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Abstract Renewable energy is built as the future of energy value chain. In particular, solar energy is being utilized at a faster pace than ever. The problem sometimes occurs that large scale Floating Solar PV (FSPV) plants have to be developed, away from the population which adds to the cost of transmission and distribution. Floating Solar PV plants have recently gained traction as a suitable alternative of ground based large scale PV installation. FSPV, not only utilizes the water as real estate, but it has a number of other advantages. For example, FSPV could utilize the existing transmission and distribution infrastructure that is the part of hydroelectric power plant anyways. In this paper, we analyze hydro-FSPV combination on a small dam in Pakistan. Our results show that FSPV could complement the existing hydroelectric production and could provide electricity in conjunction with the existing generators of the hydroelectric plant. Furthermore, we also discuss options of integrating FSPV with the existing electrical infrastructure of Ghazi Barotha Dam. [ABSTRACT FROM AUTHOR]

Abstract Adsorption desalination is an attractive and potentially competitive method of desalination among the conventional thermal desalination methods due to its ability to produce both freshwater and cooling effect. This desalination cum refrigeration system uses a low-grade heat from the solar collector to generate water vapor from the adsorber. The system employs a combined flash evaporation and thermal compression to produce potable water and cooling. In this paper, the operating and performance parameters of an adsorption desalination system has been studied. The analysis is based on the energy conservation principle applied to all processes of the theoretical cycle. The Dubinin-Astakhov model is used to describe the adsorption characteristics of the adsorbent-adsorbate pair (silica gel-water). The cycle is analyzed using the performance parameters such as fresh water production, energy consumption per kg of water produced and coefficient of performance. [ABSTRACT FROM AUTHOR]

Abstract The solar thermoelectric generation（STEG）cogeneration system can provide heating and electric power simultaneously. Precedent studies on the STEG system were focused on getting higher electrical efficiency of the system and creating a new record. Optimization of thermal performance and evaluation of thermal efficiency are usually completed by calculation or numerical simulation. In this paper, a novel design of STEG cogeneration system was proposed. The system can work in three modes according to seasonal demand of hot water and electric power. A series of experiments were carried out in different working modes under variable conditions to evaluate the performance of the system. The results show that the system can generate 0.2 kW·h of electrical energy and about 100L of hot water at 41 °C in 1 day when solar irradiation is 1000 W/m2. The collector efficiency and electrical efficiency are calculated to be 42.2% and 2.1%, respectively. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a numerical study on the effect of different operating conditions (excess air coefficient, in-furnace pressure and air ratio in zone 5) on a woodchip grate-firing boiler. First, the numerical modeling approach is validated with experimental measurement of in-furnace temperature as well as exhausted gas emissions. Subsequently, parametric studies are carried out using the validated numerical modeling approach. The modeling results indicate that, the boiler overall efficiency can be improved through adjusting the values of the operating conditions of interest. It is suggested to improve the boiler efficiency through reducing excess air coefficient, increasing in-furnace pressure and enhancing ash cooling in zone 5. [ABSTRACT FROM AUTHOR]

Abstract Primary treatment is a major component in modern sewage treatment systems; and chemical enhanced primary treatment (CEPT) process can further enhance its performance for energy recovery or process improvement. With significant benefits on small footprint and sludge dewaterability, CEPT process has been selected and applied as the major wastewater treatment technology in Hong Kong. CEPT sludge, similarly in composition to typical primary sludge, is rich in organic contents and therefore can serve as a proper source for bioenergy production after anaerobic digestion (AD). The heating value of CEPT sludge can be higher than that of secondary sludge, which is mainly composed of slowly degradable organics and microorganisms. If neglecting energy consumed to produce the coagulant a CEPT-AD system shall drive the wastewater treatment process from energy-negative practice to energy-neutral or even energy-positive systems. This paper demonstrates some of the most important substrate-related features to increase the bioenergy production in the CEPT-AD system. Attentions have been paid particularly on the analysis of physiochemical characteristics of the CEPT sludge and their impacts to the biological system with heterotrophic species. An innovative sulfide oxidation process was presented with experimental evidence to overcome the potential problems of sulfide induced growth inhibition of methanogens. It was expected that the new process could reduce approximately 0.744 kWh/m3 of energy consumption in comparing with conventional activated sludge process without nutrient removal. [ABSTRACT FROM AUTHOR]

Abstract With the access of the renewable DGs such as wind turbines and photovoltaic generations, network operation state is uncertain due to the randomness of these renewable DGs. This paper proposes a novel optimal method of the active distribution network (ADN) considering the uncertain conditions and the coordination control of source-network-load. By optimizing the controllable distributed power output, controlling the network switches, and managing the demand-side load synchronously, the impact of distributed renewable energies can be reduced and the reliable operation of ADN can be ensured. The chance constrained programming is used to deal with the uncertainties. The proposed model is settled by the improved teaching-learning-based optimization algorithm (ITLBO) and the performance of the algorithm is verified by the comparison with the TLBO in the modified IEEE 33-bus distribution system. [ABSTRACT FROM AUTHOR]

Abstract Liquid desiccant regeneration is an important part of liquid desiccant air conditioning system and consumes the majority of the system's power. Conventional methods for liquid desiccant regeneration use thermal energy to regenerate the liquid desiccant. One of the biggest problems for thermal regeneration is that the liquid desiccant should be cooled down before dehumidification. Furthermore, the efficiency for liquid desiccant regeneration drops under high temperature and humidity climates. In comparison, electrical regeneration, such as electrodialysis (ED), may solve the problems above. No phase change is involved in this process. In addition, low electrical energy is required and photovoltaic power is capable of proving the necessary energy. In this paper, the performance of liquid desiccant regeneration by photovoltaic electrodialysis (PV-ED) was experimentally investigated by considering two important factors, including the initial desiccant concentration and current intensity. The results showed that the initial desiccant concentration and current intensity had big impact on the performance of the system. Lower desiccant concentration and higher current intensity contributed to the current efficiency and solute transport, respectively. In addition, the energy consumption per unit solute migration increased with the increase of both current intensity and desiccant concentration. The results also indicated that the PV-ED regenerator performed better when the initial desiccant concentration was low and current intensity was high. [ABSTRACT FROM AUTHOR]

Abstract This paper deals with two main aspects of Photovoltaic systems. One is the analysis of Photovoltaic panel using the datasheet values provided on the PV panel and the other is to find the exact values of parameters of PV panel. Characterization of PV panels refers to the ability to predict the panel's output for given ambient conditions. To predict the exact characteristics and for exact mathematical modeling of PV panel, it is essential to find the parameters of the solar panel rather than assuming the parameters in modeling. One of the objectives of this study is to find the parameters like series resistance and shunt resistance values in single diode model by analyzing the relationship between different parameters. The analyzing process will cover the parameter estimation from the given datasheet parameters of solar panel, and mathematical algorithm involved in finding the solar panel parameters. [ABSTRACT FROM AUTHOR]

Abstract Accurate and efficient parameter extraction of PV models from I-V characteristic curves is significant for modeling, evaluation and fault diagnosis of PV modules/arrays. Recently, a large number of algorithms are proposed for this problem, but there are still some issues like premature convergence, low accurate and instability. In this paper, a new improved shuffled complex evolution algorithm enhanced by the opposition-based learning strategy (ESCE-OBL) is proposed. The proposed algorithm improves the quality of the candidate solution by the opposition-based learning strategy. Moreover, the basic SCE algorithm evolves with the traditional competition complex evolution (CCE) strategy, but it converges slowly and is prone to be trapped in local optima. In order to improve the exploration capability, the complex in the basic SCE is evolved by a new enhanced CCE. The ESCE-OBL algorithm is compared with some state-of-the-art algorithms on the single diode model (SDM) and double diode model (DDM) using benchmark I-V curves data. The comparison results demonstrate that the proposed ESCE-OBL algorithm can achieve faster convergence, stronger robustness and higher efficiency. [ABSTRACT FROM AUTHOR]

Abstract Material properties and surface morphology of nanostructures have impact on optical characteristics of nanostructures. More and more arrays of nanostructures are investigated to regulate and control surface radiation characteristics. However, the majority of the object surfaces are random rough surfaces in daily life, the radiation characteristics of which are widely used in various fields including remote sensing, photovoltaic utilization and thermal control. Therefore, the radiation characteristics of random rough surfaces are important for both academic research and practical applications. In this paper, a recombination random nanostructure consisting of conical structures and nanopores based on silicon substrate was prepared by plasma etching and chemical corrosion. The three-dimensional coordinate data of the recombination structure surface are obtained by atomic force microscopy, the radiation characteristics of the recombination random nanostructure is investigated by numerical calculation and experimental measurement, which has excellent antireflection characteristics over 300nm-1100nm. The influence of the incident angle and polarization state on the radiation characteristics are analysed. [ABSTRACT FROM AUTHOR]

Abstract This paper presents an overview of state-of-the-art in single- and multistage wood biomass gasification technologies and assesses their economic efficiency. We compare the cost of electricity generated through the use of different types of fuel (gas, diesel, coal, wood chips and wood pellets) and show that the most promising technology for processing biomass is multi-stage gasification. [ABSTRACT FROM AUTHOR]

Abstract Building energy systems are gradually changing from a single form of conventional energies to a multi-energy system that usually includes multiple renewable energy sources. The poor reliability and controllability of renewable energies are likely to cause mismatches between supply and demand, which significantly affect the energy efficiency of the whole building. This paper proposes a systematic methodology for the design optimization of building energy systems integrated by a multiple renewable energy source. A unified mathematical model of multi-energy systems is established based on the concept of energy-hub, in which the core idea is to use a matrix approach to standardize the unified modeling of a variety of building energy processes including energy generation, energy utilization and energy storage. The operating performance of system with different energy sources mixes and system configurations can be effectively predicted. Lifecycle total cost of the entire system, mainly consisting of initial cost and operating cost, is used as the objective function to identify the best design scenarios for sustainable building development. A case study is conducted on the application of the proposed method for optimal design of a typical hybrid renewable energy system in Beijing. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a dynamic stall model to predict the unsteady airloads on wind turbine airfoils. The proposed model is based on the Beddoes-Leishman (B-L) model and modifications are carried out for wind turbine applications. The lift, drag, and pitch moment of the S809 airfoil oscillating in stall-development and deep-stall regimes are predicted. Validation against available experimental data shows overall good agreement. [ABSTRACT FROM AUTHOR]

Abstract Distributed energy storage system (DESS) is an effective way in adapting to increasing penetration of distributed generations (DGs) and will play an important role in the operation of active distribution networks (ADNs). However, the high capital cost and limited life cycles restrict the further development of DESS. In this paper, an operational strategy based method for economic evaluation of DESS is proposed. Firstly, rate of return is set as the economic evaluation index. Then, the economic operation model is established. By applying convex relaxation, the original nonlinear programming (NLP) model is converted into an effectively solved second-order cone programming (SOCP) model. Finally, the effectiveness of the economic evaluation method is verified on the modified IEEE 33-node test feeder. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the microwave-assisted oil extraction from Aegle marmelos Correa seed. The oil extraction process parameters were optimized based on response surface methodology considering acetone and heptane as solvent and the effect of solvent polarity on oil yield were also studied. The optimized results reveal that oil extraction by MAE method was more efficient than maceration method. The maximum oil extraction yield 42.6% was obtained for the following optimized conditions: the solid-liquid ratio of 1:8, irradiation power of 340 W and at 20 min. Thermodynamic activation energy and enthalpy required for the oil extraction are found to 16.428 kJ/mol and 13.543 kJ/mol respectively. Biodiesel yield of 93% was obtained by undergoing microwave transesterification with 1:6 oil to methanol ratio, 60 ºC reaction temperature and 0.5 wt.% catalyst at 10 min. Physicochemical properties of biodiesel were evaluated as per EN 14214 and ASTM D6751 standards. It has been found that Aegle marmelos Correa seed oil could be a suitable source for biodiesel production to meet the future energy demand. [ABSTRACT FROM AUTHOR]

Abstract Significant progress has been made in transparent thermal insulation coating by various effective materials in recent years. More recently, Low-E coating, as a high reflection coating, has been applied in many buildings, but the coating would cause light pollution due to visible light reflection, resulting in prohibiting use in many countries. Hence, a novel transparent thermal insulation coating based on ATO/Black TiO2 is proposed in this paper. The bilayer coating exhibited a high near infrared light blocking rate of 86%, and the visible light transmittance was about 62%. Meanwhile, the structural thin films had excellent photocatalytic property, which could degrade approximately by 45% of methylene blue in 3 hours under fluorescent lamp. The double layered coating had shown a water contact angle of lower than 5° after activating. Overall, these structural films show a great potential for applications in energy conservation windows. [ABSTRACT FROM AUTHOR]

Abstract We design a hybrid multi-criteria decision-making analysis (MCDA)-based framework to evaluate competing alternative jet fuels (AJFs). Our analysis on AJFs is based on a wide range of criteria with different forms of data and relations and reflect stakeholders' view and opinions. This contrast with conventional cost-benefit analysis which typically focuses on the economic benefits at the expense of environmental, technological and social aspects. Our work adds value to understand developing technologies to date, technical barriers to commercialization, other development drivers such as the availability and willingness of financial institutions to finance, businesses to invest in AJFs productions and its supply chains in the UK, policy support and regulation, and likely commercialization and scale-up potentials. By focusing on motives, attitudes and stakeholders rather than merely the technical and economic aspects of AJFs, our paper makes an important contribution to the field. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the combustion behavior of the in house developed Porous Radiant Burner (PRB) applicable in industrial incinerators or bio-medical solid waste disposal systems. The PRB developed to operate in the range of 5-10 kW firing rate is of double layer porous media technology. These layers are composed of Silicon Carbide (SiC) and Alumina (Al 2 O 3) porous matrices which acts as the combustion and preheat zones, respectively. Keeping the geometric parameters of the burner constant, this work investigates the performance of the newly developed PRB in terms of its emission characteristics and combustion efficiency. This is done by varying the firing rate (5-10 kW) and the equivalence ratio (ϕ) within the stable operating range of 0.75 - 0.97. To obtain a comparative analysis, the tests were also performed in a Conventional Burner (CB) using the same variables. Study suggests that because of the possibility of lean combustion in PRB, the pollutant emission from such burners are quite low as compared to its counterpart. Results shows improved combustion efficiency and a decrease of 95% and 85% CO and NOx values, respectively, from biogas combustion in the newly developed PRB. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates the analysis of a terrain characteristics parameter which is responsible for the accurate wind resource estimation for a site. In this paper, the effect of terrain dependent parameters such as Wind shear exponent, Roughness Index, RIX (Ruggedness Index factor) and roughness length has been discussed for a site in Central India Region. Whole one year measured met mast wind data has been taken using anemometer and wind vane at 10 m and 25 m height respectively above ground level. The digitized elevation and roughness model of the corresponding site shows the roughness class 4 (roughness length 1.2525m). The wind data has been extrapolated up to 80m height by using power and log law models which provide the power density near about 120 W/m2. As per the micro sitting guidelines for the virtual wind farm installation 5D X 7D mapping has been selected which Indicates the total power output by installing 8 Vestas V- 90 1.8 MW wind turbine from WAsP is 31.561 GWh and from windPRO is 28.083 GWh. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a thermoeconomic analysis of a solar combined heating and power (S-CHP) system based on hybrid photovoltaic-thermal (PV/T) collectors for the University Sport Centre (USC) of Bari, Italy. Hourly demand data for space heating, swimming pool heating, hot water and electricity provision as well as the local weather data are used as inputs to a transient model developed in TRNSYS. Economic performance is evaluated by considering the investment costs and the cost savings due to the reduced electricity and natural gas consumptions. The results show that 38.2% of the electricity demand can be satisfied by the PV/T S-CHP system based on an installation area of 4,000 m2. The coverage increases to 81.3% if the excess electricity is fed to the grid. In addition, the system can cover 23.7% of the space heating demand and 53.8% of the demand for the swimming pool and hot water heating. A comparison with an equivalent gas-fired internal combustion engine (ICE) CHP system shows that the PV/T system has a longer payback time, i.e., 11.6 years vs. 3 years, but significantly outperforms the ICE solution in terms of CO 2 emission reduction, i.e., 435 tons CO 2 /year vs. 164 tons CO 2 /year. These findings suggest that even though the economic competitiveness of the proposed PV/T S-CHP system is not yet favourable when compared to the alternative gas-fired ICE-based system, the S-CHP solution has an excellent decarbonisation potential, and that if this is of importance in the wider sense of energy-system decarbonisation, it is necessary to consider how the higher upfront costs can be addressed. [ABSTRACT FROM AUTHOR]

Abstract Biomass drying has always been a big issue in biomass thermal treatment. Especially in pyrolysis, combustion and gasification, water evaporation is a necessary step before other reactions can take place. This paper presents a detailed drying for single poplar particle pyrolysis under nitrogen. In this model, the transport equations are numerically solved using finite volume method to obtain the pressure, temperature and species fractions. Two different water contents found from literature are applied to test the model. The result shows that this numerical model can predict water behavior during biomass drying process of pyrolysis. [ABSTRACT FROM AUTHOR]

Abstract The paper introduced a smart renewable energy based microgrid system which is composed of three subsystems: solar photovoltaic subsystem, air source heat pump subsystem and energy storage subsystem. This microgrid system was applied to the demonstration project located in Xining City, Qinghai Province, China. The energy performance of the smart renewable energy based microgrid system was evaluated and compared with that of traditional energy supply system which totally depends on the electricity grid and natural gas. The comparison study demonstrates that the proposed hybrid energy supply system is superior to traditional system, significantly decreasing additional energy consumption for buildings and reducing pollutant emissions. [ABSTRACT FROM AUTHOR]

Abstract Air pollution and increased CO 2 concentration in atmosphere and other energy related issues caused a transformative shift in energy system which contributes to increased utilization of renewables as alternative to generate green energy carriers. The potential of renewable resources in different region and potential energy conversion have been largely considered by many researcher in many countries. The energy conversion technologies to produce heat, electricity, and transportation fuels have made impressive technical advances. Sweden has also been challenging with mitigation of CO 2 emission and trying to shift into a fossil fuel free system in all energy sectors. This paper deals with the current status of fuel demand and supply in the transport sector in a County in Sweden. A scenario for a fossil fuel free transport sector at a regional level is developed to investigate the potential biofuel production from regionally produced straw. The results and analysis indicate that the potential for cereal based bioethanol production in the region is sufficient to meet the biofuel demand of the County. Using the fallow land for cereal cultivation, it is feasible to shift into a fossil fuel free transportation system where all passenger cars are fueled by bioethanol. The results and finding from the current paper will be used to develop further study on optimization of local biofuel production integrated with CHP plants considering application of other feedstock such as municipal wastes. [ABSTRACT FROM AUTHOR]

Abstract As a CCHP (combined cooling, heating and power) system becomes more and more complicated, the optimization of capacity configuration and operation strategy turns into a critical issue. In this paper, we put forward a two-layer programming approach which can solve the optimal design and dispatch problem simultaneously. On the first layer, stochastic selection algorithm (SSA) and non-dominated sorting genetic algorithm-II (NSGA-II) are both used to solve the design problem including the optimization of equipment type and capacity, with the goal of minimizing the total lifecycle cost and the pollutant emissions. On the second layer, mixed-integer linear programming (MILP) algorithm is applied to explore a dynamic optimal scheduling scheme, and achieve the lowest operating costs, based on hourly analysis of load characteristics through a whole year. The first layer optimization is based on the optimal results of the second layer. A modelling analysis case of a hospital CCHP system in Chongqing, China is carried out. The economic and environmental goals of Pareto optimality are achieved by applying the two-layer optimization method. The results comparison between SSA and NSGA-II indicates that the former algorithm is much easier and faster, and proofs that the proposed method is reliable. [ABSTRACT FROM AUTHOR]

Abstract This paper reports numerical investigation on combustion characteristics, NO and CO emission for the optimization and simulation of gas instantaneous water heater operation with partial premixed combustion. A 3D model in real dimensions is performed using Computational Fluid Dynamics (CFD) to simulate the gas instantaneous water heater, including burner, combustion zone and heat exchanger. Comparisons between numerical and experimental results show that the simulation can predict flow field, temperature field, NO and CO concentration fields in the gas water heater with acceptable accuracy. The effects of fire holes distribution primary air coefficient, air ratio on NO and CO emission are all investigated. [ABSTRACT FROM AUTHOR]

Abstract CO 2 heat pumps have drawn a great deal of attention owing to their advantages of high efficiency and environmental friendly for heating water under low ambient temperature. However, the system performance is not desirable and shows a lower COP for space heating, especially for a radiator as heating terminal, due to the higher inlet water temperature at the gas cooler, which causes a large throttle loss when the refrigerant flow through the throttling device. To tackle this issue, a transcritical CO 2 heat pump system integrated with thermal energy storage (TES) systems was developed in this paper. The heating performance of the proposed system was investigated using TRNSYS 17.0 based on a typical single family rural house located in Beijing, China. The results showed that the heating capacity and energy consumption decreased by 21 and 24%, respectively, and the heating seasonal performance factor (HSPF) of the proposed system increased by 4% in comparison with the baseline system (without TES) during the entire heating period. It has been proved that the proposed system showed a better performance for space heating with a radiator terminal at low ambient temperature. [ABSTRACT FROM AUTHOR]

Abstract A polymer electrolyte fuel cell (PEFC) produces electrical energy thanks to the electrochemical reaction carried out inside the cell. During the energy conversion, water molecules are also produced in the cathode side and this can affect the diffusion parameters of the gas diffusion layers (GDLs). The generated water-drops due to the reaction may block the reactant gases and produce material oxidation. The mentioned phenomena influence the performance of the PEFCs. This paper aims to describe and quantify the impact on diffusion parameters of GDLs when the presence of formed water-drops inside the layer is considered. This study considers digitally generated GDLs, and the parameters considered are porosity, gas-phase tortuosity and diffusibility. The fluid flow behavior through the three-dimensional porous domain representing the GDL is obtained by using the lattice Boltzmann method (LBM). Depending on the water-drop size, the impact over the mentioned parameters can be computed. For the current study, a single water-drop has been placed into the GDL domain and its impact has been analyzed. [ABSTRACT FROM AUTHOR]

Abstract The diversity of both organic fluids and performance criteria makes the selection and evaluation of working fluids for organic Rankine cycles (ORCs) full of challenge. To overcome this challenge, this paper first reports on second-law-based analytical expressions for thermal efficiency and a turbine size parameter, which reveal key dimensionless parameters relating to operating temperatures and thermodynamic properties of organic fluids. This paper systematically screens more than 70 working fluids involving a wide range of physical and chemical properties. This study shows that specific turbine size generally increases with critical temperature, reduced ideal gas heat capacity, and the atom number of working fluids. Different-family fluids may lead to ten-fold relative differences in specific turbine size even though they have the same atom numbers. The thermal efficiency of ORCs appears to be independent of critical temperature, or at most, a weak function of critical temperature for low boiling point wet fluids and other halocarbons. This is a result of Jacob number being independent of or dependent weakly on the critical temperature of organic fluids such as alkanes, alkenes, and benzenes. [ABSTRACT FROM AUTHOR]

Abstract The free-piston gasoline engine linear generator (FPELG) is linear type power device, which couples a linear internal combustion engine and a linear electrical generator together. Free-piston gasoline engine is commonly modeled using simplified zero-dimensional models. In this paper, parametric analysis of a dual-piston type FPELG is presented, aiming to find the piston operation characteristics and the performances of the FPELG during the generating process. Model validation was undertaken with the test data from a running prototype, which showed good agreement. The results show that with fixed stroke, lower moving mass would lead to higher indicated power. With fixed moving mass, shorter stroke would make higher indicated power. The FPELG was observed to be operated at high load, and it was prone to operate at relative low speed. The influence of combustion parameters, i.e. the ignition timing and the combustion efficiency to the FPELG engine performance were also investigated respectively. [ABSTRACT FROM AUTHOR]

Abstract Fuel cell based combined heat and power systems (FC-CHP) are a promising technology which can provide efficiently both electrical power and heat to residential and industrial consumers. However, FC-CHP system are typically complex in nature where much of the complexity arises from the necessary subsystems to operate the FC itself. This paper proposes a cost effective experimental emulator that acts like a real FC-CHP system by generating its key output characteristics while avoiding the complex component design of the real system. It achieves this by using two separate electrical circuits – One known as the Heat Emulator (HE) to emulate the waste heat characteristics and another, known as the Electric Power Emulator (EPE) to emulate the electrical power generation. Both circuits involve a controllable voltage source and a resistive load. A digital controller is then pre-programmed with an accurate FC model and its role is to control the source voltage and/or load resistance in the HE and EPE circuits such that these two circuits generate accurately the FC stack's output characteristics. The HE circuit and a liquid cooling system is specifically implemented and water temperature control is used to study this system's thermal efficiency. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the effects of hydrogen blending radio and EGR rate on combustion and emission characteristics of a PFI gasoline engine with hydrogen direct-injection have been investigated by numerical modeling methods using a new generation of CFD simulation software CONVERGE. Results showed that compared with original engine, hydrogen direct-injection PFI gasoline engine had a better performance on combustion characteristics, but it also had a disadvantage of increasing NOx emissions. With the increase of hydrogen blending radio, combustion duration shortened and CA50 advanced and was closer to TDC. And CO and THC emissions decreased, however NOx emission increased. The variations of the combustion and emission characteristics followed by the increase of the EGR rate were exactly the opposite to the change of hydrogen blending radio. Considering both the combustion and emission characteristics, using moderate EGR rate (15%~20%) under high hydrogen blending radio (15%~20%) condition can realize the simultaneous improvement of combustion and emission performance. [ABSTRACT FROM AUTHOR]

Abstract Air conditioning in buildings has transformed our human lives greatly with work efficiency in commercial buildings and improved lifestyle in all weather. However, these improvements are accompanied with the negative effects from the emissions of greenhouse gases (GHG), both directly via refrigerant emissions and indirectly through electricity generation by the burning of fossil fuels. Although there were significant improvements in the efficacy of chillers since 2000, the kW/Ron of chillers for cooling for electrically driven DCS have reached an asymptotic level of 0.85±0.03 kW/Rton for the tropics and a 20% higher for the hot and dry arid climate. The levelling-off phenomenon of chillers' energy efficiency is attributed the improvements limits exploited from the efficacy of compressor and refrigerant technologies. Thus, an out-of-box solution, such as the decoupling of latent to sensible cooling in the dehumidification cum the indirect evaporative coolers (DH-IEC) to improve energy efficiency, It is projected that a quantum jump of 0.5 kWh/m3 or less is urgently needed for future sustainable cooling. In this paper, we adopted a top-down approach in evaluating the upper-bound energy savings of an economy if one were to employ the innovative DH-IEC cycle is assumed to be applied to the Singapore city state is highlighted with respect to the savings in the primary energy, emission of CO2 and the water savings of up to 40 % can be potentially achieved. [ABSTRACT FROM AUTHOR]

Abstract As a high-performance power cycle, S-CO 2 cycle has drawn a lot of attention in various energy utilization field. As one of the clean and efficient forms for coal utilization, coal-fired power plants still need novel power generation systems to have rational use of coal. So, it is necessary to explore the characteristic when a coal-fired power system integrated with S-CO 2 cycle. However, this application is confronted with many challenges related to boiler, such as pressure drop problem due to large mass flow rate and residual heat problem due to narrow CO 2 temperature difference. Focus on the residual heat problem, in this paper, a coupling analysis model between boiler and reheat S-CO 2 cycle is established. The proposed system consists of a thermal-hydraulic calculation module in boiler, a residual heat treatment module in tail flue and a thermodynamic calculation module of S-CO 2 cycle. The three modules can make the calculation results more credible for cycle characteristics. All the modules are programmed by Fortran. Base on the analysis result, the residual heat problem can be solved by raising turbine inlet pressure. But when turbine inlet temperature is higher, the turbine inlet pressure will be raised unacceptable. By adding a flue gas cooler (FGC), above limitation will be removed. So, in a certain temperature range, adding an FGC is a simple and effective way to solve residual heat problem. [ABSTRACT FROM AUTHOR]

Abstract The membrane liquid desiccant dehumidification has been proposed to resolve the carry-over problem of the conventional liquid desiccant dehumidifiers (e.g. packed-bed, spray chamber, etc.). Many earlier studies have been devoted to developing different types of membranes and investigating the operating conditions to achieve sufficient dehumidification performance. However, the key governing factors that control the dehumidification process have never been explored and their impacts remain uncertain. In this paper, a dimensional analysis of the cross-flow flat-plate membrane liquid desiccant dehumidifier is carried out to promote in-depth understanding of the fundamental dehumidification process and to investigate its dominant physical mechanism. A membrane liquid desiccant dehumidifier prototype has been developed and tested under different conditions. A 3-D CFD model is formulated to predict the heat and mass transfer performance of the dehumidifier, and its dimensionless form is developed via an appropriate scaling analysis. The relative importance of the relevant dimensionless groups in the dehumidification process is discussed, and correlations are developed to predict and optimize the dehumidified air conditions. [ABSTRACT FROM AUTHOR]

Abstract Moderate or intense low-oxygen dilution (MILD) combustion is a promising technology for reducing pollutant emissions while maintaining high thermal efficiency. Recently, MILD combustion has been expected to be applied in combination with oxy-fuel combustion for carbon capturing and storage (CCS). This paper presents a numerical study of methane MILD combustion in O 2 /N 2 , O 2 /CO 2 and O 2 /H 2 O, in order to deepen the knowledge to the combined form, namely oxy-MILD combustion. Firstly, steady computational fluid dynamics (CFD) simulation was carried out inside a closed lab-scale MILD combustion furnace following the previous experiment conducted in O 2 /N 2. Detailed in-furnace temperature and species data as well as laminar flame speed were used to validate the CFD models and the chemical reaction mechanism. Subsequently, flame structure and turbulence/reaction interaction were examined under the three atmosphere conditions. The results suggest that oxy-MILD (diluted with either CO 2 or H 2 O) combustion exhibits larger reaction zone and higher likelihood to be operated under distributed reaction regime in comparison with air-MILD (diluted with N 2). Specifically, CO 2 is the most preferable diluent among N 2 , CO 2 and H 2 O to achieve MILD combustion regime. [ABSTRACT FROM AUTHOR]

Abstract The performance of thermodynamic cycle strongly depends on the properties of working fluids. A gas-fuelled hot water system based on coupling of an organic Rankine cycle and an air source heat pump cycle (ORC-ASHP) was investigated in this paper. This system is integrated with a gas burner to provide heat for ORC. The power generated in ORC is used to drive the air source heat pump cycle. Comparisons on the system performance are presented for seven different organic working fluids, with emphasis on the effect of thermodynamic properties of the working fluids. In terms of fuel-to-heat efficiency, benzene, toluene and cyclohexane have better performance for the high temperature heat source. The results indicate that working fluids presenting higher decomposition temperatures shows a higher fuel-to-heat-efficiency. When benzene is used as working fluids, the fuel-to-heat efficiency reaches 161.7% and 139.47% to provide 50 °C and 65 °C hot water respectively. [ABSTRACT FROM AUTHOR]

Abstract Based on the porous theory, a three-dimensional model is presented in this paper to study heat and mass transfer characteristics of moisture soil, which was considered as unsaturated porous media. Compared with saturated model and experiment results, the simulation is validated on the heating mode of the heat pump system. The distribution of the geo-temperature is predicted by using the model. Moreover, the evaporation especially surface evaporation is taken into account. The influencing factors such as soil saturated moisture content, soil actual moisture content and wind velocity are also studied in simulation. The results show that the evaporation has a great impact on the soil temperature field. Under the surface evaporation effect, the soil temperature decreases quickly in soil exothermic process and increases slowly in the recovery process. As the soil moisture rate and wind velocity increasing, the soil temperature falls quickly and recovers slowly under the intermittent operation of the heat pump system. The opposite results have been obtained with the effect of soil actual moisture content. Furthermore, all the results indicate that the effect attenuates with the depth of soil. [ABSTRACT FROM AUTHOR]

Abstract The present paper describes a generalized scaling-up methodology applied to Polymer Electrolyte Membrane Fuel Cells. The use of proper scaling-up algorithms can reduce testing costs within fuel cell manufacturing process by evaluating full stack performance (i.e., impedance behavior) from a single cell/short stack measurement. The algorithm here described relies on a former approach developed by the authors and consists in a generalized methodology combining information measured on single cell and simple physical models (e.g., charge transfer resistance expressed through Tafel equation). A robust technique for the identification of cell reference operational state, such as membrane hydration, from non-scaled data is also introduced. Connection between charge transfer resistance and limiting current is established through diffusion losses modelling. Single cell internal states are estimated by means of inverse models function of numerical intercepts of measured cell spectrum. Stack impedance estimation is then performed through stack internal states assumptions. To prove the consistency and robustness of the proposed methodology, literature data used to design and test the former algorithm version are here considered for algorithm testing and verification. [ABSTRACT FROM AUTHOR]

Abstract Uncertainty is a common and unavoidable problem for the design of a new energy system. As a potential power system for the next generation aircraft, the Adaptive Cycle Engine (ACE) has attracted attention in many aero-engine developed countries. However, the introduction of new technology and the requirement of wider adaptability bring more uncertainties to the ACE system performance design process. To better utilize the advantage of the ACE performance, a robust design methodology should be applied. This paper analyzes the source of uncertainties, studies the method of addressing these uncertainties, and presents a design architecture to direct the robust design. The results show that the increase of knowledge and application of other universal design theories are helpful to eliminate the epistemic uncertainties. The uncertainty quantification methods, such as probabilistic method and interval analysis method, can be applied to address the aleatory uncertainties. Under the direction of a wheel-shaped design architecture, the robust design of ACE system performance can be completed through the further study at different design levels and the iteration between them. This design methodology can be applied to the design process of other energy systems with many new technical characteristics. [ABSTRACT FROM AUTHOR]

Abstract The hydrogen powered precooled aeroengine is highly expected to drive future advanced hypersonic vehicle. The paralleled heat release and compression system has shown its crucial role of guaranteeing the favorable performance of the engine. However, the superior performance of the paralleled system is based on complicated structure with separated flow paths, large scale heat exchangers and unique design of turbomachinery. A trade-off analysis in this paper shows that the paralleled design causes the increase in heat exchanger weight and size, and the high demands of component reliability. Besides, the working conditions, such as corrected rotate speed and flow path size of the compressors inside a system are considerably different from each other. It is proved that a comprehensive evaluation, including considerations on performance, negative effects, and technological challenges, is fundamental to the development of the paralleled heat release and compression system of hypersonic aeroengine. [ABSTRACT FROM AUTHOR]

Abstract This paper describes an integrated power unit (IPU) supplying bleed air and shaft power for main engine starting, aircraft environment control, and in-flight emergency power demand. The zero-dimension steady-state numerical simulation model of the IPU is built for both the normal air breathing (NAB) mode and the stored energy (SE) mode. The design point of the IPU is set in the NAB mode and the off-design performance calculations are accomplished for both modes. The Altitude-Mach characteristic of the NAB mode and the altitude characteristic of the SE mode are discussed and the fundamental control laws of the SE mode are established to minimize stored air consumption. The overall efficiency of the IPU is illustrated in the paper for the two modes. [ABSTRACT FROM AUTHOR]

Abstract Thermoelectric devices have significant thermal stress and deformation affected by the temperature difference, which affecting their working stability and life span. In this paper, thermoelectric pairs are allocated in the x, y and z directions respectively to a single thermoelectric pair. And the maximum stress and deformation in all schemes are calculated by the finite element analysis. The results show that the interaction of the thermoelectric pairs in the z direction makes the maximum stress and the deformation decrease. The interaction of the z -direction thermoelectric pairs is beneficial to the reliability of thermoelectric devices. When designing thermoelectric devices, reducing the number of arrangement in the x, y directions and increasing the number of arrangement in the z direction can effectively improve their working stability and life span. [ABSTRACT FROM AUTHOR]

Abstract Data-driven gas path analysis is a current research topic for energy fields for it can provide continuous monitoring to ensure safe and reliable operation of energy systems like gas turbine engines, wind turbines and distributed energy systems. The method utilizes information delivered by sensors to track equipment performance degradation during operation. In recent years, the rapid development of novel energy technologies promotes the progress of the method, but it also brings challenges. Energy systems are now becoming more and more complicated with strong nonlinear performance, highly coupled components and complex control laws. At present, an effective and universal diagnostic method to deal with energy systems with highly nonlinear dynamic performance has not been found. In this paper, a method called multi-state gas path analysis method is put forward to address the problem. The core idea of the method is to create sub-models to extend data available for modelling and diagnosing. The method integrates topological data analysis and transfer learning to construct a sub-model diagnostic network for nonlinear modelling. It allows designers to deal with highly nonlinear dynamic systems while preventing prohibitive computation effort. The method has been applied to an engine platform and verified. It achieves the same 92% diagnostic accuracy with only half data acquisition cost compared to a traditional data-driven gas path analysis method. [ABSTRACT FROM AUTHOR]

Abstract In order to more accurately predict the impact of solid oxide fuel cells to stack life on standby and shutdown, this paper proposes a modeling method based on experimental data. Which is based on Elman neural network(NN). At the same time, a main factor is considered in the modeling process which is the effect of cooling rate on the stack. In the process of modeling, the most obvious cooling rate is used to modeling. There are two different influencing factors on classify, the training set and the verification set respectively. After the reliability of the model, the Solid Oxide Fuel cell (SOFC) stack life prediction is carried out. From the predict results and the experimental results, it is found that the prediction results are good and the high precision. [ABSTRACT FROM AUTHOR]

Abstract This paper selects the working fluids for Trilateral cycle from two unique perspectives. The first aspect is to match the heat sources temperature with the critical temperature of working fluids, in which the thermal efficiency, exergy efficiency and utilization of heat source are chosen as the evaluation indicators. A better performance can be achieved when the heat source temperature approaches to the critical temperature of working fluid. From the aspect of expander, working fluids are selected to reduce volumetric flow ratio of expander and the size of expander, which have the lager vapor pressure at condensing temperature (VP), lager density at expander outlet and lower critical temperature. N-butane and R152a show higher net power output and lower volumetric flow ratio of expander among 13 studied working fluids. Two functions of expander volumetric flow ratio with respect to critical temperature of working fluid and VP have been gotten respectively. Furthermore, it can be concluded the suitable heat source temperature range of a TLC system is moderate temperature. [ABSTRACT FROM AUTHOR]

Abstract Solid oxide fuel cell is a device that can convert chemical energy directly into electricity. Its advantages, such as high efficiency, low emission, quiet operation, fuel flexibility, bring about the broad application prospect. However, it is difficult to obtain the temperature distribution in the existing planar cross flow solid oxide fuel cell through the experiment. In this paper, a control orient two-dimensional differential equation model is established for a planar cross flow solid oxide fuel cell based on the finite node method, and an iterative algorithm for calculating the real time voltage of the fuel cell is proposed for the model. Based on the model, the temperature distribution of the fuel cell in the test and system configuration is simulated. The simulation results show that the model can reflect the thermoelectric characteristics of the planar cross flow solid oxide fuel cell, especially the temperature distribution of the fuel cell. The SOFC temperature distribution modeling in this paper is helpful for the development of temperature distribution observers and design related control methods in later studies. [ABSTRACT FROM AUTHOR]

Abstract Improving the efficiency of organic Rankine cycle (ORC) is the ultimate goal of the researchers with thermodynamic background. As the "blood" of ORC, the working fluid plays a vital role to the improvement of the performance. The thermos-physical properties parameters, transport parameters and other parameters of working fluids could directly affect the efficiency, safety, stability and economy of ORC. With the increasing requirements on working fluids, it is difficult to find a pure working fluid not only with satisfied thermodynamic performance but also permissible enverimental protection and safety. In contrast, zeotropic working fluid, which is mixed with two or more pure working fluids, is easier to meet the requirements of thermos-physical properties, environmental and safety. But at the present stage, the application of zeotropic working fluids in ORC still adapted or employed the methodology originated from what we learn from pure working fluids. Under such circumstances, the temperature glide of zeotropic working fluids improves system efficiency while the composition shift would in turn reduce system efficiency. Thus, 3D-ORC is proposed in this paper to provide zeotropic working fluids a full play on performance improvement of energy conversion. The performance of 3D-ORC is calculated for the recovery of waste heat of internal combustion engines and compared with the simple ORC using pure and zeotropic working fluids. The results show that the performance of 3D-ORC is better than simple ORC under the same conditions. [ABSTRACT FROM AUTHOR]

Abstract One of the most critical challenges for the turbine-based combined cycle (TBCC) propulsion system utilized in the next generation hypersonic aircraft lies in the efficient operation from Mach 0 to Mach 5. This results in a need to investigate the well matching of the hypersonic inlet and the TBCC engine along the wide flight regime. In order to get better installed performance of Mach 5 TBCC engine, Newton-Raphson algorithm is adopted to investigate the integrated optimization design of the multi-variable combination adjusting laws of inlet/TBCC engine in different flight sections which include the hypersonic cruise section, the climbing section of ramjet mode and the climbing section of turbofan mode. How to guarantee the variable geometries function of the inlet/engine efficiently along the wide flight regime is one of the most critical technology challenges. The innovation point of the paper lies in that it affords an integrated optimization design of the adjustable geometries of inlet and the control laws of TBCC engines, using the multi-dimensional Newton-Raphson algorithm, which can achieve lower fuel consumption and better installed performance along the wide operating range, which is beneficial for the conceptual design and performance research of Mach 5 TBCC propulsion system. Meanwhile, the integrated optimization design method could also be applied to the power systems of multiple adjustable mechanisms, in order to increase the energy efficiency. [ABSTRACT FROM AUTHOR]

Abstract ORC is a mature technology that can be used for Waste Heat Recovery (WHR) of Internal Combustion (IC) Engines. Direct Evaporation of the organic fluid from the hot exhaust is an interesting option compared to the often preferred intermediary thermal oil loop choice due to its thermal efficiency potential and reduction of system footprint and weight. However, concerns due to dynamic variability of the hot source still hinder its consideration. In this paper, a comparison of the dynamic response of ORC evaporators with both indirect and direct evaporation is performed, under fluctuations of an IC engine exhaust according to relevant frequencies and amplitudes of a standard driving cycle. The results show the range of frequencies and amplitudes of hot source fluctuations for which direct evaporation is most feasible and the range for which special consideration must be taken. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a layered perovskite oxide NaLaTiO 4 with sodium-ion conductivity is proposed as a highly active, sulfur tolerant and stable anode for solid oxide fuel cells (SOFCs). The cell with NaLaTiO 4 -infiltrated samaria-doped ceria (SDC) anode shows high power outputs and favorable stability over 200-hour operation with 1000 ppm H 2 S-H 2 as fuel at 800 oC. The excellent sulfur tolerance of NaLaTiO 4 is attributed to its polarity, high surface basicity, oxygen vacancy concentrations and water storage capability. These results may open up new avenues for the design of high-performance, sulfur-tolerant anodes for SOFCs. [ABSTRACT FROM AUTHOR]