Investigation of the Liquid–Vapor Separator Efficiency on the Performance of the Ejector Used as an Expansion Device in the Vapor-Compression Refrigeration Cycle

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Ayşe Uğurcan Atmaca ◽  
Aytunç Erek ◽  
Orhan Ekren
Keyword(s):  
Performance Improvement ◽  
Separation Efficiency ◽  
Area Ratio ◽  
Refrigeration Cycle ◽  
Entrainment Ratio ◽  
Operation Conditions ◽  
Vapor Compression Refrigeration Cycle ◽  
The Difference ◽  
Ejector Cycle ◽  
Liquid Vapor

Abstract Ejector expansion refrigeration cycle with reference to the constant pressure mixing theory is investigated to display the effects of the liquid–vapor separator efficiency on the performance, entrainment ratio, and area ratio at various operation conditions. Reversible ejector assumption is used for the highest theoretical performance limit, whereas efficiency of the liquid–vapor separator and all ejector components is added to the model to calculate more realistic performance improvement potentials. R1234yf and R1234ze(E) having low global warming potential values are used in the analyses. Zero-dimensional thermodynamic models are constructed applying the conservation equations between the inlets and outlets of the refrigeration cycle and ejector components. Percentage performance decrease is higher when the mixing section and the separator efficiency is added to the model at higher condenser temperatures compared with the lower evaporator temperatures according to the investigated operation ranges. Vapor and liquid separation efficiency affects not only the performance but also the design of the ejector although it is an external component since it has influence on the area ratio and entrainment ratio. Finally, the difference between the percentage performance improvement of the reversible ejector cycle and the realistic ejector cycle including the separator and ejector components efficiencies is as high as 35% at the highest investigated condenser temperature for R1234yf.

scholarly journals Parametric analysis of a combined ejector-vapor compression refrigeration cycle

2020 ◽  
Vol 15 (3) ◽  
pp. 398-408
Author(s):  
I Ouelhazi ◽  
Y Ezzaalouni ◽  
L Kairouani
Keyword(s):  
Current Model ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Entrainment Ratio ◽  
Constant Area ◽  
Vapor Compression Refrigeration Cycle ◽  
Vapor Compression Refrigeration

Abstract From the last few years, the use of efficient ejector in refrigeration systems has been paid a lot of attention. In this article a description of a refrigeration system that combines a basic vapor compression refrigeration cycle with an ejector cooling cycle is presented. A one-dimensional mathematical model is developed using the flow governing thermodynamic equations based on a constant area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The current model is based on the NIST-REFPROP database for refrigerant property calculations. The model has basically been used to determine the effect of the ejector geometry and operating conditions on the performance of the whole refrigeration system. The results show that the proposed model predicts ejector performance, entrainment ratio and the coefficient of performance of the system and their sensitivity to evaporating and generating temperature of the cascade refrigeration cycle. The simulated performance has been then compared with the available experimental data from the literature for validation.

scholarly journals Effects of Nozzle Exit Position on Condenser Outlet Split Ejector-Based R600a Household Refrigeration Cycle

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5160
Author(s):  
Yongseok Jeon ◽  
Hoon Kim ◽  
Jae Hwan Ahn ◽  
Sanghoon Kim
Keyword(s):  
Pressure Drop ◽  
Internal Pressure ◽  
Nozzle Exit ◽  
Performance Characteristics ◽  
Coefficient Of Performance ◽  
Cycle Performance ◽  
Refrigeration Cycle ◽  
Refrigeration System ◽  
Entrainment Ratio ◽  
Ejector Cycle

The objective of this study is to investigate the performance characteristics of a small-sized R600a household refrigeration system that adopts a condenser outlet split (COS) ejector cycle under various operating and ejector geometry conditions. The coefficient of performance and pressure lifting ratio of the COS ejector cycle were analyzed and measured by varying the entrainment ratio, compressor speed, and nozzle exit position. The optimum nozzle exit position in the COS ejector cycle adopted to achieve the maximum cycle performance was proposed as a function of the compressor speed and entrainment ratio. The optimum nozzle exit position was 0 mm when the entrainment ratio and compressor speed were low, and it increased as the entrainment ratio and compressor speed increased owing to the associated internal pressure drop in the suction section.

Effect of Operational Parameters on a Novel Combined Cycle of Ejector Refrigeration Cycle and Kalina Cycle

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Candeniz Seckin
Keyword(s):  
Energy Content ◽  
Power Production ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Entrainment Ratio ◽  
Extensive Discussion ◽  
Kalina Cycle ◽  
Operation Conditions

A Kalina cycle is coupled to an ejector refrigeration cycle to generate power and refrigeration outputs, simultaneously. Ejector refrigeration cycle is driven by the heat which is extracted from a high-temperature/pressure stream of Kalina cycle working fluid since the energy content of this fluid stream is not directly utilized in power production in the Kalina cycle. Supplied heat to the proposed combined cycle is produced by combustion of biomethane which is obtained from anaerobic digestion of biomass, namely, food waste. System reactions to altering operation conditions (entrainment ratio, condenser pressure, evaporator pressure, and superheating degree) in terms of refrigeration production, power production, energy efficiency, exergy efficiency, and exergy of produced power and refrigeration are analyzed. The results are reported for R290, R134a, and R152a working fluids of the ejector refrigeration cycle and an extensive discussion of the results are provided. It is shown that the entrainment ratio strongly affects the thermal and exergy efficiency results. The highest thermal and exergy efficiency results are performed when R290 and R134a are used, whereas the lowest thermal and exergy efficiencies are obtained when R152a and R290 are used as the refrigerant, respectively.

Performance Analysis of Refrigerants R1234yf, R1234ze and R134a in Ejector-Based Refrigeration Cycle

2018 ◽  
Vol 26 (03) ◽  
pp. 1850026 ◽  
Author(s):  
Ajay Kumar Yadav ◽  
Neeraj
Keyword(s):  
Heat Pump ◽  
Power Plants ◽  
Operating Conditions ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Entrainment Ratio ◽  
Evaporator Temperature ◽  
Wide Range ◽  
Vapor Compression Refrigeration Cycle ◽  
Vapor Compression Refrigeration

Performance enhancement of refrigeration and heat pump systems by cycle modification is an emerging research topic now-a-days to reduce the electricity consumption leading to mitigate the problems related to the environmental pollution by utility power plants. Due to no moving parts, low cost, simple structure and low maintenance requirements, the use of two-phase ejector has become a promising cycle modification recently. Use of ejector as an expansion device by replacing the throttle valve in the vapor compression refrigeration cycle seems to be one of the efficient ways to reduce the throttling losses or the expansion irreversibility in the refrigeration/heat pump cycle. Ejector also reduces the compressor work by raising the suction pressure to a level higher than that in the evaporator leading to the improvement of COP. The present work aims to evaluate the performance of an ejector based vapor compression refrigeration cycle under a wide range of operating conditions. Two newly proposed refrigerants i.e., R1234yf and R1234ze, and commonly used refrigerant R134a are considered for simulation and a comparative study has been carried out. A numerical model is developed and a parametric study of important parameters such as entrainment ratio, high side pressure (condenser pressure) and evaporator temperature are analyzed for the improvement of COP of the system. Results show that the COP of the R1234ze is highest compared to R1234yf and R134a for the given evaporating and condensing temperature.

scholarly journals Design of an Ejector Working in Combined Ejector - Vapor Compressor Refrigeration Cycle

2021 ◽  
Vol 31.2 (149) ◽  
pp. 141-146
Keyword(s):  
Cooling Capacity ◽  
Area Ratio ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Evaporator Temperature ◽  
Vapor Compression Refrigeration Cycle ◽  
Condenser Temperature ◽  
Vapor Compression Refrigeration

In this paper, a calculation program is developed to design ejector working in a combined ejector – vapor compression refrigeration cycle. R134a is selected as the refrigerant for the ejector sub-cycle, and R410A is selected for the compressor sub-cycle. The effect of operating conditions and cooling capacity are examined. The results show that the area ratio increases with the increasing of generator temperature and intercooler temperature; and decreases with the increasing of condenser temperature and evaporator temperature. When the generator temperature, condenser temperature, intercooler temperature and evaporator temperature are 80°C, 34°C, 15°C, 0°C respectively, the area ratio is 8.55 and independent with cooling capacity. The design equations of significant dimensions based on operating conditions and cooling capacity are also introduced. The results show that R134a ejetor which is designed for simple ejector cycle is not suitable for combined cycle.

Performance of Ejector Refrigeration Cycle for Automotive Air Conditioning

2016 ◽  
Vol 819 ◽  
pp. 202-206
Author(s):  
Reza Maziar ◽  
Kasni Sumeru ◽  
M.Y. Senawi ◽  
Farid Nasir Ani
Keyword(s):  
Compression Ratio ◽  
Air Conditioning ◽  
The Other ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Entrainment Ratio ◽  
Automotive Air Conditioning ◽  
Average Improvement

In this study, two experiments were performed, one with the conventional compression refrigeration cycle (CRC) and the other with an ejector refrigeration cycle (ERC). The CRC system for automotive air conditioning was designed, fabricated and experiments were conducted. The system was then retrofitted with an ejector as the expansion device and experiments were repeated for the ERC system. Calculations of the entrainment ratio, compressor compression ratio and coefficient of performance (COP) were made for each cycle. The calculations showed that ERC has some advantages over the CRC. In this study, an average improvement of 5% in COP has been obtained for the ERC compared with the CRC.

scholarly journals Performance improvement of double-tube gas cooler in CO2 refrigeration system using nanofluids

2015 ◽  
Vol 19 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Jahar Sarkar
Keyword(s):  
Performance Improvement ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Cooling Capacity ◽  
Inlet Temperature ◽  
Refrigeration Cycle ◽  
Particle Volume ◽  
Transcritical Carbon Dioxide ◽  
The Given ◽  
Theoretical Analyses

The theoretical analyses of the double-tube gas cooler in transcritical carbon dioxide refrigeration cycle have been performed to study the performance improvement of gas cooler as well as CO2 cycle using Al2O3, TiO2, CuO and Cu nanofluids as coolants. Effects of various operating parameters (nanofluid inlet temperature and mass flow rate, CO2 pressure and particle volume fraction) are studied as well. Use of nanofluid as coolant in double-tube gas cooler of CO2 cycle improves the gas cooler effectiveness, cooling capacity and COP without penalty of pumping power. The CO2 cycle yields best performance using Al2O3-H2O as a coolant in double-tube gas cooler followed by TiO2-H2O, CuO-H2O and Cu-H2O. The maximum cooling COP improvement of transcritical CO2 cycle for Al2O3-H2O is 25.4%, whereas that for TiO2-H2O is 23.8%, for CuO-H2O is 20.2% and for Cu-H2O is 16.2% for the given ranges of study. Study shows that the nanofluid may effectively use as coolant in double-tube gas cooler to improve the performance of transcritical CO2 refrigeration cycle.

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