Search

The exploitation of renewable energy sources and the use of primary energy saving techniques have been recognized as key solutions to face climate changes. The consequent energy policies are pushing the transition from a centralized power generation system to a distributed polygeneration system able to meet simultaneous heating, cooling and electricity demand. However, small scale polygeneration plants do not ensure any primary energy and cost saving without a proper sizing and operation of the plant. Furthermore, a flexible configuration of the waste heat recovery system (WHRS) adopted for polygeneration purposes can be equally important. Therefore, starting from the experimental data concerning a 15 kW micro-CHP plant previously designed and prototyped, the paper addresses the performance assessment of a CHCP plant configuration based on the same basic engine-electric generator system through the 1D thermo-fluid dynamic characterization of an alternative double water circuit WHRS. This configuration, delivering thermal power at different temperature level, could be useful to meet thermal and cooling demand from different user or when seasonal energy demand occurs. This paper also provides an effective approach for the design of WHRS which are capable to ensure a reasonable matching between the temperature level required by the user and that provided by the plant. In this way, being the energy saving dependent on the thermal power recovered and actually exploited, and so on the temperature level which characterizes the user's heat demand, primary energy savings are more easily achievable even when small scale polygeneration applications are considered. Results shows the possibility of supplying an absorption chiller and obtaining a coolling capacity of about 10.5 kW from the resulting CHCP plant configuration. [ABSTRACT FROM AUTHOR]

Most of existing solar ventilation envelope systems adopt a single structure including a glass cover a massive wall, which possesses the drawbacks of low thermal efficiency and poor stability. In recent decades, auxiliary power generation devices, led by photovoltaic (PV), have made epochal achievements in integrated building applications, while the superior thermal regulation capability of thermal storage materials, represented by phrase change materials (PCM), has further helped to improve the thermal environment of buildings, and the above two technologies have demonstrated great energy conservation potential. In order to explore the application and synergistic effect of the above two energy-conservation technologies in passive ventilation envelopes, a novel functional ventilation building envelope (FVBE) integrated with PV panel and PCM is proposed in this paper. A comprehensive exploration of the influence of various key parameters on the thermal performance of the FVBE-PV/PCM system. The electrical and thermal performance of the system is explored based on different seasonal climates. Specifically, effects of thickness as well as the melting temperature of PCM and the air channel width has been provided in this study. Taking the inner wall surface temperature (T inner_wall), equivalent indoor load (Q load) and electrical efficiency (η e) as evaluation indexes, the thermal efficiency, electrical performance and the coupling mechanism was assessed. Specifically, the coupling mechanism between the thermal performance and electrical performance of the FVBE-PV/PCM system was analyzed from the perspective of combined heat and power, revealing the functional characteristics of the system. Meanwhile, the article conducted a comparative study on the thermal and electrical performance of a typical building integrated PV (BIPV), FVBE-PV system FVBE-PV/PCM system. In particular, energy and exergy analysis is carried out to characterize the energy utilization of the FVBE-PV/PCM system in different structural systems. The research found that increasing the thickness of both the PCM and air channel leads to lower indoor temperature and heat flux, with different optimal phase transition temperatures for summer and winter. Although the FVBE-PV system exhibited a maximum 3.12 % reduction in power generation efficiency compared to the BIPV system due to increased PV temperature caused by air layer insulation, incorporating PCM can reduce exergy losses by an average of 31.731 % to mitigate this drawback and improve energy efficiency. Additionally, the analysis revealed varying coupling correlations between thermal performance and power generation based on two key parameters. This study could contribute to the functional improvement of the building envelope and simultaneous indoor thermal regulation. • A FVBE system is proposed for power generation and indoor thermal regulation. • The numerical model of FVBE-PV/PCM is developed. • The influence of several parameters are analyzed. • Energy and exergy analysis on different systems are clarified. • Coupling relationship between electrical and thermal performance are explored. [ABSTRACT FROM AUTHOR]

CO 2 injection into unconventional gas reservoir has been recognized as a promising approach to enhance unconventional gas recovery (CO 2 -EUGR) and sequester CO 2 geologically. The CO 2 -EUGR is a complex multi-physics coupling process. To accurately assess the effectiveness of different injection strategies, this paper firstly presents a non-isothermal compositional two-phase flow model coupling with geomechanics, in which a multicomponent adsorption kinetics is incorporated to separate free phase and adsorbed phase. A hybrid numerical approach combining EbFVM and GFEM is used for numerical solutions. The performance of different injection strategies for CO 2 -EUGR is evaluated. The results indicate that CO 2 injection is able to improve CH 4 recovery significantly, over 90 % of injected CO 2 can be adsorbed in reservoirs, The performance of CO 2 -EUGR is permeability dependent, the displacement effect occurs earlier when reservoir permeability is higher; Increase in temperature of injected gas and mixed CO 2 /N 2 injection can further improve CH 4 recovery, especially for low permeability gas reservoirs; Mixed gas injection also enables displacement effect to occur earlier; Cyclic injection can hardly lead to increase in CH 4 production, especially when reservoir permeability is higher, while it can cause an increase in amount of adsorbed CO 2 during injection period. Based on these findings, a geothermal-assisted CO 2 -EUGR method is proposed. • An efficient non-isothermal compositional model coupling with geomechanics is developed for CO 2 -EUGR. • The performance of different CO 2 injection strategies is evaluated quantitatively. • The occurring of displacement effect and performance of CO 2 -EUGR depend on reservoir permeability. • Increasing temperature of injected gas and mixed CO 2 /N 2 injection can further improve CH 4 recovery. [ABSTRACT FROM AUTHOR]

A novel solar grading collector/regenerator system with heat recovery is proposed in this paper and a mathematical model of system is established. Numerical simulation shows that heat recovery does increase the performance of system reaching increments of 104% and 320% respectively for grading solar collector/regenerator with all heat recovery (Mode E) and single solar collector/regenerator with heat recovery (Mode C). There occur critical points of performances between the single and grading collector/regenerators. The regeneration efficiencies of Mode E were increased by 12.2%, 10.7% and 75% at ambient temperature of 40 °C, relative humidity of 90% and solar radiation intensity of 600 W/m 2 respectively compared with Mode C. The critical flow-rates of air and solution are in the ranges of 220 kg/h to 260 kg/h and 17 kg/h to 42 kg/h respectively corresponding with the plate of 1 ∼ 3 m length. The regeneration efficiency of Mode E with a 3-m plate was increased by 24% compared with 1-m plate. The application scopes of environmental parameters and solution concentration are given in this paper and it is concluded that the grading regeneration is beneficial to regenerating the solution of high concentration in the conditions of low solar radiation intensity and high temperature as well as high humidity. [ABSTRACT FROM AUTHOR]

This paper construct a CCHP and renewable energy based hybrid energy system driven by distributed energy resources (DERs CCHP). Then, the paper constructs performance indexes from energy, economic and environment. Thirdly, the paper proposes a multi-objective optimization model for DERs CCHP system under four optimization of energy rate (ER), total operation cost (TOC), carbon dioxide emission reductions (CER) and joint optimization. Finally, Guangzhou Higher Education Mega Center (GHEMC) in China is taken as the object for comparatively analyzing the operation performance of DERs CCHP system and CCHP system driven by natural gas (NG CCHP system). Results show: Joint optimization mode could balance the results of different optimization modes. DERs CCHP system shows better operation performance. ER of ER optimization, CER optimization and joint optimization are higher than that of NG CCHP system. NPV of all optimization modes is positive, IRR are bigger than the expected yield rate. DERs CCHP system could reduce CO 2 emission by utilizing wind energy and solar energy to replace NG. The sensitivity analysis indicates the performance of the DERs CCHP system will become better with the increase of chiller COP, decrease of NG price and wind-photovoltaic equipment cost. [ABSTRACT FROM AUTHOR]

Tubular solid oxide fuel cell (TSOFC) converts a great part of chemical energy within fuel into high-grade waste heat, leading to a decrease in overall fuel efficiency. In this paper, a steady-state hybrid system model based on TSOFC and two-stage annular thermoelectric generator (TATEG) is proposed. Considering various kinds of irreversible effects, mathematical model for the hybrid system is explicitly formulated and verified to guarantee the accuracy. Energetic and exergetic performance indexes of the hybrid system and subsystems are obtained, and the corresponding performance characteristics are revealed. Calculation results display that the power density, energetic and exergetic efficiencies of TSOFC-TATEG hybrid system can be 15.29 %, 11.25 % and 11.25 % higher than that of stand-alone TSOFC, respectively. The power density, energetic efficiency and exergetic efficiency of TSOFC-TATEG hybrid system are all increased by 5.65 % compared to that of TSOFC-ATEG hybrid system. Furthermore, this study reveals that enhancing the performance of the hybrid system is attainable through regulating variables, such as elevated operating temperatures, optimal quantities of thermoelectric elements, appropriate ratios between thermoelectric element numbers, well-considered thermocouple thickness, suitable thermocouple radial width, and the judicious selection of parameters like annular shape or height ratio. • A geometry-matching TATEG is proposed to recover the waste heat from TSOFC. • Performance indicators are mathematically deduced based on model formulation. • Hybridization of TATEG enables to improve the TSOFC power density by 15.29 %. • The proposed system is superior to the sole TSOFC in terms of performance. • Effects of some decisive design parameters and operation conditions are revealed. [ABSTRACT FROM AUTHOR]

Based on constructal theory, the disc-shaped solid–gas reactors combined heat and mass transfer are investigated in this paper. Radial- and branched-pattern of the discs are considered, and the two pattern discs are optimized based on entropy generation rate minimization. The results show that there exist a minimum value of the entropy generation rate and the corresponding optimal construct of the reactor. The minimum entropy generation rate increases with the increase in the radius of the first order disc; therefore, a proper radius of the first order disc should be adopted according to the practical demand of the reactor. The performance of the reactor can be improved by increasing the material amount of the integrated collector or reducing the number of elemental tributaries and the thermodynamic parameter η . The design pattern of the disc depends on the relationship of the critical radius and disc radius. Moreover, the heat transfer or mass transfer models are special cases of the heat and mass transfer model in this paper. [ABSTRACT FROM AUTHOR]

A 3D (three-dimensional) model of VRB (vanadium redox flow battery) with interdigitated flow channel design is proposed. Two different stack inlet designs, single-inlet and multi-inlet, are structured in the model to study the distributions of fluid pressure, electric potential, current density and overpotential during operation of VRB cell. Electrolyte flow rate and stack channel dimension are proved to be the critical factors affecting flow distribution and cell performance. The model developed in this paper can be employed to optimize both VRB stack design and system operation conditions. Further improvements of the model concerning current density and electrode properties are also suggested in the paper. [ABSTRACT FROM AUTHOR]

This paper proposes a combined cooling, heating and power (CCHP), and multi-effect desalination system to supply cooling, heating, power and freshwater. The proposed system mainly includes a gas turbine (GT), a multi-effect desalination unit with a thermal vapor compressor (MED-TVC), an organic Rankine cycle (ORC) integrated with a steam ejector refrigerator (SER), and heat exchangers. The mathematical model is developed to thermodynamically conduct energy-exergy analysis, and a parametric study is performed to explore the effects of key design parameters such as air compressor pressure ratio, inlet air temperature of air compressor, pinch point temperature difference of waste heat boiler, motive steam pressure of MED-TVC unit, TVC compression ratio and working medium flow rate of ORC on the system performance. The proposed system can provide power, heating, cooling and freshwater at loads of 31.25 MW, 1.108 MW, 4.203 MW and 85.89 kg/s under the design conditions. The electrical, the exergy, and the overall energy efficiencies of the present system are 36.44%, 41.26% and 46.70%, respectively. The results indicate that the power output of GT can be increased by precooling the inlet air of air compressor, and the integration of GT with MED-TVC unit, ORC and heat exchangers can efficiently recover the waste heat from exhaust gas based on the principle of "energy cascade utilization". In addition, the largest exergy destruction occurs in the combustion chamber followed by regenerator 1 and the MED-TVC unit. • Energy and exergy analysis of a poly-generation system is presented. • Waste heat is recovered based on the principle of "energy cascade utilization". • Organic Rankine cycle is integrated with a steam ejector refrigerator. • The inlet air of GT is precooled to improve the power output. [ABSTRACT FROM AUTHOR]

Organic Rankine cycle (ORC) is a promising power cycle to convert low-grade thermal energy. The quick and easy evaluation of the potential working fluids lacking thermophysical property data is important for the working fluid selection of ORC. This paper proposes a systematic framework of working fluid evaluation from the molecular structure perspective, which couples the quantitative structure property relationship (QSPR) and universal equations of state. The thermodynamic performance of ORC is first correlated with four key thermophysical properties based on universal equations of state. Then, these thermophysical properties are obtained from the corresponding QSPR models based on the molecular structure of working fluids. The influence factors of ORC performance at a micro level are investigated using the QSPR models. Moreover, the effects of molecular characteristics on thermal efficiency are analyzed. The criteria for working fluid design/selection are recommended aiming at the improvement of thermal efficiency. The proposed framework shows sufficient accuracy with the relative errors of −0.41 - 15.85% and mean absolute error of 8.29% compared with the results based on REFPROP. It is found that the cyclization of carbon chain is an ideal method for the working fluid design based on alkanes and alkenes. This work can provide new insights for the evaluation, selection, and design of working fluids on the molecular structure level. • A framework of working fluid evaluation based on molecular structure is proposed. • Micro influence factors of ORC performance are investigated. • Effects of molecular characteristics on thermal efficiency are analyzed. • Criteria for working fluid design/selection are recommended. [ABSTRACT FROM AUTHOR]

In this paper, based on the mathematical models of microalgae growth, the performance of microalgae growth in nitrogen-limited and light-limited continuous culture is investigated and the effect of important factors on the growth is examined. The dilution rate and the influent inorganic nitrogen concentration have been shown to have a significant influence on the growth of microalgae in continuous culture. In order to obtain a maximum productivity of microalgae, lower dilution rate is better for a lower influent inorganic nitrogen concentration and an optimal dilution rate can be obtained for a higher influent inorganic nitrogen concentration. There is an optimal influent inorganic nitrogen concentration corresponding to maximum microalgae productivity, and the optimal value for lower dilution rate is far higher than that for higher dilution rate. This paper will lay a foundation for the design of the operational parameters of continuous culture PBR (photobioreactor). [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the application of the AHP (analytic hierarchy process) method to evaluate bioenergy developments regarding their regional sustainability in a case study area (Tayside and Fife/Scotland). Achieving regional sustainable bioenergy generation is challenging due to the complexity of this sector and the multidimensionality of the sustainability goal. The paper presents a complete and comprehensive AHP application by taking account of two different scenarios and their alternatives, C&I (criteria and indicators) and preferences of bioenergy experts. Although, case-specific C&I weighting and performance assessments are required to make this study valuable for similar decision making situations, the rather generic scenarios allow elements of this study to be transferred to a wide range of decision making situations within the energy and particularly the bioenergy field. The detailed analysis of results, including analyses by end node C&I and by alternatives, demonstrates that decentralized bioenergy generation should be preferred to achieve regional sustainable bioenergy generation in the case study area. Sensitivity analyses explore variations of the subjective judgments made on the different levels of the AHP hierarchies. The results of the sensitivity analyses show that all results can be considered robust. [Copyright &y& Elsevier]

Abstract: Based on a traditional SOFC (solid oxide fuel cell) hybrid power system, three different SOFC hybrid power systems with zero-CO2 emission are proposed in this paper and their performances are analyzed and compared. The anode outlet gas of SOFC burns with the pure oxygen and the concentration of CO2 is greatly increased. In order to maintain the appropriate turbine inlet temperature, three different measures (steam injection, CO2 gas injection and heat exchange layout) are taken. Because the outlet flue gas of the afterburner mainly consists of CO2 and steam, the CO2 in the flue gas can be captured easily by the condensation method after the recovery of work and heat. With the exergy analysis method, this paper studies the exergy loss distributions of every unit of SOFC hybrid systems with CO2 capture and reveals the variation rules of exergy loss distributions. The effects of the main operating parameters on the overall performances of SOFC hybrid systems with CO2 capture are also investigated. The results show that the zero CO2 emission SOFC hybrid systems still have higher efficiencies, which only decrease about 3–4% compared with that of the basic SOFC hybrid system without CO2 capture. [Copyright &y& Elsevier]

Abstract: In this paper, a waste heat recovery system is proposed where a high speed turbocharged diesel engine acts as the topper of a combined cycle with exhaust gases used for a bottoming Rankine cycle. The paper describes a mathematical model to evaluate the performance of Rankine cycle system with a reciprocating piston expander. The paper focuses on the performance evaluation and parameter selection of the heat exchanger and reciprocating piston expander that are suitable to waste heat recovery of ICE (internal combustion engine). The paper also describes the experimental setup and the preliminary results. The simulation results show that a proper intake pressure should be 4–5 MPa at its given mass flow rate of 0.015–0.021 kg/s depending on the waste heat recovery of a turbocharged diesel engine (80 kW/2590 rpm). The net power and net power rise rate at various ICE rotation speeds are calculated. The result shows that introducing heat recovery system can increase the engine power output by 12%, when diesel engine operates at 80 kW/2590 rpm. The preliminary experimental results indirectly prove the simulation model by two negative work loops in the P–V curve, under a low intake pressure and steam flow rate condition. [Copyright &y& Elsevier]

Abstract: There is a growing concern about the impact of energy system decarbonisation on natural resources, such as raw materials and freshwater. Along this line, this paper assesses the needs for cooling water and construction materials of pulverised coal combustion (PF), integrated gasification combined cycle (IGCC) and natural gas combined cycle (NGCC) power generation technologies with and without CCS (Carbon capture and storage). Moreover, the paper evaluates how the integration of CCS technologies influences the economics and operational performance of power plants providing up-dated techno-economic indicators. Introduction of CO2 capture results in an increase of specific water consumption compared to a conventional plant which is more significant in the cases of PF and NGCC (56–62% and 50%) than in IGCC (9–12%). Therefore, the large scale deployment of CCS can have a significant impact on freshwater resources. The introduction of CO2 capture also increases significantly the amount of plant construction materials. The increase is up to 100% for concrete and steel and up to 27% for copper and polyethylene. The cost of construction materials is 8–15% of total investment costs, hence any changes in their prices can have a measurable impact on the cost of a plant and hence on the competitiveness of the underlying technology. [Copyright &y& Elsevier]

Abstract: This paper examines a TMS (thermal management system) of a range-extended EV (electric vehicle), which operates on its battery before the gasoline engine engages. In this period of independence of the ICE (internal combustion engine), the vehicle performance characteristics such as range, power for acceleration, fuel economy and emissions depend solely on the battery performance. Since the magnitude and uniformity of temperature in battery packs has significant impact on their performance, it is imperative to keep the battery temperature within optimal performance levels through a capable TMS that can efficiently transfer heat within the vehicle. The objective of this paper is to analyze the refrigerant and coolant circuits in the vehicle for cooling during high ambient temperatures and determine the irreversibilities and areas for improvement within these circuits. A second law analysis is used to examine the areas of low exergy efficiency in the system and minimize the entropy generation. Based on the analysis, the energetic COP (coefficient of performance) ranges of 1.8–2.4 and exergetic COP ranges of 0.26–0.39 are calculated for the system. Various parametric studies have been conducted and the most significant impact on the overall exergetic COP is found to be the ambient temperature. [Copyright &y& Elsevier]

Abstract: This paper discusses the opportunities and challenges of implementing District Heating (DH) in Canada, with focus on the network design and operation. We selected for case study an urban area in Ottawa. First, we proved that the medium-temperature district heating (MTDH) (70°C≤ T supply ≤90°C) had better energy delivery performance than high-temperature district heating (HTDH) (T supply >100°C), decreasing the heat loss by approximately 40%. The low-temperature networks (T supply <60°C) achieved even lower heat losses, but they required additional capital investment. The implementation of low-temperature district heating (LTDH) should be considered, thanks to the capability of including more renewable energy and excess industrial waste heat. Next, the simulations show that DH can be implemented to supply present heating loads with medium temperature DH, and operate in the future at low temperature, after energy saving measures have been implemented in the buildings. Areas having linear heat densities greater than 3MWh/(myr) could economically be supplied by DH. Areas with linear heat density below 1.5MWh/(myr) are considered not practically feasible with the current energy market situation in Canada. The paper discusses critical issues and quantifies the performance of design concepts for DH supply to low heat density areas. DH is a fundamental energy infrastructure and is part of the solution for sustainable energy planning in Canadian communities. [Copyright &y& Elsevier]

Abstract: This paper reports on a specific phenomenon, noticed during steam injection experiments on a microturbine. During the considered experiments, measurements indicated an unsteady inlet air temperature of the compressor, resulting in unstable operation of the microturbine. Non-continuous exhaust air recirculation was a possible explanation for the observed behaviour of the microturbine. The aim of this paper is to investigate and demonstrate the effects of exhaust recirculation on a microgasturbine. Depending on wind direction, exhaust air re-entered the engine, resulting in changing inlet conditions which affects the operating regime of the microturbine. For this paper, a series of experiments were performed in the wind tunnel. These series of experiments allowed investigation of the effect of the wind direction on flue gasses flow. Next to the experiments, steady-state simulations of exhaust recirculation were performed in order to study the effect of exhaust recirculation on thermodynamic performance of the microturbine. Dynamic simulations of the non-continuous recirculation revealed the effects of frequency and amplitude on average performance and stability. Results from simulations supported the important impact of exhaust recirculation. Wind tunnel tests demonstrated the influence of the wind direction on recirculation and revealed the necessity to heighten the stack, thus preventing exhaust recirculation. [Copyright &y& Elsevier]

The impact of local depth-wise velocity profiles on tidal turbine performance is important. Although the use of standard power laws for predicting velocity profiles is common, these laws may underestimate the magnitude of the depth-wise velocity shear and power attenuation. Predicting the performance of a tidal turbine in a high velocity shear is crucial in terms of power extraction. This paper discusses the dimensional scaling of a turbine using CFD and experimental data. Key performance characteristics (power, torque and thrust coefficients) were studies with increasing diameters and velocities, by generating. a series of non-dimensional curves. This provides a first order approximation for matching turbine performance characteristics to site conditions. The paper also shows that the use of a volume-averaged velocity derived from the upstream velocity profile can be used to determine these key performance characteristics. These are within 2% of those determined assuming a uniform flow. The paper also shows that even changes in the blade pitch angle results in new turbine characteristics under uniform velocity conditions and it is expected that these can be used for profiled flow. [ABSTRACT FROM AUTHOR]

Abstract: In this paper a thermoeconomic approach is applied to the dynamic model of a Power System in order to investigate the effects of the control system on the primary energy consumption and on the economic costs of the product. To achieve this objective, various control strategies are compared when variations of the operation condition, due to some internal or external causes, are produced. These variations cause the intervention of the control system, which rearranges the operating condition in order to have the controlled quantities within acceptable ranges. Generally the plant efficiency changes, depending on the selected strategy. A microturbine is considered as the case study. The analysis here proposed allows one to quantify the effect of the control on the performance variation of the components. The approach associates an exergetic cost and a thermoeconomic cost to the control system operation, which expresses the additional resource (primary energy and economic resources) consumptions that may be associated to the control. The impact on the initial and final steady states as well as the transient evolution are considered. This can be usefully applied to improve energy system operation acting on the control system, both in the off-design steady states and transient operations. In the particular application considered in this paper, reductions of about 8% in fuel consumption and 5% in the total costs are achieved. Concerning transient operation, it is shown that the control system can produce large variation in the operation costs. [Copyright &y& Elsevier]

This paper presents an innovative use of waste heat recovered from a cement slag for multigeneration purposes, including power, ammonia, heat, hot water and oxygen production. A novel approach of ammonia production is employed in this study. The proposed system consists of four major subsystems; copper-chlorine (Cu-Cl) cycle, cryogenic Air Separation Unit (ASU), ammonia synthesis reactor and two steam Rankine cycles. The Aspen plus 9.0 version is employed for modeling and simulation of the proposed system. A comparative study is also conducted considering the different CuCl cycle based integrated systems for multigenerational purpose with numerous energy sources. The parametric studies are carried out by varying parameters, namely flow rate, compressor and turbine discharge pressures and ammonia reactor conversion rate. The exergy analysis is comprehensively conducted for each of the system components through exergy balance equations and exergy efficiencies. The overall exergy efficiency of the designed system is found to be 36.1%. Further results are also presented and discussed. • An innovative use of waste heat recovery for ammonia and power production. • Power, ammonia, heat, hot water and oxygen production are system outputs. • Ammonia production rate of 13 mol/s and electric power of 3422 kW is achieved. • The overall exergy efficiency of the designed system is found to be 36.1%. [ABSTRACT FROM AUTHOR]

In this paper, an integrated system aiming for heating and cooling production using solar energy is investigated. The system consisting of a solar driven adsorption chiller and radiation heating coupled with thermal energy storage is analysed thermodynamically, and its overall performance is assessed through energy and exergy efficiencies. The main goal is to compare performances of the system equipped with different thermal energy storage tank. Two thermal storage tank arrangements - a water TES and PCM TES - are discussed. These cases are later compared with the reference system without a storage tank. The results of the energy and exergy analyses of the reference case without thermal storage show that the seasonal energy and exergy efficiencies are 24.2% and 10.5%. Furthermore, by introducing thermal storage, energy and exergy performances of the system have improved significantly compared to the reference case. The annual energy and exergy efficiencies of the integrated system with water TES were 31.9% and 14.3%, respectively. Moreover, it was observed that the annual energy and exergy efficiencies of the system with PCM TES are slightly higher than for the system with water TES (1.5 and 0.7% points, respectively) for the same storage capacity. • System consisting of a solar driven adsorption chiller and radiation heating coupled with storage tank is investigated. • Energy and exergy analysis were performed on system and component level. • Annual energy and exergy analyses of the reference case without thermal storage were 24.2% and 10.5%. • Improvement of the performance by introducing the thermal storage. • Annual efficiencies of the phase change material storage tank are higher than for the sensible water tank system. [ABSTRACT FROM AUTHOR]

Abstract The present paper investigates the aerodynamic and aeroacoustic characteristics of H-rotor Darrieus vertical axis wind turbine combined with a promising energy conversion technology, namely wind-lens, employing computational approaches. The Darrieus turbine adequate for low wind speed and urban area conditions. However, its aerodynamic and aeroacoustic characteristics are very complicated. Thus, the main scope of the current work is to enhance the aerodynamic performance of the introduced turbine and then assess the noise production accomplished with such enhancement. The studies are taken on two phases, the first phase is parametric 2D CFD simulations, employing the unsteady Reynolds-averaged Navier-Stokes (URANS) approach, to optimize the design parameters of the wind-lens. The second phase is a 3D CFD simulation of the full turbine using a higher order numerical scheme employing a hybrid RANS/LES method. An estimate of the aeroacoustic noise of the turbine is quantified using the Ffowcs Williams-Hawkings (FW-H) method. As a result, the optimal design parameters of the wind-lens are achieved and the optimized configuration shows a superior augmentation in power generated of about 82 % increase in the power coefficient at a speed ratio of 2.75. However, the turbine equipped wind-lens produces more noisy operation compared to the non-shrouded turbine. Highlights • Wind-lens technology is used to improve the Darrieus turbine aerodynamic performance. • A noise assessment accompanied by the improvement is carried out. • The investigations performed based on DDES approach after 2D URANS parametric study. • The wind-lens with a cycloidal diffuser produce 82 % increase in Power coefficient. • The turbine with wind-lens increases the impulsive loading noise level. [ABSTRACT FROM AUTHOR]

Abstract This paper presents an Optimal Control Problem (OCP) tailored to assess the system performance of a rigid wing Airborne Wind Energy (AWE) pumping system prior to real flight tests. The proposed method is validated against experimental data obtained using a small prototype designed by the Dutch company Ampyx Power B.V. Within such analysis, it is shown that a non-optimized closed-loop flight control system can generate power to within 10% of the open-loop optimal flight trajectories. Additionally, results demonstrate that the system efficiency does not depend on the trajectory topology, though a significant change in terms of trajectory shape is observed for different wind speeds as a result of trajectory constraints. Highlights • The average power output is not sensitive with respect to the trajectory shape. • The power curve can be obtained prior to real flight test experiments. • The proposed method is validated via real flight test experiments. • Circular trajectories are compared against lemniscate trajectories. • Optimized flight trajectories change significantly for different wind speeds. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines the performance of a new Marnoch heat engine, which uses dry air and a pneumatic piston assembly to convert thermal energy to electricity. The system has unique capabilities of operating over temperature differentials less than 100 K. Unlike a common Stirling engine, the heat exchangers and piston assembly are not co-located, which is beneficial for positioning of heat exchangers in various configurations. This paper presents an operational laboratory-scale, proof-of-concept Marnoch heat engine (MHE), including its performance and power generation capabilities. It also presents a thermodynamic analysis of the system. Based on the MHE results, component modifications are made to improve its performance. The configuration has an efficiency of about thirty percent of a Carnot heat engine operating in the temperature range between 272 K and 372 K. Experimental data is acquired to provide verification of the predictive model, as well as demonstration of the MHE’s capabilities for efficient generation of electricity from waste heat sources. [Copyright &y& Elsevier]

Abstract: In previous papers the authors demonstrated that significant energy savings can be achieved in air-conditioning through the use of a hybrid plant in which a vapor-compression inverse cycle is integrated with an air dehumidification system working with hygroscopic solution and hydrophobic membrane. The advantage of this system lies in the fact that the refrigeration device operates at a higher evaporation temperature than that of a traditional system, in which dehumidification is achieved through condensation. In the proposed hybrid system the supplied air is simultaneously cooled and dehumidified in an air–solution membrane contactor. The LiCl solution is cooled by means of a vapor-compression inverse cycle. The solution is regenerated in another membrane contactor by exploiting the exhaust air and the heat rejected by the condenser. The paper reports a study of the steady-state behavior of the system in summer climatic conditions on varying some significant climatic parameters, such as the latent load of the conditioned space and the outdoor and indoor relative humidity. The performances of the hybrid system are compared with those of a traditional direct-expansion air-conditioning plant. Results of the simulations reveal that energy saving may exceed 60% when the latent load in the conditioned environment is high. [Copyright &y& Elsevier]

Abstract State of charge estimation is one of the most critical factors to solve the key issues of monitoring and safety concerns of an electric vehicle power battery. In this paper, a state of charge estimation approach using subtractive clustering based neuro-fuzzy system is presented and evaluated by the simulation experiments using advanced vehicle simulator in comparison with back propagation neural network and Elman neural networks. Input parameters to model the state of charge estimation approach using subtractive clustering based neuro-fuzzy system are current, temperature, actual power loss, available and requested power, cooling air temperature and battery thermal factor. Data collected from 10 different drive cycles are utilized for the training and testing stages of the state of charge estimation model. Experimental results illustrated that the proposed model exhibits sufficient accuracy and outperforms both neural network and Elman neural network based models. Thus, the proposed model under different drive cycles show remarkable advancement in state of charge estimation with high potential to overcome the drawbacks in traditional methods and therefore provides an alternative approach in state of charge estimation. In addition, a sensitivity analysis is also performed to determine the importance of each input parameter on output i.e. state of charge. Highlights • An SC-ANFIS model to estimate the battery state of charge is developed. • The proposed model exhibits sufficient accuracy and outperforms other advanced models. • The model requires a simple training procedure and is evaluated using 10 diversified unseen driving cycles. • Different statistical metrics are adopted for the model state of charge estimation performance evaluation. • Sensitivity analysis is performed to determine the influence and importance of input variables on battery state of charge. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, performance of new configuration of Micro-gas turbine cogeneration and tri-generation systems, with a steam ejector refrigeration system and Heat recovery Steam Generator (HRSG) are studied. A micro-gas turbine cycle produces 200 KW power and exhaust gases of this micro-gas turbine are recovered in an HRSG. The main part of saturated steam in HRSG is used through a steam ejector refrigeration system to produce cooling in summer. In winter, this part of saturated steam is used to produce heating. In the first part of this paper, performance evaluation of this system with respect to Energy Utilization Factor (EUF), Fuel Energy Saving Ratio (FESR), thermal efficiency, pinch point temperature difference, net power to evaporator cooling load and power to heat ratio is carried out. It has been shown that by using the present cogeneration system, one can save fuel consumption from about 23% in summer up to 33% in winter in comparison with separate generation of heating, cooling and electricity. In the second part of this paper, exergy analysis of the system has been done. It has been shown that combustion chamber; HRSG and heat exchanger are recognized as the largest sources of exergy losses respectively. [Copyright &y& Elsevier]

Abstract: This paper presents the detailed laboratory experimental results of a low-temperature Organic Rankine Cycle (ORC) engine coupled with a Reverse Osmosis (RO) desalination unit. In a previous work, the identification of performance of the scroll type expander was presented. At that primary experimental phase an electric brake was co-axially connected to the expander to act as the mechanical load of the ORC engine. The identification of behaviour of the integrated ORC–RO system is a research step ahead since the electric brake is replaced by the RO desalination unit representing the actual system''s mechanical load. Several characteristic quantities of both energy supply (ORC) and demand (RO) side have been measured and are illustrated in the current paper. The results show that ORC can be effectively used to exploit low-temperature thermal sources (i.e. in the range from 40 to 70°C) for desalination of sea or brackish water through the RO process. Such low-temperature values can be available from excess industrial heat, solar collectors and geothermal fields making the ORC–RO process an alternative desalination variant. However, it becomes clear that the system performance strongly depends on the corresponding operation point. [Copyright &y& Elsevier]

The aim of this paper is to present three years of an evaluation of the performance and degradation rate of three different crystalline silicon-based photovoltaic (PV) modules in the Saharan environment. The PV modules are: mc-Si (multi-crystalline), c_Si (mono-crystalline, back contacted) and HiT (heterojunction with intrinsic thin-layer); they are installed in Saida which is located at the proximity of Algeria’s Sahara. Two methods were used to calculate the degradation rate; the effective peak power of the PV modules and the temperature corrected performance ratio. It was found that the HIT technology performs worse than the other technologies with the highest degradation rate, ranging from −1.53%/year to −1.92%/year. The mc_Si PV and c_Si PV module technologies present a lower degradation rate than the HIT technology in the range of −0.74%/year to −0.83%/year and −0.58%/year to −0.79%/year respectively. [ABSTRACT FROM AUTHOR]

Almost all of the researches about the photovoltaic-thermoelectric (PV-TE) hybrid system focus on the steady-state performance assuming solar irradiance is constant (1000 W/m 2 ) and ignoring the influence of changing solar radiation with time. In this paper, a theoretical model for obtaining the coupling system one-day performance is established. Detailed one-day changes in coupling system temperatures, powers, efficiencies are revealed. The thermal concentration ratio is discussed and is optimized to increase the one-day average efficiency. Influences of photovoltaic efficiency temperature coefficient, thermoelectric Z value, water cooling mass and velocity are discussed. The one-day performances of pure PV and PV-TE hybrid system are compared. The results show that the coupling system can obtain the highest one-day average efficiency by optimizing the thermal concentration ratio. The highest one-day average efficiency of the hybrid system decrease with the rise of the photovoltaic temperature coefficient and increase with the thermoelectric Z value augmenting. The mass of the cooling water has a remarkable positive effect on the hybrid system performance while the impact of the cooling water velocity is tiny. The hybrid system one-day capability is preferable to the pure PV system when the thermoelectric Z value is large or the photovoltaic temperature coefficient is small. [ABSTRACT FROM AUTHOR]

Batteries are the crucial link in accelerating the penetration of renewables in distributed grid systems. With multiple sources (most of which are intermittent), there is a need to optimize the usage of these energy storage systems. It is vital to have a charging algorithm to intelligently charge the battery, considering the losses and state of health. Several battery charging techniques exist for most of the mainstream batteries such as lithium ion and lead acid batteries. These charging algorithms are developed for specific battery chemistries to optimize the charging operation by controlling the charging current. There has been no specific charging methodology proposed, considering the uniqueness of flow batteries. In this paper a flow battery model is developed to accommodate the implementation of charging protocols by controlling the current and flow rate in real time. The aim is to demonstrate a methodology where different user requirements can be programmed for efficient operation of the battery to perform a given task. The control is established by an intuitive fuzzy logic controller for changing the input variables based on the intrinsic losses, pump power loss and the capacity decay due to the aging of the battery. The need for such a controller to handle different scenarios of operation arises from the vast applicability of large scale energy storage. A simple example of such a system is proposed with demonstrating three operator selectable modes namely Autonomous (A), Energy bias (E) and Time bias (T). In each case, a specific current value and flow rate value is selected by the controller and is fine-tuned during the charging process. The values are tuned for specific modes of operation and different aspects of the battery performance are studied for these modes. This work demonstrates a method to leverage the use of a physical model based system in a high level user interface for controlling flow batteries. [ABSTRACT FROM AUTHOR]

This paper deals with the comparison between volumetric expanders (screw, scroll and rotary vane) and an Inlet Forward Radial (IFR) micro turbine for the exploitation of an on board Organic Rankine Cycle (ORC) energy recovery system. The sensible heat recovered from a common bus engine (typically 8000 cc) feeds the energy recovery system that can generate sufficient extra power to sustain the air-conditioning system and part of the auxiliaries. The concept is suitable for all kind of thermally propelled vehicles, but the application considered here is specific for an urban bus. The ORC cycle performance is calculated by a Process Simulator (CAMEL Pro) and the results are discussed. A preliminary design of the considered expanders is proposed using ad-hoc made models implemented in MATLAB; the technical constraints inherent to each machine are listed in order to perform the optimal choice of the expander based on efficiency, reliability and power density. Last step will be the selection of the expander that suites the specific technical and design requests. The final choice relapsed on the screw motor, for it is the best compromise in terms of efficiency, lubrication and reliability. [ABSTRACT FROM AUTHOR]

In this paper, the mathematical models of pre-heated and internally-heated liquid desiccant regenerator are established including parallel flow, counter flow and cross flow with two kinds of different flow directions of heated water respectively. Simulation results reflect that regeneration performances of the internally-heated are about 2–4 times that of the pre-heated in most conditions, greatly depending on the ratios of flow-rate of solution to air ( m s / m a ) and water to air ( m w / m a ) respectively. The regeneration performances, when the heated-water flows counter to solution, are superior to that of heated water parallel to solution. And the regeneration performances generally increase with increases in the NTU 1 and NTU 2 while a fitted curve combining NTU 1 with NTU 2 occurs to indicate the fastest increase in regeneration performance. Although the concentration difference increases with the m s / m a reducing, the evaporation rate gets its maximum value when the ratio of mass flow-rate of solution to air is equal to 0.2. The regeneration performances increase with increasing air temperature and decreasing its moisture content as well as linearly increase with higher inlet temperature of heated-water, but decrease with increasing solution concentration. The proposed regeneration mode and flow pattern will be helpful in the design and optimization of the regenerators. [ABSTRACT FROM AUTHOR]

This paper presents different Maximum Power Point Tracking (MPPT) methods belonging to different classes as well as two overviews. The first was about the procedures used in the test and evaluation of MPPTs. The second is an overview of Fuzzy Logic Controller (FLC) MPPTs and improved MPPTs. Conventional MPPTs such as Perturb and Observe (P&O), Hill Climbing (HC) and Incremental Conductance (InCond); Improved MPPTs (are the modified versions of conventional MPPTs) such as Improved Incremental Conductance (Improved-InCond) and intelligent MPPTs such as FLC have been implemented and tested under two different levels of irradiance and temperature. A detailed description about the hardware and software implementation platforms (designed and built in our laboratory) is provided. Based on measured data, the MPPTs under consideration have been evaluated and compared in terms of different criteria, showing the advantages and disadvantages of each one. The comparison results showed that Improved-InCond gives a fast convergence to the MPP(Maximum Power Point). Whereas, FLC is able to adapt to the variation of irradiance and temperature levels. Thereby, a good performance is obtained wherein the MPP is reached in a short time as well as the power ripples are very small. [ABSTRACT FROM AUTHOR]

This paper presents the environmental analysis of a solar photovoltaic power generation (SPPG) plant model, proposed for small off-grid communities. The analysis carefully considers both the life cycle energy- and the emission-related impacts of the plant's components, such as the PV array and the balance of system (BOS). Results reveal that a proposed 54.15 kW SPPG plant has global warming potential (GWP) ranging from 72,445 to 75,085 kg CO 2 −eq. The results further show that the battery system accounts for ∼85–90% of the plant's GWP impact. The battery also accounts for ∼68–75% of the total cumulative energy demand (CED) of 7.01–10.36 × 10 6 MJ. The energy payback times (EPT) for the PV-only range from 2.12 to 4.39 years, while a relatively higher value of 9.41–10.36 years was obtained for the PV and the BOS. The net energy ratio (NER) values of 4.56–9.43 and 2.24–2.52 were obtained for the PV-only and the PV with BOS, respectively, for a lifetime of 20 years. The NERs obtained for a lifetime of 25 years were 5.7–11.79 and 2.41–2.66, while the values obtained for a 30-year lifetime range from 6.83 to 14.15 and 2.54 to 2.78. These results have been obtained under different solar irradiation levels, lifetimes and performance ratios (PRs) of 1450–2200 kWh/m 2 /yr, 20–30 years and 60–80%. The research outputs demonstrate that the battery system has the highest life cycle energy and emissions impact because of its relatively shorter lifespan and the replacements over the system's lifetime. However, a sensitivity analysis reveals that the impact of the battery reduces as the lifespan increases. In addition, the GWP and the EPTs increases as the PRs are decreased, while the NERs are reduced. The significance of the study is that it reveals the effect of solar irradiation, lifetimes, PRs and the battery lifespan on the SPPG plant's environmental performance, which can be a basis for understanding solar PV life cycle impact for different locations around the world. [ABSTRACT FROM AUTHOR]

During automotive urban driving conditions and future homologation cycles, automotive radial turbines experience transient conditions, whereby the same operate at very high blade speed ratios and, thus, at very low power outputs. Under those conditions, the turbine power output might not be enough to feed the mechanical power needs of the compressor. Typical fast one-dimensional full engine simulations rely on steady-state performance maps to characterize the turbocharger. Due to the restricting compressor braking power, extreme off-design measurements cannot be obtained in standard gas stands without using an external brake instead of the compressor or without using a motor attached to the turbocharger shaft. Such turbocharger assemblies cause shaft balancing issues inherent to the connection to a brake operating at high rotational speeds or need basic changes of the turbocharger geometry. This paper presents a novel approach for turbine performance map measurements at very low expansion ratio and very low mass flow without the aforementioned issues. The method uses the turbocharger compressor as a centrifugal turbine, providing mechanical power to the shaft and enabling turbine performance measurements from points of very high expansion ratio up to very low pressure ratio. It is even possible to measure at almost zero flow rate in the turbine when it consumes shaft power instead of producing it. This experimental procedure that can be applied to whatever turbocharger produces valuable information for the development and validation of turbine performance models aiming to extrapolate its behaviour at off-design conditions. [ABSTRACT FROM AUTHOR]

In this paper, a novel compressed air energy storage system is proposed, integrated with a water electrolysis system and an H 2 -fueled solid oxide fuel cell-gas turbine-steam turbine combined cycle system. In the charging process, the water electrolysis system and the compressed air energy storage system are used to store the electricity; while in the discharging process, the H 2 -fueled solid oxide fuel cell-gas turbine-steam turbine combined cycle system and the compressed air energy storage system are set to generate electricity, achieving zero carbon emissions in the whole process. The waste heat from the exhaust air and the hot oil of the compressed air energy storage system is recycled by the feedwater of the H 2 -fueled solid oxide fuel cell-gas turbine-steam turbine combined cycle system, leading to an improvement in the energy efficiency. Based on the simulation using ASPEN Plus and EBSILON Professional, energy, exergy, economic, and sensitivity analyses were applied to evaluate the performance of the proposed system. The results show that the round-trip efficiency, energy storage density, and exergy efficiency of the compressed air energy storage system can reach 68.24%, 4.98 MJ/m3, and 64.28%, respectively, and the overall efficiency of the whole integrated system improves by 1.33%. • A CAES is coupled with a water electrolysis system and an H 2 -fueled SOFC-GT-ST system. • Using feedwater to cool the exhaust air and oil can recycle the waste heat. • System integration can achieve zero carbon emission and improve energy efficiency. • Energy, exergy, economic, and parametric analyses are deeply evaluated. [ABSTRACT FROM AUTHOR]

Inspired by traditional Chinese architecture, a curved PV roof integrated with copper indium gallium selenide (CIGS) cells is designed, which not only manifests Chinese aesthetic elements but also could generate electricity. Considering solar radiation distribution on curved PV cells different from that on traditional flat cells, this paper builds a radiation distribution model to calculate the radiation on the curved surface and an electrical model based on 5-parameter model to predict the power output of PV cells with different connections (independent output; in parallel; in series). An experimental rig was built, and the theoretical model was validated. Results showed that the CIGS cells on the west side of the curved surface performed better in electricity generation than the CIGS cells on the east side did; the CIGS cells in parallel generated more power than the cells in series did. The annual performance prediction shows that CIGS cells on the west side generate 155.18 kWh, which is 21.49% more than on the east side; CIGS cells in parallel generate 275.96 kWh, which is 12.56% more than the cells in series; The electrical generation of the curved PV roof is 7.41% less than the flat roof does. Parametric analysis is also conducted. • Simulation model of the electrical performance of a curved PV roof is built. • Different connection methods of the curved PV cells are discussed. • Impacts of some parameters on the electrical performance are analyzed. • Annual electrical performance analyses are investigated in Hefei. • Flat and curved PV roofs are compared numerically. [ABSTRACT FROM AUTHOR]

In this paper, a novel compressed air energy storage (CAES) system integrated with a waste-to-energy plant and a biogas power plant has been developed and evaluated. In the charging process, the feedwater of the waste-to-energy plant recovers the compressed heat of the compressed air in the CAES system. In the discharging process, the compressed air is heated by the energy obtained from the waste-to-energy boiler, and then replaces the compressor of the gas turbine system by burning with the biogas in the combustor directly. Via the system integration, some major equipment of a conventional CAES system can be saved, and the performance of the CAES system can be improved. Based on a 500 t/d waste-to-energy plant and a typical biogas power plant, the energy, exergy, and economic analyses of the proposed system were performed. As a result, a higher round-trip efficiency of 69.55% can be achieved, and the major exergy loss occurs in the throttle valve. Furthermore, the dynamic payback period of the proposed CAES system is 4.35 years, 4.74 years shorter than that of a conventional CAES system. Overall, the integrated system can improve the performance of the CAES system and promote the development of energy storage technology. • A CAES is coupled with a WtE plant and a biogas power plant to improve the efficiency. • The flue gas out of the gas turbine in biogas power plant is fed into the WtE boiler. • The compressed air is cooled by the feedwater for saving the heat storage equipment. • The compressed air is passed into the combustor to replace the compressor. • Energy, exergy, economic, and parametric analyses are deeply evaluated. [ABSTRACT FROM AUTHOR]

Energy internet is an effective way to fulfill carbon neutrality, since it has the advantages of high-efficiency energy utilization. As an important part in energy internet market, multi-energy transaction reflects complementarity of multi-energy sources and provides guidance for future development. However, there still lacks an effective index system for multi-energy transaction evaluation and a reliable method to flexibly handle the subjectivity and vagueness during the evaluation process. In this paper, an effective index system and its extraction method and a comprehensive evaluation approach are proposed to reliably assess the multi-energy transaction performance of the energy internet market. Firstly, an interval type-2 fuzzy decision-making trial and evaluation laboratory (IT2F DEMATEL) method and λ-adversarial interpretive structural modelling (λAISM) approach are combined to extract a 14-indicator index system, the proposed method not only investigates the interrelationship between the indicators but also calculates the influence degree between them. Secondly, to control the vagueness and uncertainty involved in expert judgement, a novel non-deterministic method, combining fuzzy comprehensive evaluation and credibility-based analytic hierarchy process (AHP) with variable rough precision theory, is developed to evaluate the multi-energy transaction performance. Finally, two real-world demonstration projects in northern and southern China are investigated for case studies. The evaluation score of the multi-energy transaction in DZZ town has improved by 25.77 from 2018 to 2021, reaching a "good" performance of 78.09; while the score of XB town has improved by 19.34, reaching an "excellent" performance of 84.32 in 2021. Comparative analysis shows that the extracted index system contains the minimum required information, and the proposed evaluation method can effectively handle the linguistic imprecision and cognition vagueness caused by expert judgements. [Display omitted] • A 25-indicator comprehensive index system is established for the multi-energy transaction evaluation of energy internet market. • An IT2F DEMATEL-λAISM method is proposed, and 14 key indicators are extracted considering causality and influences between the multi-energy transaction evaluation indicators. • A novel integrated fuzzy performance evaluation approach is proposed for multi-energy transaction evaluation. • Judgement credibility and variable rough precision theory are considered to deal with the subjectivity and uncertainty of evaluation through flexible fuzzy boundaries. [ABSTRACT FROM AUTHOR]

Anaerobic digestion is one of the most effective and environment-friendly waste management techniques. It not only treats the organic fraction of municipal solid waste, but at the same time it can be considered as one of the potent renewable energy sources due to generation of methane during digestion process. The technology is not new and has been commercialised from early 1980s. But, the data suggests that it is not still widely applied for energy recovery from organic wastes at centralised level. The reason may be poor methane yield due to operational issues and process instability. There were numerous studies already done at the lab scale, now it is the time to replicate the outcomes of lab-scale studies to the full scale plant. Further studies are required to make the anaerobic digestion techno-economically sustainable. This paper presents a detailed review of essential process parameters and identifies gaps and solutions for effective implementation of the anaerobic digestion of organic fraction of municipal solid waste. The paper also presents the effect of co-digestion, pre-treatments and inhibition on the performance of anaerobic digestion. The paper will help the readers in understanding the process, operation and control of anaerobic digestion technology. • Instability of reactor is mainly caused due to variation in process parameters. • Co-digestion is very important in process performance improvement. • Only 9.7% of the operating anaerobic digestion plant involves co-digestion. • Digestate from anaerobic digestion are not recommended for direct application on soil. • Pre-treatment improves digestion efficiency, but increases the cost. [ABSTRACT FROM AUTHOR]

In order to satisfy seasonal energy demand and to decrease energy consumption of the building during the whole year, this paper presents a hybrid BIPV/T solar wall system. In winter, BIPV/Air mode is adopted to provide space heating and generate electricity for the building. During rest of the year, system is conducted in BIPV/Water mode to create hot water and electricity simultaneously. Firstly, the experiments are conducted under each mode respectively. Secondly, mathematical models are established and verified by the experimental results. Thirdly, parameter analyses are introduced to evaluate performance of the system under different situations. The main results are: (1) Daily experimental electrical output and efficiency are 0.12 kWh & 7.6% in summer and 0.65 kWh & 12.5% in winter. (2) Based on experimental results, water tank temperature is over 40 °C in summer, and the average temperature of the experimental room is 18.6 °Cin winter. (3) The optimal water flow velocity in summer is proved to be 0.04 L/s by parameter study. (4) The system is able to achieve passive space cooling in summer. (5) Based on simulation analysis, the system can provide space heating efficiently in winter. • This paper introduces a hybrid BIPV/T solar wall system to satisfy the building's annual demand. • Experiments are conducted in BIPV/Water and Air mode, respectively. • Mathematical models are established and verified by experimental results. • System's performance in different situations are investigated under different working modes. [ABSTRACT FROM AUTHOR]

The analysis of the degradation of thin-film single junction a-Si PV (photovoltaic) modules and its impact on the output power of a PV array under outdoor long term exposure located in Jaén (Spain), a relatively dry and sunny inland site with a Continental-Mediterranean climate is addressed in this paper. Furthermore, a new procedure of solar cell model parameters extraction experimentally validated is presented. The parameter extraction procedure allows obtaining main model parameters of the solar cells forming the PV array from monitored data of the PV system in real operation of work. Results obtained of the evolution of each one of the solar cell model parameters along the PV system outdoor long term exposure campaign are analysed in order to achieve a better understanding of the performance changes of the PV modules and the behaviour of the output power of the PV array. [ABSTRACT FROM AUTHOR]

This paper presents a high spatial resolution based method for design and operation of a low temperature district heating system and evaluates its feasibility and energy and exergy performance through case comparison. Selected case area is existing district in North Japan. The district heating system design and operation follows a bottom-up approach. The study scope takes into account the demand side, distribution and supply side where biomass CHP (combined heat and power) plant is selected as main supply source. Radiating floor heating system model is used to estimate building temperature requirement. Results indicate that low temperature heating is infeasible for non-residential buildings in North Japan at high loads. Improving building insulation decreases heating quality demand considerably. Low temperature district heating performs better than medium temperature, especially in terms of exergy efficiency, however requires a bit larger pipe diameter indicating cost trade-off between installation and operation cost. Implementing cascade configuration based on quality level of building energy demand results in highest system performance. Lower network temperature provides least net primary energy consumption primarily due to higher electricity generation of CHP plant. This transcends to favourable system exergy efficiency of low temperature operation due to high quality of electricity, increasing the exergy of the product. [ABSTRACT FROM AUTHOR]

Energy security ranks high on the policy agenda of many countries. Accordingly, to provide policy guidance, a large and growing body of literature has proposed metrics to measure security of (primary) energy supply which are then applied in cross-country energy security assessments. In general, the data used in these assessments are based on production-oriented energy accounting frameworks. In doing this, these studies neglect additional indirect foreign energy consumption – i.e. consumption of energy embodied in traded goods. This paper highlights this issue. It provides and applies a methodology that allows including indirect foreign energy consumption into commonly used energy security indicators. In particular, it shows that the inclusion of foreign primary energy embodied in traded goods does not only change values of energy security indicators but also alters perceptions on regional energy security performance over time as well as relative to other regions' performance. [ABSTRACT FROM AUTHOR]

Due to the intermittence and fluctuation of wind resource, the increasing penetration level of wind power will bring huge challenges to maintain the stability of power system. In order to smooth the wind power output, additional controllable power from conventional power plant or energy storage system is required. In current paper, one basic scheme of liquid carbon dioxide storage system is proposed. The parametric analysis is conducted to examine the effect of some key thermodynamic parameters on the performance of this scheme. Subsequently, the basic scheme is improved according to the results. The mathematical models of two improved schemes are developed and the performance analyses are conducted. According to the results, the optimal scheme and configuration are determined. After optimization analysis and comparison analysis, compared to the other energy storage systems, the round trip efficiency of Scheme 3 is acceptable in consideration of the energy generated per unit volume of storage. As a conclusion, the optimal scheme has a good potential for storing wind power in large scale and offers an attractive solution to the challenges of the increasing penetration level of wind power. [ABSTRACT FROM AUTHOR]

In this paper, a novel self-adaptive anode feeding pattern is introduced to optimize the output and the dynamic response of the μDMFC (micro direct methanol fuel cell). The RSM (response surface methodology) is applied to optimize the anode flow rate, with two input parameters considered in this study, i.e., the methanol concentration and the operating current. In addition, the hardware circuit of anode self-adaptive supply system is realized based on the calculation results from RSM. Furthermore, the tests of system functionalities, including the pulse control test of micro peristaltic pump, the current collection test, and the flow rate monitoring of the self-adaptive feeding module are conducted. Finally, a metal-based μDMFC is designed and fabricated to evaluate the output performance when the cell patterned with or without the self-adaptive system. The experimental results reveal that the novel feeding pattern can increase the output voltage under different operating conditions, and reduce the voltage response time during the current transition. [ABSTRACT FROM AUTHOR]

This paper presents the parametric optimization and performance analysis of ORC (organic Rankine cycle) system using GA (genetic algorithm) for recovering exhaust waste heat of a diesel engine. First, the effects of three key parameters, including evaporation pressure, superheat degree and condensation temperature on the system performances are conducted with POPA (net power output per unit heat transfer area) and EDR (exergy destruction rate) as objective functions. The optimal evaporation pressure, superheat degree and condensation temperature corresponding to the maximum POPA and the minimum EDR are provided under engine various operating conditions. Subsequently, as a key component of the ORC system, the performance of a fin-and-tube evaporator used in this ORC system is evaluated. The results show that the optimal evaporation pressures are mainly influenced by the engine operating conditions, whereas the superheat degree and the condensation temperature present a slight variation over the whole operating range. Furthermore, the PPTD (pinch point temperature difference) in the evaporator may occur at different positions with the variation of engine operating conditions. At engine maximum rated power point, the ORC system can achieve maximum POPA of 0.74 kW/m 2 , and the ratio of maximum effective heat transfer area to actual area of the evaporator is 69.19%. [ABSTRACT FROM AUTHOR]

This paper deals about an experimental application of an ORC (organic Rankine cycle) in a ceramic industry for low grade waste heat recovery. The ORC module used in this application was initially designed and constructed to satisfy the main specifications for an efficient power system, highlighting a volumetric expander with large built-in volume ratio. Furthermore, the performance of the ORC was experimentally characterized in a test bench in a previous work, achieving a maximum gross electrical efficiency of 12.32%. Taking this as a starting point, the aim of this work is to verify the performance of this ORC operating in actual industrial conditions, besides to profiting the information extracted from the application to assess its profitability. For this, the system performance is experimentally characterized in the industry, discussing and comparing the results obtained to laboratory data. From these experimental results a model of the system is developed, which allows predicting the net electrical production of the system along a typical year of operation and quantifying the energy and environmental benefits of the project. Moreover, from the electrical generation, investment costs required and industrial electricity price, a feasibility study is conducted to address the profitability of the application. [ABSTRACT FROM AUTHOR]