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Abstract In this study, the external surface of a finned tube was coated by 13X zeolite powder, and the CO2 adsorption equilibrium and dynamics were investigated experimentally. A slurry consisting of dionized water, 13X zeolite powder, and Acrylic latex emulsion (ALE) was used to coat the finned tube. The finned tube was coated by deep coating method. The equilibrium isotherms were measured at the range of 20–90 °C and fitted well by the dual-site Langmuir model. The average difference between the model and the results obtained from the experiments is about 2.5%. The nitrogen adsorption/desorption at 77 K was used for characterization of adsorbents. A 11% reduction was observed in pore volume and surface area. The dynamic test showed that the desorption of adsorbed CO2 takes place in about 14 s which is an order of magnitude faster than the fastest developed method. A conservative criterion was developed for estimating adsorbent working capacity. This criterion showed that the working capacities of the adsorbent are about 80% of its ideal values.

Abstract In this paper, a numerical study is conducted in order to investigate the effect of pulsation of air flow at the cathode side of Proton Exchange Membrane (PEM) fuel cell with interdigitated flow field. A two dimensional, isothermal, two-phase, unsteady multi-component transport model is used in order to simulate the transport phenomena. The obtained results are discussed in terms of the influence of flow pulsation on water management and cell performance. The results prove the effectiveness of flow pulsation on improving water removal from cell, enhancing reactants transports to the reaction sites, and increasing the cell performance expressed by increment in the cell limiting current density and maximum output power. The effects of pulsation frequency ( f ), amplitude ( Amp ), and mean inlet pressure ( P in ) on the performance and the output power of the cell, are also investigated. The performance of the cell has no dependency on the frequency range considered in this study. However, as the pulsation amplitude increases the increment in the cell performance is more obvious. Moreover, applying flow pulsation at low flow rates leads to higher efficiency in water removal and performance enhancement.

This paper presents a Direct Lyapunov based control technique for active power filtering in electric grids. The proposed technique through the interfacing system is designed with the goal to compensate the harmonic current components and reactive power provoked by the nonlinear grid-connected loads. In the method, based on multilevel converter topologies, active power in fundamental frequency is injected from the main grid, which results in unity PF (power factor) between grid currents and load voltages. The performance of the proposed control technique in a SAPF (Shunt Active Power Filter) model is validated in both dynamic and steady-state operating conditions. The simulation results show that the proposed scheme can effectively compensate the system background harmonics and improve the performance of the line current harmonics. The main benefit of this approach is that it prevents current overshoot as the proposed model connects to the grid.

The present investigation is designed to analyze the energy consumption rate, cumulative exergy demand (CExD), water footprint, and environmental impacts in canned apple production using life cycle assessment (LCA) technique. Data envelopment analysis (DEA) was also used to identify effective measures in increasing apple orchard efficiency. The needed information was collected through questionnaires and face-to-face interviews in 2020 in the West Azerbaijan state of Iran. The result showed that energy consumption in apple production was 60,026.48 MJha−1. According to the DEA findings, the efficiency of apple orchards in the research area is low, and micronutrients and phosphate have the most potential to reduce. Furthermore, the number of efficient units based on technical performance, net performance and performance scale were 35, 93 and 35. There is a potential saving of 6073.15 MJha−1 of energy. Economic indices such as net return, benefit-to-cost ratio, and investment productivity were 3391.99 $ha−1, 1.75, and 6.003 kg$−1, respectively. The results of LCA+DEA illustrated that abiotic depletion has the greatest potential for reduction among environmental indicators, with a reduction rate of 35%. CExD outcomes determined that the rates of non-renewable fossil (812.16 MJt−1) for apple gardens mostly come from nitrogen and diesel fuel.

Abstract A novel integrated energy system based on a geothermal heat source and a liquefied natural gas heat sink is proposed in this study for providing heating, cooling, electricity power, and drinking water simultaneously. The arrangement is a cascade incorporating a flash-binary geothermal system, a regenerative organic Rankine cycle, a simple organic Rankine cycle, a vapor compression refrigeration cycle, a regasification unit, and a reverse osmosis desalination system. Energy, exergy, and exergoeconomic methods are employed to analyze the suggested system. A parametric study based on decision variables is carried out to better assess the system performance. Four different multi-objective optimization problems are also carried out. At the most excellent trade-off solution specified by the TOPSIS method, the system attains 29.15% exergy efficiency and 1.512 $/GJ total product cost per exergy unit. The main output products are consequently calculated to be 101.07 kg/s cooling water, 570.44 kW net output power, and 81.57 kg/s potable water.

In the present study, a novel combined system consisting of solid oxide fuel cell (SOFC), organic Rankine cycle (ORC), and compressed air energy storage (CAES) is proposed, investigated, and optimized. The SOFC and CAES models are validated individually to ensure the accuracy of the results. Here, the grey wolf multi-objective optimization (MOGWO) approach is applied to find the optimal system design and performance. For this, a trained neural network is provided to the MOGWO algorithm as a fitted function, and multi-objective optimization is carried out on it. The most significant benefit of the suggested method is time-saving. The proposed system's thermodynamic performance is investigated from the energy, exergy, economic, and environmental (4E) points of view at three periods, including full-time, charging, and discharging periods. The results indicate that the Levenberg-Marquardt training algorithm has the best performance among all of the algorithms. The value of exergetic round trip efficiency (ERTE), total cost rate, and CO2 emission at the best optimum point are obtained as 45.7%, 34.2 $/h, and 0.22 kg/kWh, respectively.

Abstract Although many studies have concerned effect of different kind of biodiesel fuel on engine, there are no information about the comparison between different biodiesels in a comprehensive study and with consideration of pilot injection and EGR system. Therefore, the aim of this study is to have a comprehensive investigation of the effect of pilot injection timing and EGR system, as common ways to reduce engine emissions, on engine combustion, emissions and performance while using of different kind of the biodiesel. The brassica, cardoon, coffee, waste cooking oil biodiesels and standard diesel fuels were evaluated fuels. However, the results of the study depicted that different characteristics of the considered fuels had changed the engine response to variation of injection strategy and EGR application. The maximum reduction of combustion duration compare to diesel fuel (17.7%) was related to coffee biodiesel. Moreover, Coffee biodiesel has lowest pressure rise rate. On the other hand, cardoon had shortest ignition delay and highest combustion temperature. In addition, maximum retardation of combustion position was for brassica biodiesel fuel (19.07%). Although the N O x emission has decreased due to application of EGR (up to 86%) and pilot injection (up to 29.3%), high EGR rate in high IMEP has changed the combustion quality due to sewer changes in the combustion quality. In this condition, CO and THC emission increased severely. Higher viscosity and lower oxygen content of the coffee and cardoon biodiesel than diesel fuel decreased combustion quality and caused the higher THC, CO and soot emissions and lower N O x emissions than brassica and WCO biodiesel fuels in higher EGR rates and IMEPs. It can be stated that pilot injection and EGR are two parameters which are effective significantly on the engine characteristics and the adjusting of these parameters should be done properly specially according to the used fuel properties.

This paper designs and models a fully decentralized peer-to-peer (P2P) energy token market for small-scale prosumers using blockchain technology in a smart grid environment in the presence of the demand response (DR) program and demurrage mechanism. As the market players, prosumers in the local distribution network are considered in two groups, producers (sellers) and consumers (buyers). Using smart contracts, all sellers and buyers in the proposed market can engage in bilateral energy token transactions (P2P) with each other under an agreed price and with the retail market at a certain price. Furthermore, the local consumers can participate in price-based DR programs and shift their consuming load to the periods with high local generation. Demurrage mechanism is applied to avoid energy token accumulation and enhance attraction for local transactions. With demurrage in place, the redemption value of energy-backed tokens reduces with time. A fully decentralized approach called the primal-dual sub-gradient method is developed to clear this fully decentralized energy market in the presence of DR programs and demurrage. The proposed market-clearing scheme guarantees the global and feasible solution without requiring the players' private information. Numerical studies demonstrated the feasibility and effectiveness of the proposed energy token market and the decentralized approach for its clearing.