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

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 816
Author(s):  
JV Herrera-Romero ◽  
Dario Colorado-Garrido
Keyword(s):  
Heat Exchanger ◽  
Heat Source ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Cascade System ◽  
Working Fluids ◽  
Temperature Range ◽  
Source Temperature ◽  
Compression Cycle ◽  
Absorption Cycle

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).

scholarly journals KAJI PERFORMANSI REFRIGERAN R-290, R-32, DAN R-410A SEBAGAI ALTERNATIF PENGGANTI R-22

2021 ◽  
Vol 4 ◽  
pp. 133-139
Author(s):  
Rikhard Ufie ◽  
Cendy S. Tupamahu ◽  
Sefnath J. E. Sarwuna ◽  
Jufraet Frans
Keyword(s):  
Air Conditioning ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Vapor Compression ◽  
Know How ◽  
Evaporation Temperature ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Refrigeration Capacity

Refrigerant R-22 is a substance that destroys the ozone layer, so that in the field of air conditioning it has begun to be replaced, among others with refrigerants R-32 and R-410a, and also R-290. Through this research, we want to know how much Coefficient of Performance (COP) and Refrigeration Capacity (Qe) can be produced for the four types of refrigerants. The study was carried out theoretically for the working conditions of the vapor compression cycle with an evaporation temperature (Tevap) of 0, -5, and -10oC, a further heated refrigerant temperature (ΔTSH) of 5 oC, a condensation temperature (Tkond) of 45 oC and a low-cold refrigerant temperature. (ΔTSC) 10 oC and compression power of 1 PK . The results of the study show that the Coefficient of Performance (COP) in the use of R-22 and R-290 is higher than the use of R-32 and R-410a, which are 4,920 respectively; 4,891; 4.690 and 4.409 when working at an evaporation temperature of 0 oC; 4.260; 4,234; 4.060 and 3.812 when working at an evaporation temperature of -5 oC; and amounted to 3,730; 3,685; 3,550 and 3,324 if working at an evaporation temperature of -10 oC. Based on the size of the COP, if this installation works with a compression power of 1 PK, then the cooling capacity of the R-22 and R-290 is higher than the R-32 and R-410a, which are 3,617 respectively. kW; 3,597 kW; 3,449 kW and 3,243 kW. If working at an evaporation temperature of 0 oC; 3.133 kW; 3.114 kW; 2,986 kW and 2,804 kW if working at an evaporation temperature of -5 oC; and 2,741 kW; 2,710 kW; 2,611 kW and 2,445 kW if working at an evaporation temperature of -10oC.

Performance of Working Fluids for Power Generation in a Supercritical Organic Rankine Cycle

2012 ◽  
Author(s):  
Rachana Vidhi ◽  
Sarada Kuravi ◽  
Saeb Besarati ◽  
E. K. Stefanakos ◽  
D. Yogi Goswami ◽  
...  
Keyword(s):  
Power Generation ◽  
Heat Source ◽  
Thermal Efficiency ◽  
Thermodynamic Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluids ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Organic Fluids

This paper reports on the performance of various organic refrigerants and their mixtures as working fluids for power generation in a supercritical Rankine cycle (SRC) from geothermal sources. Organic fluids that have zero or very low ozone depletion potential and are environmentally safe are selected for this study. Geothermal source temperature is varied from 125–200°C, and the cooling water temperature is changed from 10–20°C. The effect of varying operating conditions on the performance of the thermodynamic cycle has been analyzed. Operating pressure of the cycle has been optimized for thermal efficiency for each fluid at each source temperature. The condensation pressure is determined by the cooling condition and is kept fixed for each condensation temperature. Energy and exergy efficiencies of the cycle have been obtained for the pure fluids as a function of heat source temperature. Mixtures of organic fluids have been analyzed and effect of composition on performance of the thermodynamic cycle has been studied. It is observed that thermal efficiency over 20% can be achieved for 200°C heat source temperature and the lowest cooling temperature. When mixtures are considered as working fluids, the thermal efficiency of the cycle is observed to remain between the thermal efficiencies of the constituent fluids.

INFLUENCE OF THE SOLUTION HEAT EXCHANGER EFFICIENCY ON THE PERFORMANCE OF A SINGLE EFFECT H2O-LiBr ADIABATIC ABSORPTION SYSTEM

2011 ◽  
Vol 19 (02) ◽  
pp. 107-112 ◽  
Author(s):  
GEYDY GUTIÉRREZ URUETA ◽  
PEDRO RODRÍGUEZ AUMENTE ◽  
MARIA RODRÍGUEZ HIDALGO ◽  
ANTONIO LECUONA NEUMANN
Keyword(s):  
Heat Exchanger ◽  
Strong Solution ◽  
Heat Transfer Process ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Test Facility ◽  
Absorption System ◽  
Experimental Conditions ◽  
Single Effect ◽  
Absorption Cycle

This work analyzes the effect that particular operating conditions of a single effect H2O - LiBr adiabatic absorption system have on a plate-type solution heat exchanger efficiency. The corresponding influence of such efficiency on the performance of facility under study is evaluated. As a result of the design of experimental test facility, the functioning of the strong solution circuit leads to take into account some particular operating conditions which affect the correct performance of the solution heat exchanger. For some experimental conditions, the strong solution side is not completely filled by the solution fluid. As a consequence of this, the heat transfer process is affected, reducing the solution heat exchanger efficiency and changing greatly the resulting coefficient of performance (COP) of the absorption facility. In order to illustrate this phenomenon, this paper offers graphical results including: solution working temperatures, solution heat exchanger efficiency and COP in a time sequence of an experiment, as well as for fixed steady-state operating conditions. These results show the importance of a correct functioning of the solution heat exchanger on the performance of an absorption system. The results are useful for researchers interested in new absorption cycle designs.

Analysis of novel regenerative thermo-mechanical refrigeration system integrated with isobaric engine

2020 ◽  
pp. 1-27
Author(s):  
Ahmad K. Sleiti ◽  
Wahib Al-Ammari ◽  
Mohammed Al-Khawaja
Keyword(s):  
Heat Source ◽  
Environmental Effects ◽  
Power Efficiency ◽  
Waste Heat ◽  
Working Fluid ◽  
Refrigeration System ◽  
Cooling Systems ◽  
Working Fluids ◽  
Source Temperature ◽  
Heat Source Temperature

Abstract Refrigerants of the conventional cooling systems contribute to global warming and ozone depletion significantly, therefore it is necessary to develop new cooling systems that use renewable energy resources and waste heat to perform the cooling function with eco-friendly working fluids. To address this, the present study introduces and analyzes a novel regenerative thermo-mechanical refrigeration system that can be powered by renewable heat sources (solar, geothermal, or waste heat). The system consists of a novel expander-compressor unit (ECU) integrated with a vapor compression refrigeration system. The integrated system operates at the higher-performance supercritical conditions of the working fluids as opposed to the lower-performance subcritical conditions. The performance of the system is evaluated based on several indicators including the power loop efficiency, the coefficient of performance (COP) of the cooling loop, and the expander-compressor diameters. Several working fluids were selected and compared for their suitability based on their performance and environmental effects. It was found that for heat source temperature below 100 °C, adding the regenerator to the system has no benefit. However, the regenerator increases the power efficiency by about 1 % for a heat source temperature above 130 °C. This was achieved with a very small size regenerator (Dr = 6.5 mm, Lr = 142 mm). Results show that there is a trade-off between high-performance fluids and their environmental effects. Using R32 as a working fluid at heat source temperature Th=150 °C and cold temperature Tc1=40 °C, the system produces a cooling capacity of 1 kW with power efficiency of 10.23 %, expander diameter of 53.12 mm, and compressor diameter of 75.4mm.

scholarly journals Nucleation and Condensation of Magnesium Vapor in Argon Carrier

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1441
Author(s):  
Jibiao Han ◽  
Daxue Fu ◽  
Junhua Guo ◽  
Zonghui Ji ◽  
Zhihe Dou ◽  
...  
Keyword(s):  
Heat Source ◽  
Flow Rate ◽  
Vapor Condensation ◽  
Condensation Temperature ◽  
Atomic Collisions ◽  
Condensation Zone ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Vapor Partial Pressure ◽  
Condensed Product

The nucleation and condensation of Magnesium (Mg) vapor carried by argon gas (Ar) were examined. The condensation of Mg vapor at a heat source temperature of 1273–1473 K and Ar flow rate of 0.1–0.4 m3/h was analyzed. The result indicated that the condensation temperature is affected by the heat source temperature and Ar flow rate, and the condensation temperature of Mg vapor was 1013.3 K at a heat source temperature of 1473 K and Ar flow rate of 0.2 m3/h. The effects of Mg vapor partial pressure and temperature of the condensation zone on the nucleation and condensation of Mg vapor carried by Ar were calculated and analyzed in terms of atomic collisions and critical nucleation radius. Increased vapor oversaturation and decreased condensation temperature were favorable for liquid nucleation growth. The Mg condensation products in Ar flow rate of 0.2 m3/h at a heat source temperature of 1473 K were analyzed by XRD, SEM, and EDS, which indicated that the condensed product was of high purity and not easily oxidized in Ar flow. In this paper, the quality of Mg vapor condensation was controlled, which provided the theoretical and experimental basis for a continuous Mg production process.

scholarly journals Exergy Analysis of Two-Stage Organic Rankine Cycle Power Generation System

Entropy ◽  
2020 ◽  
Vol 23 (1) ◽  
pp. 43
Author(s):  
Guanglin Liu ◽  
Qingyang Wang ◽  
Jinliang Xu ◽  
Zheng Miao
Keyword(s):  
Heat Source ◽  
Organic Rankine Cycle ◽  
Exergy Efficiency ◽  
Working Fluid ◽  
Two Stage ◽  
Working Fluids ◽  
Source Temperature ◽  
Split Ratio ◽  
Heat Source Temperature ◽  
Stage System

Organic Rankine cycle (ORC) power generation is an effective way to convert medium and low temperature heat into high-grade electricity. In this paper, the subcritical saturated organic Rankine cycle system with a heat source temperature of 100~150 °C is studied with four different organic working fluids. The variations of the exergy efficiencies for the single-stage/two-stage systems, heaters, and condensers with the heat source temperature are analyzed. Based on the condition when the exergy efficiency is maximized for the two-stage system, the effects of the mass split ratio of the geothermal fluid flowing into the preheaters and the exergy efficiency of the heater are studied. The main conclusions include: The exergy efficiency of the two-stage system is affected by the evaporation temperatures of the organic working fluid in both the high temperature and low temperature cycles and has a maximum value. Under the same heat sink and heat source parameters, the exergy efficiency of the two-stage system is larger than that of the single-stage system. For example, when the heat source temperature is 130 °C, the exergy efficiency of the two-stage system is increased by 9.4% compared with the single-stage system. For the two-stage system, analysis of the four organic working fluids shows that R600a has the highest exergy efficiency, although R600a is only suitable for heat source temperature below 140 °C, while other working fluids can be used in systems with higher heat source temperatures. The mass split ratio of the fluid in the preheaters of the two-stage system depends on the working fluid and the heat source temperature. As the heat source temperature increases, the range of the split ratio becomes narrower, and the curves are in the shape of an isosceles triangle. Therefore, different working fluids are suitable for different heat source temperatures, and appropriate working fluid and split ratio should be determined based on the heat source parameters.

scholarly journals An Improved Analysis Method for Organic Rankine Cycles Based on Radial-Inflow Turbine Efficiency Prediction

2018 ◽  
Vol 9 (1) ◽  
pp. 49 ◽  
Author(s):  
Peng Li ◽  
Zhonghe Han ◽  
Xiaoqiang Jia ◽  
Zhongkai Mei ◽  
Xu Han ◽  
...  
Keyword(s):  
Heat Source ◽  
Ambient Temperature ◽  
Operating Conditions ◽  
Condensation Temperature ◽  
Analysis Method ◽  
Source Temperature ◽  
Evaporation Temperature ◽  
Turbine Efficiency ◽  
Heat Source Temperature ◽  
Radial Inflow Turbine

The organic Rankine cycle (ORC) has been demonstrated to be an effective method for converting low-grade heat energy into electricity. This paper proposes an improved analysis method for the ORC system. A coupling model of the ORC system with a radial-inflow turbine efficiency prediction model is presented. Multi-objective optimization was conducted for a constant turbine efficiency ORC system (ORCCTE) and a predicted turbine efficiency ORC system (ORCDTE), and the optimization results were compared. Additionally, a sensitivity analysis was conducted with respect to the heat source temperature and the ambient temperature. It can be found that the predicted turbine efficiency decreases with the increasing evaporation temperature, and increases with the increasing condensation temperature. The turbine efficiency is not constant and it varies with operating conditions. The distribution of the Pareto frontier for ORCCTE system and ORCCTE system is different. Compared with the ORCCTE system, the ORCDTE system has a lower optimal evaporation temperature, but a higher optimal condensation temperature. The deviation between the predicted turbine efficiency and the constant turbine efficiency increases with the increasing heat source temperature but decreases with the increasing ambient temperature. Thus, the difference in the theoretical analysis results between ORCCTE system and ORCDTE system increases with the increasing heat source temperature but decreases with the increasing ambient temperature.

scholarly journals Analysis of the use of adsorption processes in trigeneration systems

2013 ◽  
Vol 34 (4) ◽  
pp. 35-49 ◽  
Author(s):  
Andrzej Grzebielec ◽  
Artur Rusowicz
Keyword(s):  
Heat Source ◽  
District Heating ◽  
Coefficient Of Performance ◽  
Heating Systems ◽  
Research Results ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
District Heating Systems ◽  
Adsorption Processes

Abstract The trigeneration systems for production of cold use sorption refrigeration machines: absorption and adsorption types. Absorption systems are characterized namely by better cooling coefficient of performance, while the adsorptive systems are characterized by the ability to operate at lower temperatures. The driving heat source temperature can be as low as 60-70 °C. Such temperature of the driving heat source allows to use them in district heating systems. The article focuses on the presentation of the research results on the adsorption devices designed to work in trigeneration systems.

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