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In response to the ongoing optimization of energy systems and the promotion of clean energy, this paper introduces a new high-efficiency cogeneration system based on proton exchange membrane fuel cells (PEMFC). Named the Transcritical Combined Cooling Heating and Power with Subcooling Coupled ORC (CPTSO) system, it undergoes energy, exergy, economic, and environmental (4E) assessments to evaluate its performance in both summer and winter modes. This paper also analyzes the effects of key factors on the new system's performance. The results indicate that the new system performs more effectively overall and achieves faster cost recovery during winter operations. With varying degrees of subcooling (ΔT subcooling), the system's average energy efficiency, fuel energy saving ratio (FESR), exergy efficiency, and pollutant reduction in winter are 60.97 %, 4.51 %, 17.16 %, and 33.35 % higher, respectively, than in summer. Changes in the main evaporation temperature (T e) result in winter improvements of 74.37 % in energy efficiency, 16.86 % in FESR, 17.6 % in exergy efficiency, and 45.5 % in pollutant reduction compared to summer. Similarly, adjustments to the outlet temperature of the gas cooler (T g) lead to winter increases of 56.75 % in energy efficiency, 0.49 % in FESR, 17.1 % in exergy efficiency, and 29.3 % in pollutant reduction over summer values. [ABSTRACT FROM AUTHOR]

Converting solar energy using the Parabolic Trough Collector (PTC) to produce electrical energy and supply industrial heat is one of the most prominent and most popular sustainable and renewable, widely used throughout the worldwide due to its effectiveness and benefit returns. For this reason, this study aims to investigate the effectiveness of these power plants under a specific climatic conditions and analysis the results come out from the simulation using an EES developed model. The analysis investigates the energy and exergy of the PTC plant coupled with Turboden ORC cycle. The presented model allows us to preview the theoretical results and derive the expected results smoothly, with the possibility of development for a better control of the use of renewable energies in the industrial field. The thermal efficiency of the ORC cycle increases as the heat output increases until it reaches an almost constant value above 2801 [kW] in heat output with a output capacity of the ORC cycle about 1 [MW].

Abstract This study has attempted to compare two thermodynamic cascade cycles, which in this paper are presented as Systems A and B. System A was consisted of a steam Rankine cycle (SRC) as a top cycle and an organic Rankine cycle (ORC) as a bottom cycle. System B was consisted of the same SRC as the top cycle and a Kalina cycle as the bottom cycle. The comparison of both systems has been made by changing a number of parameters. The chosen parameters for this comparison were bottom cycle mass flow rate, aperture area of the collector, top cycle condensing pressure, and bottom cycle turbine inlet and outlet pressures. Also, a short economic evaluation has been made between two proposed cascade cycles (Systems A and B). The result indicated that the Kalina cycle shows superiority over the ORC as the bottom cycle in a solar‐driven SRC. Furthermore, it was determined that the most effective parameters on the overall efficiency of the systems are the condensing pressure of the top cycle and the outlet pressure of the bottom cycle turbine. Also, among the chosen parameters, the outlet pressure of the bottom cycle turbine had the highest effect on the efficiency of the bottom cycles. Considering the economic aspect, the results showed that the levelized costs of energy for both systems are quite equal at 0.011 ($/kWh).

This study has attempted to compare two thermodynamic cascade cycles, which in this paper are presented as Systems A and B. System A was consisted of a steam Rankine cycle (SRC) as a top cycle and an organic Rankine cycle (ORC) as a bottom cycle. System B was consisted of the same SRC as the top cycle and a Kalina cycle as the bottom cycle. The comparison of both systems has been made by changing a number of parameters. The chosen parameters for this comparison were bottom cycle mass flow rate, aperture area of the collector, top cycle condensing pressure, and bottom cycle turbine inlet and outlet pressures. Also, a short economic evaluation has been made between two proposed cascade cycles (Systems A and B). The result indicated that the Kalina cycle shows superiority over the ORC as the bottom cycle in a solar‐driven SRC. Furthermore, it was determined that the most effective parameters on the overall efficiency of the systems are the condensing pressure of the top cycle and the outlet pressure of the bottom cycle turbine. Also, among the chosen parameters, the outlet pressure of the bottom cycle turbine had the highest effect on the efficiency of the bottom cycles. Considering the economic aspect, the results showed that the levelized costs of energy for both systems are quite equal at 0.011 ($/kWh). [ABSTRACT FROM AUTHOR]

This work is an energy study of an organic Rankine cycle (ORC) for the recovery of thermal energy by comparing three organic fluids. This cycle is considered to be a promising cycle for the conversion of heat into mechanical energy suitable for low temperature heat sources; it uses more volatile organic fluids than water, which generally has high molecular weights, thus allowing operating pressures at temperatures lower than those of the traditional Rankine cycle. A thermodynamic model was developed using the Engineering Equation Solver (EES) software to determine its performance using different working fluids (toluene, R245fa and R123) under the same operating conditions, taking into account the effect of certain operating parameters and the selection of organic fluids on cycle performance. The results obtained show that the toluene organic fluid has the best thermal efficiency of the cycle compared to the other fluids; 14.38% for toluene, 13.68% for R123 and 13.19 for R245fa.

This study presents an energy study of an Organic Rankine Cycle ORC by comparing three organic fluids. The latter is considered as a promising cycle for the conversion of heat into mechanical energy adapted to low-temperature heat sources; it uses more volatile organic fluids than water, which generally has high molecular weights, thus allowing operating pressures at temperatures lower than those of the traditional Rankine cycle. This study devoted to the energy analysis of the ORC cycle, taking into account the effect of the operating temperatures and the choice of the organic fluid on the cycle performance. The utilized three fluids were Toluene, R245fa and R123. The results obtained show that the Toluene organic fluid has the best energy efficiency of the cycle with 7.45%.

To solve the problem of multi-objective performance optimization based on ant colony algorithm, a multi-objective performance optimization method of ORC cycle based on an improved ant colony algorithm is proposed. Through the analysis of the ORC cycle system, the thermodynamic model of the ORC system is constructed. Based on the first law of thermodynamics and the second law of thermodynamics, the ORC system evaluation model is established in a MATLAB environment. The sensitivity analysis of the system is carried out by using the system performance evaluation index, and the optimal working parameter combination is obtained. The ant colony algorithm is used to optimize the performance of the ORC system and obtain the optimal solution. Experimental results show that the proposed multi-objective performance optimization method based on the ant colony algorithm for the ORC cycle needs a shorter optimization time and has a higher optimization efficiency.

Energy optimization is performed on hybrid solar-geothermal power plant working according to Organic Rankine Cycle and installed in southern Tunisia. The performances of four different configurations of the power plant are studied. Mass and energy balances are established for the different compounds. The effects of the main operating parameters such as the geothermal water temperature, ambient temperature and direct normal irradiation on the power plant performances are analyzed. A code is established using Engineering Equation Solver software (EES) to perform the required calculations. Obtained results show that the hybrid solar-geothermal power plant with a heat recovery system is the most suitable configuration design giving a better overall energy efficiency of 15.77 and13.11% and a maximum net power of 1089 and 1882 kW in winter and summer, respectively. However, in the summer season, using a heat recovery system can valuable only when the water temperature is higher than 66°C. For air-cooled condenser, the suitable condensing pressure is 1 bar in winter and 1.9 bars in summer. [ABSTRACT FROM AUTHOR]

To solve the problem of multi-objective performance optimization based on ant colony algorithm, a multi-objective performance optimization method of ORC cycle based on an improved ant colony algorithm is proposed. Through the analysis of the ORC cycle system, the thermodynamic model of the ORC system is constructed. Based on the first law of thermodynamics and the second law of thermodynamics, the ORC system evaluation model is established in a MATLAB environment. The sensitivity analysis of the system is carried out by using the system performance evaluation index, and the optimal working parameter combination is obtained. The ant colony algorithm is used to optimize the performance of the ORC system and obtain the optimal solution. Experimental results show that the proposed multi-objective performance optimization method based on the ant colony algorithm for the ORC cycle needs a shorter optimization time and has a higher optimization efficiency. [ABSTRACT FROM AUTHOR]

The thermodynamic study of a small scale cooling system combining an ORC cycle and a refrigeration cycle is carried out. The system includes the same components as those used for ejection cycles except that a combination of a vane compressor and a vane expander replaces the usual ejector. Real fluids properties, efficiencies of the pump, the compressor and the expender and pressure drops are considered. The isentropic efficiency of the expander was measured experimentally and the data were used in the thermodynamic model to simulate the complete system in steady state. The system is designed for operating with a 2 kW heating source at 65 °C corresponding to the heat rejected by a domestic PEMFC-type cell and a parametric study assess its performance, compactness and sensitivity when operating at off design. The evaporating temperature varies from −9.5 °C to +10.5 °C and the condensing temperature varies from 20.1 to 40.1 °C. Over the 12 fluids tested here, R1270 appears to be the most promising fluid, providing high performance, good compactness, low environmental nuisance and low off design sensitivity. [ABSTRACT FROM AUTHOR]

The performance of a 5MW el indirect ORC cycle coupled to linear solar collectors with different technologies is assessed, aiming at evaluating the effect of different control strategies on annual electricity output. Two different solutions are considered for solar collectors: a state-of-the-art parabolic trough collector with Therminol VP1 as heat transfer fluid (HTF), reaching 390 °C as maximum temperature within the solar field, and a cheaper Linear Fresnel Reflector (LFR) with Therminol 55, limited to an operating temperature of 310 °C. A simplified procedure is firstly proposed in order to identify the organic fluid that guarantees the highest performance under design conditions. Toluene is the selected working fluid in a saturated regenerative Rankine cycle configuration. After fluid selection, a more detailed analysis involving turbine sizing and piping estimate is carried on in order to set optimal on-design parameters such as the evaporating pressure of the working fluid. Finally, yearly electricity production is calculated taking into account off-design performance of all plant components as a function of the effective solar radiation. Two different off-design control strategies are considered for the turbine, namely sliding pressure and constant pressure at the turbine inlet. The levelized cost of electricity (LCOE) is computed for both cases. For high temperature collectors the LCOE results respectively about 180 €/MWh with partial admission and 175 €/MWh with sliding pressure off-design control strategy. LFR technology leads to similar LCOE when its specific cost is about half than the parabolic trough collector. [ABSTRACT FROM AUTHOR]

This paper compares a traditional district heating (DH) system with a low temperature DH system based on a combined heat and power (CHP) system using Organic Rankine Cycle (ORC). Both systems supply the same amount of heat, but it is shown that the system based on CHP using ORC is more effective and uses less fuel. This in turn results in less carbon dioxide emissions. The most advantageous configuration improving the real efficiency of the ultra-low temperature heating system seems to be a system combining a central heat pump and a station based on modern ORC technology which also provides an independent (off grid) electricity supply. • Analytical model of low temperature district heating supplied by CHP ORC is shown. • Electrical energy from ORC is used to supply DH pumps and heat domestic hot water. • Such DH system is more effective and it uses less fuel than traditional (3G) one. • Such DH systems emits less CO 2 and no external electricity is required. • The novelty includes also more flexible response to changing heat and cool demand. [ABSTRACT FROM AUTHOR]