Exergy Loss Research Articles

Proposal design and thermodynamic optimization of an afterburning-type isothermal compressed air energy storage system integrated with molten salt thermal storage

The isothermal compressed air energy storage is a potential technique for large-scale energy storage. In this study, the molten salt thermal storage is integrated with the afterburning-type isothermal compressed air energy storage system, which uses liquid piston compression technique, to enhance the thermal performances. Thermodynamic models of the hybrid energy storage system were developed, and the genetic algorithm was used to optimize multiple parameters to enhance the energy efficiency. Four operation modes, i.e., the high, medium-high, medium-low, and the low output power modes were proposed, to enhance the operational flexibility of the hybrid energy storage system. When the system operates in the operation mode of medium-low output power, a portion of afterburning heat is stored in the molten salt and used in the operation mode of low output power. Results show that the roundtrip efficiency of high, medium-high, medium-low, and the low output power modes are 63.57 %, 59.33 %, 57.13 %, and 83.28 %, respectively. Exergy analysis was carried out to quantify the irreversibilities of key components. In the three modes of operation with afterburning, the combustion chamber has the highest portion of exergy loss, and in the operation mode without afterburning, the exergy loss of heat exchangers is higher than that of expanders.

Calculation of exergy losses, exergy efficiency and cooling coefficient of refrigerant R22

This study presents a detailed analysis of the exergy losses, exergy efficiency, and cooling coefficient of performance (COP) for the refrigerant R22 in refrigeration systems. Exergy analysis, which considers both the quantity and quality of energy, is used to identify and quantify the irreversibilities within the system. The objective of this analysis is to provide insights into the areas of inefficiency and potential improvements for enhanced energy performance. Results indicate that the exergy losses in R22 systems are primarily associated with the compressor and expansion valve, highlighting these components as key targets for efficiency improvements. The exergy efficiency was found to vary significantly with operating conditions, suggesting that system performance could be optimized through appropriate design and control strategies. Additionally, the cooling COP of R22 was evaluated, demonstrating its effectiveness in converting input energy into cooling capacity under various conditions. This analysis contributes to the broader understanding of R22's thermodynamic performance and offers a foundation for developing more sustainable and efficient refrigeration technologies.

Impact of collector aspect ratio on the energy and exergy efficiency of a louvered fin solar air heater

Solar air heaters have huge applications in renewable energy utilization segments concerning the issues of space heating, drying, and ventilation systems. Performance prediction of such systems largely depends upon the design of the collector itself. The present study has highlighted the influence of various aspect ratios of the collector on the thermal and exergy performance of louvered finned solar or air heaters. In this context, an experimental analysis has been carried out to compare the performance of LFSAH with conventional PSAH. These results show that an increase in aspect ratios enhances thermal efficiencies of heat transfer and the systems. An aspect ratio of 4:1 showed the maximum thermal efficiencies as 81.63 % for LFSAH and 68.13 % for PSAH. On the other hand, at larger mass flow rates, the exergetic efficiency of LFSAH becomes lower owing to the larger friction and exergy losses and sometimes even lower than that of PSAH. The novelties of the present study are in emphasizing the importance of aspect ratio in optimizing solar air heater design and providing relevant insight for better energy use.

Modeling and Performance Analysis of Solid Oxide Fuel Cell Power Generation System for Hypersonic Vehicles

Advanced airborne power generation technology represents one of the most effective solutions for meeting the electricity requirements of hypersonic vehicles during long-endurance flights. This paper proposes a power generation system that integrates a high-temperature fuel cell to tackle the challenges associated with power generation in the hypersonic field, utilizing techniques such as inlet pressurization, autothermal reforming, and anode recirculation. Firstly, the power generation system is modeled modularly. Secondly, the influence of key parameters on the system’s performance is analyzed. Thirdly, the performance of the power generation system under the design conditions is simulated and evaluated. Finally, the weight distribution and exergy loss of the system’s components under the design conditions are calculated. The results indicate that the system’s electrical efficiency increases with fuel utilization, decreases with rising current density and steam-to-carbon ratio (SCR), and initially increases before declining with increasing fuel cell operating temperature. Under the design conditions, the system’s power output is 48.08 kW, with an electrical efficiency of 51.77%. The total weight of the power generation system is 77.09 kg, with the fuel cell comprising 69.60% of this weight, resulting in a power density of 0.62 kW/kg. The exergy efficiency of the system is 55.86%, with the solid oxide fuel cell (SOFC) exhibiting the highest exergy loss, while the mixer demonstrates the greatest exergy efficiency. This study supports the application of high-temperature fuel cells in the hypersonic field.

Development of a geothermal-driven multi-output scheme for electricity, cooling, and hydrogen production: Techno-economic assessment and genetic algorithm-based optimization

This study aims to develop an environmentally friendly multi-energy system for sustainable production of electricity, cooling and hydrogen. The study introduces a pioneering geothermal-based system, integrating an ejector refrigeration cycle, a dual-loop organic Rankine cycle, and a hydrogen production unit with proton exchange membrane electrolyzers. The study provides a thorough analysis of the system's energy and exergy performance, as well as its economic feasibility. Through sensitivity and parametric analyses, the research identifies key parameters that significantly influence system performance. The system's innovative design promises minimal environmental impact while delivering multifaceted performance: generating 1.38 MW of electricity, supplying 436 kW of cooling load, and producing 5.39 kg/h of hydrogen. In the exergy analysis, Evaporator1 is identified as the primary contributor to exergy loss, representing 34 % of the total exergy destruction. This is followed by the electrolysis unit, the condenser, and the ejector refrigeration cycle, which contribute 18 %, 14 %, and 12 %, respectively. The system achieves optimal efficiency at an organic Rankine cycle turbine1 inlet temperature of 387 K, yielding a power generation of 885.4 kW and an exergy efficiency of 26.7 %. Beyond this temperature, any further increase leads to a decline in power output due to operational disturbances. A multi-criteria optimization using genetic algorithm is applied, resulting in an optimized system with a cost rate of 18.13 $/h and an exergy efficiency of 38.96 %.

Applying Circular Thermoeconomics for Sustainable Metal Recovery in PCB Recycling

The momentum of the Fourth Industrial Revolution is driving increased demand for certain specific metals. These include copper, silver, gold, and platinum group metals (PGMs), which have important applications in renewable energies, green hydrogen, and electronic products. However, the continuous extraction of these metals is leading to a rapid decline in their ore grades and, consequently, increasing the environmental impact of extraction. Hence, obtaining metals from secondary sources, such as waste electrical and electronic equipment (WEEE), has become imperative for both environmental sustainability and ensuring their availability. To evaluate the sustainability of the process, this paper proposes using an exergy approach, which enables appropriate allocation among co-products, as well as the assessment of exergy losses and the use of non-renewable resources. As a case study, this paper analyzes the recycling process of waste printed circuit boards (PCBs) by disaggregating the exergy cost into renewable and non-renewable sources, employing different exergy-based cost allocation methods for the mentioned metals. It further considers the complete life cycle of metals using the Circular Thermoeconomics methodology. The results show that, when considering the entire life cycle, between 47% and 53% of the non-renewable exergy is destroyed during recycling. Therefore, delaying recycling as much as possible would be the most desirable option for minimizing the use of non-renewable resources.

Synergistic enhancement for energy-saving, emission reduction and profit improvement in iron and steel manufacturing system: Strategies for parameter regulation and technologies integration

The steel industry, characterized by high energy consumption and carbon emission, poses a significant threat to global energy and environmental security. In response to the energy conservation and dual-carbon targets, the steel industry must urgently find sustainable pathways for transformation and development. Steel production structure optimization and the application of cutting-edge technologies have been proven to be highly effective. However, the complexity and variability of actual production conditions highlight the absence of a methodology capable of adapting to real production scenarios, elucidating influencing principles across multiple factors, analyzing synergistic mechanisms of multiple indicators, and proposing collaborative control strategies. Furthermore, the potential for technology applications that are closely integrated with the company’s resource endowment remains uncertain, leading to an unclear overall strategy for energy saving and carbon reduction. This study develops a multi-scale optimization and evaluation model for ISMP, incorporating interconnected and matching processes, as well as nested multi-indicators, in response to the context. Subsequently, the disturbance mechanisms of various factors are accurately identified and a multi-indicator synergistic control strategy and framework are proposed. Following optimization, the exergy loss, energy consumption, carbon emission intensity, cost, and pollutant emissions of ISMP per tonne of steel are reduced by 1418.70 MJ, 42.93 kgce, 154.79 kg, 171.21 CNY, and 0.0168 kg, respectively. Additionally, measures such as reducing moisture content in coking coal can effectively regulate multiple indicators. Based on the proposed sensitivity quantification method, the temperature of hot blast is identified as the most effective controllable factor. Technologies like hydrogen-rich fuel injection, integrated waste heat recovery, and solar photovoltaic & energy storage have shown favorable prospects, according to analysis conducted from various angles regarding economic viability and potential for energy-saving and carbon reduction. However, the application of aforementioned technologies may be limited by financial consideration, necessitating cautious and judicious investment choices.

Optimisation of Brayton cycle CO2-based binary mixtures: An application for waste heat recovery of marine low-speed diesel engines exhaust gas

The energy-saving capabilities and efficient operation of marine low-speed diesel engines (MLDE) is a key emphasis for the main power source for ocean transportation. The purpose of the supercritical carbon dioxide recompression Brayton cycle (SCRBC) is to capture and utilise waste heat emitted by the engine's exhaust gas. However, the SCRBC performance will be severely affected by the large temperature fluctuations of ocean-going vessels during operation and high ambient temperatures in the cabin. A SCRBC model was built using the exhaust gas test data as the boundary conditions and validated using the Sandia National Laboratory (SNL) test data. The physical characteristics of the working fluids were evaluated by adding other fluids to CO2 in specific proportions to modify the critical point and increase cycle efficiency. The results demonstrated that employing CO2-based binary working fluids with low alkane and hydrogen sulfide (H2S) enhanced the recovery power, with the most significant increase obtained by the addition of 16.48 % H2S, which increased the power by 9.72 kW and improved the Brayton cycle efficiency by 3.31 %. Compared to the MLDE at 100 % load, the total efficiency increased by 1.77 % and the BSFC decreased by 6.76 (g kW−1 h−1) using CO2-H2S as the working fluid. The analysis of the SCRBC system component exergy losses showed that the cooler had the highest exergy losses. Adding other fluids to CO2 reduced the exergy losses of each component with the SCRBC system exergy losses decreasing from 162.97 to 129.90 kW and the exergy loss efficiency decreasing from 24.24 % to 22.65 %. The use of CO2-based binary working fluids specifically designed for ambient temperature may be expanded to other engines to enhance the efficiency of waste heat recovery.

Enhancing efficiency and economy of hydrogen-based integrated energy system: A green dispatch approach based on exergy analysis

Hydrogen-based integrated energy system holds promise for leveraging the low carbon advantage of hydrogen, but inefficiency of electrolysis hydrogen production leads to significant exergy loss within its operation. Addressing this, this paper focuses on the energy-saving and economic operation of the hydrogen-based integrated energy system, proposes a novel green dispatch approach using loss cost as the objective function and establishes a refined loss cost accounting model based on exergy analysis theory. Firstly, derived from the analogy of exergy loss, the concept and accounting framework of system loss cost are proposed. Secondly, employing exergy analysis and consistent unit exergy cost principle, equipment operation loss cost is calculated through energy, exergy flows analysis and cost allocation. Thirdly, utilizing the total of equipment operation loss cost, wind curtailment penalty cost, and transmission line loss cost as the objective function, a green dispatch model is formulated to minimize overall loss cost while ensuring energy balance and other constraints. Finally, simulations analysis are conducted. The results show that compared to economic dispatch, minimized exergy loss dispatch and multi-objective dispatch methods, proposed approach increases exergy efficiency by 0.54 %, reduces cost by 6.13 % and increases the scale of hydrogen utilization by 3.45 %, respectively.

Energy, Exergy, environmental and economic based experimental investigation of solar air heater using a novel arc rib geometry

To enhance the thermal efficacy of solar air heaters, the most efficient method is to disturb the viscous layer by roughening the surface using the artificial rib. In this research, a discrete apex-down arc-shape rib geometry on a roughened plate is used to examine the energy-exergo and economic- environmental based performance of solar air heater. By changing the Reynolds number from 3000 to 14,000 and maintaining a gap width to rib height ratio of 4, a relative height rib ratio of 0.045, and a pitch to rib height ratio of 10, the effects of arc rib angles of 30, 45, and 60 degrees are studied. The environmental exergy loss was determined to be substantial, between 70 % and 80 %. Maximum system to air exergy loss occurs at Reynolds number of 3000 with 5.64 W. At a temperature parameter of 0.0377 m2K/W, both the thermal and exergetic efficiencies are at their highest, at 77.60 % and 3.81 %, respectively. In comparison to a plate having a plain surface, the suggested apex-down discrete arc rib performs better based on energy payback time, usable yearly energy, and enviro-economic criteria. Finally, at rib angle of 30°, the conditions that optimize the heat transfer and energy payback time, energy cost, exergo-economic, and enviro-economic characteristic of the current artificially roughened geometry of solar air heater.

Energy, exergy and advanced exergy analyses on Garri “1” combined cycle power plant of Sudan

Thermal power plants account for 39% of Sudan's electricity grid. Consequently, enhancing the performance of these plants is crucial for bolstering the Sudanese energy sector. This paper presents an analysis of energy, conventional exergy, and advanced exergy for 180-MW Garri “1” combined cycle power plant in Sudan. The study focuses on assessing the enhancement potential of this power plant to provide guidance for performance improvement and identify optimal areas for enhancement within the plant's components. The energy and classical exergy analyses results indicated that the highest energy losses occur in the stacks (55.1%), while the largest source of exergy destruction is combustion chambers (50.98%). Furthermore, the lowest contributions to energy and exergy losses are from the deaerators (0.15% energy and 0.32% exergy) and auxiliary systems (0.22% energy and 2.85% exergy). The overall energy and exergy efficiencies of the plant were found to be 36.1% and 34.1%, respectively. The advanced exergy analysis exhibited that the ratios of unavoidable to avoidable exergy destruction and endogenous to exogenous exergy destruction are 87.95% to 12.05% and 68.3% to 31.7%, respectively. Moreover, it was shown that the primary source of avoidable endogenous exergy destruction is the combustion chambers (48.53%). Furthermore, the improvement potential in the plant's exergy efficiency was found to be only 3%, suggesting the need for optimization of operational parameters to enhance overall performance. The current paper offers valuable insights into enhancing efficiency of Sudanese energy sector, with implications for optimizing the energy sector in similar developing countries.

A theoretical thermodynamic investigation on solar-operated combined electric power, heating, and ejector cooling cycle driven by an ORC turbine waste heat, tri-generation cycle system

The current study investigated a solar thermal power plant to simultaneously produce multiple energy outputs, including electric power, process heating, and cooling. This integrated approach aligns with the concept of a tri-generation system, where three different forms of energy are produced from a single source. The study involves a parametric analysis, where the impact of each influencing parameter including, turbine inlet temperature, and turbine inlet pressure is systematically varied with DNI ranging from 600 W/m2 to 1000 W/m2 to understand its effects on both first-law and second-law efficiencies. Further, the exergy analysis shows the irreversibility's occur within the system. Notably, the central receiver and heliostat are identified as major sources of exergy loss. The comparison to a combined power and heating (CPH) cycle without an ORC-ejector indicates that the additional technologies significantly contribute to improving the system's performance, approximately 3.97 % and 2.3 % for both efficiencies, respectively.

The evaluation of hydrogen production of a multistage cooling system's performance

In the present research, a new cycle of scramjet open recuperator cooling to produce power and hydrogen is presented. In which, the power generation subsection uses the waste heat in the scramjet cooling process as a cycle heat source and produces electric power. In this research, some of the power generated in the cycle is used to power a Polymer Electrolyte Membrane (PEM) electrolyzer that produces hydrogen. An analysis of the energy and exergy has been conducted to assess the system's performance. With a fuel mass flow rate of 0.45 kg/s, the cooling capacity of the system is 10.2 MW, net power production is 4.1 MW, and 45.1 kg/h of hydrogen is produced. The exergy analysis revealed that the PEM electrolyzer had the highest exergy loss at over 48%, followed by the first cooling path at over 32%. The energy and exergy efficiency of the system are 14.2% and 19.2%, respectively. The parametric study indicated that increasing the mass flow rate leads to higher power production and cooling capacity. Additionally, at a constant fuel mass flow rate, power production increases with higher pressure behind the pump.

Performance investigation of a high-temperature absorption-compression heat transformer with liquid refrigerant injection

The high-temperature heat pump technology is a promising approach to utilizing low-temperature waste heat while meeting industrial demands for high-temperature heat. However, existing high-temperature heat pump systems face challenges including insufficient temperature lift, system complexity, and rapid performance degradation at high output temperature. This paper proposes a novel, structurally simple high-temperature absorption-compression heat transformer, aiming to recover heat below 100 °C and achieve a large temperature lift above 70 °C. The system is analyzed from the aspects of energy, exergy, key parameters that impact its performance, and techno-economic comparison. Results show that injecting liquid refrigerant into the compressor chamber mitigates high superheat effects on the compressor, allowing for higher absorption pressure. The system achieves an output temperature of around 170 °C, with the compressor outlet temperature below 120 °C. Moreover, some liquid refrigerant evaporates by absorbing compressor superheat. This reduces power consumption of the compressor, heat input of the evaporator, and overall system exergy loss. Thus, the proposed system demonstrates improvements of 6.5 % and 7.5 % in coefficient of performance and exergy coefficient of performance, respectively. Besides, it is feasible to achieve absorption temperatures exceeding 170 °C by increasing the solution concentration or the pressure ratio, with the former being the more cost-effective approach. Furthermore, the specific costs of the proposed system are more than 20 % lower than those of other types of high-temperature heat pumps, demonstrating its superior economic feasibility.

Optimizing waste heat recovery with organic Rankine cycles: A novel graphical approach based on Exergy-Enthalpy diagrams

The Organic Rankine Cycle (ORC) is a widely-used waste heat recovery approach, that converts low-grade heat into shaft work. This paper introduces a graphical methodology using Exergy-Enthalpy (Ex-H) diagrams, for evaluating and designing ORCs. ORC thermodynamics can be represented by approximate triangular exergy profiles without compromising accuracy. The exergy profile of the heat-absorbing process is crucial to ORC performance. Approximate triangular exergy profiles can be constructed for any ORC configuration to predict ORC performances, such as work output, exergy loss, and thermal efficiency. Furthermore, a systematic graphical approach is developed for integrating waste heat streams and ORCs, with step-by-step procedures outlined. The evolution procedure of the ORC exergy profile can determine working fluid selection and operating conditions. This visually intuitive yet scientifically rigorous tool clarifies the complex relationships between fluids, parameters, and system performance. Two case studies demonstrate the method's effectiveness, confirming it as a valuable tool for ORC design.

Analysis of Heat Exchanger for Single-Phase Cooling Applications using Micro-channels of Copper Material

The design of a microchannel heat exchanger can be achieved using various approaches. The design includes various materials, such as ceramics, silicon, metals, and polymers, that are used to make microchannels, depending on their specific requirements. Polymers such as silicon, glass, and other polymeric materials are utilized on metallic substrates. The current study includes microchannels fabricated from metallic copper. Further, the design solutions do not consider the implications of the second law of thermodynamics. Hence, performing an energetic analysis of microchannels is imperative to design and assess thermodynamic systems that use them efficiently. One technique to improve a thermodynamic system's efficiency is using a well-designed microchannel heat exchanger with excellent energetic performance. This can be achieved by creating a thermodynamic system that eliminates energetic losses and limits only unavoidable losses. The use of high-conductivity material like copper also achieves this. To identify possible reasons for exergy loss and perhaps address them, a thorough energetic analysis of an existing heat exchanger is necessary. A microchannel heat exchanger with 19 microchannels in a flat tube is considered for this study. The study finds the energetic losses, which are useful for the thermal design of the heat exchanger.

Thermo-economic and environmental analyses of supercritical carbon dioxide Brayton cycle for high temperature gas-cooled reactor

The supercritical carbon dioxide (sCO2) Brayton cycle demonstrates special advantages for the high temperature gas-cooled reactor (HTGR) delivered into commercial operation recently in China, with its high efficiency, compactness, flexibility, and safety compared to the conventional steam Rankine cycle. However, the large temperature rise of 500 °C for the HTGR brings new challenges for the design of sCO2 cycle. Here, we present the first study on the thermodynamic, economic, and environmental performance of the HTGR-sCO2 system using the energy, exergy, economic, and environmental (4E) evaluation method. The cascaded sCO2 cycle made up of two independent sCO2 cycles is proposed, which are arranged in series on the cold side of reactor heat exchanger. We show that the cascaded sCO2 cycle can utilize the heat absorption from HTGR effectively by optimizing the cycle configurations of top and bottom sub-cycles. The improved cascaded sCO2 cycle minimizes the exergy loss, and increases the thermal efficiency to 43.2% when compared to the steam Rankine cycle of HTGR demonstration power plant and the single recompression cycle. By balancing the fixed-capital investment cost with the net power, the levelized cost of electricity can be reduced to 0.0283$/kWh. The life-cycle GHG emission intensity of HTGR-sCO2 systems is about 6.5gCO2,eq/kWh, which is much smaller than that of coal-fired power plants, suggesting a great potential for decarbonization of the HTGR-sCO2 system. Our study may find implications for the advancement of the sCO2 Brayton cycle in next-generation nuclear power plant.

Comparison analysis of three CO2-based binary mixtures performing in the supercritical Brayton cycle for molten salt energy storage

It is generally acknowledged that using CO2-based binary mixtures as working fluids in supercritical recompression Brayton cycle for waste heat recovery is a promising technique. This study examines the performance of CO2-Kr (0.76/0.24) and CO2-Xe (0.56/0.44) mixtures, comparing them with pure CO2. Both thermodynamic and thermo-economic considerations are taken into account to establish optimal parameter settings. The findings suggest that the minimum system temperature should be around but not below the critical temperature of the working fluid. The system performs badly at lower pressures and shows nearly the same at higher pressures, with 25 MPa being the recommended value for the main compressor. When the system split ratio and the low temperature recuperator temperature difference are well matched, the heat exchangers exhibit an optimal temperature distribution. The exergy loss distributions of the exchangers in the CO2-Kr and CO2-Xe systems are likewise rather uniform when the input pressure of the main compressor is above the critical pressure of the fluid, typically between 0.2 MPa and 0.4 MPa, enhancing system efficiency. The corresponding temperature difference of the LTR should be within 5 °C above or below the critical temperature of the fluid. This advantageous feature is not immediately apparent in the pure SCO2 cycle.

Phase modulation analysis on a cavity-structured single-unit thermoacoustic refrigerator

The establishment of traveling-wave-dominated acoustic fields within the regenerator is crucial for developing highly efficient thermoacoustic refrigeration systems. The present work introduces a novel looped, single-unit, direct-coupling thermoacoustic refrigerator, incorporating an optimally dimensioned cavity at a strategic location to maximize system performance. Central to this research is the systematic exploration of the phase modulation mechanism. This exploration involves adjusting the dimensions of the cavity structure, tracking its evolution from initial absence to full integration. The research method includes comprehensive evaluations of steady-state performance, onset characteristics, exergy loss, and axial parameter distribution analysis. The findings are visually depicted through simulations, highlighting the cavity's role in acoustic field modulation and its consequent impact on system efficiency. With the integration of an optimally sized and positioned cavity, the system's cooling efficiency improves by more than 2.5 times compared to the efficiency of a structure without cavities. A prototype replicating the proposed design was then constructed and experimentally tested. The results reveal a close correlation between the simulated and experimental data, affirming the analysis's accuracy and dependability. These studies effectively elucidate the significance of the cavity in looped single-unit thermoacoustic refrigerators and provide valuable insights for the development of more efficient phase modulation structures.

Towards the dual heat sources recovery applied by organic Rankine cycle: An experimental assessment

The organic Rankine cycle (ORC) is a potential methodology for the thermal-power conversion of renewable energy (geothermal, solar, etc.). Towards the energy integrated application, the single heat source driven ORC could not satisfy the industrial development. In this work, a R1233zd(E)-based ORC driven by dual heat sources has been experimentally studied, and the dynamic system characteristics were primarily carried out. Considering the higher-temperature heat source with 100 °C–130 °C and the lower-temperature heat source with 55 °C–85 °C, the behaviors of the devices are evaluated, and the overall system performance are compared. After that, the comprehensive analysis on the effect of heat source temperatures is developed from the energy and exergy aspects. The results show that the net output and thermal efficiency mostly depend on the higher-temperature heat source. Both of the increasing temperature of the two heat sources would contribute to the enhancement of exergy efficiency, due to the increase in net output and the decrease in exergy loss, respectively. The contribution of the coordinate of the two heat sources are highlighted. Considering the combinations of heat sources with 130 °C/55 °C, 100 °C/55 °C,100 °C/85 °C, 130 °C/85 °C, the thermal efficiencies are sequentially 9.19 %–8.26 %, 7.24 %–6.98 %, 7.38 %–7.35 %, 8.83 %–8.29 %, and the exergy efficiencies are 13.03 %–11.80 %, 10.59 %–10.27 %, 12.12 %–11.98 %, 13.82 %–13.16 % in sequence.