comfort related parameters to control the ventilation system. By introducing sources of Volatile Organic Compounds (VOCs) into a Modelica building energy and IAQ model of a typical Belgian apartment the occupant-dependent (CO 2 and RH) smart ventilation can be assessed for non-occupant dependent pollutants (VOCs). For three given smart ventilation systems, ten different households, with varying sizes and occupants are simulated. The results show that the presence of other family members influences the exposure to VOCs of an individual. One of the three smart ventilation systems is analyzed in detail, for this system, the minimum DALY count is 14.75 yr and maximum is 17.72 yr. They also show that the energy use of the building can be quite different although the only changing parameter in the simulation are the occupants. For the different simulated households, the minimum yearly energy use is 731kwh and maximum yearly energy use is 1319kwh. Similar results are obtained for the other two cases. Overall, the three smart ventilation systems show significant energy savings compared to the continuous nominal reference system but the expected impact on health increases. When designing a simulation-based assessment framework for residential ventilation, the occupant's behavior will always be an unknown factor to consider. The results indicate that in developing a simulations-based assessment framework, it is recommended to not assume just one household as in doing so, the system performance is not properly checked with regards to health and energy use during the lifetime of the system and the related expected variation in household types and sizes. The results in this paper confirm that a stochastic approach for assessing residential smart ventilation systems based on health-related pollutants (VOCs) should be investigated further. [ABSTRACT FROM AUTHOR]

• A well-functioning space heating system can operate below 70 °C for 98% of the year and below 55 °C for 71% of the year. • The performance gap between measured and calculated energy use is widening across building age groups, with a clear increase for post-1980 buildings. • Pre-1980 buildings can operate with supply temperatures below 70 °C for 96–99% of the year and below 55 °C for 67–71% of the year. • Building envelope improvement, whilst recommended, is not a pre-requisite for using low-temperature supply in pre-1980 buildings. • Post-1980 buildings could have limitations in respect of using low-temperature heat under windy conditions. Decarbonising heat in the UK by 2050 will require the wider adoption of low-temperature heat. Current systems, largely relying on gas boilers, have design operating temperatures of 82/71 °C (supply/return) while new standards for 4th Generation District Heating are 55/25 °C. Local authorities must set-up strategies to get their buildings "Heat network ready" but this raises the question of the ability for existing buildings to use low-temperature heat. The aim and the novelty of this paper is to establish a relationship between an energy 'performance gap' in Scottish public buildings and their ability to use low-temperature heat. This performance gap has been evaluated for 121 non-domestic buildings, primarily schools, operated by The City of Edinburgh Council. Space heating system are assumed oversized by 10%. The results show that renovation of the building envelope, while highly desirable, is not a pre-requisite for using low-temperature heat in pre-1980 constructed buildings, which represent 64% of the stock. It also highlights that post-1980 buildings, predominantly utilising mechanical ventilation systems, demonstrate an increasing performance gap which could limit their ability to use reduced operating temperature, especially in windy conditions. [ABSTRACT FROM AUTHOR]

Ground source heat pumps (GSHP) are one of the most efficient systems that offer a promising reduction in greenhouse gas emissions and energy use in buildings; however, the electrification of buildings' heating and cooling using GSHP is facing two critical challenges: its high initial cost and potential adverse impact on the electrical grid. In this paper, to address these challenges, two novel systems are proposed in which a battery, a water thermal storage tank, and a phase change material (PCM) thermal storage tank are integrated, in different configurations, with a conventional GSHP system. In these systems, the grid electricity during off-peak periods is stored as heat or electricity in the thermal or battery energy storage systems. The stored energy is then used in peak building load conditions to reduce the peak power demand on the grid. New numerical models are developed to quantify the proposed systems' benefits. Furthermore, these newly proposed systems are compared with the conventional systems used in Quebec, Canada, and three previously proposed worldwide systems. Simulations are conducted for different commonly used design practices, including undersized and adequately sized heat pump capacities. The results show that the proposed systems can reduce the peak power demand and total energy requirement of a conventional system by up to 65.4% (9.28 kW) and 67.0% (19,722 kWh), respectively. Furthermore, the proposed systems' borehole length decreases by up to 21.8% (39 m) compared to the conventional GSHP system. [ABSTRACT FROM AUTHOR]

• An ICRH antenna has been built for the largest stellarator in the world, Wendelstein 7-X. This is also the first time that an ICRH antenna is constructed for such a stellarator. • The antenna is installed in Wendelstein 7-X and is ready for operations. • Main aims are: heating of stellarator plasmas, plasma startup (especially at low magnetic field, where ECRH cannot be used), fast particle generation to test the confinement properties of the optimized magnetic configuration of Wendelstein 7-X and wall conditioning. The ICRH antenna for the stellarator Wendelstein 7-X (W7-X) aims at delivering RF power levels up to about 1.5 MW in the frequency range 25–38 MHz with pulse lengths up to 10 s. The antenna was constructed and tested in the institute IEK-4 of the Research Centre Jülich, and subsequently installed at W7-X. The paper will review the physics design, the construction and installation in W7-X, and the commissioning plans for the ICRH system in the coming months. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive assessment of the humid air turbine-based waste heat recovery system with respect to different flow configurations in the air saturator. The novelty of this work is to provide a holistic approach to the environmental and thermoecological assessment of Maistosenko cycle-based waste heat recovery units by considering three configurations of air saturator namely, counter-flow, cross-flow, and mixed-flow configuration. In other words, the assessment is carried out to evaluate the performance improvements while comparing the environmental as well as thermoecological perspectives. This provides a broader and wholesome perspective allowing a wider application of these configurations, especially in different climatic conditions experiencing varying ambient temperatures. The ambient temperature is particularly important when air is used as working fluid and routed in three different configurations within the heat recovery unit i.e., air saturator. The addition of humidity in the air saturator tends to improve the performance of bottoming cycle depending on the air direction within the saturator which has a counter, cross and mixed flow configurations. Moreover, ambient or dead state temperature is considered one of the influencing parameters on the performance of considered heat recovery configurations. With the rising ambient temperatures up to 50 °C, owing to intensive heat waves and sustained droughts; the performance indicators of power generation units indicate as much as 25% reduction in the sustainability index along with 10% lowering of energy and exergy efficiencies. In this regard, the flow configuration and efficiency of air saturators become critically important especially as a heat recovery unit while working in intense operating conditions. The results have suggested that counter configuration can offer the highest among of net-work marking 51.9 MW whereas the cross-flow configuration can mark only 49.78 MW. Thermoecological assessment has suggested that the ambient temperature of this type of powerplant can be less than 40 °C. It is concluded that the optimal configuration is counter-flow configuration for the waste heat recovery in gas turbines based upon second law and thermoecological assessment. • Three improved humid air waste heat recovery configurations are proposed. • Integrating energy assessment with heat and mass transfer characteristics are studied. • Evaluation based upon exergy, thermoecological, and life-cycle cost analysis are done. • New configuration of counter-arrangement air saturator offers the best performance. [ABSTRACT FROM AUTHOR]

For a linear heat transfer system, the unit step response of the temperature field to any system inputs, such as internal and external heat sources, is specific. This means that there is a definite temperature response correlation between any spatial points in the system spatiotemporally, which is independent of the system inputs. It is significant to achieve a quantitative description of the temperature response spatiotemporal correlation between the spatial points for solving the temperature field reconstruction problem of the heat transfer system with unknown inputs. In this paper, a temperature response spatiotemporal correlation model (RSTCM) of the heat transfer system is established originally to reveal the inherent quantitative relationship between the responses of any system spatial points theoretically. Firstly, an external description of the spatiotemporal mapping relationship of the heat transfer process is established according to the heat transfer equations. Furthermore, a basic RSTCM form is proposed and a response spatiotemporal correlation matrix is determined with the help of the external description. Finally, considering the ill-posed characteristic of the response spatiotemporal correlation problem, the regularization technology is employed to transform the original problem into a well-pose problem and to provide a response spatiotemporal correlation matrix with regularization. Effectiveness of the RSTCM is verified by the existing heat transfer experimental data. Besides, adaptability of the proposed model is demonstrated by the achieved numerical experiment results on a two-dimensional heat transfer system. [Display omitted] • The temperature response spatiotemporal correlation is revealed for a heat transfer system. • A temperature response spatiotemporal correlation model (RSTCM) of the heat transfer system is established. • The response spatiotemporal correlation matrix is constructed by regularization. • Effectiveness of the RSTCM is verified by experimental data. • The RSTCM lays a foundation for temperature field reconstruction independent of heat sources. [ABSTRACT FROM AUTHOR]

We consider a Timoshenko system with partially Kelvin–Voigt damping, and with Cattaneo/Fourier type heat conduction. When the Timoshenko system with only heat conduction or only partially Kelvin–Voigt damping, some authors showed the non-exponential stability. In this paper, we add the Kelvin–Voigt damping in the thermoelastic Timoshenko system, and prove that the system is also not exponentially stable in cases of Fourier and Cattaneo type heat conduction, whether the wave speeds are equal or not. Additionally, we prove the semigroup decays with the optimal rate t − 1 2 . [ABSTRACT FROM AUTHOR]

In this paper the aerothermal heating of a reusable launch vehicle with the material parameters depending on temperature is retrieved. An additional information, necessary for solving the corresponding inverse problem, is taken from the temperature values in the selected point of thermal protection system. Minimization of the constructed functional, defining the error of approximate solution, is executed with the aid of Levenberg–Marquardt method. Whereas the direct problem, needed to be solved in order to determine the value of functional mentioned above, is solved by using the implicit scheme of the finite difference method. In this approach a system composed from three layers is considered, which represents an integrated thermal protection system with material parameters depending on temperature. [ABSTRACT FROM AUTHOR]

Current heat transfer systems in the industry may result in problems such as low efficiency and environmental pollution. In this paper, the influence of heater power, speed and direction of rotation cylinders, and underfloor heating power are investigated on the Nusselt number in a water-filled enclosure with Pr = 5.4 numerically and experimentally based on the Arduino control unit. The enclosure is under constant heat flux from the bottom wall. Using the mixed-Taguchi method and according to different considered cases, 36-state experiments were designed in the range of 2 × 10 8 < R a < 8 × 10 8 and R e < 4000. The problem was simulated by using the Realizable k-ε turbulence model, in 3D steady-state mode. Isotherms and streamlines were reported for each case and analysis revealed that the speed of rotation and the heater power has a more important role than other parameters on the heat transfer rate. In the best situation with a maximum speed of cylinders (S = S (max)), maximum floor heating system ( q f ˙ = q f ˙ (max)) , and maximum power of the heater ( q r ˙ = q r ˙ (max)) the Nusselt number is 110.5 with an almost 22% increase in heat transfer rate. A polynomial surf fit for Nusselt number according to Re, Ra proposed and there are three parts to the variation range of Nusselt numbers based on Richardson numbers. [Display omitted] [ABSTRACT FROM AUTHOR]

The following comments address an inappropriate implementation of a theoretical relationship and some incorrect qualitative and quantitative findings in the paper, as mentioned above. Therefore, this analysis clarifies the article "Numerical study on the conjugate effect of joule heating and magneto-hydrodynamics mixed convection in an obstructed lid-driven square cavity." [International Communications in Heat and Mass Transfer 37 (2010), 524–534]. [ABSTRACT FROM AUTHOR]

Nowadays, utilization of micro/mini channel heat sinks (MCHS) has become a popular solution for cooling of electronic systems and maintaining their operating temperature in a desired range. Increasing the contact surface area between fluid and solid zones by geometrical modifications is a promising solution that significantly affects thermal performance and heat transfer in these systems. In this paper, considering thermohydraulic performance, the effect of creating grooves on the middle-placed barriers of a minichannel heat sink is investigated to access a criterion for favorable temperature performance. Evaluating different geometrical parameters of barriers and grooves including cross section, depth and position of horizontal groove as well as vertical groove distance, simultaneous employment of optimal horizontal and vertical groove in the channel at different Reynolds numbers is studied. Outputs including channel base temperature, friction factor ratio and total thermal resistance are studied to evaluate the performance of the proposed minichannel. Results indicate that vortex formation adjacent to solid walls considerably enhances the heat transfer and variation of each geometrical parameters offers a performance enhancement. Moreover, the best thermal performance is obtained by simultaneous employment of the horizontal rectangular groove (x = 0.45 mm, y = 0.2 mm and h g = 0.6 mm) and the vertical groove (d g = 0.4 mm). In the optimal case, the channel base temperature and the total thermal resistance reduces by 11.88 K and 27%, respectively. [ABSTRACT FROM AUTHOR]

This paper investigates experimentally the cooling performance of a concept, where the radiant ceiling is suspended from the hollow-core concrete slab and by ventilation supply in the plenum and the perforations of the ceiling tiles, ventilation air is distributed without ducts and air terminals to the occupied zone. Literature has proven that this concept allows for more streamlined installation procedures and excellent performance in terms of thermal comfort and draught. The paper reports experimental results from a climate chamber, where the concept was tested under both steady-state and quasi-steady conditions. The steady-state conditions were chosen to map the cooling performance with different air change rates, and different ventilation and water supply temperatures. The results showed that for air change rates of 3 h−1 in the occupied zone and water supply temperature of 17 °C, the cooling output from the ceiling increased by 10 %. The concept was also tested under quasi-steady conditions in a 48 h cycle to quantify the thermal buffering effect of the exposed upper concrete slab when subjected to ventilation supply air. The effect amounted to 11–12 % increased cooling capacity at the end of the working day when the driving temperatures between air, water and thermal zones were at their maximum. [ABSTRACT FROM AUTHOR]

• Work completed by the Heating and Current Drive Workpackage for DEMO during the pre-conceptual design phase (2014-2020) • The Electron Cyclotron System is the baseline for DEMO • Description of the Electron Cyclotron System • Description of the Ion Cyclotron System • Description of the Neutral Beam Heating System The European DEMO is a pulsed device with pulse length of 2 hours. The functions devoted to the heating and current drive system are: plasma breakdown, plasma ramp-up to the flat-top where fusion reactions occur, the control of the plasma during the flat-top phase, and finally the plasma ramp-down. The EU-DEMO project was in a Pre-Concept Design Phase during 2014-2020, meaning that in some cases, the design values of the device and the precise requirements from the physics point of view were not yet frozen. A total of 130 MW was considered for the all phases of the plasma: in the flat top, 30 MW is required for neoclassical tearing modes (NTM) control, 30 MW for burn control, and 70 MW for the control of thermal instability (TI), without any specific functions requested from each system, Electron Cyclotron (EC), Ion Cyclotron (IC), or Neutral Beam (NB) Injection. At the beginning of 2020, a strategic decision was taken, to consider EC as the baseline for the next phase (in 2021 and beyond). R&D on IC and NB will be risk mitigation measures. In parallel with progresses in Physics modelling, a decision point on the heating strategy will be taken by 2024. This paper describes the status of the R&D development during the period 2014-2020. It assumes that the 3 systems EC, IC and NB will be needed. For integration studies, they are assumed to be implemented at a power level of at least 50 MW. This paper describes in detail the status reached by the EC, IC and NB at the end of 2020. It will be used in the future for further development of the baseline heating method EC, and serves as starting point to further develop IC and NB in areas needed for these systems to be considered for DEMO. [ABSTRACT FROM AUTHOR]

This paper deals with the stochastic numerical analysis of moisture transfer in wood with the random diffusion coefficient after heating of wood (when temperature is already constant). The simulation is based on the unsteady-state nonlinear (the model respects the dependence of diffusion coefficients on moisture and constant temperature) diffusion of moisture with respect to the orthotropic nature of wood. The spectral solution of this problem is based on discretization the resulting random field (moisture) in the stochastic dimension by the orthogonal polynomials (generalized polynomial chaos algorithm). A Galerkin projection is applied in the stochastic dimension to obtain the deterministic set of partial differential equations that is solved by finite element method. The main purpose of this paper is to demonstrate that the stochastic spectral method based on polynomial chaos expansion can be more efficient in modeling uncertainties associated with moisture transfer in wood than Monte Carlo method mainly when considering a small number of random variables. This spectral approach has a big advantage over the Monte Carlo method (statistical approach) in terms of computer time. Numerical example of diffusion of moisture in convective drying of wood is given and there is shown that the results (mean and the standard deviation) obtained with the stochastic spectral method are in good agreement with the results of the Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

This paper deals with the analytical and experimental analysis of heat transfer in the xylem of trees and the determination of stem water content (WC). The aim of this paper was to derive and verify a new approach to WC calculation from measured temperature differences around a continuously heated needle. The configuration of heater and thermocouples of the heat field deformation (HFD) method for sap flow measurements was taken for this purpose. The suggested formula is derived from the heat conduction equation with a continuous linear source of heating. The ability of the HFD method to non-destructively determine the radial distribution of the local conditions of sap flow measurements under zero flow (referred to as K-value) was used to derive the radial distribution of WC. Examples of the application of our method on several contrasting species with different plant hydraulic architecture are given where calculated WC along stem xylem radius was compared with its direct gravimetrical measurements or with relative determination of wetness of cross-sectional stem discs using a modified differential translucence method. The proposed method enables water content measurements during continuous linear heating and is important for information about WC and sap flow together per day or season when there is possible to extrapolate the temperature difference for zero flow condition. [ABSTRACT FROM AUTHOR]

This paper presents and discusses a new methodology to determine the pre-setting of the radiator and balancing control valve, as one of the basic parameters in the process of the heating installation hydraulic balancing. Example calculations are also made for selected control valves using the proposed and alternative methodologies, including the methodology generally accepted and used in practice. A comparison of the results is presented. It is shown that the proposed methodology gives results consistent with experimental data. It is also more accurate and versatile than the other methodologies discussed in the paper. [ABSTRACT FROM AUTHOR]

Dynamic optimization of adsorbent-heat exchangers (Ad-HExs) represents a key issue for the broader diffusion of adsorption cooling and heating (ACH) technologies. This paper is a sequel to an earlier one (Sapienza et al., 2014) that described the study of an ideal Ad-HEx configuration (loose adsorbent grains placed on a flat metal plate) by a new gravimetric version of the large temperature jump method. In the present paper, the study is extended to analyse the dynamic behaviour of HExs with much more complex geometry, namely, small but representative pieces of a finned flat-tube HEx. The Ad-HEx configuration tested is obtained by filling these small HExs with loose grains of AQSOA FAM Z02. The aim of the study is to evaluate the effect of the HEx geometry, grain size and flow rate of heat transfer liquid. The results obtained are compared with a reference flat Ad-HEx configuration. The ad-/desorption dynamics is found to be nearly exponential that proves the applicability of a modified Linear Driving Force model to characterize the water ad-/desorption rate. The majority of the tests have revealed the existence of the “grain size insensitive” regime for grains of 0.3–0.7 mm size. Under this mode, the dynamic behaviour is only function of the ratio ( S / m ) = 〈heat transfer surface〉/〈absorbent mass〉. This leads to a practically important conclusion that it is not necessary to precisely select the adsorbent grain size. When the grain size becomes too small or too large the rate reduction was found that is due to inter- or intra-grain mass transfer resistances. The tested Ad-HEx configuration is proved to be quite efficient: the specific cooling power amounts to 50–66% of that obtained with the reference (ideal) one, and the average specific cooling power W 80% can reach 2.3 kW kg −1 . This power is 6–8 times higher than those reported in the literature for full scale Ad-HExs with similar cell geometry. Thus, the study showed that there is still a big room for significant dynamical improvement of real ACH units. [ABSTRACT FROM AUTHOR]

Green roofs have been proposed for energy saving purposes in many countries with different climatic conditions. However, their cooling and heating potential strongly depends on the climate and building characteristics. In particular, the increase of the thermal capacity of green roofs compared to traditional roofs, if not controlled with insulation, may lead to higher cooling and heating loads. This paper discusses the energy saving potential of green roofs adopting a variable insulation strategy. A system consisting of a plenum located between a green roof and the room underneath and a sensor-operated fan that couples (or decouples) the green roof mass with the indoor environment was developed. The fan is activated and stopped using temperature based rules; the plenum is ventilated only when the fan works, creating a variable insulation system. Four cells with an insulated traditional roof, a non-insulated green roof, an insulated green roof, and a green roof with the variable insulation system have been tested in a hot and dry climate with mild winters over several years. This paper compares and discusses different plenum control algorithms. Results are particularly promising because the variable insulating system proved to adjust the thermal capacity of the roof effectively. In summer, the non-insulated green roof and the green roof with variable insulation system achieved the lowest indoor temperature; in winter, the insulated traditional roof and the variable insulation green roof system achieved the highest indoor temperatures. Measurements are hence compared with simulations. Finally, the energy saving potential of the new green roof system is evaluated. [ABSTRACT FROM AUTHOR]

Global warming has drawn great attention in recent years because of its large impact on many aspects of the environment and human activities in buildings. One area directly affected by climate change is the energy consumption for heating and cooling. To quantify the impact, this study used the HadCM3 Global Circulation Model (GCM) to generate weather data for future typical meteorological years, such as 2020, 2050, and 2080, for 15 cities in the U.S. based on three CO 2 emission scenarios. The method was validated by comparing the projected TMY3 data using HadCM3 with the actual TMY3 data. By morphing method, the weather data was downscaled to hourly data for use in building energy simulations by EnergyPlus. Two types of residential buildings and seven types of commercial buildings were simulated for each of the 15 cities. This paper is the first to systematically study the climate change impact on various types of residential and commercial buildings in all seven climate zones in the U.S. through EnergyPlus simulations and provide weighted averaged results for national-wide building stock. We also identified geographical dependency of the impact of climate change on future energy uses. There would be a net increase in source energy consumption by the 2080s for climate zones 1–4 and net decrease in climate zones 6–7 based on the HadCM3 weather projection. Furthermore, this paper investigated natural ventilation performance in San Francisco, San Diego, and Seattle with improved natural ventilation model. We found that by the 2080s passive cooling would not be suitable for San Diego because of global warming, but it would still be acceptable for San Francisco and Seattle. [ABSTRACT FROM AUTHOR]

Energy demand prediction of building heating is conducive to optimal control, fault detection and diagnosis and building intelligentization. In this study, energy demand prediction models are developed through machine learning methods, including extreme learning machine, multiple linear regression, support vector regression and backpropagation neural network. Seven different meteorological parameters, operating parameters, time and indoor temperature parameters are used as feature variables of the model. Correlation analysis method is utilized to optimize the feature sets. Moreover, this paper proposes a strategy for obtaining the thermal response time of building, which is used as the time ahead of prediction models. The prediction performances of extreme learning machine models with various hidden layer nodes are analyzed and contrasted. Actual data of building heating using a ground source heat pump system are collected and used to test the performances of the models. Results show that the thermal response time of the building is approximately 40 min. Four feature sets are obtained, and the performances of the models with feature set 4 are better. For different machine learning methods, the performances of extreme learning machine models are better than others. In addition, the optimal number of hidden layer nodes is 11 for the extreme learning machine model with feature set 4. [ABSTRACT FROM AUTHOR]

Despite a variety of techniques available for thermal conductivity measurement, there is a lack of methods to directly measure the radial thermal conductivity of a cylinder. This presents a critical gap in heat transfer metrology, particularly in presence of anisotropic thermal conduction, such as in a Li-ion cell, where radial thermal conductivity plays a key role in determining performance and safety. This paper reports a technique for measurement of radial thermal conductivity of a cylinder by accounting for variable heat flux into the cylinder when heated on the outside. It is shown that heat flux into the cylinder from a thin heater wrapped around its surface varies significantly with time. This variation, which was neglected in past work, is accounted for by developing a variable heat flux model for experimental data analysis. For two different materials, measurements of radial thermal conductivity using this approach are shown to be in close agreement with standard thermal conductivity measurement using the transient plane source method. Radial thermal conductivity of a 26650 Li-ion cell is measured to be 0.39 W/mK. Besides contributing a new approach for thermal metrology in cylindrical systems, this work also improves the understanding of thermal phenomena in Li-ion cells. [ABSTRACT FROM AUTHOR]

Latent heat thermal energy storage is an attractive technique as it can provide higher energy storage density than conventional heat energy storage systems and has the capability to store heat of fusion at a constant (or a near constant) temperature corresponding to the phase transition temperature of the phase change material (PCM). This paper provides a state-of-the-art review on phase change materials (PCMs) and their applications for heating, cooling and electricity generation according to their working temperature ranges from (−20 °C to +200 °C). Four working temperature ranges are considered in this review: (1) the low temperature range from (−20 °C to +5 °C) where the PCMs are typically used for domestic and commercial refrigeration; (2) the medium low temperature range from (+5 °C to +40 °C) where the PCMs are typically applied for heating and cooling applications in buildings; (3) the medium temperature range for solar based heating, hot water and electronic applications from (+40 °C to +80 °C); and (4) the high temperature range from (+80 °C to +200 °C) for absorption cooling, waste heat recovery and electricity generation. Different types of phase change materials applied to each temperature range are reviewed and discussed, in terms of the performance, heat transfer enhancement technique, environmental impact and economic analysis. The review shows that, energy saving of up to 12% can be achieved and a reduction of cooling load of up to 80% can be obtained by PCMs in the low to medium–low temperature range. PCM storage for heating applications can improve operation efficiency from 26% to 66%, depending on specific applications. Solar thermal direct steam generation (DSG) is the most common electricity generation application coupled with PCM storage systems in the high temperature range, due to the capability of PCMs to store and deliver energy at a given constant temperature. The recommendations for future research are also presented which provide insights about where the current research is heading and highlights the challenges that remain to be resolved. [ABSTRACT FROM AUTHOR]

The traditional thermal protection system (TPS) of hypersonic flight vehicles is usually designed for thermal protection purpose only with low efficiency. In this paper, a thermoelectric material based multifunctional TPS structure concept is proposed and the evaluation approach of its mechanical-thermoelectric performance is developed based on a specific vehicle and a typical trajectory. The thermoelectric module in the structure can convert a certain amount of aerodynamic heat into electricity supply. The module consists of n -type Sr 0.9 La 0.1 TiO 3 compound which is fabricated based on the solid state reaction method, and the widely used p -type Ca 3 Co 4 O 9 . For a specific hypersonic flight vehicle with a typical trajectory curve, the aerodynamic heat is calculated by an engineering-based algorithm, the unsteady mechanical-thermoelectric characteristics of the structure is then analyzed based on a unit cell model and the thermoelectric conversion efficiency is finally evaluated. The results indicate that the multifunctional TPS structure has significant application potentials on the hypersonic flight vehicles. [ABSTRACT FROM AUTHOR]

An unsteady two-dimensional numerical model was used to simulate concurrent flame spread over paper-like thin solid fuels of discrete configurations in microgravity (0 g with 20 cm/s) and in normal gravity (1 g). An array of ten 1 cm-long fuel segments was uniformly distributed in the flow direction (0 g) or in the vertical direction (1 g). A hot spot ignition source was applied at the upstream leading edge of the first fuel segment. The separation distance between the fuel segments was a parameter in this study, ranging from 0 (corresponding to a continuous fuel) to 3 cm. Using this setup, the burning characteristics, spread rate of the flame base, and the solid burning rate were examined. The flame base spread rates in both 1 g and 0 g cases increase with the separation distance. This is due to the flame jumping across the gaps. For the solid burning rate, the dependency on the separation distance is different in 1 g and 0 g cases. At a flow velocity of 20 cm/s in 0 g, the flame reaches a limiting length and the flame length is approximately the same for all fuel configurations. As the separation distance increases, the heating length (the fuel area exposed to the flame) decreases, resulting in a decreasing total heat input and a decreasing solid burning rate. In 1 g, the flame is long and extends to the last fuel segment before the first fuel segment burns out. This suggests that the heating length is approximately the same in all simulated cases (∼total fuel length). However, the flame standoff distance decreases when the separation distance increases. This results in an increasing total heat input and an increasing solid burning rate. Terrestrial experiments were conducted to validate the 1 g model. The experimental results agreed reasonably with the model predictions of burning characteristics, burn durations, and flame spread rates. [ABSTRACT FROM AUTHOR]

Polycarbonate panels could be considered as a suitable and cheap solution for walls, roofs, and sheds in non-residential buildings and, at the same time, granular silica aerogel is one of the most promising nano-materials for energy saving in buildings. In the paper, three types of advanced multiwall PC panels (thickness 16, 25, and 40 mm) with translucent granular aerogel were investigated by experimental (thermal and optical) and numerical characterization. By comparing thermal performance of air and aerogel-filled PC systems, it can be noticed that the impact of the aerogel is remarkable: the reduction in U-value is 46%-68%, depending on the aerogel layer thickness. U-value is 1.4 W/m 2 K for the 16 mm thickness sample and it is 0.6 W/m 2 K when the thickness increases up to 40 mm. The systems keep their performance in horizontal position, when they are used as roofs. Light transmittance is 0.61 and 0.42 for 16 mm and 40 mm respectively and the reduction with respect to air-filled panels is acceptable (15%) for 16 mm and significant (40%) for 40 mm thickness. The aerogel has also a remarkable impact on the reflectance spectrum , especially between 400 and 1400 nm. The solar factor is 0.58 for 25 mm thickness, quite similar to the low-e glazing one. Finally, energy simulations for a case study showed that aerogel-filled PC systems outperform conventional double glazing systems both for heating and cooling energy demands. However, when compared to low-e glazings, the benefits of the translucent material (also considering the highest thickness) in the interspace are lower for heating and negligible for cooling energy demands. The aerogel-filled polycarbonate systems could be a valid solution for non-residential buildings, enhancing the thermal performance and the light control of the building envelope, especially when they are used as roofs. [ABSTRACT FROM AUTHOR]

The very low heating load of deep renovated buildings following standards such as EnerPHit, and the limited space in renovation create the need for compact heating systems. An innovative heating and ventilation system - consisting of an exhaust air to supply air heat pump combined with a heat recovery ventilation unit, both integrated into a prefabricated timber frame façade - was developed and installed in a flat during the renovation of a multi-family house in Ludwigsburg, Germany. The system and the flat were monitored for the complete heating season 2016/2017. This paper presents: (a) an analysis of the monitoring data, (b) the development and validation of the models of the system and the flat, and (c) the results of the dynamic simulations that were performed for further system optimisation. Inside the flat, good thermal comfort and indoor air quality conditions were achieved. The monitored SPF of the system was 2.8. Simulation results showed that with the optimised system and control, there can be an electricity savings of 25%. The developed system has the potential to be cost-effective due to prefabrication and low heating capacity. It represents a compact solution with moderate energy performance, appropriate for minimally disruptive renovations. [ABSTRACT FROM AUTHOR]

The complex interactions between the inclined terrain and the flow generated by the fire make the slope one of the most influencing factors on fire spread. In order to gain a deeper understanding of the mechanisms involved in wildfires spreading upslope, the investigation of flow dynamics and heat transfers is fundamental. This paper reports a series of fire spread experiments conducted across a porous bed of excelsior in a large-scale facility, under both no-slope and 30° up-slope conditions. The coupling of particle image velocimetry and video imaging allowed characterizing the flow pattern with respect to the fire front. Simultaneous heat flux measurements with high scan rate were also performed at the edge of the fuel bed. From the collected data, the increase of the rate of spread with increasing slope is attributed to a major change in fluid dynamics surrounding the flame. For horizontal fire spread, flame fronts exhibit quasi-vertical plume resulting from the buoyancy forces generated by the fire. These buoyancy effects induce an inward flow of ambient air that is entrained laterally into the fire from both sides. Flame radiation is the dominant fuel preheating mechanism. Under upslope conditions, the fire plume is tilted toward the unburnt vegetation, increasing radiation levels. The air entrainment at the burnt side of the fire strongly influences the downstream flow, which becomes attached to the surface over a characteristic length scale. Ahead of the flame front, the induced wind blows away from the fire rather than toward it, enhancing convective heating. Periodical forward bursts of flame combined with distant fuel ignitions were also observed. The heat flux measurements confirmed the existence of such convective mechanisms. [ABSTRACT FROM AUTHOR]

Actual national and international energy strategies generally encourage the use of renewable energy sources. Thermal energy storage (TES) offers various opportunities in the design of renewable energy systems. Thermochemical heat storage has gained popularity among researches because of higher energy density and lower heat loss compared to sensible and latent heat storage. On the other side solar energy has been recognized as one of the renewable energy sources with the most potential. This paper reviews thermochemical heat storage technologies and systems with emphasis on systems involving solar energy utilization in buildings. The studies are reviewed based on used storage materials, system configuration as well as models to predict and optimize system performance. [ABSTRACT FROM AUTHOR]

The discharge scenario query system, designed and deployed since 2014, is an important part of the EAST remote discharge scenario management system (RDSMS) Chai et al. [ 1 ]. Parameter analysis and extraction are the key function for classifying and querying scenarios. On EAST, the plasma control system (PCS) can parse the pre-set parameters line-by-line from future shots (taken from pre-set files in PCS server) or from past shots (taken from the MDSplus Manduchi et al. [ 2,3 ] tree) through a two-step conversion while the discharge parameters can be taken from the MDSplus tree directly without any conversion. To help with searching through enormous stock of past and future scenarios that are archived at EAST, we take advantage of the parsing procedure of the PCS and MDSplus programming by developing a “Parsing Program” to extract the pre-set and discharge parameters. This paper introduces the storage structure and parsing procedure of pre-set files, going into some detail for the latter. The other parameters, on the other hand, need little explanation as they are taken directly from the MDSplus tree. The pre-set parameters and the data analysis of the completed shot are archived in the MySQL database for future advanced scenario queries. In order to provide a cross platform tool, a remote graphical user interface has been built in form of a dynamic web page to query and evaluate parameters as well as provide scenario verification via auditors. This web-based discharge scenario query system will ultimately lead to improved work efficiency of technicians, researchers, scientists, users in general. [ABSTRACT FROM AUTHOR]

The melting process and the solidifying process of phase change material (PCM) are usually considered symmetrical in the traditional PCM heat transfer models, but there are inevitable calculation errors using these models. In this paper, a new heat transfer model of PCM based on the energy asymmetry was built, and it was validated by experimental data. It was found that the two main reasons for the energy asymmetry of the PCM were the melting temperature range and the solidifying temperature range were not the same and the supercooling problem during the cooling process. No matter for only one thermal cycle or for the multiple thermal cycles, the results from the asymmetrical model and the symmetrical model were different. Apparently, compared with the symmetrical model, the asymmetrical model had higher accuracy, and the heating/cooling process in the asymmetrical model was more consistent with the real heating/cooling process of the PCM. [ABSTRACT FROM AUTHOR]

A solid-desiccant system that utilizes low grade heat is potentially a viable add-on to conventional HVAC systems since it can help reduce power consumption significantly, for achieving indoor thermal comfort conditions. In contrast to desiccant wheels which carry out adiabatic dehumidification, isothermal dehumidification process that may be realized by a cross-flow heat exchanger is much more efficient. In this paper, a novel mathematical model is developed to simulate heat and mass exchange phenomena of a desiccant coated fin tube heat exchanger (DCFTHX). This model takes solid side mass transfer resistance as well as fin efficiency into consideration. The model is validated using experimental results in the literature. It is also compared against simplified models to establish its utility. A parametric study is then conducted to investigate the effects of geometrical parameters as well as mass flow rate of water and air velocity on dehumidification and adsorption heat removal performance of the DCFTHX as well as the performance of the augmented air-conditioning system under warm and humid ambient conditions. Under the range of parameters and conditions simulated, if low grade waste heat (50 °C hot water) is available for regeneration, integration of DCFTHX sub-system with a conventional air conditioning system can yield as high as 31% energy savings (even when the additional power consumed by pumps and blower fans is accounted for). [ABSTRACT FROM AUTHOR]

Maintaining thermal comfort in built environments is important for occupant health, well-being, and productivity, and also for efficient HVAC system operations. Most of the existing personal thermal comfort learning methods require occupants to provide feedback via a survey to label the monitored environmental or physiological conditions in order to train the prediction models. Accuracy of these models usually drops after the training process as personal thermal comfort is dynamic and changes over time due to climatic variations and/or acclimation. In this paper, we present a hidden Markov model (HMM) based learning method to capture personal thermal comfort using infrared thermography of the human face. We chose human face since its blood vessels has a higher density and it is not covered while performing regular activities in built environments. The learning algorithm has 3 hidden states (i.e., uncomfortably warm, comfortable, uncomfortably cool) and uses discretization for forming the observed states from the continuous infrared measurements. The approach can potentially be used for continuous monitoring of thermal comfort to capture the variations over time. We tested and validated the method in a four-day long experiment with 10 subjects and demonstrated an accuracy of 82.8% for predicting uncomfortable conditions. [ABSTRACT FROM AUTHOR]

The application of ground source heat pumps (GSHP) for heating and cooling of buildings is currently increasing in popularity in the UK and globally. Traditional GSHP systems use the naturally available geothermal gradient of earth for heating and cooling purposes using open loop or closed loop systems. In this paper, the use of mine water from a flooded coal mine for heating of buildings is presented using a GSHP system with an open loop configuration. The novelty of this approach is that a single shaft is used to extract the warm water and inject the cooler water back into the same shaft, thereby minimising the area needed, initial capital costs in constructing a doublet system and also potentially overcome the time consuming process to address related environmental agencies regulation regarding the discharging of the mine water. The relatively stable temperature low enthalpy of mine water contained in the abandoned and flooded coal mines are ideal to be used for both heating and cooling of buildings when used in conjunction with heat pumps. The GSHP is considered to be an effective means of reducing the carbon emission as it gives more output in the form of thermal energy in comparison to the electrical energy it consumes as input. This research work reports on the performance of the system over the winter season and its long term potential in converting the mine water from an environmental liability to a sustainable energy resource and offers a means to regenerate the former coal mining areas. [ABSTRACT FROM AUTHOR]

A variety of novel, recyclable and reusable, construction materials has already been studied within literature during the past years, aiming at improving the overall energy efficiency ranking of the building envelope. However, several studies show that a delicate control of indoor climating elements can lead to a significant performance improvement by exploiting the building’s savings potential via smart adaptive HVAC regulation to exogenous uncertain disturbances (e.g. weather, occupancy). Building Optimization and Control (BOC) systems can be categorized into two different groups: centralized (requiring high data transmission rates at a central node from every corner of the overall system) and decentralized 1 The terms “decentralized”, “distributed” and “agent-based” are considered to have similar meanings herein. 1 (assuming an intercommunication among neighboring constituent systems). Moreover, both approaches can be further divided into two subcategories, respectively: model-assisted (usually introducing modeling oversimplifications) and model-free (typically presenting poor stability and very slow convergence rates). This paper presents the application of a novel, decentralized, agent-based , model-free BOC methodology (abbreviated as L4GPCAO) to a modern non-residential building (E.ON. Energy Research Center’s main building), equipped with controllable HVAC systems and renewable energy sources by utilizing the existing Building Management System (BES). The building testbed is located inside the RWTH Aachen University campus in Aachen, Germany. A combined rule criterion composed of the non-renewable energy consumption (NREC) and the thermal comfort index – aligned to international comfort standards – was adopted in all cases presented herein. Besides the limited availability of the specified building testbed, real-life experiments demonstrated operational effectiveness of the proposed approach in BOC applications with complex, emerging dynamics arising from the building’s occupancy and thermal characteristics. L4GPCAO outperformed the control strategy that was designed by the planers and system provider, in a conventional manner, requiring no more than five test days. [ABSTRACT FROM AUTHOR]

The paper presents results of experimental research into the transmission of infrared radiation through water film. Experiments substantiate a hypothesis about the considerable role of radiative heat transfer when heating heterogeneous water drops containing opaque solid particles in high-temperature gases. We measure the temperatures of water film surface, the bottom of a cylindrical plastic cuvette and a graphite substrate. During the experiments, the typical thickness of the water film, the bottom of the plastic cuvette and the graphite substrate is 1 mm. The temperature measurements are implemented for carbonated, distilled and tap water. Results of a comparative analysis of these measurements are presented as well. The hypothesis is formulated about a significant variation in the optical properties of water under temperature fluctuations. This assumption is based on the hydrophobic properties of amphiphilic molecules. Importantly, the experimental data enable the study of rapid evaporation of a liquid at internal and external interfaces of water drops containing solid opaque particles with a further explosive fragmentation of water film. This mechanism relies on heating of the particle surface above the boiling point of water. [ABSTRACT FROM AUTHOR]

With the gradual increase of building energy consumption in recent years, the application of phase change energy storage materials in buildings has become the focus of researches. Phase change material (PCM) embedded in the envelope can increase the building inertia to keep the temperature stable. It can also store energy and release energy when needed. In this paper, the system of PCM radiant floor combined with PCM wall attached with sunspace was established. The thermal characteristics and the energy consumption of the building are studied through analyzing the data from the experimental investigation including the temperature and the heat flux. Two different buildings were built between the PCM room and the conventional room with the same dimension and building. The main test conditions are divided into passive and active control stages by comparing the air temperatures, envelope temperatures, phase transition temperatures, heat fluxes and power consumptions between the two rooms. It is concluded that the average room temperature of the experimental room is 7.15 °C higher than that of the conventional room in the passive energy storage stage. While the average energy-saving rate of PCM room was 54.27% compared with the conventional room in the active control stage. [ABSTRACT FROM AUTHOR]

Potassium dihydrogen phosphate (KDP) crystal is a kind of very crucial nonlinear optics for high-powered laser equipment as frequency conversion (doubler, tripler or quadrupler) components. In this paper, investigation on cracking behavior of sol-gel silica antireflective (AR) coatings has been performed using KDP crystal as substrate. Cracking induced by heating or moisturizing post-treatment is respectively studied, in which distinct cracking behaviors have been observed. It has been interestingly found that either temperature or humidity saltation can result in coating crack generation, but the corresponding residual stress demonstrates in completely reverse ways, giving rise to distinctive crack morphology on both crack edge and bottom. The origination and the derivation of such stress manner have been stated based on the intrinsic porous structure of sol-gel silica coating, and the critical cracking condition has been suggested dependent on the relationship between the accumulated residual stress against elastic recovery capability of such coating. [ABSTRACT FROM AUTHOR]

The guard limiter (GL) with graphite tiles of 4.6 GHz Lower Hybrid Antennas (LHA) has experienced the discharges in EAST tokamak. Much more hot spots were observed on the surface of GL tiles during the 2015–2016 campaigns. The serious ablations of GL induced by the hot spots limit the superconductor current, the plasma density and the heating power at higher parameter operations. In this paper, the GL issues are introduced with the original design. The previous improvements on the GL tiles are discussed with the ablation problems. In particular, the hotspots and the heat affected zones are discussed to predict the GL profile in accordance with the physical estimation. A trimmed region with a bevel angel of 11° is applied to avoid the heat load deposition at millimeter magnitude, which is caused by the fast electrons hitting due to the LHA heat driving. As a result, the GL ablations are confirmed to be reduced to the minimum. Moreover, it indicates that the plasma hitting would contribute most on the tiles fracture in the mid plane of the GL. In addition, new design activities on the tungsten GL are summarized in the engineering design. The new GL would be expected in the year 2017. [ABSTRACT FROM AUTHOR]

The solid-liquid phase change process in a cavity with protruding heater is of significant importance to application of phase change material (PCM). In this paper, the phase change lattice Boltzmann (LB) model has been applied and the effects of heater and inclination angle of cavity on phase change process are investigated. The results show that moving the protruding heater is able to change the temperature distribution and location of solid-liquid interface. The phase change process can be accelerated by moving the heater to middle region of cavity. Decreasing the distance between heater and cavity upper wall enhances the flow obstruction, and reduces the heat transferred through upper and right walls of heater. Furthermore, rotating the cavity changes the distance of flow from heater to cavity. Increasing inclination angle from 30° to 45° enhances the heat transfer rate of heater's upper wall and weakens that of heater's right wall. [ABSTRACT FROM AUTHOR]

District heating system brings with it the problem of achieving a fair billing service for heating of apartment buildings in the case of uneven temperature in them. The problem is most pronounced when the individual apartments are completely excluded from the heating system of the building. The model of an existing building with 24 apartments was simulated in the software EnergyPlus, for different characteristics of the thermal envelope and different conditions of use, when the apartment with the lowest energy consumption is excluded from the heating system. It was simulated the exclusion of this apartment in which people are present and the lights and electrical appliances are turned on and in which there is no presence of people and electricity consumption (the apartment is empty). As a measure of energy flow between unheated and adjacent apartments, the parameter “stolen” energy is defined. The results of the conducted simulations show that the stolen energy is reduced by the exterior and interior insulation of the building. In this paper, data on energy flow when there is interior insulation in apartments, in particular according to the current regulations in Serbia, are especially analyzed. The results show that, depending on the case and scenario, the stolen energy ranges from 27.23 to 7.97 kWh/m 2 . The insulation of interior walls of the building can significantly mitigate the problem of energy flow due to temperature differences between apartments. [ABSTRACT FROM AUTHOR]