Distribution of Articles published per year
(1970 - 2018)
(1970 - 2018)
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Article 0 Reads 0 Citations First and Second Law Analyses of Trans-critical N2O Refrigeration Cycle Using an Ejector Published: 13 April 2018
Sustainability, doi: 10.3390/su10041177
An ejector-expansion refrigeration cycle using nitrous oxide was assessed. Thermodynamic analyses, including energy and exergy analyses, were carried out to investigate the effects on performance of several key factors in the system. The results show that the ejector-expansion refrigeration cycle (EERC) has a higher maximum coefficient of performance and exergy efficiency than the internal heat exchanger cycle (IHEC), by 12% and 15%, respectively. The maximum coefficient of performance and exergy efficiency are 14% and 16.5% higher than the corresponding values for the vapor-compression refrigeration cycle (VCRC), respectively. The total exergy destruction for the N2O ejector-expansion cycle is 63% and 53% less than for IHEC and VCRC, respectively. Furthermore, the highest COPs for the vapor-compression refrigeration, the internal heat exchanger and the ejector-expansion refrigeration cycles correspond to a high side pressure of 7.3 MPa, and the highest COPs for the three types of CO2 refrigeration cycles correspond to a high side pressure of 8.5 MPa. Consequently, these lead to a lower electrical power consumption by the compressor.
Article 0 Reads 0 Citations Influence of Selected Gasification Parameters on Syngas Composition From Biomass Gasification Published: 29 March 2018
Journal of Energy Resources Technology, doi: 10.1115/1.4039601
In this study, the syngas composition exiting a biomass gasifier is investigated to determine the effect of varying selected gasification parameters. The gasification parameters considered are the mass flow rate of steam, the gasification agent, the mass flow rate of oxygen, the gasification oxidant and the type of biomass. The syngas composition is represented by its hydrogen, carbon monoxide, carbon dioxide and water fractions. The oxygen fed to the gasifier is produced using a cryogenic air separation unit. The gasifier and the air separation unit are modeled and simulated with Aspen Plus, where the gasification reactions are carried out based on the Gibbs free energy minimization approach. Finally, the syngas composition for the different types of biomass as well as the different compositions of the three types of the biomass considered are compared in terms of chemical composition. It was found that for each type of biomass and at a specified steam flow rate there is an air to the air separation unit where the gasification of the biomass ends and biomass combustion starts and as the volatile matter in the biomass increases the further the shifting point occur, meaning at higher air flow rate. It was found for the three considered biomass types and their four mixtures that, as the volatile matter in the biomass increases, more hydrogen is observed in the syngas. An optimum biomass mixture can be achieved by determining the right amount of each type of biomass based on the reported sensitivity analysis.
Article 0 Reads 0 Citations Integrated approach for sustainable development of energy, water and environment systems Published: 01 March 2018
Energy Conversion and Management, doi: 10.1016/j.enconman.2017.12.016
The Conferences on Sustainable Development of Energy, Water and Environment Systems (SDEWES) at the beginning of the 21st century have become a significant venue for researchers to meet, and initiate, discuss, share, and disseminate new ideas in various disciplines of sustainable development. In 2002, the first conference was organised in Dubrovnik, Croatia and since then, 10 more successful conferences were realised. Following the success of international conferences in Dubrovnik, the organizing committees decided to organize the main conference and regional conferences all over the world in even years. In 2016, the second regional SDEWES conference, namely the 2nd South East European Conference on Sustainable Development of Energy, Water and Environment Systems, was held June 15–18 in Piran/Portorose, Slovenia while the 11th SDEWES conference was organised in Lisbon, Portugal on September 4–8. There were 10 special sessions dedicated to various sustainability topics organised in both conferences. This special issue is based primarily upon a collection of 35 papers selected from among 538 scientific contributions presented at the 2nd SEE and 11th SDEWES Conferences. Moreover, this editorial summarises SDEWES published articles that have addressed and identified problems or provided the background for the research that is reported in the current special issue. The main topics of the selected papers address sustainable combustion technologies, renewable energy sources and sector integration, including the integration of renewable technologies in the urban environment, the integration of heat, cold, electricity and fuel production in buildings and industrial applications, heat exchangers and heat exchanger networks, the development and integration of energy storage for concentrated solar power plants, and sectorial integration of bioenergy resources and biorefineries with a particular focus on system integration for efficient and low-carbon systems.
Article 0 Reads 0 Citations Experimental study of effect of anolyte concentration and electrical potential on electrolyzer performance in thermochem... Published: 01 March 2018
International Journal of Hydrogen Energy, doi: 10.1016/j.ijhydene.2018.01.054
An important process in the copper-chlorine water splitting cycle for hydrogen production is electrolysis which occurs after a series of cycle steps that produce the constituents for the anolyte of the electrochemical cell. In this investigation, an anolyte mixture of HCl/CuCl/H2O of varying concentrations is circulated through the electrolyzer to assist in optimizing its performance. It is observed that the concentration and temperature of the anolyte directly affect the process. The efficiency of the electrolyzer is adversely affected, after running a series of experiments, due to copper deposition on the membrane. An important implication of the results is that, to determine the optimal electrolyzer performance, one needs to vary the flow rate and the concentration of anolyte, for a given constant voltage source. In addition, this work demonstrates that aqueous CuCl2 can be recovered from the waste solution exiting the electrolyzer and recycled to the hydrolysis reactor.
Article 0 Reads 0 Citations Environmental sustainability tools in the biofuel industry Published: 01 March 2018
Biofuel Research Journal, doi: 10.18331/brj2018.5.1.2
Article 1 Read 0 Citations Investigation of new mechanical heat pump systems for heat upgrading applications Published: 13 February 2018
International Journal of Energy Research, doi: 10.1002/er.4014
In this study, two novel high-temperature heat pump systems based on vapor compression cycles are introduced and examined. Three fluids (water, cyclohexane, and biphenyl) are selected and analyzed thermodynamically as prospective working fluids for the high-temperature heat pumps. These working fluids are used in cascaded cycles to upgrade the heat to a temperature of 600°C. The equations of state used in performance analysis are Peng-Robinson, non-random two-liquid model, and International Association for the Properties of Water and Steam 95. A parametric analysis is carried out to study the effects of isentropic efficiency, sink temperature, source temperature, and ambient temperature on the system performance. Both energetic and exergetic coefficients of performance (COPs) of the overall and individual cycles are determined. The COP values obtained are found to range from 2.3 to 3.8, depending upon the cycle and temperature levels. The high COP values in some instances make these systems promising alternatives to fossil fuel and electrical heating. As a possible sustainable scenario, these pumps can utilize low-grade heat from geothermal, nuclear, or thermal power plants and derive work from clean energy sources (solar, wind, nuclear) to deliver high-grade heat. The high delivery temperatures make these heat pumps suitable for processes with corresponding needs, like high-temperature endothermic reactions, metallurgical processes, distillation, and thermochemical water splitting.