A thermodynamic analysis of a flash/ORC geothermal plant using zeotropic mixtures as working fluid is carried out to investigate and improve the performance of the system from the viewpoint of first and second laws of thermodynamic. The mixtures of three hydrocarbons (Hexane, Cyclohexane and Isohexane) with two refrigerants (R245fa and R236ea) are investigated as the working fluid of organic Rankine cycle (ORC). Variation of first and second laws efficiencies, net output power and exergy destruction as a function of the mass fraction of refrigerants from 0 to 1 is reported. The results showed that the first and second laws efficiencies maximized at a specific value of refrigerant mass fraction. Also, the net power output of ORC shows an optimum amount by changing the refrigerant’ s mass fraction. Furthermore, exergy destruction in evaporator which is the main source of exergy destruction in ORC has its lowest value in the average amounts of refrigerant mass fraction. According to the results, Cyclohexane/R236ea mixture with a ratio of 0. 6/0. 4 represents the best performance from the viewpoint of energy and exergy which leads the system net output power production of 7. 31 MW.

Due to the necessity of using highly efficient power generation systems to reduce fuel consumption and air pollution, the integration of different energy systems is promising modification to achieve higher efficiency. In this paper, the integration of an Internal Reforming Solid Oxide Fuel Cell (IRSOFC)-Gas Turbine (GT)-Organic Rankine Cycle (ORC) system has been proposed. In this regard, thermodynamic modeling and simulation of the proposed system have been done to evaluate the performance of the integrated system. Also, exergetic, exergoeconomic and advanced exergetic analysis has been performed for the proposed system. The analysis of the integrated system has been carried out by using MATLAB code. Verification of thermodynamic simulation has been performed with high accuracy. Results of thermodynamic simulation show that the net power and overall cycle efficiency of the proposed cycle are increased by 1. 1 MW and 7. 7 % respectively rather initial SOFC-GT combination. The exergy analysis indicated that exergy efficiency is 40. 95%, for the proposed system and 37. 3% for the initial base case. As a result, the exergy destruction, exergoeconomic factor, cost rate per exergy unit of product and fuel, and cost rate associated with the exergy destruction for each component are calculated and evaluated. Also, endogenous/exogenous and avoidable/unavoidable parts of exergy destruction, exergy destruction costs, and capital costs have been determined and compared.

In this study, thermodynamic analysis for integration of a PEMFC with an organic Rankin cycle, and an ejector expansion vapor compression refrigeration system is presented. The input energy of the system is supplied by the waste heat of a PEMFC. Energy and exergy analysis is performed on each system component and compared with a simple ORC-VCR without an ejector. The results show that employing the ejector can improve the refrigeration capacity, energy efficiency, and exergy efficiency by 18.88%, 12.29 %, and 12.27%, respectively, compared to a simple ORC-VCR system. Moreover, the overall energy and exergy efficiency of the system is 33.43% and 5.46% higher than a standalone PEM fuel cell. Furthermore, in the parametric study, the effect of condenser temperature, evaporator temperature, ejector efficiency, PEMFC operating temperature, current density, and PEMFC operating pressure on the energy efficiency, exergy efficiency, and refrigeration capacity of the system is investigated.

Increase of fuel price and limitation of carbon dioxide emission caused development of different techniques to enhance the thermal efficiency of internal combustion engines. One of these techniques is conversion of the waste thermal energy in the engine to mechanical or electrical energies. This investigation concentrated on simulation, examination and application of waste heat from exhaust gases of MTU-16V internal combustion engine in an organic Rankine cycle based on the efficiency of first and the second laws of thermodynamics. Using 862 kW power of exhaust gases waste heat, the net powers of working fluids including R600a, R600 and R245fa were evaluated and the highest net output power was calculated to be 37. 23 kW for R245fa working fluid. This working fluid increased the output power to approximately 2% and 6% in comparison with R600 and R600a fluids, respectively. Moreover, the mentioned working fluids were examined for volumetric flow rate and required volume contraction, where the lowest value was obtained for R600a. On the one hand, the effect of turbine inlet temperature on the volumetric flow rate, and effect of turbine inlet pressure on energy efficiency, exergy efficiency and irreversibility of the whole system were investigated. On the other hand, the influence of ambient temperature increase on irreversibility of each system component was studied. Based on the obtained results, R245fa fluid showed the best performance to be used in organic cycle from the viewpoint of the first and second laws of thermodynamics.

Development of innovative thermodynamic cycles is important for the efficient utilization of low-temperature heat sources such as solar, geothermal, and waste heat sources. Binary mixtures exhibit variable boiling temperatures during the boiling process, which leads to a good thermal match between the heating fluid and working fluid for efficient heat source utilization. This study presents a theoretical analysis of a combined power cycle, which combines the organic Rankine cycle and parabolic through collectors cycle, uses different organic fluid as the working fluid and produces power. This cycle, also known as the ORC, can be used as a downstream cycle using heat source from a solar radiations, and it can using low to mid-temperature sources with concentrator or not. A thermodynamic analysis of power was presented. The performance of the cycle for a range of turbine pressure, ambient temperature, condenser pressure, altitude, and different working fluids were studied to find out the sensitivities of gross power, net power, electrical efficiency, net electrical efficiencies and plant auxiliary, effective efficiency. The thermodynamic analysis covered a broad of boiler temperatures, 250oC and pressure 20 Bar. The first law efficiencies of 11.85 % are achievable at 250oC and pressure 20 Bar with R-123 as working fluid. The cycle can reached to 19.64 % net electrical efficiency with recuperate heat exchanger that works at 44 bar pressure 250oC temperature and with R-141B as working fluid.

Energy shortage is one of the fundamental challenges of human beings in which finding a new way for optimum utilization of unique energy resources and cogeneration can be terminated to the reservation of energy or cogeneration purposes. In this paper, by using the combined Ejector Refrigeration Cycle (ERC) and Organic Rankine Cycle (ORC), in addition to producing power from Organic Rankine Cycle, we will use the waste heat recovery of condenser in the ORC for the purposes of generating cooling capacity in the ERC. Actually, the condenser of the ORC works as the evaporator of the ERC. We have considered isobutane as a working fluid of ERC and also R113, R141b, R11, R123, R245fa, R114, and isobutane as working fluids of ORC. The maximum Combined Cycle Performance is obtained when we would use isobutane and R113 as working fluids in ERC and ORC, respectively. In this case, ORC Efficiency, Combined Cycle Efficiency, and Cycle Coefficient of performance will be 19.97%, 34.69% and 0.3683, respectively. In addition to energetic analysis’ point of view, from the exergetic analysis’ one, the combined usage of R113 and isobutene by having the highest efficiency of 52.53% is an appropriate working fluids, too. Also a parametric analysis is performed for the cycle performances, based on the operational parameters of combined cycle.