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Abstract Clamping mechanisms have significant effect on the performance of polymer electrolyte membrane (PEM) fuel cells. In this paper, PEM fuel cell with new clamping mechanism is designed to study the contact pressure distribution over the active area of PEM fuel cell's membrane electrode assembly (MEA). The clamping pressure is pneumatically exerted on the PEM fuel cell assembly. A comparison between the conventional and new clamping mechanism is carried out with simulation, and the numerical results are validated against experimental investigation performed in the fuel cell technology research laboratory. The experimental results are gathered using embedded pressure measurement films in the designed single cell. The results achieved via finite element method are in good agreement with experimental results. It is concluded that the contact pressure distribution of MEA for the new clamping mechanism is more uniform than the conventional one.

Abstract Multiple energy generating cycles such as tri-generation cycles, which produce heat and cold in addition to power through burning of a primary fuel, have increasingly been used in recent decades. On the other hand, advanced exergy analysis of thermodynamic systems by splitting exergy destruction into endogenous and exogenous parts identifies internal irreversibilities of each of the components and the effect of these irreversibilities on the performance of other components. Therefore, main sources of exergy destruction in cycles can be highlighted and useful recommendations in order to improve the performance of thermodynamic cycles can be presented. In the present work, a tri-generation cycle with 100 MW power production, 70 MW heat and 9 MW cooling capacity is considered. For this tri-generation cycle, effects of various thermodynamic parameters on the amount of endogenous and exogenous exergy destructions, exergy loss and the amount of fuel consumption, are investigated. The results indicate that, increasing compressor pressure ratio, pre-heater outlet temperature and excess air leads to better combustion and lower exergy loss and fuel consumption. Increasing the mass flow rate of steam generator, while keeping the cycle outlet temperature constant and considering cooling capacity variable, lead to increase the first- and second-law efficiencies of the cycle.

This study investigates the thermoeconomic performance of a new integrated system including a regenerative two stage organic Rankine cycle which is coupled with a parabolic trough collector via a thermal storage tank. The cold energy of liquefied natural gas (LNG) is used to absorb the heat duty of condenser. The LNG subsystem not only allows the ORC cycle to produce more power by reducing its condensate pressure, but also provides the system with extra power via the LNG expander and chilled water. The system is capable of producing power with solar fraction of a hundred percent during the day. The thermoeconomic analysis is performed to optimize the system for design point conditions. The analysis also reveals the exergoeconomic criteria on system components. Results show that solar collector has the most value of Z˙+C˙D which is due to both high exergy destruction and high investment costs of solar collector. Also, storage tank and condenser are the second and third important components with respect to exergoeconomic criterion. Parametric analysis is performed on the system to show the effects of eleven key thermodynamic parameters on system performance. In order for optimization, the product cost rate and exergy efficiency are chosen as the objectives. Eleven decision variables including inlet temperature and pressure of the turbines, heat exchanger minimum temperature differences along with the mass flow rate of storage tank, condensate pressure and LNG pressure were chosen according to parametric analysis. With the aid of TOPSIS decision making technique, the optimal point was selected among the Pareto frontier of the genetic algorithm. Results show that system can reach the efficiency of 19.59% and product cost rate of 3.88 million dollars per year.

Abstract Building integrated ETFE foils are used as the absorbing structure in the solar energy targeted applications. These foils as a building transparent material have been drawing much more attention for the past decades. In addition, integration of amorphous photovoltaic cells with these ETFE foils is taken into account due to the low production cost and its resistance to high operating temperatures. In the present study, a Building integrated Photovoltaic thermal (BIPV/T) ETFE cushion roof was numerically modeled and the thermal and electrical performances of this system were obtained in two cases: the cushion with the steady state mass flow and the cushion with the air pressure regulator system. Verification of the modeling was performed by comparing the model's results with the available experimental data in the literature. The main strength of the present modeling is consideration of the air pressure regulator system in the modeling process which has not been studied yet. The result of the present study showed that the present model predicts the BIPV/T ETFE cushion performance with a reasonable accuracy and can predict the system performance under different operating conditions. The results also showed that in case of the cushion with the steady state mass flow, the power generation is 15% higher than that of the cushion with the pressure regulator system. However, the cushion with the steady state mass flow has a low net output generated power due to the high consumed power of the blower.

Abstract Recovery of waste heat in large industrial plants is nowadays an important topic of thermal optimization. In the present study, energy, exergy, and exergoeconomic analysis of an integrated system, Tehran's waste-to-energy power plant coupled with an organic Rankine cycle (ORC), is analyzed. Parametric study of essential parameters (moisture content, pinch point temperature differences of the HROG, steam generator's superheat temperature difference, and steam turbine inlet pressure) is performed thermodynamically. The best system performance achieved using R123 as the working fluid of ORC. After implementation of the waste-heat-recovery system into the WtE plant, with R123 the energy and exergy efficiencies increase from 17.27% to 19.51% and 14.49%–16.36%, respectively. Exergy analysis reveals that the gasifier and steam generator are the main source of exergy destruction in the overall system. Additionally, the results of single-objective optimization based on maximum exergy efficiency and minimum total product unit cost were calculated. Furthermore, multi-objective optimization based on genetic algorithm using MATLAB software is implemented to find the optimum point with respect to exergy efficiency and total product unit cost as the objective functions. The exergy efficiency and total product unit cost at the optimum point, considering multi-objective optimization, are 19.61% and 24.65 $/GJ, respectively.

Abstract The performance of microwave-assisted fluidized bed drying of soybeans was simulated (using a previously validated mathematical model) and analyzed based on the first- and second law of thermodynamics. The energy and exergy analysis were carried out for several drying conditions. The effects of inlet air temperature, microwave power density, bed thickness and inlet air velocity on the efficiencies and inefficiencies of drying process have been simulated and discussed. Generally, application of microwave energy during fluidized bed drying enhanced the exergy efficiency of drying process. However, the results showed that it was more efficient not to apply microwave energy at the first stage of fluidized bed drying process. The application of higher levels of drying air temperature led in higher exergy efficiencies. The values of mean relative deviations for the predictions of efficiencies and inefficiencies of drying process were less than 14%, compared with those calculated using experimental data.

Abstract Industry and agriculture in Malaysia are the main contributors to economic growth and employment. These sectors also play an important role in Malaysia's total exports. The question then is whether technological innovation, sectoral output, and exports growth have had a real impact on these two sectors, which are very important for policy-making. This paper attempts to empirically identify such relations using econometric methods, including an autoregressive distributed lag (ARDL) bounds testing method and a dynamic ordinary least squares (DOLS) during 1978–2018. The results confirmed that overall long-run economic growth is the main contributor to the increase in energy consumption with a greater magnitude than in the short-run. In the long-run, an increase of 1% in economic growth leads to an increase of 4.6% and 1.1% in energy demand in agriculture and industrial sectors, respectively. Exports are the second largest contributor to energy demand in the overall economy and the agriculture sector. Finally, the technological innovation that enhances energy efficiency is only effective in reducing energy consumption in the industrial sector, which ultimately reduces emissions.

Abstract Battery State of Power (SoP) estimation is one of the most crucial tasks of the battery management system in electric and hybrid electric vehicles. The inevitable error in estimates of battery State of Charge (SoC) and State of Health (SoH) is a cause of inaccuracies towards estimating the SoP for an aged battery. To overcome this, the present study aims to propose a new approach for predicting an aged cell SoP in which no a priori knowledge of battery SoH is required and the estimation method is robust to inaccuracies of SoC estimates. Accordingly, a combined reference mode of constant-current and constant-voltage is utilized to estimate fresh cell SoP which is then adapted to various aging states using a model-less control system. The control system, which belongs to a class of fuzzy logic-based controllers, benefits form a closed-loop framework leading to a more reliable and accurate SoP estimate. For verification, an experimental setup comprised of fresh and aged LiFePO4 cell samples is designed and the extracted data are utilized in a Model-in-the-Loop simulation for a hybrid electric vehicle. The results demonstrate the improved accuracy and robustness of SoP estimation while achieving a guaranteed safe operation of battery.