scholarly journals A REVIEW ON SUB-COOLING IN VAPOR COMPRESSION REFRIGERATION CYCLE FOR ENERGY SAVING

2019 ◽  
Vol 81 (5) ◽  
Author(s):  
Kasni Sumeru ◽  
Mohamad Firdaus Sukri ◽  
Muhamad Anda Falahuddin ◽  
Andriyanto Setyawan

Vapor compression refrigeration cycle (VCRC) is widely used in refrigeration and air conditioning (R&A) systems. Sub-cooling is used to improve the coefficient of performance (COP) of the R&A system by enhancing the cooling capacity. This paper presents various sub-cooling methods, which have been established and applied to enhance the performance of the VCRC.  In a simple cycle of VCRC, the exit of the condenser is at saturated liquid line. Further cooling of the exit condenser to the sub-cooled region can result in an increase in the cooling capacity due to low vapor quality refrigerant entering the evaporator. As a result, the refrigerant absorbs more heat in the evaporator. The lower the quality of the refrigerant entering the evaporator, the higher the cooling capacity that is produced by the evaporator. This cooling capacity improvement results in an increase in the COP. In the present study, four sub-cooling methods are reviewed, which are liquid-suction heat exchanger, dedicated mechanical sub-cooling, integrated mechanical sub-cooling and condensate assisted sub-cooling. The advantages and drawbacks of each method, as well as future research direction in this research domain were discussed in detail.

2020 ◽  
Vol 15 (3) ◽  
pp. 398-408
Author(s):  
I Ouelhazi ◽  
Y Ezzaalouni ◽  
L Kairouani

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.


2019 ◽  
Vol 18 (2) ◽  
pp. 19
Author(s):  
L. S. Santana ◽  
J. Castro ◽  
L. M. Pereira

Vapor-compression refrigeration systems require a significant amount of electrical energy. Therefore, there is a need for finding efficient ways of operating this equipment, reducing their energy consumption. The use of heat exchangers between the suction line and the liquid line can produce a better performance of the thermodynamic cycle, as well as reduce it. The present work aims at an experimental analysis of the suction/liquid heat exchanger present in a freezer running with refrigerant fluid R-134a. Three different scenarios were used in order to evaluate the thermal performance of the refrigeration cycle. The first scenario was the conventional freezer set up to collect the required data for further comparison. Moreover, the second and third scenarios were introduced with a 20 cm and 40 cm suction/liquid heat exchanger, respectively, into the system. From the experiments, it was observed that the heat exchange does not significantly affect the coefficient of performance (COP) of the freezer. It was concluded from this work that the best scenario analyzed was the 20 cm suction/liquid heat exchanger where most of the thermodynamic properties were improved, one of them being the isentropic efficiency.


Author(s):  
Rabah Touaibi ◽  
Hasan Koten

An energy analysis study carried out on a vapor compression refrigeration cycle using refrigerants with low global warming potential (GWP) of the Hydro-Fluoro-Olefin (HFO) type, in particular R1234yf and R1234ze fluids to replace HFC refrigerants . Computer code was developed using software for solving engineering equations to calculate performance parameters; for this, three HFC type fluids (R134a, R404A and R410A) were selected for a comparative study. The results showed that R1234ze is the best refrigerant among those selected for the mechanical vapor compression refrigeration cycle. The thermodynamic analysis showed the effect of the evaporator temperature (-22 °C to 10 °C) and the condenser temperature (30 °C to 50 °C) on the steam cycle performance. Compression refrigeration, including the coefficient of performance. The results showed that the HFO-R1234ze with low GWP gives the best coefficient of performance of 3.14 close to that of the R134a fluid (3.17). In addition, R1234ze is considered an alternative fluid to R134a for their ecological properties.


Author(s):  
Lal Kundan ◽  
Kuljeet Singh

An attempt has been made to improve the heat transfer characteristics of the vapor compression refrigeration cycle using nanorefrigerant (R134a and Al2O3, size 20 nm). The performance parameters such as, coefficient of performance, cooling capacity, energy consumption, and temperature drop across condenser and evaporator have been investigated and analyzed. This has been done by varying the mass fraction of nanoparticles of Al2O3 (0.5–1 wt%) and the flow rate of nanorefrigerant. The investigation has been carried out using three types of nanorefrigerants, i.e. pure R134a, R134a+Al2O3 (0.5 wt%), and R134a+Al2O3 (1 wt%) at flow rates of 6.5 L/h and 11 L/h, respectively. The coefficient of performance of the refrigeration system using 0.5% of Al2O3 (wt%) is found to be improving with volume flow rates of nanorefrigerant, i.e. 7.20% for 6.5 L/h and 16.34% for 11 L/h. The use of nanorefrigerant (R134a+Al2O3) has also resulted in a significant increase in the cooling capacity of the refrigeration system. A substantial drop in the temperature across the condenser (3.0–23.77%), and gain in temperature across the evaporator (4.69–39.30%) is also observed for the refrigeration system under investigation.


2021 ◽  
Vol 31.2 (149) ◽  
pp. 141-146

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.


2007 ◽  
Vol 259 (2) ◽  
pp. 195-200 ◽  
Author(s):  
S. Figueroa-Gerstenmaier ◽  
M. Francova ◽  
M. Kowalski ◽  
M. Lisal ◽  
I. Nezbeda ◽  
...  

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