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The main concern in this paper is to analyze the heat, mass and motile microorganisms transfer rate in the magnetohydrodynamic (MHD) convective flow of tangent hyperbolic material. Analysis is studied in presence of both nanoparticles past an exponential surface. Nanofluid containing gyrotactic microorganisms in addition to nanoparticles is considered. Analysis is carried out in presence of an inclined magnetic field. In fact the idea here is to use the microorganisms just to stabilize the suspended nanoparticles due to bioconvection generated by the combined effects of buoyancy forces and magnetic field. Brownian motion, thermophoretic and Newtonian heating are also studied. The resulting systems of nonlinear systems have been solved by homotopic procedure. The velocity, temperature, nanoparticle concentration and density of motile microorganisms are examined graphically. The skin friction coefficient, local Nusselt, Sherwood and motile microorganism numbers are numerically discussed for the active involved parameters. It is observed that velocity profile is decreased by both magnetic parameter and angle of inclination. It is also noted that the temperature profile increases for larger Nb but it decreases for nanoparticle concentration. [ABSTRACT FROM AUTHOR]

This paper investigates the heat transfer and fluid flow in a lid-driven cavity filled with CuO-water nanofluid and heated by a corner heater. The left vertical wall is cooled isothermally and moves upward. The corner heater is configured to be acting in the horizontal and vertical right walls. The remainder walls are adiabatic. Temperature dependent models for thermal conductivity and dynamic viscosity have been invoked. The governing equations have been solved using finite difference method. The governing parameters are nanofluid volume fraction φ = 0.0 – 0.07, Richardson number Ri = 0.01 – 100, Reynolds number ( Re = 100 – 300) and five configurations of corner heater governed by the distance of its lower edge Δ = 0 – 1. The results show that for low and intermediate values of Richardson number (i.e., Ri = 0.01 and Ri = 1) the effects of the nanoparticles on heat transfer enhancement is not greatly pronounced. However, for high values of Richardson number (i.e., Ri = 10 and Ri = 100) the Nusselt number enhances due to the addition of nanoparticles. A single case of heat transfer deterioration, due to the presence of nanoparticles, is observed for the case of Ri = 0.01 and Δ = 0. For all studied Richardson numbers, the case of Δ = 0 gives the best scenario for heat transfer when compared to other heater's location. [ABSTRACT FROM AUTHOR]

Thermal energy storage (TES) systems with phase change materials (PCMs) as a known energy storage technology have a high potential for increasing the energy efficiency of buildings. In fact, the use of PCMs with various approaches, either active or passive, in the building helps to maintain the temperature in the thermal comfort range for occupants through decreasing the temperature swings, and lower energy consumption by the load reduction/shifting. Due to the significance of this issue, many research works have been carried out on the application of PCMs in buildings. In this study, the experimental works in the fields of PCMs in buildings are taken into account. The papers are classified based on heating, cooling, and air-conditioning. Besides these, the applications of nano-PCMs in buildings are reviewed. According to what has been carried out up to now, the gaps are identified and analyzed for preparing useful suggestions for future works. The recommendations and suggestions are presented at the end of the chapters as well as the conclusion, and the literature is summarized in some tables. [ABSTRACT FROM AUTHOR]

The conventional reliability evaluation of district heating networks is generally based on restrictive assumptions aiming to simplify the reliability assessment process, e.g., the hypothesis of the unrepairable system and constant outside temperature. Due to such simplifications, the reliability indices retain constant and unchangeable during the heating season, which is infeasible to reveal the changeability of reliability of heating networks. Concerning such deficiencies, this paper presents a novel study to modify these assumptions, and further analyze the influence of changeable outside temperature on the reliability of heating networks based on the state-space method. In this study, in terms of the dynamic state-determination criterion, structural and functional reliability indices are proposed to evaluate dynamic reliability of heating networks. In reality, the realistic state-determination is the critical foundation of reliability evaluation, which directly determines the accuracy of the reliability assessment. Hence, the dynamic state-determination criterion is introduced in this study, concerning both the external and internal conditions of consumers. Combined with the state probabilities, functional reliability indices consider two functional parameters, i.e., the heat power and the indoor temperature, to reflect the changeability of heat-supply ability and the resultant effects of failures on internal status of consumers under changeable external conditions. As a pilot study, the proposed reliability evaluation indices are applied to a real looped heating network in Harbin, China. The results indicate that the outside temperature significantly affects the reliability of heating networks. It is observed that the reliability and availability demonstrate a ladder growth with the increasing of outside temperature. According to the changeability of reliability, the weaknesses and the key components of the system can be figured out. Therefore, advanced preventive measures can be taken to reduce failures of components and improve the reliability of heating networks. [ABSTRACT FROM AUTHOR]

The temporal fluctuation of solar energy resources often require the utilization of thermal energy storage to increase the level of solar energy. Solar energy systems that are used to meet the heating demands of buildings can be implemented in a variety of system configurations, ranging from energy production and storage at the building-level, to centrally located production and storage components coupled with a district-heating network. In this paper, quasi-steady state simulation models are used to evaluate the impact that different design configurations of decentralized and centralized solar thermal systems (with short- and long-term storage) have on the overall economic cost of the energy provision and the degree of solar energy utilization. A suburban neighbourhood in Switzerland consisting of 11 buildings is selected as a case study. Simulation results suggest that building-level long-term storage configurations out perform all other system configurations in terms of solar fraction and system efficiencies for the given case study. Furthermore, the results demonstrate that the location of the thermal storage and the separation of short- and long-term storage are crucial issues that affect the performance of building-level renewable energy sources, and thus merit further investigation. [ABSTRACT FROM AUTHOR]

During the master planning of neighbourhoods, design decisions related to the urban layout and typology affect the building form and availability of solar radiation considerably. The influence of those decisions on the energy demand for heating is often neglected however because appropriate energy simulation tools are lacking. This paper proposes a simple and accurate design tool to assess the solar gains and heating energy demand in buildings during the master planning phase of neighbourhoods. Detailed information on building geometry, constituting building elements and solar obstructions, is extracted from a 3D neighbourhood model using a plugin implemented in the modelling software SketchUp. This information is used to assess the heating energy demand of the buildings in the neighbourhood based on the dynamic Equivalent Heating Degree Day (dEHDD) method. Furthermore, the associated financial and environmental impacts are calculated based on an integrated life cycle approach, combining Life Cycle Costing (LCC) and Environmental Life Cycle Assessment (E-LCA) respectively. The design tool proposed is implemented for the Belgian context and used to analyse a number of schematic residential neighbourhood models with diverse built densities. The analysis reveals substantial differences in heating energy demand, life cycle financial and environmental costs. Neighbourhoods with a high built density and compact building types have a lower heating energy demand with potential reductions of up to 40% compared to neighbourhoods with a low built density and detached building types. [ABSTRACT FROM AUTHOR]

An accurate model and numerical method to simulate heat transfer for radiative heating of granular media is developed based on a modified Monte Carlo – ray tracing method and the Mie scattering theory. The effect of scattering on the radiative transfer and heat diffusion in semi-transparent polymer powder beds during laser sintering process is investigated via a 3D numerical model based on Discrete Elements Method (DEM) specifically developed for this purpose. In particular we show that DEM in combination with the specially developed Monte Carlo method is far more suitable to simulate radiative heat transfer and heat diffusion in a granular bed, polymeric or metallic, than the Finite Element Method (FEM). The method presented in this paper is particularly suitable for the simulation of additive manufacturing processes where similar radiative phenomena are of central importance. [ABSTRACT FROM AUTHOR]

Heat loss from rotary kilns accounts for certain amounts of the total energy consumption in chemical and metallurgical industries. To reduce the heat loss, a parallel and a series-parallel heat recovery systems with nine heat recovery exchangers are proposed to preheat the cold water in this paper. Experimental measurements are carried out to determine the heat transfer coefficient equations of each heat recovery exchanger. Then, the heat recovery systems are analyzed to deduce the mathematic relation between the design parameters and the system requirements, i.e. the temperatures and heat transfer rates of the nine heat recovery exchangers. The total heat transfer area, the total power consumption and the entropy generation due to heat transfer and fluid flow are set as the objective functions in four multi-objective optimization (MOO) cases. With the aid of the genetic algorithm in the Matlab 2015, the optimized operational and structural parameters are obtained. Finally, the MOO results are compared with that of the single objective optimization (SOO) method and the original values. The optimization results show that the MOO method are more suitable for the operational parameters design of the heat recovery systems compared with the SOO method. The required total heat transfer area and the total power consumption are decreased by at least 12.1% and 13.7%, respectively. Besides, as the entropy generation due to heat transfer and fluid flow decrease in the MOO cases, the corresponding heat transfer area and power consumption of the heat recovery system decrease, respectively. [ABSTRACT FROM AUTHOR]

• This paper proposes a heating load decomposition method. • An IASHP prototype is produced based on the heating load decomposition method. • The advantages of the heating load decomposition method are demonstrated. • Maximize the heating performance of IASHP unit applied in severe cold region. • Heating performance of IASHP unit assisted with electric heating system is discussed. Although the inverter air-source heat pump (IASHP) and composite systems have a characteristic of energy conversion, the design of IASHP and the application of IASHP assisted with additional heat sources are absent based on the relationship between the demand side and supply side. Therefore, this paper proposes a heating load decomposition method to design IASHP with an auxiliary heat source system to offer users heating in severe cold regions. Specifically, the heating load decomposition method divides the heating load of the civil building into three regions by seeking heating energy balance points. It can get an optimal heating energy balance point with the best HSPF and an optimal design heating energy balance point with the best evaluating parameter. On these grounds, we produce an IASHP prototype. The experimental results confirm the superiority of the heating load decomposition method. Compared to the traditional design method, it improves by 6.5%-12.6% of heating capacity and 2.3%-17.4% of COP of IASHP porotype. Besides, the heating performance of IASHP assisted with an electric heating system selected by an optimal heating energy balance point is better than that of an independent IASHP heating system. In contrast, electric heating only pays 6.7% of the heating capacity of the IASHP unit operated at −27.0 °C of ambient temperature. [ABSTRACT FROM AUTHOR]

This paper investigates factors associated with variation in daily total (electricity and gas) energy consumption in domestic buildings using linked pre-COVID-19 smart meter, weather, building thermal characteristics, and socio-technical survey data covering appliance ownership, demographics, behaviours, and attitudes for two nested sub-samples of 1418 and 682 British households selected from the Smart Energy Research Laboratory (SERL) Observatory panel. Linear mixed effects modelling resulted in adjusted R2 between 63% and 80% depending on sample size and combinations of contextual data used. Increased daily energy consumption was significantly associated (p -value < 0.05, VIF < 5) with: households living in buildings with more rooms and bedrooms, that are older, more detached, have air-conditioning, and experience colder (more heating degree days) or less sunny weather; households with more adult occupants, more children, older adult occupants, higher heating temperature setpoints, and that do not try to save energy. The results demonstrate the value of smart meter data linked with contextual data for improving understanding of energy demand in British housing. Accredited UK researchers are invited to apply to access the data, which has recently been updated to include over 13,000 households from across Great Britain. This paper provides guidance on appropriate methods to use when analysing the data. [ABSTRACT FROM AUTHOR]

The repercussions from excessive penetration of uncoordinated Home Energy Management Systems (HEMSs) have proven to be pernicious in the distribution system regarding contingencies, instabilities, and rebound peaks. This paper aims to design a distributed coordination technique with the required topology to coordinate transactive HEMSs with demand response enabled electric baseboard heater thermostats to avoid the detrimental effects of uncoordinated HEMSs in a residential group. Specifically, the proposed technique establishes a consensus to fulfill individual as well as shared objectives by modifying consumers' consumption patterns. The shared objective is to flatten the aggregated profile and decrease the total cost in the grid. In addition, an incentive policy has been designed to pay a total reward to the team for encouraging consumers to participate in the coordination. The presented coordination technique comprises a Shapley game-based reward-sharing mechanism and an incentive-compatible mechanism, where the team's gain is distributed among the players based on their contribution. Besides, the coordination leads to agents' complementary decision-making and mitigates the grid challenges. The functionality and effectiveness of the proposed coordinated HEMSs algorithm are tested for a set of different case studies based on user preferences and coordination levels. The simulation results indicate that the proposed coordination improves aggregated profile's load factor up to 0.85 and reduces the electricity bill by 21.4%. [Display omitted] • A HEMSs coordination is proposed to handle grid challenges and individual objectives. • An incentive is designed to encourage consumers to participate in coordination. • Reward-sharing and incentive-compatible mechanisms are proposed to distribute gain. • The coordination improves aggregated profile's load factor from 0.45 up to 0.85. • The aggregated electricity bill of the residential group decreased by up to 21.4%. [ABSTRACT FROM AUTHOR]

• A new renewable energy based heating system for buildings is presented. • A mathematical model of the systems is developed using a TRNSYS software. • System components models are validated with experimental data. • The system covers 100% of building heating demand. • The yearly average COP higher than 4.8 is achieved. The Renewable Energy System for Residential Building Heating and Electricity Production (RESHeat) system has been realized for heating and cooling residential buildings. The main components of the RESHeat system are a heat pump, photovoltaic modules, sun-tracking solar collectors and photovoltaic/thermal modules, an underground thermal energy storage unit, and a ground heat exchanger. One of the main novelties of the RESHeat system is efficient ground regeneration due to the underground energy storage unit. During a heating season, a large amount of heat is taken from the ground. The underground energy storage unit allows the restoration of ground heating capability and the heat pump's coefficient of performance (COP) to be kept high as possible for consecutive years. The paper presents an energy analysis for a residential building that is a RESHeat system demo site, along with integrating the RESHeat system with the building. The experimentally validated components coupled with the building model to achieve the system performance in TRNSYS software. The results show that the yearly average COP of the heat pump is 4.85 due to the underground energy storage unit. The RESHeat system is able to fully cover the heating demand of the building using renewable energy sources and an efficient underground energy storage system. [ABSTRACT FROM AUTHOR]

• An improved thermodynamic analysis method is presented and validated. • Unsteady local conductive and radiative entropy generation rates are analyzed. • Exergy storage rate and exergetic efficiency is obtained. • An uniform and centralized heating strategy is proposed. This paper presents an improved thermodynamic analysis method used to evaluate the irreversibility and efficiency of a coupled conductive-radiative heat transfer process. The exergy analysis of the conductive-radiative process is developed based on the exergy balance equation. In the method, the local entropy generation rates due to the radiative heat transfer and heat conduction processes are calculated. Based on the entropy generation analysis, an exergy analysis is performed, the stored exergy of the system and the exergetic efficiency are determined, and the thermodynamic efficiency of the system is further evaluated. The results are verified by the principle of exergy balance and the exergy generation rate calculated by the method does not deviate from the theoretical value by more than 0.1%. Four heat source distributions are specified in the numerical analysis, which include completely uniform, partially uniform, and non-uniform heat source distributions in the numerical analysis. The effects of heat source distribution, conductive-radiative coefficient and total heat generation rate of medium on entropy generation and stored exergy of system are investigated. The numerical results show that the average temperatures and exergy storage rate of the systems with partially uniform heat source distribution are 5.1–79.7 K and 6.8–49.8% higher than the other distributions, and uniform and centralized heat generation in the internal region of the system is proposed. The total stored exergy of the systems has a tendency to first increase and then decrease, reaching its maximum at N = 1 as the conduction and radiation coefficients increase, and increasing as the total heat generation rate increases. [ABSTRACT FROM AUTHOR]

• Insulation deterioration of coils under varying weather conditions is investigated and actions were taken to revive machine operation. • Sequence and consequences of fall in the insulation resistance of coils due to moisture condensation is studied. • Different techniques are employed to recover and maintain the insulation resistance of the different coils under high humidity range. Insulation resistance (IR) of electromagnetic (EM) coils show a tremendous variation with the changing weather condition. This effect has a major impact on the operation of the ADITYA-U tokamak operation schedule. The failure of EM coil insulation can lead to terrible failure of the coil system and subsequently, the component and respective power system. Series of circumstances are driven to check their impact on the relative humidity (RH) and simultaneously their effect on the IR of the EM coils has been observed. Different techniques are employed to control the humidity and temperature of the experiment hall to maintain the IR of the different EM coils within the experimental limits. In this paper, different factors have been reviewed which affect and change the IR values of the EM coils. Experience gained during years of operation during insulation strength degradation and its recovery is presented in this work. [ABSTRACT FROM AUTHOR]

This paper addresses the modelling and optimal control of district heating systems connected to the electrical grid, with the goal of maximizing their operational efficiency and enabling the participation to electricity markets. Being these systems governed by nonlinear large-scale dynamical models, a novel procedure is proposed, which enables to obtain suitable models for optimization, and consisting in a combination of physical and identified piece-wise linear models. A two-phase optimization and control scheme is then designed, including an offline scheduling problem for participating to the day-ahead energy market, and an online Model Predictive Control system, minimizing the energy consumption of thermal generators while properly satisfying the users thermal demand. The proposed methodology is developed considering a real district heating plant, owned by the energy company A2A S.p.A. and supplying the city of Novate Milanese (Italy), and different experiments on the plant have been carried out. The experimental results and achieved performances are promising, showing a significant reduction of the operational costs and overall gas consumption. • A new modelling of district heating systems suitable for optimization is proposed. • The participation to energy markets by district heating systems is addressed. • A MPC strategy is designed, maximizing system efficiency during online operation. • The designed solution is tested on a real plant for few days with promising results. [ABSTRACT FROM AUTHOR]

• World's first grid-scale PHES demonstrator system has been described. • Performance of a novel heat pump/engine has been tested and losses are quantified. • Round-trip efficiency of the system has been identified numerically. • Round-trip efficiency is within a range of 70–80 % for single storage cycle. • Periodic operation can yield a steady global round-trip efficiency of about 73 %. Among the known energy storage technologies aiming to increase the efficiency and stability of power grids, Pumped Heat Energy Storage (PHES) is considered by many as a promising candidate because of its flexibility, potential for scale-up and low cost per energy storage unit. Whilst there are numerous demonstration systems under development, as it stands the only PHES demonstration system to be realised at scale is located in Hampshire, UK. This paper aims to present the results and analysis obtained from its commissioning and testing as part of an on-going study. The system was designed to offer a nominal power size of 150 kW e and energy storage capacity of 600 kWh e for an 8-hour storage cycle. This work presents evidence of the system Round-trip efficiency (RTE), which is considered as a fundamental performance metric for large-scale energy storage technologies. Recorded Pressure-Volume (P-V) measurements from recent heat pump/engine testing at part-load offers useful insight in terms of overall performance. Models are also developed to simulate the system to finally predict the performance at full-load conditions. The system and principle of operation are described first, followed by mathematical modelling outlining heat transfer mechanism and associated key losses involved in thermodynamic processes within components, and finally results are presented and compared at different operating conditions using different working gases. The results show good agreement with earlier studies, which indicate that expected electricity-to-electricity RTE is quite comparable to other mature technologies such as Pumped Hydropower Storage and Compressed Air Energy Storage. The cyclic operation of the system is also discussed. One-off storage cycle results in lower RTEs compared to a load-levelling cyclic operation where the efficiency is significantly improved due to stable packed-bed behaviour and better utilisation after an initial transient state. [ABSTRACT FROM AUTHOR]

Although electric power networks and district heating networks are physically coupled, they are not operated in a coordinated manner. With increasing penetration of renewable energy sources, a coordinated market-based operation of the two networks can yield significant advantages, as reduced need for grid reinforcements, by optimizing the power flows in the coupled systems. Transactive control has been developed as a promising approach based on market and control mechanisms to coordinate supply and demand in energy systems, which when applied to power systems is being referred to as transactive energy. However, this approach has not been fully investigated in the context of market-based operation of coupled electric power and district heating networks. Therefore, this paper proposes a transactive control approach to coordinate flexible producers and consumers while taking into account the operational aspects of both networks, for the benefit of all participants and considering their privacy. A nonlinear model predictive control approach is applied in this work to maximize the social welfare of both networks, taking into account system operational limits, while reducing losses and considering system dynamics and forecasted power supply and demand of inflexible producers and consumers. A subtle approximation of the operational optimization problem is used to enable the practical application of the proposed approach in real time. The presented technique is implemented, tested, and demonstrated in a realistic test system, illustrating its benefits. • Transactive control design for coupled electric power and district heating networks. • Development and application of an accurate and computationally efficient system model. • Technical and economic optimal system operation considering participant privacy. [ABSTRACT FROM AUTHOR]

• Indoor thermal environment and AC usage behavior was investigated for low-quality centrally heated dwellings. • 90% of AC trigger temperature is 15 ℃ for the living room and 14 ℃ for the bedroom. • The heating demand drivers of cool housing are identified by heteroskedasticity-robust Ordinary Least Square. • The study presents new knowledge for appropriate way to meet actual heating demand while reducing energy use. • Relationships between indoor temperature, heath and energy use are discussed. In northern China, district heating systems without terminal control typically serve thousands of end-users, thus inevitably some users suffer from insufficient warmth and others are overheated indoors due to hydraulic imbalances. This paper aimed to understand the indoor thermal conditions and the actual heating demand in low-quality centrally heated dwellings. The driving force of heating demand was analyzed based on a smartphone survey of 233 households in cold climates, and field measurements of winter indoor thermal environment and AC supplemental heating behavior were conducted in a sample of 13 cool dwellings. Logistic regression and heteroskedasticity-robust Ordinary Least Squares were adopted to assess AC usage patterns and driving forces of heating demand, respectively. New knowledge has been gathered regarding average temperatures of 17.4 ℃ and 16.8 °C in cool housing living rooms and bedrooms, respectively, outside the human thermal comfort zone. Simultaneously, intermittent and partial AC usage patterns induced by time and air temperature were observed in these cool end-users for the comfort. The average daily running time of AC devices was 2.0 h for the living room and 1.8 h for the bedroom. There were statistically significant base linking occupants' heating demands to education level, household income, tenure type, presence of children, thermal experience and heating system. However, it was not a significant factor for household size. In addition, a rebound effect of building energy efficiency improvements on the interior temperature was also noticed. The results of this study shed light on better and target-oriented residential internal temperature or heating system design for both thermal comfort requirements and energy-savings. [ABSTRACT FROM AUTHOR]

An effective quantification of the energy absorbed and supplied by latent heat thermal energy storage (LHTES) units is critical to maximise their use within thermal systems. An effective control of the charging and discharging processes of these units demands an accurate estimation of the state-of-charge (SoC). However, a direct and reliable SoC estimation requires incorporating internal sensors to monitor the temperature gradient of the phase change material (i.e. the storage medium), resulting in higher instrumentation costs and technical specifications. These issues may be relieved by adopting state observers for SoC estimation to drastically reduce the number of measurements. This paper bridges this gap by presenting a novel and direct method for estimating the SoC of LHTES units, both for heating and cooling applications, based on a non-linear state observer. The observer is based on a simple one-dimensional dynamic model of the thermal store and the thermophysical properties of the storage medium and the heat transfer fluid, which are usually provided by manufacturers. This enables the estimation of the internal temperatures of the LHTES unit and, in turn, SoC calculation. The observer implementation is simple as it requires three measurements only as input variables (i.e. the mass flow rate and the input and output temperatures of the heat transfer fluid). The SoC estimation approach is assessed through dynamic simulations of two LHTES units: one for a heating application and one for a cooling application. The results show that the SoC can be estimated with root mean square and mean absolute errors of less than 4.6% and 3.62%, respectively, compared with experimental measurements. • The specific latent heat value of phase change materials is dynamically modelled using probability density functions. • A non-linear observer estimates the temperature of a phase change material in thermal energy storage units. • The state-of-charge of latent heat thermal energy storage units is calculated using the observer outputs. • A calculation method of the state-of-charge is proposed to reduce the computation time. • Implementation and verification of non-linear observers and state-of-charge calculation method is performed using MATLAB. [ABSTRACT FROM AUTHOR]

• Novel methodology for calculating cost-optimized refurbishment roadmaps is presented. • Coupling of building model for refurbishment and system model for heating technologies. • Refurbishment roadmap include timing and refurbishment measures for specific buildings. • Applying the optimization achieves cost savings of 6–16 % and CO 2 savings of 6–59 % • Heat pumps play a central role in the context of CO 2 reduction. A novel methodology for calculating optimized refurbishment roadmaps is developed in this paper. The aim of the roadmaps is to determine when and how should which component of the building envelope and heat generation system be refurbished to achieve the lowest net present value. The integrated optimization approach couples a particle swarm optimization algorithm with a dynamic building simulation of the building envelope and the heat supply system. Due to a free selection of implementation times and refurbishment depth, the optimization method achieves the lowest net present value and high CO 2 reduction and is therefore an important contribution to achieve climate neutrality in the building stock. The method is exemplarily applied to a multi-family house built in 1970. In comparison to a standard refurbishment roadmap, cost savings of 6–16 % and CO 2 savings of 6–59 % are possible. The sensitivity of the refurbishment roadmap measures is analyzed on the basis of a parametric analysis. Robust optimization results are obtained with a mean refurbishment level of approx. 50 kWh/m2/a of the building envelope. The preferred heat generation system is a bivalent brine-heat pump system with a share of 70 % of the heat load being covered by the electric heat pump. [ABSTRACT FROM AUTHOR]

• A second 1.2 MW/53 keV high-energy neutral beam (NBI-2) procured, manufactured and installed on TCV. • NBI-2 is designed to probe plasma physics issues of higher plasma density, fast ion plasma interactions with static and dynamic fields and plasma rotation. • The higher NBI-2 energy together with NBI-1 (1.3 MW/28 keV) greatly enhances the operational space for fast ion studies and plasma heating with up to 2.5 MW NBH power. The TCV tokamak continues to leverage its unique shaping capabilities, flexible heating systems and modern control system to provide a stepladder approach for extrapolations of experimental results from different machines to ITER and DEMO. TCV's configurational flexibility has recently been enhanced by the installation of two heating neutral beams, new dual frequency gyrotrons, removable divertor gas baffles together with upgrades of its diagnostic infrastructure. Plasma regimes with high plasma pressure, a wider range of temperature ratios and significant fast-ion population are now attainable on TCV. A 1.3 MW/28 keV heating beam (NBI-1) has been operated on TCV from 2015 introducing the direct ion auxiliary heating. A second 1MW/50–60 keV high-energy neutral beam (NBI-2) has since been procured, manufactured and installed on TCV in July 2021. NBI-2 injected near anti-co-linearly to NBI-1 is designed to probe plasma physics issues of higher plasma density, fast ion plasma interactions with static and dynamic fields and plasma rotation. The higher NBI-2 energy greatly enhances the operational space for fast ion studies. NBI-2 commissioning is presently ongoing in parallel with TCV experiments using both NBIs. This paper summarises the experience with intensive use and improvements of the NBI-1, together with the status of NBI-2 commissioning. [ABSTRACT FROM AUTHOR]

Abstract: Microturbines offer new perspectives in small-scale heat and power production however their profitability depends strongly on the yearly amount of running hours. The non-continuous heat demand often leads to a reduction in running hours. This paper proposes an alternative by recuperating the lost thermal power through the injection of heated water in the micro Gas Turbine (mGT). Water injection is considered a successful way to increase power and efficiency in industrial gas turbines and similar effects are expected for microturbines. This paper reports on a series of simulations of water injection performed on a Turbec T100 mGT. The goal of this study was to investigate the potential of water injection in the mGT cycle using an adiabatic black box method in the Aspen® process simulation tool. Past experiments with steam injection on the T100 demonstrated the potential of introducing steam/water in the microturbine cycle. Calculations revealed that the key parameters for maximum heat recuperation are stack and pinch temperature. Simulations showed that most of the exhaust heat can be recovered through injection of heated water after the compressor, resulting in an 18% decrease in fuel consumption and an absolute increase in electrical efficiency of 7%. [Copyright &y& Elsevier]

Abstract: The neutral beam (NB) system for ITER is composed of two heating neutral beam injectors (HNBs) and a diagnostic neutral beam injector (DNB). A third HNB can be installed as a future up-grade. This paper will present the design development of the components between the injectors and the tokamak; the so-called ‘front end components’: the drift duct consists of the NB bellows and the drift duct liner, the vacuum vessel pressure suppression system box (VVPSS box), the absolute valve, and the fast shutter. These components represent the key links between the ITER tokamak and the vessels of the NB injectors. The design of these components is demanding due to the different loads that these components will have to stand. The paper will describe the different design solutions which have to be implemented regarding the primary vacuum confinement, the power handling capability and the remote maintenance operations. The sizes of the components are determined by the large cross section of the neutral beam. The power handling capability is driven by the anticipated re-ionization of the neutral beam and the electromagnetic fields in this region. The drift duct bellows (with an inner diameter of 2.5m) shall guarantee a leak tight vacuum enclosure during the vertical and radial displacements of the ITER vacuum vessel. The conductance of the VVPSS box must be maximized in the available space. The absolute valve remains a challenging development. The total leak rate through the valve must be ≤1×10−8 Pam3/s when the valve is closed. Due to the radiation environment, the seals of the gate valve will be metallic. An R&D program has been launched to develop a suitable metallic seal solution with the required dimensions. The maximum allowed closing time for the fast shutter shall be less than 1s. For all these components the leak tightness will be guaranteed by a welded lip seal and the mechanical stability by bolted structures. [Copyright &y& Elsevier]

Abstract: Heating, Ventilation and Air-Conditioning (HVAC) systems account for more than 15% of the total energy consumption in the US. In order to improve the energy efficiency of HVAC systems, researchers have developed hundreds of algorithms to automatically analyze their performance. However, the complex information, such as configurations of HVAC systems, layouts and materials of building elements and dynamic data from the control systems, required by these algorithms inhibits the process of deploying them in real-world facilities. To address this challenge, we envision a framework that automatically integrates the required information items and provides them to the performance analysis algorithms for HVAC systems. This paper presents an approach to identify and document the information requirements from the publications that describe these algorithms. We extend the Information Delivery Manual (IDM) approach so that the identified information requirements can be mapped to multiple information sources that use various formats and schemas. This paper presents the extensions to the IDM approach and the results of using it to identify information requirements for performance analysis algorithms of HVAC systems. [Copyright &y& Elsevier]

This paper presents the evaluation of the performance of a ground source heat pump system monitored plant providing heating/cooling to an office building located in the Universitat Politècnica de València in Spain. The system was designed using GLHEPRO software and it has been monitored since 2005. Once a ground source heat pump has been designed, it is important to analyze its performance along the years after its construction and check whether the design was appropriate and the simulation predictions were consistent with real experimental measurements. This paper first presents the impact of the GSHP system in the ground thermal response. The simulations obtained in GLHEPRO software will be analyzed and compared to experimental measurements. The second purpose of this work is to compare the performance simulation results of a complete ground source heat pump system model built in TRNSYS, with the experimental measurements which have been registered and collected for one cooling day. Numerical predictions and experimental results are compared and discussed. [ABSTRACT FROM AUTHOR]

Abstract: Due to the unique properties of near-critical fluid, trans-critical/supercritical CO2 based natural circulation loop (NCL, or thermosyphon) has been proposed in many energy conversion systems, such as solar heater, waste heat recovery, next generation nuclear cooling, etc. This paper presents an experimental investigation of a near-critical CO2 thermosyphon. The closed thermosyphon is specially designed for high pressure experiments, where natural convection is achieved only by heating and cooling of fluid in the loop. The system is operated in wide range of pressures from around 6.0 to 15.0MPa in the near-critical region. It is found that the NCL flow will change from unstable sub-critical two-phase flow to stable liquid flow, and then become stable supercritical circulation with the increase of system initial pressure. The heat transfer behaviors are analyzed for stable flow conditions mainly for supercritical region. General variations of the fluid temperature, mass flow rate and loop pressure are presented in this paper. In the steady supercritical region, the heat transfer performance of the cooler show very small changes with bulk mean fluid temperature, and at the heater better heat transfer is found for conditions close to the pseudo-critical point. The heat transfer dependency on operation pressure and evolution mechanisms are also discussed in detail in this paper. [Copyright &y& Elsevier]

[Display omitted] This paper introduces a non-linear grey-box (GB) model based on stochastic differential equations that describes the heat dynamics of a school building in Denmark, equipped with a water-based heating system. The building is connected to a local district heating network through a heat exchanger. The heat is delivered to the rooms mainly through radiators and partially through a ventilation system. A monitoring system based on IoT sensors provides data on indoor climate in the rooms and on the heat load of the building. Using this data, we estimate unknown states and parameters of a model of the building's heating system using the maximum likelihood method. Important novelties of this paper include models of the water flow in the circuit and the state of the valves in the radiator thermostats. The non-linear model accurately predicts the indoor air temperature, return water temperature and heat load. The ideas behind the model lay a foundation for GB models of buildings that use different kinds of water-based heating systems such as air-to-water/water-to-water heat pumps. Such GB models enable model predictive control to control e.g. the indoor air climate or provide flexibility services. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dynamic evaluation of economic and energy benefits due to thermostatic valve installation. • Dynamic evaluation of economic and energy benefits due to heat metering installation. • The adoption of both thermostatic valves and heat metering least to a payback period lower than 2 years. • Analysis carried out considering several shapes of typical building. The aim of this paper is to propose a novel approach in order to accurately calculate the energy and economic savings due to the use of heat metering and thermostatic valves in residential buildings. The paper aims at proving that the present simplified approaches used in European Legislation may lead to significantly underestimate the profitability of this technology. The study is developed for four different typologies of buildings located in the city of Naples (South of Italy), including their geometrical and thermophysical properties. The buildings are first modelled in Google Sketchup and subsequently linked to the TRNSYS environment, which also includes a detailed model of the piping systems. The models allow one to evaluate, for every period of the year, energy demand, energy supplied by radiators, heat gains, transmission, etc. The developed models are used to calculate energy demands for three scenarios for each type of building: centralized heating systems not equipped with heat metering; thermostatic valves without heat metering; heat metering and thermostatic valves. The possible savings related to thermostatic valves and heat metering are estimated using the developed model. The results are compared with the ones provided by the Italian Standards. Results show that the thermostatic valves adoption leads to a significant reduction, up to 50%, of the thermal energy demand of the residential buildings and that all the proposed systems exhibit a remarkable economic profitability, with a payback period lower than 1.7 years. [ABSTRACT FROM AUTHOR]

Abstract: In this paper an inverse boundary design problem of combined natural convection–radiation is solved. The aim of this paper is to find the strength of heaters in a step-like enclosure to produce desired temperature and heat flux distribution on the design surface. The finite volume method for transition flow (which causes a faster convergence) is used as the direct solver of the energy and momentum equations. The SIMPLE algorithm is utilized to satisfy pressure–velocity coupling in order to solve the free convection heat transfer. Also, the backward Monte Carlo method is employed in order to be able to compute the distribution factors and carry out the radiant exchange calculations. Finally, the goal function which is defined on the basis of square root error is minimized by means of conjugate gradients method. The effects of variation of range of parameters such as the Rayleigh number, temperature ratio, radiation conduction parameter and the emissivity coefficient of insulated surfaces on the relative root mean square and heat flux are investigated and results are compared. The results demonstrate the efficiency and the accuracy of the proposed method. [Copyright &y& Elsevier]

Abstract: Experimental measurements in a spray cooling test rig were carried out for two different heater surface roughnesses and for two different types of nozzles with the dielectric refrigerant R134a. In this paper, results of the sprayed refrigerant film thickness measurements are presented. The influence of the volumetric flow rate, the surface roughness and the type of nozzle (through the spray parameters) on the total average film thickness is analyzed and discussed. In a companion paper, results of the heat transfer measurements are presented. It has been found that there is a relation between the variations of the average Nusselt number and of the film thickness along the spray cooling boiling curve. The heat transfer regimes along that curve are related not only to a variation in the average Nusselt number but also to changes in the film thickness. The qualitative analysis of those variations served to better understand the heat transfer mechanisms occurring during the spray cooling. [Copyright &y& Elsevier]

Abstract: Directive 2010/31/EU adopted that by the end of 2020 all new buildings should be nearly Zero-Energy Buildings (nZEB) and Member States should achieve cost-optimal levels by ensuring minimum energy performance requirements for buildings. This paper discusses how low should be the energy required by a nZEB, in the context of housing energy consumption in a Mediterranean climate (Lisbon). For selected houses built after 1990, the calculated primary energy loads for regulated uses – heating, cooling and domestic hot water – are found to be below 90kWh/(m2 year). Applying the cost-optimal solutions of thermal insulation and glazing type and considering energy efficiency improved systems, this study concludes that housing energy loads are ‘low’ for the indicative range of 70kWh/(m2 year) for regulated uses or 100–110kWh/(m2 year) for total uses, taking primary energy indicators (PEI) from EN 15603. Assuming PEI from Passive House Planning Package or those to be assumed in Portugal for 2013, the threshold decreases to 60kWh/(m2 year) for regulated uses or 90–100kWh/(m2 year) for total uses. Only the first nZEB condition is explored by this paper. The second condition requires that the nZEB energy load is covered by a ‘significant’ part of renewable energy sources produced on-site or ‘nearby’. [Copyright &y& Elsevier]

Abstract: The contact condition between the welding tool and the workpiece in friction stir welding (FSW) is believed to be critically important to understand the heat generation and material flow behaviour. Both of these are difficult to study experimentally. In previous simulation studies, the contact conditions that occur during FSW are generally described as stick and/or slip, according to different methodologies but these descriptions have their limitations. In the study described in this paper, the thermal and mechanical outcomes from models with prescribed stick and slip conditions were compared to identify the results and drawbacks of assuming different contact conditions. This paper presents a new combination method for characterising the contact conditions that occur during FSW. This new method yields more reasonable heat generation estimates, as validated by the experimental thermal measurements. [Copyright &y& Elsevier]

Abstract: The paper critically reviews and explores the impact of renewable energy heat policies to induce technological change in Ireland. It is in response to the challenge of better understanding the broad effects and attributes of renewable energy policy instruments in Ireland and beyond. Using the Irish residential sector as a case study, and analysing data of more than 31,600 technology installations under the Irish Government''s Greener Homes Scheme [GHS], the paper assesses the extent to which policy makers may be informed of the willingness of consumers to adopt these technologies in their homes. In doing so, it attempts to provide valuable guidance for policy evaluation in relation to renewable energy in the residential sector. It represents investment decisions and technological choice by the end user and reflects the growing concern among energy policy markets regarding the representation of user preferences. The overall intent is to investigate the implications of analysing different variables and their contribution to making more balanced renewable energy policies. It provides a critical analysis of the Greener Homes Scheme, the key instrument for implementing Ireland''s renewable heating policy from 2006 to 2010, established to induce technological change within the residential sector. In assessing the impact of the Scheme, attention focuses on decision frameworks for technological choice and the treatment of market and behavioural failures. It considers how consumers have responded to new technological policies aimed at deploying renewable heat technologies, and the specific policies aimed at advancing certain technologies over others. Through a case study investigation, the paper explores the relationship and dependencies that influence consumers'' decision-making regarding the choice of renewable energy heating technologies in the domestic sector in Ireland. Consumer preferences and their subsequent investment decisions, motives and technological choice are reflected. It concludes that while economic factors are important, a much broader variety of determinants is required when analysing the process of adoption of technology. [Copyright &y& Elsevier]

Abstract: With the development of urbanization in China, more and more high-rise residential buildings are constructed, mostly with 10–15 stories. Solar water heating system has been widely used in low-rise residential buildings in China, while its application in high-rise apartment is still in the initial stage. In this paper, the current application situation of solar water heating system in urban residential buildings of China is investigated. Additionally, demonstration projects of high-rise residential building are introduced, in which the application feasibility and limitation of solar water heating system are emphasized and some appropriate planning types of that are discussed. Finally, this paper analyzes the applicability of solar water heating systems integrated design in typical high-rise apartments from various aspects (such as architectural elevation, architectural plane and detailed construction) in the planning and designing phase. [Copyright &y& Elsevier]

Abstract: This paper presents a new calculation of neutral gas heating by precipitating auroral electrons. It is found that the heating rate of the neutral gas is significantly lower than previous determinations below 200km altitude. The neutral gas heating arises from the many exothermic chemical reactions that take place from the ions and excited species created by the energetic electrons. The calculations show that less than half the energy initially deposited ends up heating the neutral gases. The rest is radiated or lost in the dissociation of O2 because the O atoms do not recombine in the thermosphere. This paper also presents a new way of calculating the heating rate per ionization that can be used for efficient determination of the overall neutral gas heating for global thermosphere models. The heating rates are relatively insensitive to the neutral atmosphere when plotted against pressure rather than altitude coordinates. At high altitudes, the heating rates are sensitive to the thermal electron density and long-lived species. The calculations were performed with the Field Line Interhemispheric Plasma (FLIP) model using a 2-stream auroral electron precipitation model. The heating rate calculations in this paper differ from previous heating rate calculations in the treatment of backscattered electrons to produce better agreement with observed flux spectra. This paper shows that more realistic model auroral electron spectra can be obtained by reflecting the up going flux back to the ionosphere at the upper boundary of the model. In this case, the neutral gas heating rates are 20%–25% higher than when the backscattered flux escapes from the ionosphere. [Copyright &y& Elsevier]

Abstract: Nowadays, heating energy demand has become a significant estimator used during the design stage of any new building. In this paper we are proposing a model to predict the heating energy demand, based on the main factors that influence a building''s heat consumption. It was found out that these factors are: the building global heat loss coefficient (G), the south equivalent surface (SES) and the difference between the indoor set point temperature and the sol-air temperature. In the second part of this paper, multiple dynamic simulations were carried out in order to determine the values of the inputs and output data of the future prediction model. Using the obtained database, a multiple regression prediction model was further used to develop the prediction model. In the last part of this paper the model results was validated with the measured data from 17 blocks of flats. Moreover, in this article it is also shown the comparison with the results calculated using the building''s energy certification methodology. A detailed error analysis showed that the model presents a very good accuracy (correlation coefficient of 0.987). In conclusion, the proposed model presents the following characteristics: three inputs and one output, simplicity, large applicability, good match with the simulations and with the energy certification calculations, human behavior correction. [Copyright &y& Elsevier]

This paper includes the validation of ANN solutions by reliable experiments to research the heat transfer characteristics in an actual size room in a laboratory. Experimental tests have been done in an experimental chamber at a constant height and a floor area. Heating through three different wall configurations is implemented during experiments. Furthermore, various ANN techniques in Matlab are employed to study the thermal behaviors of the problem with regard to the alterations of heat transfer coefficients. Backpropagation learning methods of Levenberg-Marquardt, Bayesian regularization, resilient backpropagation and scaled conjugate gradient with multilayer perceptron network are used in order to show the artificial intelligence’s predictability area. Reference temperatures for corresponding heat transfer coefficients, heated wall temperatures and supply water temperatures are assigned as input variables, while convective, radiative and total heat transfer coefficients are defined as outputs. In conclusion, developed and detailed ANN model predicted heat transfer coefficients very successfully in tolerable deviation proportions from experimental findings. Also, the influence of supply water temperature on these coefficients was revealed. Moreover, the estimations of the ANN approach have been compared with the radiant heating and cooling data in the literature and a strong consistency has been noticed. [ABSTRACT FROM AUTHOR]

The mobilized thermal energy storage (M-TES) system is a promising alternative to conventional heating systems to meet the heat demand for distributed users. This paper provided a techno-economic assessment of the M-TES system based on a case study in China. According to the analysis of the design specifications of the heating system, the suitability of matching the M-TES with existing heating systems was analyzed. The results show that the M-TES is appropriate for use with heating systems with a fan-coil unit and under-floor pipe. Containers and operating strategies for the M-TES with different transportation schemes were also designed. The maximum allowed load of the M-TES container is 39 t according to the discussion of transportation regulations on the road. The cost and income of the M-TES in the study case were estimated, and the net present value (NPV) and payback period (PBP) were also calculated. The best operating strategy is the use of 2 containers and 4 cycles of container transportation per day, with a PBP of approximately 10 years. The M-TES is applicable for middle and small-scale heat users in China. [ABSTRACT FROM AUTHOR]

Forecasting and predicting coalfield fire and coal concealed fire are difficult components of coal fire control, and there is currently a lack of widely applicable effective methods for these processes. Electromagnetic radiation (EMR) has the advantage of multi-direction cross-locating and has been widely used to monitor and provide early warnings for coal and rock dynamic disasters. In this paper, the time-varying characteristics of EMR during 3 metamorphic grades of the coal-heating process were studied. EMR signals were clearly generated in different metamorphic grades of the coal-heating process. The variation trend of the EMR signals was different for 3 metamorphic grades of coal. According to R/S statistical analysis of the EMR signal time series, all Hurst values were greater than 0.5 and the correlation coefficient was above 0.9. There is a positive correlation between the EMR signals and coal temperature. In the coal-heating process, the EMR signal intensity varied if the EMR test frequency was 1 kHz, 15 kHz and 50 kHz. Thermal deformation and thermal cracking of the coal body occurred in the coal-heating process. The free electrons and electric dipole in coal migrate and generate EMR. Based on the changing characteristics of the EMR in the coal-heating process, we present the conceptual design of a method to detect concealed fire in underground mines. [ABSTRACT FROM AUTHOR]

Heating electrification powered by distributed renewable energy generation is considered among potential solutions towards mitigation of greenhouse gas emissions. Roadmaps propose a wide deployment of heat pumps and photovoltaics in the residential sector. Since current distribution grids are not designed to accommodate these loads, potential benefits of such policies might be compromised. However, in large-scale analyses, often grid constraints are neglected. On the other hand, grid impact of heat pumps and photovoltaics has been investigated without considering the influence of building characteristics. This paper aims to assess and quantify in a probabilistic way the impact of these technologies on the low-voltage distribution grid, as a function of building and district properties. The Monte Carlo approach is used to simulate an assortment of Belgian residential feeders, with varying size, cable type, heat pump and PV penetration rates, and buildings of different geometry and insulation quality. Modelica-based models simulate the dynamic behavior of both buildings and heating systems, as well as three-phase unbalanced loading of the network. Additionally, stochastic occupant behavior is taken into account. Analysis of neighborhood load profiles puts into perspective the importance of demand diversity in terms of building characteristics and load simultaneity, highlighting the crucial role of back-up electrical loads. It is shown that air-source heat pumps have a greater impact on the studied feeders than PV, in terms of loading and voltage magnitude. Furthermore, rural feeders are more prone to overloading and under-voltage problems than urban ones. For large rural feeders, cable overloading can be expected already from 30% heat pump penetration, depending on the cable, while voltage problems start usually at slightly higher percentages. Additionally, building characteristics show high correlations with the examined grid performance indicators, revealing promising potential for statistical modeling of the studied indicators. Further work will be directed to the assessment of meta-modeling techniques for this purpose. The presented models and methodology can easily incorporate other technologies or scenarios and could be used in support of policy making or network design. [ABSTRACT FROM AUTHOR]

Many energy policies set a goal of decreasing the carbon emissions of the energy sector by up to 100%, including the electricity grid. This is a long term and gradual process. Energy systems in cities will likely be the starting point for greenhouse gas emissions mitigation since they account for 80% of global carbon emissions. This paper analyses the impact on urban districts of decarbonizing the electric grid supply. A multi-objective optimization model has been developed that combines the optimal design and operation of distributed energy systems, the design of district heating (DH), electricity grid constraints based on linearized alternating current (AC) power flow and grid upgrade options. A number of scenarios were defined corresponding to different levels of renewable energy share in the electricity grid. For each scenario, we analyse the changes to the design and operation of the urban energy system, the impact on the district heating potential, and the impact on the operation of the distribution grid as well as the grid upgrade potential. The results showed that the renewable share of the grid has a large impact on the optimal solutions obtained. When the renewable share is below 55%, a lot of photovoltaic (PV) electricity has to be used to offset the carbon emissions from the grid. Conversely, when the renewable share is above 70%, the use of PV decreases and heating systems become electrified by producing heat with heat pumps (HP). District heating is used regardless of the renewable share in the grid, but as carbon emissions limits are tightened the potential of DH decreases. Only when the renewable share in the electricity grid is 100% it is possible to have a carbon-neutral district. In the carbon optimal solutions of each scenario there is no need for DH, but the grid has to be upgraded to enable electrification of the heating system. [ABSTRACT FROM AUTHOR]

This paper presents a new methodology for the estimation of power capacity profiles for smart buildings. The capacity profile can be used within a demand-side management system in order to guide the building temperature operation. It provides a trade-off between the quality of service perceived by the end user and the requirements from the grid in a demand-response context. We use a data-fitting approach and a multiclass classifier to compute the required profile to run a set of electric heating and cooling units via an admission control module. Simulation results validate the performance of the proposed methodology under various conditions, and we compare our approach with neural networks in a real-world-based scenario. [ABSTRACT FROM AUTHOR]

Surface reconstruction and phase transformation in nanomaterials can result in a significant rise in temperature due to the release of stored energy called “latent heat.” To simulate this behavior, we propose a hybrid continuum partial differential equation for non-Fourier heat transfer with a stochastic source term modeled using a kinetic Monte Carlo (KMC) algorithm for time-dependent rates to account for the latent heat release as the temperature is changing. The parameters required for the method are obtained through independent atomistic calculations. This includes energy barriers for KMC rates obtained using nudged elastic band calculations, and the non-Fourier thermal parameters obtained using a novel thermal parameter identification scheme described in this paper. As a demonstration of the approach, we study the superheating of silicon nanobeams observed in non-equilibrium molecular dynamics (NEMD) simulations. In these simulations, silicon (001) surfaces undergo a reconstruction from the ideal diamond crystalline surface to a reconstructed structure involving the formation of rows of dimers along a 〈 110 〉 direction. This reconstruction is accompanied by latent heat release that causes the nanobeam to dramatically superheat. The evolution of the nonuniform temperature profile along the nanobeam predicted by the continuum–KMC method is in excellent agreement with the NEMD results. A logarithmic dependence of the superheating temperature on nanobeam length is observed and theoretically discussed. [ABSTRACT FROM AUTHOR]

Laminar forced convection nanofluids based non-Newtonian flow in a horizontal parallel channel with multiple regions of heating and cooling are investigated, taking into account the inhomogeneous distribution of nanoparticles. The non-Newtonian behaviour of nanofluids is described by the power-law model. The velocity, temperature and concentration fields, heat transfer coefficient ratio, and pressure drop are obtained numerically by solving the coupled momentum, energy and concentration equations. Results based on assumption of homogeneous and inhomogeneous distribution of nanoparticles are compared with each other. It is found that the detailed information of velocity, temperature and pressure drop obtained by these two opposite assumptions are largely different. The non-uniform distribution of nanoparticles has a much weaker influence on temperatures compared to the uniform distribution; and the non-uniform distribution of nanoparticles in the base fluid results in a smaller pressure drop than the uniform cases do. The above findings highlight the necessity and significance of studying the effects of nanoparticles’ sedimentation and precipitation on heat and mass transfer for related industrial applications. And the thermal performance of power-law nanofluids investigated in this paper may shed some light on more efficient design of heat exchangers. [ABSTRACT FROM AUTHOR]

Process effluents recovery can be a tremendous source of revenue as well as a smart way to reduce their environmental footprint for industrial processes. Reusing effluents for heating purposes or reducing resource consumption can lead to substantial operating costs savings if the capital investments required to implement recovery networks are depreciated over an adequate period of time. This paper presents a mixed-integer linear programming model to design mass allocation and heat exchanger networks simultaneously. Mass streams are characterized by their composition and properties. A superstructure is presented to define the interactions between mass allocation and heat exchanger networks. Non-isothermal mixing can occur before and after the heat exchanger network. The objective function is the total annualized costs of both networks. It takes into account the annual operating costs for energy and mass requirements and the capital costs of the heat exchanger network. Two literature case studies are presented to demonstrate the model performances. [ABSTRACT FROM AUTHOR]

Optimal microgrid design is a challenging problem, especially for multi-energy microgrids with electricity, heating, and cooling loads as well as sources, and multiple energy carriers. To address this problem, this paper presents an optimization model formulated as a mixed-integer linear program, which determines the optimal technology portfolio, the optimal technology placement, and the associated optimal dispatch, in a microgrid with multiple energy types. The developed model uses a multi-node modeling approach (as opposed to an aggregate single-node approach) that includes electrical power flow and heat flow equations, and hence, offers the ability to perform optimal siting considering physical and operational constraints of electrical and heating/cooling networks. The new model is founded on the existing optimization model DER-CAM, a state-of-the-art decision support tool for microgrid planning and design. The results of a case study that compares single-node vs. multi-node optimal design for an example microgrid show the importance of multi-node modeling. It has been shown that single-node approaches are not only incapable of optimal DER placement, but may also result in sub-optimal DER portfolio, as well as underestimation of investment costs. [ABSTRACT FROM AUTHOR]

In a central heating, ventilation, and air conditioning (HVAC) system, the set-points for several local control loops have a significant influence on the overall energy performance of the system. Real-time optimization (RtOpt) of those set-points has therefore been widely studied. However, due to the nonlinear dynamics of the HVAC system as well as the constraints associated with the system operation, real-time optimization always suffers from a heavy on-line computational load when those set-points are optimized simultaneously. To overcome this problem, multiplexed real-time optimization (MRtOpt) has been developed, which optimizes only one set-point at a time but with a faster optimization frequency. Because frequently resetting the set-points introduces artificial disturbances into the local control loops and may deteriorate the system stability, this paper presents a study to enhance the system stability of the multiplexed real-time optimization by integrating a degree of freedom (DOF) based set-point reset to renew the set-points instead of the conventional step-change set-point reset. The control performance of the integrated strategy was investigated using case studies. The results showed that around 10% of the energy saving was achieved by the proposed method compared with a method without real-time optimization. When compared with the conventional real-time optimization method, the proposed method resulted in around 70% computational load reduction, and over 26% reduction in the tracking errors of the local control loops. [ABSTRACT FROM AUTHOR]

A power supply (20 V, 10 kA) for powering the filamentary cathode has been procured, interfaced and integrated with the centralized control system of Large Volume Plasma Device (LVPD). Software interface has been developed on the standard Modbus RTU communication protocol. It facilitates the dashboard for configuration, on line status monitoring, alarm management, data acquisition, synchronization and controls. It has been tested for stable operation of the power supply for the operational capabilities. The paper highlights the motivation, interface description, implementation and results obtained. [ABSTRACT FROM AUTHOR]

In this paper, a novel variable stiffness finger actuated by heating the embedded SMA fibers is proposed. First, the concept of the variable stiffness mechanism and fabrication of the finger which can demonstrate continuous deformation are presented. Then, the parameters of the SMA used for variable stiffness are identified, which are used to model the phase transformation processes of its Young’s modulus. In addition, experimental results show that the bending stiffness of the soft finger can be changed by heating the embedded SMA-3 fibers, resulting in a range of increase 49%. And, the model of the input current for SMA-3 wires and pulling force F 2 used to bend the soft finger is established. At last, the reaction force F 3 of the soft finger’s tip for different displacement is discussed with finite element analysis model, which is in qualitative agreement with the experimental results. The maximum range of increase for F 3 is 45.3% when the stiffness changed. [ABSTRACT FROM AUTHOR]

In continental climates heating accounts for a significant part of the total energy consumption of a residential building with average thermal characteristics of the envelope. Solar heat gains have to be used wisely in order to reduce the energy need for heating. Glazed ratio of the facades, orientation of the transparent area and thermal mass has to be properly chosen in order to obtain the desired utilization factor. In this paper the effects of window size, thermal mass and window orientation on the balance point temperature are analysed in case of a reference room. The calculation methodology given by EN ISO 13790 standard was used. Measurements were done in order to validate the model. Performing the calculus on 48 different cases it was shown, that differences of even 11% can appear between the energy demands for heating (for similar overall heat transfer coefficients of the external building elements). [ABSTRACT FROM AUTHOR]