Organic Fluids Research Articles

Research Progress on Direct Contact Evaporation Heat Transfer between Two Immiscible Working Fluids

AbstractThe direct contact evaporation heat transfer of two immiscible fluids can realize low‐temperature differential heat transfer, which is an important method to improve the heat transfer coefficient. This article focuses on the dispersed phase of organic working fluids and the continuous phase of immiscible inorganic fluids and summarizes the research on direct contact evaporation heat transfer in the past 15 years. The main research methods include theoretical analysis, numerical models, and experimental research. The evaporation process of a single droplet mainly involves bubble droplet growth, droplet configuration and discriminant, droplet shape change, rising speed and path, etc. In practice, dispersed phases mostly exist in populations, and the research mainly focuses on collisions, coalescence, and rupture between droplets and bubbles, as well as on the number and size distribution. The volumetric heat transfer coefficient is used to reflect the heat transfer capacity of the heat exchanger. The factors affecting evaporation heat transfer performance are complex, and increasing the uniform mixing of bubbles is an important method to improve the heat transfer coefficient. In the future, direct contact evaporation heat transfer is expected to be promoted to multiple fields.

Comparison Of The Electricity Generation Potentials Of Solar ORC Designed With Different Fluids Depending On Instantaneous Solar Radiation In Four Districts Of Türkiye

In this study, the solar Organic Rankine Cycle (ORC) system was analyzed to meet some of the electrical energy needed in large and medium-sized buildings and large enterprises such as hotels from solar energy. A simulation study was conducted for different districts in Türkiye that are rich in solar energy potential. These counties and the provinces they are affiliated with; Silifke-İçel, Alanya-Antalya, Bodrum-Muğla, Çeşme-İzmir. The power value transferred to the ORC was determined by considering the instantaneous radiation values and sunshine durations for the districts. The performance of solar ORC was determined by comparing fluids from three different organic fluid types. Organic fluids and types used in design; benzene-aromatic hydrocarbon, cyclohexane-alkane, octamethylcyclotetrasiloxane (D4)-siloxane. Considering the maximum electrical energy values obtained from Solar ORC in the summer months, it was seen that 205 MWh electricity generated was obtained for Silifke with benzene at a heat source temperature of 223 oC in July. Maximum solar parabolic trough collector (PTC) specific electric power value was determined as 59.52 W/m2 in Alanya district with benzene in June. When the four districts are evaluated together, it has been determined that benzene performs better than cyclohexane by 3.8% on average and 23% better than D4. When the annual electrical energy values are examined, the highest production was determined as 1625 MWh with benzene fluid in Alanya district.

Potential development of organic Rankine cycle (ORC) power generation system by utilizing heat from natural hot-spring in Malaysia

Organic Rankine Cycle (ORC) is widely used because of its ability to work with low and medium-grade heat resources. ORC basically operate by using organic working fluid which allows the application of Rankine Cycle to be operate at various range of heat resources depend on the properties of working fluid. This allows wide application of ORC power cycle at temperature below 370 °C where the steam-based Rankine Cycle are no longer efficient. This present paper discusses the potential development of micro power generation based on the ORC concept by utilizing heat from natural hot spring in Malaysia. The performance of the systems is analysed based on three different working fluids which are R134a, R410a and R245-fa. The comparison was done by the variation of hot water inlet temperatures in the range of 50 °C to 75 °C at the evaporator and 25 °C of ambient water at the condenser. The results indicates that R245-fa had 9 % thermal efficiency when the hot water inlet temperature is 75 °C which is the highest among the other working fluids in the similar condition. Meanwhile, the ideal power output of turbine is also analysed. The R410 can generate 2.38 kW power output when the input temperature of hot water is 75 °C which is the highest as compared to other working fluid at similar condition. Therefore, it can conclude that the micro-scale power generation systems can be developed based on ORC power cycle by utilizing heat resources by natural hot spring in Malaysia.

Multi-criteria thermo-economic analysis of solar-driven tri-generation systems equipped with organic Rankine cycle and bottoming absorption refrigeration and Kalina cycles

Optimal thermo-economic integration of renewable energy sources with multi-generation energy systems is a prime research topic today. The present study proposes a multi-criteria evaluation method of such integration, based on combined heating and power (CHP), and combined cooling and power (CCP) scenarios, for three different solar intensities. Three novel solar-driven tri-generation systems are selected. They include different organic Rankine cycle (ORC) architectures and a Kalina cycle system (KCS) and a double-effect absorption refrigeration cycle as bottoming cycles. Evaluation of the tri-generation systems, both with and without the KCS system, indicates a performance improvement of up to 23% in various thermoeconomic characteristics when the KCS system is present. Selection of the suitable tri-generation system for each condition and optimization of the working fluid are carried out based on a multi-attribute decision-making method. P-xylene is found as the optimal organic working fluid for ORC and ORC (ORC integrated with internal heat exchanger) based systems, and benzene for the regenerative ORC-based system in both CHP and CCP scenarios. Multi-criteria analysis shows that ORC-based system outperforms other systems with net outranking flow of 0.44 (0.39) for CHP (CCP) application. The optimal configuration gives 95.6 M$ and 1.99 years for net present value and dynamic payback period, and 83.03% and 34.55% for energy and exergy efficiencies, respectively.

Organic Vacuum Pump Fluids for the Vacuum Pumping of Fusion Power Plants

Vacuum pumps are the heart of the fusion fuel cycle, but most currently proposed pumping technologies are not capable of handling the required flow rates and vacuum pressures. Oil-containing vacuum pumps can readily meet the flow requirements, but vacuum fluids will degrade in fusion-relevant environments due to contact with tritium and exposure to high-energy radiation. Here, we describe a methodology to screen vacuum fluid candidates and purify these candidate fluids post oxidation, post exposure to deuterium, and post exposure to gamma radiation (<7.5 MGy) to simulate a process in which vacuum fluids can be recovered and regenerated during the fusion fuel cycle. A series of oils, including a highly purified mineral oil, phenyl silicone oil, and a polyphenyl ether, are shown to be suitable candidates for vacuum pumping. Additionally, we describe a simple purification methodology to remove oxidized functionalities and the associated isotopologues induced by contact with deuterium from the candidate vacuum fluids This purification methodology can also be applied to radiological damage with moderate effect. Finally, we demonstrate that the sorbents can be regenerated through electromagnetic microwave digestion.

Performance prediction and design of CO2 mixtures with the PR-VDW model and molecular groups for the transcritical power cycle

Nowadays, CO2 mixture has been widely considered as the working fluid of power cycle. However, how to select appropriate fluid from the numerous organic fluids has to be solved, so as to achieve the high-efficient power cycle. Thus, in this work, PR-VDW and GCM-PR-VDW models are respectively developed to predict the properties of CO2 mixture. Under the given operating conditions, the prediction deviations of cycle performance are obtained and the influences of cycle temperature, pressure and mixing ratio on prediction accuracy are explored. The results show that PR-VDW model has high prediction accuracy for the thermal properties and cycle performance of CO2 mixtures. The prediction deviations of cycle efficiency and net work are 11.38% and 6.88%, respectively. For the GCM-PR-VDW model, cycle efficiency and net work have deviations 15.65% and 8.65%, respectively. On this basis, with the maximum output power as the optimization objective, the optimal organic working fluid and its ratio in CO2 mixture are determined by employing GCM-PR-VDW model. Under the given heat source conditions, it is found that CO2+R32 (0.23/0.78, molar ratio) is the optimal mixture for the transcritical power cycle, and the corresponding cycle efficiency and net work are 16.48% and 1148.04 kW, respectively.

Weakened AMOC related to cooling and atmospheric circulation shifts in the last interglacial Eastern Mediterranean

There is limited understanding of temperature and atmospheric circulation changes that accompany an Atlantic Meridional Overturning Circulation (AMOC) slowdown beyond the North Atlantic realm. A Peqi’in Cave (Israel) speleothem dated to the last interglacial period (LIG), 129–116 thousand years ago (ka), together with a large modern rainfall monitoring dataset, serve as the base for investigating past AMOC slowdown effects on the Eastern Mediterranean. Here, we reconstruct LIG temperatures and rainfall source using organic proxies (TEX86) and fluid inclusion water d-excess. The TEX86 data show a stepwise cooling from 19.8 ± 0.2° (ca. 128–126 ka) to 16.5 ± 0.6 °C (ca. 124–123 ka), while d-excess values decrease abruptly (ca. 126 ka). The d-excess shift suggests that rainfall was derived from more zonal Mediterranean air flow during the weakened AMOC interval. Decreasing rainfall d-excess trends over the last 25 years raise the question whether similar atmospheric circulation changes are also occurring today.

An Analysis of the Heat Transfer Characteristics of Medium-Shallow Borehole Ground Heat Exchangers with Various Working Fluids

Medium-shallow borehole ground heat exchangers (BGHEs) utilize a burial depth ranging from 200 to 600 m. The heat exchange capacity of a single medium-shallow BGHE is higher than that of a single shallow BGHE. Compared to medium-deep BGHEs, the cost of medium-shallow BGHEs is lower, and both heating and cooling can be achieved, while the former can only be used for heating. However, there is a relative lack of research on the heat transfer characteristics of medium-shallow BGHEs, especially on the influence of the working fluid type on the heat transfer performance of BGHEs. This study aimed to investigate the impact of different working fluids on the performance of medium-shallow BGHEs. First, a heat transfer model for medium-shallow BGHEs was established considering the ground temperature gradient and geothermal heat flow, and its accuracy was validated using experimental test data. Second, the model was used to compare and analyze the effects of various working fluids on the heat transfer performance, pressure loss, and potential environmental benefits of BGHEs. Based on economic analysis, CO2 was determined to be the most suitable working fluid among the organic fluids considered. Finally, the influence of the number of boreholes and the type of working fluid on the heat transfer performance of borehole clusters consisting of 2 and 4 boreholes was analyzed using the superposition principle. The results indicated that CO2 could provide the highest heat transfer among the various working fluids selected in this study, as its heat extraction and heat dissipation were approximately 15% and 12% higher than those achieved by water. Isobutane (R600a) achieved the highest net heat and emission reduction, surpassing water by 66.7% and 73.6%, respectively. Regarding the four boreholes, the outlet temperature of the BGHEs gradually decreased at the end of each heating season. After 10 years of operation, the value decreased by approximately 2 °C. The results in this paper provide a theoretical basis and technical guidance for the rational selection of working fluids and improvements in the heat transfer performance of BGHEs, which could promote the development and application of medium-shallow geothermal energy sources.

Performance Analysis of Organic Rankine Cycle with Internal Heat Regeneration: Comparative Study of Binary Mixtures and Pure Constituents in Warm Regions

There are various organic compounds that can be utilized in the organic Rankine cycle as working fluids. The selection of a suitable working fluid is complicated due to the large number of options and factors affecting the choice, such as thermodynamic properties, environmental impact, cost, etc. This study evaluates seven different pure organic compounds and twenty-one of their binary zeotropic mixtures as potential working fluids for the organic Rankine cycle powered by a heat source at 200 °C. The pure organic fluids show higher exergy efficiency, higher specific net power output, and lower heat exchange area requirements compared to the binary mixtures. Among the pure fluids, RE347mcc performs the best in terms of exergy efficiency, followed by neopentane, isopentane, and pentane. Cyclopentane exhibits the highest power production capacity per unit mass flow rate of the working fluid. Two mixtures, pentane/Novec 649 and cyclopentane/Novec 649, showed significantly higher exergy efficiency than their individual components, but at significantly lower specific power production capacity. The study presents an interesting trade-off between exergy efficiency and heat exchange area, indicating that a small increase in exergy efficiency can lead to a large decrease in the required heat exchange area. The outcomes of this study can help in selecting suitable working fluids for ORC operation with a heat source at 200 °C.

Experimental detection of inadequacies and improvements for a geothermal power plant using single shaft double turbine binary Organic Rankine cycle as power system

The present paper dealt with the performance analyses and improvement probabilities detection for the present geothermal power plant. In addition, the present study aimed to present an analysis methodology for manufacturers and users to detect deficiencies, inadequacies and probable improvements for a present system. In this study, a geothermal power plant was used as a sample system for the analyses. Analyses were applied to the plant regarding energy, exergy, economic and environmental aspects. After comprehensive analyses, it was observed that the power consumption of the fans shows dramatic change depending on the seasons. For this reason, if the location and site conditions of the facility are suitable, performing the cooling processes with water-cooled condensers instead of air-cooled condensers was suggested. Moreover, by keeping the acceptance of saturated steam inlet at the turbine, it is thought that an increase in system performance will be achieved by designing a pump system that can increase organic fluid pressures up to partially higher pressures. In addition to all these, it was recommended to analyse the effect of integrating a superheater to bring the organic fluid to the superheated vapour phase at the turbine inlet.

Bi-objective optimization and environmental assessment of SOFC-based cogeneration system: performance evaluation with various organic fluids

Heat recovery offers multiple advantages, such as reducing energy consumption, promoting environmental sustainability, and enhancing productivity. Consequently, in this study, a bi-evaporator organic flash cycle (BEOFC) is utilized to recover heat from a solid oxide fuel cell (SOFC) and serves as a heat recovery unit. The BEOFC is a groundbreaking system that generates cooling and electricity. It boasts a dual-evaporator design that cools air at two distinct temperatures. Examining various organic fluids for better BEOFC performance entails evaluating their thermodynamic, environmental, and economic aspects. Based on the results, R227ea is selected as the optimal working fluid for BEOFC due to its superior performance. Subsequently, a parametric study is conducted and a bi-objective optimization of the proposed system is performed, where the objective functions comprise minimizing the total unit cost of products (TUCP) and maximizing the exergy efficiency. Optimized performance can be achieved when TSS1= 364.5 K, Teva1= 273.1 K, TSOFC= 897.3 K, and JSOFC= 5004 A/m2. At this point, the exergy efficiency and TUCP surge by 2.63%-point and 27.1% compared to the initial state. However, there is a rise of 7.26% in CO2 emission rate, 13.15% in sustainability index, and 8.8% in the total exergoeconomic factor when compared to the base case.

Techno-economic investigation of integrated biodiesel internal combustion engines and transcritical organic Rankine cycles for small-scale combined heat and power generation

The work presents an integrated system for combined heat and power generation based on a topping biodiesel internal combustion engine (ICE) and a bottoming transcritical organic Rankine cycle (TORC). A 0D/1D mathematical model is developed to evaluate the performance of the innovative biodiesel system in design and off-design conditions for a wide range of rated power and organic fluids. The analysis highlights that the TORC integration improves the total full load electric power by more than 12%, and the engine size significantly influences the integrated system performance. The total electric efficiency increases from 35.0% to 47.9%, whereas the thermal efficiency decreases from 27.2% to 19.8% when the ICE’s nominal power moves from 10 kWel to 500 kWel.Afterward, a multi-objective investigation is carried out to define the most suitable power of the proposed biodiesel system and its capability to satisfy the energy request of specific users. A thermal self-consumption equal to 100%, an electric self-consumption larger than 94%, and a payback time of 5.2 years are found. Lastly, a sensitivity analysis demonstrates the economic feasibility of the proposed biodiesel integrated system for a wide range of prices of energy vectors and system components.

Chemo-Mechanical Behavior of Bentonite-Sand Mixtures Inundated with Organic Pore-Fluid

ABSTRACT Bentonite-sand mixture is considered to be a potential liner material for landfill facilities owing to its excellent sorption potential and swelling characteristics. Such liner materials are expected to perform satisfactorily if the hydraulic conductivity is maintained less than 10−7 cm/s and thereby inhibiting the migration of the generated leachate. However, the performance assessment of these liners in the presence of highly concentrated organic fluids and under the overburden stresses that is usually expected in landfill conditions is scarce. Therefore, in the present work, the hydraulic performance of the bentonite-sand mixtures in the presence of the organic compounds commonly encountered in the landfill leachate is studied, which is a need of the hour. Flow tests were performed to evaluate the hydraulic conductivity of different bentonite-sand mixtures in unhydrated conditions and permeated with varied proportions of methanol-water and ethanol-water mixtures. The study reveals that the proportions of the organic pore fluids significantly influence the hydraulic conductivity of the bentonite-sand mixtures. A very good linear relationship was observed between the pore fluids’ dielectric constants and the hydraulic conductivity of the bentonite-sand mixtures. The chemo-mechanical behavior suggests that the conventional bentonite-sand mixtures perform poorly in terms of the hydraulic and swelling characteristics with the change in the dielectric constant of the organic fluids. The microstructural analysis also supports the experimental findings that as the dielectric constant of the fluid are reduced, the effective flow path through the soil increases considerably resulting in higher hydraulic conductivity.

UO2-fueled microreactors: Near-term solutions to emerging markets

We perform a scoping study of seven classes of microreactor technologies with a diverse set of coolants, that is, heat pipes, sodium, lead–bismuth, helium, FLiBe, organic fluid and light water. A point design is developed for each reactor class under a consistent set of assumptions about road transportability, irradiation cycle length, passive decay heat removal and reactivity control. All reactors have a thermal spectrum and use low-enriched (≤5%) uranium dioxide fuel, which is readily available and inexpensive. Mature moderator materials, in-core structural and cladding alloys were selected in this study including graphite, Zircaloy and stainless steel 316H. We compare the economic potential of these point designs according to a set of figures of merit including the cost of fuel, coolant, major equipment, instrumentation and control (I&C) systems as well as the complexity of operations and maintenance (O&M).The results of our analyses confirm that economies of scale work against microreactors competitiveness, i.e., relatively small absolute costs become high costs per unit energy generated because of the low power output. We find that all designs have very high fuel costs because of the relatively low achievable burnup, and high I&C costs (in particular for the reactor protection system), compared to traditional large light water reactors. Coolant costs are also notably high for the lead–bismuth cooled, organic-cooled and especially FLiBe-cooled systems. The constraints adopted in this study limited the heat pipe reactor’s operating temperature to 650 °C, which resulted in low core power density and low electric power output, thus yielding a poor economic performance. When technology maturity, operating experience, O&M complexity and our estimated costs are holistically taken into account, we judge that the most promising designs examined in this study are (in no particular order) the Na-cooled reactor, the HTGR, the organic-cooled reactor and the water-cooled reactor.

Selection of Organic Fluid Based on Exergetic Performance of Subcritical Organic Rankine Cycle (ORC) for Warm Regions

The organic Rankine cycle (ORC) exhibits considerable promise in efficiently utilizing low-to-medium-grade heat. Currently, there is a range of organic fluids available in the market, and selecting the appropriate one for a specific application involves considering factors such as the cycle’s thermodynamic performance, plant size, and compatibility with turbomachinery. The objective of our study is to examine the exergetic performance of the ORC with internal heat regeneration. We analyze 12 different organic fluids to evaluate their suitability based on parameters like exergy efficiency and heat exchange area requirements. Additionally, we investigate the need for internal heat regeneration by comparing the overall exergy performance with a simpler ORC configuration. To ensure broad applicability, we consider source temperatures ranging from 150 to 300 °C, which are relevant to industrial waste heat, geothermal sources, and solar energy. For each case, we calculate specific net power output and the UA value (heat exchanger conductance) to gain insights into selecting the appropriate organic fluid for specific source temperatures. Cyclohexane, benzene, isopropyl alcohol, and hexafluorobenzene show poor exergy efficiency due to their high boiling points. Pentane and cyclopentane provides the highest exergy efficiency of 62.2% at source temperature of 300 °C, whereas pentane is found to be the most suitable at source temperatures of 200 and 150 °C with exergy efficiency of 67.7% and 61.7%, respectively. At 200 °C source temperature, RE347mcc achieves 65.9% exergy efficiency. The choice of organic fluid for a given heat source is highly influenced by its critical properties. Moreover, the normal boiling temperature of the organic fluid significantly impacts exergy destruction during the condensation process within the cycle.

Process design and simulation study of an electricity generation plant utilizing low-grade wasted thermal energy using aspen Hysys software

An analysis of the operational parameters of a small-scale electrical generation facility that uses the thermal energy contained in the flue gases from rubbish waste incineration is the goal of this study. To assess this system, the organic Rankine cycle (ORC) thermodynamic system was used. Since the organic fluid has a lower boiling point than water and can be evaporated with less thermal energy, it was chosen as a heat transfer medium instead of water. Aspen Hysys was utilized as a simulation tool, while R11 was used as the working fluid. To maximize the amount of available electrical output power, the plant's operational temperature, working fluid flow rate, and pressure are all maximized. According to the simulation's findings, flue gas may generate electric power between the ranges of 3.12 – 29.71 kW at working pressures between 2.5 and 3.5 bar and working fluid flow rates between 3.600 and 7200 kg/h when the temperature is between 50 and 95 oC. The system reaches a thermal efficiency of about 8.30 at 350 kPa of working fluid pressure.

Genesis of Calcite Veins in 8# Coal Seam of the Upper Carboniferous Benxi Formation, Southeastern Margin of Ordos Basin

The 8# coal seam in the Benxi Formation of the southeastern margin of the Ordos Basin is a deep coal seam with abundant coalbed methane resources. Calcite veins are commonly developed within the 8# coal seam, and their formation processes and mechanisms have significant implications for the enrichment of deep coalbed methane. Genesis of the calcite veins was analyzed to reveal the impact of the calcite veins formation on coalbed methane accumulation, with an integrated application of petrographic study by thin section, cathodoluminescence analysis, carbon-oxygen isotope analysis, and homogeneous temperature measurements of fluid inclusions. The research findings indicate that the calcite veins in the 8# coal seam can be classified into three stages: C1, C2, and C3. The diagenetic fluids of C1 primarily originated from contemporaneous seawater. The fluids responsible for the formation of C2 primarily consist of organic fluids enriched in biogenic gas, whereas the fluids contributing to the formation of C3 are primarily associated with liquid hydrocarbons originated form decarboxylation of organic matter. Furthermore, the development of both C2 and C3 is influenced by deep hydrothermal fluids resulting from tectonic heating events during the Early Cretaceous. By combining analysis of the hydrocarbon accumulation history and burial history in the study area, it has been established that C2 formation occurred during the Late Triassic to Early Jurassic, while C3 formation took place during the Late Jurassic to Early Cretaceous. The exploration and production practices in the study area have firmly established the crucial significance of the formation and evolution of calcite veins within the 8# coal seam for the migration and accumulation of coalbed methane. The research outcomes provide valuable insights for the exploration of deep coalbed methane enrichment areas.

Energy and exergy analyses for organic Rankine cycle driven by cooling water of passenger car engine using sixteen working fluids

In this study, energy and exergy analyses of an organic Rankine cycle (ORC) for waste heat recovery from a passenger car engine cooling water are performed numerically. Sixteen different organic working fluids were selected according to their high-performance indicators recommended in the literature, their physical and chemical properties, and their environmental impact. Appropriate matching conditions between the low-temperature Rankine cycle with the engine cooling system and the properties of the working fluid were established. Thermodynamic models based on the first and second thermodynamic laws are developed. The ORC's cycle thermal efficiency, exergy destruction, and second law efficiency are assessed to choose the most suitable working fluid. The analyses investigate how the thermo-physical characteristics of the working fluid affect the performance metrics.Results show that ORC operating with R245fa and R123 as working fluids have the highest thermal efficiencies (7.76% and 7.49 % respectively), and low exergy destructions (1.538 kW and 1.586 kW respectively) in addition to moderately low mass flow rate necessity. The passenger car engine with ORC operated by R245fa as a working fluid shows an average value of 9.7 % fuel saving over the studied engine speeds and loads range.

Parametric study on the exergy analysis of a dual evaporator cooling cy-cle powered by the organic Rankine cycle

This study conducts a parametric study based on the energy and exergy analysis of a combined cycle composed of an organic Rankine and dual evaporator cooling cycles. The mechanical power supplied provides the mechanical compression refrigeration cycle with two evaporators. The influence of operating temperature, including the impact of the evaporator temperature of the organic Rankine cycle and the effect of dual evaporator cooling cycle evaporator temperature, were investigated; in this case, three organic fluids were employed such as R134a, R290, and R600. The results indicate that using R600 as the working fluid for both cycles enhance the system performance, and the energy efficiency of the combined system grows from 27.10 % to 40.22 %.The performance factor of the dual evaporator cooling cycle increases from 3.25 to 3.29 for the evaporating temperature of the first evaporator and from 2.07 to 4.28 for the second evaporator. Moreover, it is also noted that the exergy efficiency of the dual evaporator cooling cycle decreased from 40.03 % to 30.18 % for the first evaporator and increased by 32.47 % to 38.82 % for the second evaporator.

Evaluating the thermal efficiency and net power output of ORC for three wet fluids

Low-grade heat can be successfully recovered from waste energy sources for power production by an organic Rankine cycle (ORC). In this work, reheat ORC has been studied with three different wet organic fluids. The performance of R1270, R152a and Cyclopropane has been modelled in an ORC operated by a source of heat of 413.15K. The reheat ORC model contains economizer, evaporator, superheater, reheater, two turbine, pump and condensers. With variable turbine inlet temperature and reheat pressure, the net power output and thermal efficiency have been estimated. The results show that there exists an optimum temperature at the turbine inlet maximizing . The increase of reheat pressure gives only a marginal growth in the cycle efficiency, but it rises the with about 16.88 %, 16.26 % and 13.23 % for R1270, R152a and cyclopropane respectively.