Range Of Heat Source Temperatures Research Articles

Integrated Air-Bridge Tandem Thermophotovoltaics with High Efficiency over a Broad Heat Source Temperature Range

Integrated Air-Bridge Tandem Thermophotovoltaics with High Efficiency over a Broad Heat Source Temperature Range

Numerical Study of a Three-Bed Adsorption Chiller Employing an Advanced Mass Recovery Process with Different Cycles

In this paper, the performance comparison between two different cycles has been numerically studied. In cycle1, the configuration of beds in the three bed chiller with mass recovery were taken as uniform in size but in cycle2 the configuration of Hex3 is taken as half of Hex1 or Hex2 (where Hex1 and Hex2 are identical). In the present numerical solution, the heat source temperature variation is taken from 70°C to 90°C (for both cycle) and along with coolant inlet temperature at 30°C and the chilled water inlet temperature at 14°C. Silica gel-water is chosen as adsorbent-refrigerant pair. In the new strategy, if any one bed (3rd bed) is connect with the evaporator during pre-heating or pre-cooling time then it will give better performance than that of existing system. In this strategy, mass recovery process also occurs in all bed. Results show that the cooling capacity (CC) and coefficient of performance (COP) of the cycle1 is much better than that of the cycle2 in the range of heat source temperature from 700C to 900C.

Thermal efficiency investigation for organic Rankine cycle and trilateral flash cycle using hydrofluoroether working fluids

The thermal efficiency of the organic Rankine cycle (ORC) is higher than the trilateral flash cycle (TFC) using normal dry working fluids. On the contrary, the thermal efficiency of TFC outperforms the thermal efficiency of ORC by using super dry working fluids at specific conditions. This study aims to investigate thermal efficiency for TFC and ORC cycles using HFE7100 and HFE7500, classified as super dry working fluids. The effect of two techniques was studied on the thermal efficiency of ORC and TFC: the recuperator cycle (RORC and RTFC) with various ratios of effectiveness and the partial evaporator organic Rankine cycle (PE-ORC), with various ratios of vapor quality. The results indicated that the recuperative heat exchanger helps convert the super dry behavior to be like normal dry. Therefore, using HFE7100 required 0.2 effectiveness of recuperative heat exchanger, while for HFE7500, 0.4 effectiveness is needed. A partial evaporator cannot help convert the super dry's behavior to the normal dry fluid completely, while it has the crucial role of moving the intersection point towards critical temperatures (Tcr), which increases the range of heat source temperatures that assist super dry fluids to behave as normal dry fluids. However, PE-ORC can be a good competitor to TFC at vapor quality (x = 0.1, and x = 0.2) and (x = 0.1), and it has higher thermal efficiency than ORC at vapor quality (x = 0.9) and (x = 0.8 and x = 0.9) for HFE7100, and HFE7500 respectively.

Solar-driven chemisorption cogeneration system integrated with thermal energy storage

In this study, a power and cooling cogeneration system is introduced, consisting of a chemisorption cycle, a latent heat thermal energy storage (TES) system employing phase change materials (PCM), and a solar system employing compound parabolic collectors (CPC). The system is targeted at being employed in a residential area in Shiraz City and TRNSYS and MATLAB software environments are utilized to simulate and assess the system. In the system, power is generated by a turbine with the pressure difference elicited through the chemical reaction in the chemisorption cycle. Also, the cooling is produced via the evaporation of ammonia in the evaporator. The effect of the supplied hot source temperature for the reaction in the adsorbent bed was investigated. It was observed that in the 100–200 °C heat source temperature range, the total energy efficiency increased from 0.313 to 0.467 and the COP for the refrigeration process reduced from 0.71 to 0.53. Also, the maximum overall energy and exergy efficiency in this temperature range were 0.46 and 0.405, respectively. Also, at the heat source temperature of 200 °C, the average maximum electrical power and cooling capacity were gauged at 2.7 kW and 14.5 kW, respectively. In the TES system with a volume of 1.5 m3, the maximum achievable capacity was 250 kWh and the solar system showed its highest temperature in July and August. It was observed that heat source temperature augments the production capacity of the system while it reduced the coefficient of performance (COP) of the system. Sustainable development goals (SDG) impact [Display omitted]

Thermodynamic and economic analysis of organic Rankine cycle combined with flash cycle and ejector

Increasing the net output power of the Organic Rankine Cycle (ORC) can increase the possibility of developing low-medium temperature heat sources. It is equally important to effectively control the system's economy. So, subcritical double-pressure ORC combined with flash cycle and ejector (S-EFDPORC) and transcritical ORC combined with flash cycle and ejector (T-EFDPORC) are proposed in present work. The thermodynamic and economic analyses on five proposed systems within the heat source temperature range of 100 °C–200 °C are conducted. The net output power and levelized energy cost (LEC) are treated as optimization objectives in thermodynamic and economic performance comparisons, respectively. The non-dominated sorting and three multi-objective optimization methods (LINMAP, TOPSIS, and Shannon Entropy) are used to perform the multi-objective optimization. The results show that S-EFDPORC and T-EFDPORC can both effectively improve the net output power compared with subcritical double-pressure ORC (S-DPORC) and transcritical double-pressure ORC (T-DPORC), while subcritical ORC combined with flash cycle and ejector (S-EFORC) can only improve the net output power within a certain temperature range. When the optimization objective is the net output power, compared with S-DPORC and T-DPORC, the growth rate of net output power in S-EFORC is more than 20% when the temperature is below 160 °C. When the temperature of the heat source is below 160 °C or above 180 °C, the growth rates of net output power of S-EFDPORC and T-EFDPORC increase more than 25%. When LEC is treated as optimization objective, compared with S-DPORC and T-DPORC, S-EFORC reduces LEC by more than 10%. S-EFDPORC and T-EFDPORC increase the LEC of the system, and the maximum growth rates of LEC are 30% and 60% respectively, resulting in worse economic performance. With three multi-objective optimization methods, both S-EFDPORC and T-EFDPORC can increase net output power, but their economy will deteriorate at most heat source temperatures. Although S-EFORC increase the net output power when the heat source temperature is below than 177 °C, LEC reduces throughout the heat source temperature range.

Thermodynamic Analysis and Optimization of the Micro-CCHP System with a Biomass Heat Source

In this article, new multiple-production systems based on the micro-combined cooling, heating and power (CCHP) cycle with biomass heat sources are presented. In this proposed system, absorption refrigeration cycle subsystems and a water softener system have been used to increase the efficiency of the basic cycle and reduce waste. Comprehensive thermodynamic modeling was carried out on the proposed system. The validation of subsystems and the optimization of the system via the genetic algorithm method was carried out using Engineering Equation Solver (EES) software. The results show that among the components of the system, the dehumidifier has the highest exergy destruction. The effect of the parameters of evaporator temperature 1, ammonia concentration, absorber temperature, heater temperature difference, generator 1 pressure and heat source temperature on the performance of the system was determined. Based on the parametric study, as the temperature of evaporator 1 increases, the energy efficiency of the system increases. The maximum values of the energy efficiency and exergy of the whole system in the range of heat source temperatures between 740 and 750 K are equal to 74.2% and 47.7%. The energy and exergy efficiencies of the system in the basic mode are equal to 70.68% and 44.32%, respectively, and in the optimization mode with the MOOD mode, they are 87.91 and 49.3, respectively.

Bifacial Thermophotovoltaic Energy Conversion

Thermophotovoltaic (TPV) energy conversion efficiency has recently surpassed 30%. The key behind such high efficiency is the inclusion of a highly efficient mirror in the rear of the TPV cell that turns back to the thermal emitter the outband energy photons. Efficiencies over 50% could be theoretically attainable by approaching a mirror reflectance of 100%. However, the very few percent of outband absorption significantly deteriorate the conversion efficiency, especially at low emitter temperatures. Thus, current research focuses on developing advance mirror designs able to reach an extreme high outband reflectance over 95%. In this article I propose a bifacial TPV cell that enables very efficient photon recycling without using mirrors and that is less sensitive to outband optical losses. The key to this design is that the cell is introduced in a thermal emitter enclosure where it is irradiated from both sides. Then, outband photons transmit through the cell and are reabsorbed in the emitter. Therefore, the optical losses linked to the mirror/cell interface are eliminated, potentially enabling higher photon recycling efficiencies. This article presents a detailed balance simulation of an edge-cooled bifacial TPV cell to demonstrate that bifacial configuration enables higher conversion efficiencies and twice much as power density than monofacial designs, the latter being an advantage for moderate temperature and low-cost TPV power generation. Therefore, bifacial TPV cells are appealing for developing practical high-efficient and low-cost TPV devices for power generation in an extended range of heat source temperatures.

Analysis of Organic Rankine Cycle efficiency and vapor generator heat transfer surface in function of the reduced pressure

In the paper presented is analysis of the influence of reduced pressure on efficiency and heat transfer area of vapor generator of Organic Rankine Cycle (ORC) in case of subcritical and supercritical parameters of operation. Compared are two cases of subcritical and supercritical ORC featuring a similar arrangement of heat source supply and heat removal, that is featuring the same temperatures of working fluid before the turbine, and the same condensation temperature in the respective cycles. The analysis is helpful in selection of the appropriate pressure in the vapor generator. In accomplished analyses a selection of wet ORC working fluids are scrutinized for a given range of heat source temperatures with respect to influence on efficiency of thermodynamic cycle and vapor generator area of heat transfer on installation and operation costs to illustrate the issue. Investment cost of a vapor generator in the ORC cycle accounts for a main share of expenditure alongside the cost of the expanding machine. Results of calculations show that from the point of view of cycle efficiency and size of vapor generator the pressures close to critical fluid pressure are usually optimal. Some working fluids feature even an optimal pressure. For the region close to critical point authors elaborated own method for heat transfer coefficients elaboration, which is useful in more exact estimations of heat transfer process in vapor generator. In case of a heat source with a relatively high temperature, it is better to consider a thermodynamic cycle with supercritical parameters even if as a result the vapor generator is slightly larger than for the case of a subcritical cycle. There will always be a more pronounced gain in efficiency compared to the expense induced by the heat transfer surface area of vapor generator.

Experimental investigation of organic Rankine cycle performance using alkanes or hexamethyldisiloxane as a working fluid

• An organic Rankine cycle is investigated experimentally. • Alkanes and hexamethyldisiloxane are selected as a working fluid. • Thermal efficieny and exergy efficiency are assessed under different operating conditions. • The maximum thermal efficiency is 8.0%, accompanied by an exergy efficiency of 25.2%. • Hexamethyldisiloxane is found to be a better working fluid than the alkanes under all conditions. An experimental investigation of the organic Rankine cycle (ORC) is carried out using butane, pentane, cyclopentane or hexamethyldisiloxane as a working fluid. Thermal and exergy efficiencies are used to assess system performance over a wide range of heat source temperature, turbine inlet pressure and superheating degree. The results indicate that both of these efficiencies increase with rising heat source temperature and turbine inlet pressure. Under the present experimental conditions, without using an optimized turbine, the highest thermal efficiency and exergy efficiency are 8.0% and 25.2%, respectively. The results show that hexamethyldisiloxane is a better working fluid than the alkanes under all studied experimental conditions. Moreover, it is found that a small superheating degree may be beneficial. Exergy loss analysis indicates that most of the loss occurs in the evaporator and that a working fluid with a high critical temperature is advantageous for ORC systems driven by a heating cycle with a heat transfer fluid.

Dynamic Modeling and Comparison Study of Control Strategies of a Small-Scale Organic Rankine Cycle

The control strategy is crucial for the effective and safe operation of the ORC system. A transient model of the ORC system was developed in the present work and validated by the experimental data of a 4 kW ORC prototype. Then, the effect of heat source temperature on the dynamic response and operation characteristics of the ORC system were analyzed. Five control strategies were compared: the constant working fluid mass flow rate mode, constant vapor superheat mode, constant vapor temperature mode, constant evaporation pressure mode and constant output power load mode. Under the constraint that the working fluid at the expander inlet should be superheated, we found that the constant vapor superheat mode enabled the safe operation with the largest range of heat source temperature, while the other four modes were only available for a certain temperature range. Apart from the constant output power mode, the constant evaporation pressure mode can also provide a relatively stable performance for the ORC unit. The variation of the thermal efficiency was limited when the heat source temperature was higher than 125 °C, except for the constant vapor temperature mode. Considering the high performance and stable operation of the ORC system, it is necessary to have different operation modes combined in the control strategy according to the specific working scenarios.

Performance of binary zeotropic mixtures in organic Rankine cycles (ORCs)

Compared to pure fluids, zeotropic mixtures have the potential to lower the irreversibilities in low temperature Rankine cycles by better temperature profile matching of the working fluid with the heat source/sink. However, having a gliding temperature does not guarantee performance boost over pure fluids, as many factors influence the exergy efficiency of the cycle. In this study, 25 pure fluids and 104 binary mixtures of natural working fluids are analyzed in subcritical ORCs with heat source temperature range of 125–300 ℃ and different condensing conditions and the results are investigated within two frameworks: (1) comparing the mixtures to their pure constituents, (2) comparing the mixtures to the best performing pure fluid. In one behavior type, the performance of the mixture falls between the performance of its pure constituents for all evaporator pressure range, and the mixture provides no benefit. However, some mixtures could provide performance boost in a specific evaporator range. Therefore, the maximum allowable evaporator pressure plays an important role in the performance comparison of zeotropic mixtures to their pure constituents. Mixtures which outperform their pure constituents in the first perspective, are further analyzed in the second perspective. Finally, a screening method is presented to map the binary mixtures with performance boost compared to their pure constituents and high absolute exergy efficiency. This method is based on the key thermophysical properties of the fluids including critical temperature and normal boiling point, as well as working conditions such as heat source and heat sink temperature and PPTD in the evaporator and the condenser.

Thermodynamic study of carbon dioxide transcritical refrigeration cycle with dedicated subcooling and cascade recooling

Stimulated by the fast development of cold chain commodity market and a large amount of demand in cold storages, the application of CO2 refrigeration system is to enhance remarkably. Owing to the low critical temperature of CO2, the dedicated subcooling technology is widely-used in the CO2 transcritical refrigeration cycle to increase the system performance. In this regard, reducing the compressor power of subcooling subcycle and extending the working range of heat source temperature is highly important for the mechanical subcooling technology and absorption one, respectively. Motivated by such purpose, the CO2 transcritical cycle with dedicated subcooling and cascade recooling is presented and the thorough investigation is performed thermodynamically. The proposed system is compared with layouts with dedicated mechanical subcooling and dedicated absorption one at first. Subsequently, the effect of recooling capacity ratio, the critical parameter for the system performance, is analyzed in-depth. Finally, the optimum recooling capacity ratio for different conditions is fitted by the neural network approach. Compared to layouts with dedicated mechanical subcooling and dedicated absorption one, the secondary compressor work goes down by 28.5% and the lower limit of heat source temperature is extended by 4 °C, respectively in the proposed system. The paper is favorable for the development and performance improvement of CO2 transcritical refrigeration systems.

Cascaded dual-loop organic Rankine cycle with alkanes and low global warming potential refrigerants as working fluids

A cascaded dual-loop organic Rankine cycle (CD-ORC) consisting of a high-temperature ORC (HT-ORC) and a low-temperature ORC (LT-ORC) with a shared heat exchanger is studied. Thermal efficiency is investigated as a key indicator for system performance over a wide range of heat source temperature ranging from 170 °C to 330 °C. The relation between the thermal efficiency and the critical temperature of the working fluids is explored. For this purpose, six alkanes and 31 refrigerants with a low GWP (≤150) are considered as working fluids in the HT-ORC and the LT-ORC, respectively. Cyclohexane and cyclopentane are found to be suitable for the HT-ORC with a maximum thermal efficiency of 19.13% and 18.03%. The thermal efficiency of both loops is highly affected by the working fluids since it increases with the critical temperature. As a whole, the CD-ORC may achieve a total thermal efficiency of 25.24%, 24.88% and 24.60% when using the working fluid combinations cyclohexane-R1366mzz(Z), cyclohexane-R1233zd(E) or cyclohexane-butane. This indicates that low GWP refrigerants are well-suited for LT-ORC. Compared to regular ORC, CD-ORC systems may achieve a thermal efficiency that is better by around a quarter.

Comparative investigations of sorption/resorption/cascading cycles for long-term thermal energy storage

Long-term thermal energy storage is one of the potential and critical solutions to solve the mismatching between thermal energy supply and demand. Even though single-stage sorption cycle, resorption cycle and multi-stage cascading cycle have been proposed for long-term thermal energy storage, the results are difficult to be utilized for selecting optimal cycles because most of them are investigated under different conditions and their performances are not compared under the same criterion experimentally. Herein, the experimental comparative study of different energy storage cycles is implemented for a wide range of heat source temperature and output temperature. For cycles with CaCl2/expanded nature graphite treated by the sulphuric acid (ENG-TSA) sorption bed as the output side, CaCl2/NH4Cl-NH3 cascading cycle has distinct advantage on effective discharging time. Under the general working conditions with relatively high heat source temperature and low output temperature, CaCl2-NH3 sorption cycle is the optimal choice. For cycles with MnCl2/ENG-TSA sorption bed as the output side, MnCl2-NH3 sorption cycle has the maximum thermal energy storage density, thermal energy storage efficiency and temperature lift of 420 kJ·kg−1, 0.51 and 15.0 °C, respectively, at high heat source temperature of 175 °C. Under the critical conditions such as the heat source temperature lower than 155 °C, MnCl2/CaCl2-NH3 cascading cycle is more suitable and shows optimum adaptability to unsteady heat source. The experimental results exhibit the suitable working range of heat source temperature and output temperature for different cycles, and the guidance is revealed for selecting optimal cycles for different types of low-grade thermal energy.

Performance improvement of supercritical carbon dioxide power cycle at elevated heat sink temperatures

The supercritical carbon dioxide power cycle has emerged as an advanced power generation system owing to its better efficiency, compactness, and capability to synergize with a broad range of boundary conditions. Its superior performance is due to the liquid-like compression near the critical point. However, this phenomenon deteriorates significantly for elevated heat sink temperatures and is therefore highly detrimental to the cycle performance. Thus, this study proposed and investigated an integrated power and refrigeration cycle scheme to curtail the effects of elevated heat sink temperatures. A theoretical model of the proposed scheme based on industrial flue gases was developed, and the influence of heat sink at a range of heat-source temperatures (200–500 °C) was examined. Subsequently, benchmark cases are established and optimized, and the performance improvement with respect to the benchmark case is reported, with net power as the performance indicator. The optimization of the benchmark case reveals that the simultaneous optimization of low- and high-pressure levels of the cycle is necessary to maximize the net power. The parametric investigation of the proposed configuration shows that the performance is sensitive to the saturation temperature in the evaporator of the refrigeration cycle and to the ratio of low- and high-pressure levels in the power cycle. Therefore, the proposed case was optimized for both influencing parameters for each boundary condition. The results show that for a given heat-source temperature, higher heat sink temperatures favor the proposed design. For the heat-source temperatures of 200 °C, the benchmark case is superior for all heat sink conditions, whereas for 300 °C, 400 °C, and 500 °C, the proposed system results in an increase in power generation of 10.67%, 7.2%, and 5.2%, respectively, at a sink temperature of 50 °C. Finally, a case study with molten salt as the heat source was conducted, and the results indicated that the proposed scheme outperformed the benchmark case by 32.87% in terms of net power. The results are significant in simplifying the design of pressurization components and performance improvement of the supercritical carbon dioxide power cycle at elevated heat sink temperatures.

Near-Field Thermophotovoltaic Conversion with High Electrical Power Density and Cell Efficiency above 14.

A huge amount of thermal energy is available close to material surfaces in radiative and nonradiative states, which can be useful for matter characterization or energy harvesting. Even though a full class of novel nanoengineered devices has been predicted over the last two decades for exploiting near-field thermal photons, efficient near-field thermophotovoltaic conversion could not be achieved experimentally until now. Here, we realize a proof of principle by using a micrometer-sized indium antimonide photovoltaic cell cooled at 77 K and approached at nanometer distances from a hot (∼730 K) graphite microsphere emitter. We demonstrate a near-field power conversion efficiency of the cell above 14% and unprecedented electrical power density outputs (0.75 W cm-2), which are orders of magnitude larger than all previous attempts. These results highlight that near-field thermophotovoltaic converters are now competing with other thermal-to-electrical conversion devices and also pave the way for efficient photoelectric detection of near-field thermal photons.

Investigation of a Thermal Power Pumping cycle system using alternative working fluids

ABSTRACT This paper presents a comparative analysis of the potential working fluids for a promising thermodynamic cycle (Thermal Power Pump cycle) for the utilisation of low-grade heat. The cycle was analyzed along with nucleate boiling correlations and film condensation analysis for variable heat source temperatures (50–150°C) using nine potential working fluids. The working fluids showed varying degrees of cycle performance and system size requirements. Among the working fluids, cyclopentane seems to be an attractive choice of working fluid, due to its superior cycle performance over the wide range of heat source temperatures with moderate system size requirements. For temperatures above 146°C and below 60°C, water and n-pentane are selected, respectively. Working fluids with stronger molecular forces seem to approach the properties of an ideal working fluid for better performance of the system.

Experimental investigation, model validation and application of twin-screw expanders with different built-in volume ratios

Organic Rankine Cycles (ORC) are a promising technology to generate power from low temperature heat sources and can therefore help transform current energy systems into renewable ones. However, ORCs are often affected by a wide range of operating conditions with a high share of part load operation. Therefore, detailed component models are necessary for the design of these ORC modules. In this study, systematical experimental investigations were conducted on two identical twin-screw expanders with different built-in volume ratios. The expander measurements covered the entire operational range of the ORC test rig and the expander by methodically varying rotational speed, mass flow, inlet pressure and superheating at constant expander outlet pressure. The experimental data is then utilized to validate a semi-empirical model of the twin-screw expander. Subsequently, the validated expander model is used to determine the optimum built-in volume ratio of an expander supplied by a wide range of heat source temperatures and mass flows and fluctuating heat source mass flows.The experimental results show increasing filling factors with decreasing rotational speeds and maximum isentropic efficiencies at intermediate pressure ratios. The maximum isentropic efficiency achieved is 64%. The model validation shows a satisfactory accuracy of the model within a 10% deviation for data with the same built-in volume ratio. Changing the built-in volume ratio requires the adjustment of the model parameters, because the amount of internal leakage changes. The simulations used to determine the optimum built-in volume ratio show the importance of the selection of the optimum built-in volume ratio in dependency of the heat source. Furthermore, particular attention has to be paid to the operational range of the expander (mainly the rotational speed), since it can significantly limit the power output.

Isobaric Expansion Engines Powered by Low‐Grade Heat—Working Fluid Performance and Selection Database for Power and Thermomechanical Refrigeration

A database is developed for the most suitable working fluids for Worthington‐type and Bush‐type isobaric engines based on their performances for a wide range of heat source temperature, from 40 to 300 °C, and operating pressures from 1 to 100 bar. Thermodynamics models are developed and simulated to study the effects of different operating temperatures and pressures on the efficiency and back work ratio of both engines. Results show that in temperature range from 40 to 60 °C, the achieved efficiency is less than 4% for most cases, suggesting that practical applications in this range are very limited. Ammonia and R32 show the highest efficiencies (≈11%) at high pressure of 50 bar for the temperature range of 100–300 °C. The refrigerant R161 has high performance for pressures between 10 and 50 bar for the full range of temperatures from 80 to 300 °C, which makes R161 the choice fluid for a wide range of applications. Novel applications are introduced, which integrate these isobaric engines with vapor compression refrigeration systems. The thermodynamic cycles of the heat driven compressor with the selected working fluids as in the current study and the simplified technological solutions are crucial components of the study novelty.

Comparative Study of a Compression–Absorption Cascade System Operating with NH3-LiNO3, NH3-NaSCN, NH3-H2O, and R134a as Working Fluids

This research presents a comprehensive bibliographic review from 2006 through 2020 about the state of the art of the compression–absorption cascade systems for refrigeration. In consequence of this review, this research identifies the significant development of systems that consider lithium bromide as a working fluid; however, the use of other working fluids has not been developed. This study is motivated toward the development of a parametric analysis of the cascade system using NH3-LiNO3, NH3-NaSCN and NH3-H2O in the absorption cycle and R134a in the compression cycle. In this study, the effect of the heat source temperature, condensation temperature in the compression cycle, the use of heat exchangers in the system (also known as economizers) and their contribution to the coefficient of performance is deepened numerically. The economizers evaluated are the following: an internal heat exchanger, a refrigerant heat exchanger, a solution refrigerant heat exchanger, and a solution heat exchanger. Mass and energy balance equations—appropriate equations to estimate the thermophysical properties of several refrigerant–absorbent pairs—were used to develop a thermodynamic model. The studied heat source temperature range was from 355 to 380 K, and the studied condensation temperature range in the compression cycle was from 281 to –291 K; additionally, the importance of each economizer on the coefficient of performance was numerically estimated. In this way, NH3-NaSCN solution in the absorption cycle and R134a in the compression cycle provided promising numerical results with the highest COPs (coefficient of performance).