Sharif Digital Repository

Performance optimization of a single-effect lithium bromide water absorption refrigeration system is the subject of this paper. First, the thermodynamic model of the system wasderived based on the first and second law analysis of an absorption refrigeration cycle with LiBr-water as the working fluid pair. Then, the effects of different design parameters such as the generator inlet hot water temperature, evaporator inlet chilling water temperature and absorber and condenser inlet cooling water temperatures on the performance of the systemwere investigated. In order that, by defining the coefficient of performance (COP), exergy efficiency (Second-law efficiency) and total cost function of the... 

Feasibility investigation of a humidification dehumidification (HDH) desalination system driven by an absorption-compression heat pump cycle (ACHPC) is carried out in this paper. The proposed hybrid desalination system uses both heating capacity of the discharged brine as a waste heat for the ACHPC and mechanical power of the ACHPC for the HDH system. The system's performance is investigated under different optimal design modes, using genetic algorithm (GA) as the most robust tool for optimization. A steady-state mathematical model based on the mass, energy, exergy, and exergoeconomic balance equations for components of the proposed system is developed and the predicted results are validated... 

Exploration of the ejector refrigeration cycle (ERC) in the combination with well-known power cycles to produce cooling output as well as power output is highlighted in recent decades. Since organic Rankine cycle (ORC) is practically usable than other power cycles, a combination of the ORC/ERC in a novel form is presented. Power and refrigeration sub-cycles are combined by a common condenser in separate loops to form dual-loop power/refrigeration cycle. The exhaust of the turbine is mixed with the outlet flow of the ejector, and then the mixed flow is fed into the condenser. Thermodynamic and thermoeconomic analysis of the proposed cycle are carried out with different working fluids (i.e.,... 

This paper deals with reconstruction of conventional combined cooling and power (CCCP) cycle for producing simultaneous power and cooling outputs for triple applications of freezing, refrigeration and air-conditioning. The proposed systems are integrated from organic Rankine cycles (ORCs) and an ejector refrigeration cycle (ERC). Single- and multi-objective optimisations of the proposed systems are conducted from energy, exergy and exergoeconomic viewpoints, using genetic algorithm (GA). The results of optimisation revealed that the thermal efficiency of the basic triple-evaporator CCP (B-TECCP) and regenerative TECCP (R-TECCP) systems can be improved by 7.48% and 6.23%, respectively,... 

In this paper, inspired by a gas turbine power plant, the interaction between plant-soil processes has been simulated. It is aimed to indicate that solar energy in the photosynthesis process is equivalent to the fuel in combustion chambers. In the glucose production process, when solar exergy is considered as a fuel, 99.4% of total exergy cost is supplied by solar exergy and only 0.6% of the exergy cost is provided by nutrients’ content. In general, 30% of the total exergy entering the Calvin cycle is consumed in glucose production and the remaining 70% is related to biomass generation (as flue gas in the gas turbine). Moreover, 98% of the total exergy cost of the soil box is related to... 

Transcritical-CO2, supercritical-CO2, and organic Rankine cycles are numerically investigated and compared in simple Rankine, Rankine with internal heat exchanger, and regenerative Rankine configurations to assess their thermodynamic and thermoeconomic performance indicators. Subsequently, the systems are optimized using a multi-objective optimization method. Pareto optimal solutions are provided to present the trade-off between thermodynamic and thermoeconomic indicators. In addition, scatter plots of decision variables are presented to ascertain the optimal operating range of input variables. The results show that transcritical-CO2 systems can generate the highest power. The levelized cost... 

In the present study a comprehensive thermoeconomic modelling of a heat recovery steam generator (HRSG) for a typical 4MW class gas turbine is performed. Usually, the thermoeconomic analyses involve a thermodynamic model of the HRSG and an economic model dedicated to assess the cost. In this study, different configurations of single and dual pressure level HRSGs are optimized and afterward compared to find the economical design. For these configurations thermodynamic model calculates the performance and the energy balance of systems at the optimal operating conditions which are derived from optimization model, and economic model estimates total cost per unit of produced energy. Finally,... 

Exergy and exergoeconomic analyses have been used to set out weaknesses of the postcombustion CO2 capture unit of Besat power plant that uses an ammonia absorption refrigeration system for CO2 liquefaction. The energy required for the absorption system is provided by the flue gas. The liquefied CO2 is used for beverage and food industries. The exergoeconomic costs of all utility streams and processes are calculated through a systematic method of assigning exergetic cost relations to the streams. The results point out that the exergy destruction of the CO2 stripper and absorber columns are the highest, and according to the cost-based information, potential locations for the process... 

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... 

In the present study, a micro solar Combined Cooling, Heating and Power (CCHP) system based on Organic Rankine Cycle (ORC) is thermodynamically and exergoeconomically investigated. Adding a storage tank will lead to the sustainable supply of energy for summer and winter seasons. The model of conservation of energy, conservation of mass, and conservation of linear momentum are applied in order to energy analysis, while a model based on the first and the second laws of thermodynamics are used to exergy analysis. Determining the effective parameters of the system efficiency, including turbine input pressure, turbine inlet temperature, turbine output pressure, and evaporator temperature leads to... 

Despite the fact that humidification-dehumidification (HDH) desalination systems can be driven by various renewable or waste heat energies, many of the available renewable technologies are expensive in some parts of the globe. Hence, proposing and developing high-efficient mechanical-based HDH units can be an encouraging alternative which is more highlighted in recent investigations. In pursuance of this objective, three innovative mechanical-driven HDH units are simulated and the results are compared with each other. The simulated hybrid desalination system consists of a HDH unit and an ethane ejector expander transcritical refrigeration cycle (ethane-EETRC). The simulated hybrid systems... 

The yearly thermo-economic performance is dynamically investigated for three solar heating and cooling systems: solar heating and absorption cooling (SHAC), solar heating and ejector cooling (SHEC), and heating and solar vapor compression cooling (HSVC). First, the effects of important design parameters on the thermo-economic performance of the systems to supply the heating and cooling loads of the building are evaluated. The systems are parametrically analyzed with the weather conditions of Tehran, Iran. The results show that the life cycle costs (LCC) of the SHAC and HSVC systems are alike and much lower than those of the SHEC system. The HSVC system exhibits the best performance from... 

The aim of this study is to provide a solution for supplying distilled water used in indirect water bath heaters in the pressure reduction stations. A particular type of distilled water production system consists of a typical solar still and a heat pipe heat exchanger was constructed for recovering heat from the exhaust of an indirect gas heater. The system was tested under the climatic conditions of Semnan-Iran. Experimental results showed that in active type, the average daily production rate of distilled water would be 2.06 times higher than passive type. Also, in the proposed system, the average daily energy efficiency and the exergy efficiency would be 65.5% and 41% higher than the... 

In this paper energy, exergy and thermoeconomic analysis of a combined cooling, heating and power (CCHP) system has been performed. Applying the first and second laws of thermodynamics and economic analysis, simultaneously, has made a powerful tool for the analysis of energy systems such as CCHP systems. The system integrates air compressor, combustion chamber, gas turbine, dual pressure heat recovery steam generator (HRSG) and absorption chiller to produce cooling, heating and power. In fact, the first and second laws of thermodynamics are combined with thermoeconomic approaches. Next, computational analysis is performed to investigate the effects of below items on the fuel consumption,...