Sharif Digital Repository

The exergoeconomic analysis is a powerful tool to study an energy system and provide rational decision-making for it. This paper is aimed at exergoeconomic optimization and sensitivity analysis evaluation of the results of a commercial parabolic trough collector (PTC). First, an analysis of optical, thermal, exergy, and economic equations of the PTC system is presented. Then, the objective function and variables are optimized through MATLAB software using the hybrid algorithm code. The objective function as the exergy loss rate is a combination of exergy loss and system cost. The evaluation of the results has been carried out considering the radiation intensity in different months of the... 

Bi-evaporator electricity/cooling cogeneration systems can be a favorable addition to the integrated power plants since the generated cooling load should be addressed for different demands. More consequentially, taking advantage of such an integral set-up operated with highly reliable heat source such as biogas can be appreciable for nowadays industries. Regarding this demand, an innovative bi-evaporator electricity/cooling cogeneration system is introduced at first. Next, the suggested system is integrated with a gas turbine cycle fueled by biogas. In the subsequent part, the plausibility of the introduced integrated power plant is examined from first and second laws of thermodynamics (as... 

An innovative bi-evaporator electricity/cooling cogeneration system fueled by biogas is introduced. The plausibility of the introduced integrated power plant is examined from thermodynamic and economic vantage points. Later, single- and multi-objective optimization of the reckoned system are achieved by selecting appropriate parameters as decision variables and thermal and exergy efficiencies and total unit product cost (TUPC) of the system as objective functions. Four optimum modes of thermal efficiency optimum design (TEOD), exergy efficiency optimum design (EEOD), cost optimum design (COD), and multi-objective optimum design (MOOD) are selected for optimization and the attained results... 

An industrial condensate stabilizer unit is simulated with HYSYS 3.1 software when the excessive water is present on the trays. Effects of reboiler temperature, excess water flow rate, and incoming stream temperature on the Reid vapor pressure (RVP), temperature distribution along the column and impurity concentrations along the stabilization column, as well as, energy usage are studied. In addition, the optimal location for the water draw tray for the condensate stabilizer column is found. It is observed that the presence of water draw pan in the column leads to about 15% and 28% reduction, respectively, in the reboiler and the compressor duties compared to the industrial case without water... 

In this study, a combination of energy and exergy analysis is applied for the industrial sulfur recovery unit (SRU) in commercial simulation software. The data of energy and exergy are obtained from the simulator and Excel (for physical and chemical exergy), respectively. In doing so, five intensified SRU configurations namely: (1) hot gas bypass (2) acid gas bypass (3) inlet stream preheating (4) acid gas enrichment and (5) oxygen (air) enrichment are compared in terms of energy production, reaction furnace temperature, sulfur recovery and pollutant emission into environment. Then, irreversibility in these five arrangements is compared and all the proposed methods show higher useful exergy... 

From a thermal point of view, zeotropic mixtures are likely to be more efficient than azeotropic fluids in low-temperature power cycles for reduction in exergy destruction occurring during heat absorption/rejection processes due to their suitable boiling characteristics. In this study, comprehensive energetic and exergetic analyses are mathematically performed for an organic Rankine cycle (ORC) system employing a potential binary zeotropic working fluid, namely R717/water. For this purpose, initially mass, energy, and exergy balance equations are derived. With regard to the similarity in molar mass of R717 (17.03 g mol −1 ) and water (18.01 g mol −1 ), there is no need to alter the size of... 

Multigeneration systems (MGSs) driven by renewable sources are proved as cutting-edge technologies for multiple productions purposes to curb greenhouse gas emissions. With this regard, a novel geothermal-based MGS is proposed to produce multiple commodities of cooling, heating, power, and hydrogen, simultaneously, using liquefied natural gas (LNG) as cold energy recovery. The system is composed of an organic Rankine cycle (ORC), an ejector refrigeration cycle (ERC), an LNG power generation system, and a proton exchange membrane (PEM) electrolyzer system. To demonstrate the feasibility of the proposed MGS, energy, exergy, and exergoeconomic analysis are employed as the most effective tools... 

Heat pumps as the only end-use cooling/heating technology with a Coefficient of Performance (COP) greater than one, have attracted a great deal of attention over the past decade. In this study, the long-term energy and exergy analysis of four different types of heat pump systems: a common Air Source Heat Pump (ASHP), an ASHP with Ground Air Heat Exchanger (GAHE), a Ground Source Heat Pump (GSHP) with Horizontal Ground Water Heat Exchanger (HGWHE), and a GSHP with Vertical Ground Water Heat Exchanger (VGWHE) is performed. It is considered that all systems are used for space cooling and heating of a residential building. A mathematical model that takes into account the variations of building... 

Extraction of thermal heat from a salinity-gradient solar pond (SGSP) as a way of accumulating solar energy, stockpiling and taking merit of it for medium and low temperature demands is presented as an interesting topic in recent decades. This reliable supply of heat can be used for low-temperature refrigeration systems to yield cooling load for residential applications. For this purpose, theoretical investigation of ejector refrigeration cycle (ERC) driven by a SGSP is carried out to produce cooling output. Also, thermoelectric generator (TEG) is used as a potential device replacing condenser of the ERC for the sake of bolstering performance of the fundamental system by producing power,... 

Solar pond is a type of solar collector that stores solar energy in the form of heat. The solar pond can be used as a low-temperature heat source for electricity generation. In this paper, to find the most suitable power cycle for power generation from the solar pond, the performance of the Organic Rankine Cycle (ORC), Trilateral Flash Cycle (TFC) and their modified forms with an open feed liquid heater and an internal heat exchanger for different working fluids was investigated. Water was considered as the heat transfer fluid which transfers the stored heat from the solar pond to the working fluid of the cycle. The results indicate that in all cases, the energy and exergy efficiency of the... 

This article works with performance improvement of the conventional combined cooling/power (CCP) cycles to augment energy and exergy efficiencies of the previous systems. For this target, a conceptual configuration of cascade ejector refrigeration system (CERS) is proposed and is joined with organic Rankine cycle (ORC) to generate power and cooling outputs. The introduced CCP system can generate cooling load at two various temperatures for freezing and air-conditioning usages. For power sub-cycle, basic ORC and recuperative ORC with turbine bleeding are selected as topping cycles. Thermodynamic and exergoeconomic assessments of the cycles are done, leading to provision of the working... 

Wind turbine size has increased to megawatt capacity, and the related technologies and facilities have improved, including the cooling systems. Currently, all of the heat generated by wind turbine components is wasted to the environment. This study presents a conceptual design of a novel method for waste heat recovery of a wind turbine using an organic Rankine cycle (ORC). An organic Rankine cycle is implemented to the wind turbine as a part of the cooling system. The proposed system is thermodynamically modeled to evaluate the amount of recovered energy. Seven working fluids are chosen and investigated in the simulations to estimate the working fluid effect. The results revealed that the... 

Hybridization of biogas and geothermal energies for power plants can present a promising way to resolve drawbacks of each individual heat source from economic viewpoint, especially when low-temperature geothermal heat source is posited. Concerning this aspect of hybrid renewable heat sources, a novel hybrid biogas-geothermal multigeneration system was proposed in the first part of our study, which was modeled under privilege of thermodynamic laws. In continuation of our previous study, the current study is performed to investigate economic, environmental, and enviroeconomical aspects of the introduced system. Furthermore, single and multi-criteria optimizations of this integrated system are... 

Due to its unique properties, helium has wide application in different industries and scientific fields, which has turned it into a strategic material. Helium liquefaction plants include wide temperature range from 300 k to 4.2 k, so these plants have high energy consumption. A lot of studies have done to optimize the operation of these cycles. In this research, an exergy analysis is performed for a liquid helium production plant. The optimal performance of 3 and 4 stage cycles is extracted using parametric study and the results are compared with those of Collins dual-expander cycle. The results show that by increasing the number of cooling stages, not only the compressor optimum discharge... 

In this paper, exergy analysis of a steam power plant located in southern Iran named Zarand power plant has been studied. In order to optimize the performance of the Rankine cycle and achieve higher exergy efficiency, several parameters have been considered as decision variables. Knowing that there is the ability to change some of the parameters in the specific range in the process of electricity production in power plant, temperature and output pressure of the boiler and output pressure of four steps of extraction turbine have been selected as six decision variables. Also, exergy efficiency has been considered as the objective function. For this purpose, the exergy efficiency of the system... 

Due to its unique properties, helium has wide application in different industries and scientific fields, which has turned it into a strategic material. Helium liquefaction plants include wide temperature range from 300 k to 4.2 k, so these plants have high energy consumption. A lot of studies have done to optimize the operation of these cycles. In this research, an exergy analysis is performed for a liquid helium production plant. The optimal performance of 3 and 4 stage cycles is extracted using parametric study and the results are compared with those of Collins dual-expander cycle. The results show that by increasing the number of cooling stages, not only the compressor optimum discharge...