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1.
R134a is the most widely used refrigerant in domestic refrigerators. It must be phased out soon according to Kyoto protocol due to its high global warming potential (GWP) of 1300. In the present work, an experimental investigation has been made with hydrocarbon refrigerant mixture (composed of R290 and R600a in the ratio of 45.2:54.8 by weight) as an alternative to R134a in a 200 l single evaporator domestic refrigerator. Continuous running tests were performed under different ambient temperatures (24, 28, 32, 38 and 43 °C), while cycling running (ON/OFF) tests were carried out only at 32 °C ambient temperature. The results showed that the hydrocarbon mixture has lower values of energy consumption; pull down time and ON time ratio by about 11.1%, 11.6% and 13.2%, respectively, with 3.25–3.6% higher coefficient of performance (COP). The discharge temperature of hydrocarbon mixture was found to be 8.5 to 13.4 K lower than that of R134a. The overall performance has proved that the above hydrocarbon refrigerant mixture could be the best long term alternative to phase out R134a.  相似文献   

2.
In the present work, the possibility of using R152a and hydrocarbon refrigerants (such as R290, R1270, R600a, and R600) as alternatives to R134a in domestic refrigerators has been assessed theoretically. The refrigerants are assessed over wider range condensing and evaporator temperatures. The assessment was done with standard parameters such as pressure ratio, volumetric cooling capacity (VCC), coefficient of performance (COP), compressor input power, compressor discharge temperature, and total equivalent warming impact (TEWI). The results obtained showed that pure hydrocarbon refrigerants are not suitable to be used as alternatives to R134a due to its mismatch in VCC. R152a has approximately the same VCC with about 9% higher COP and lower values of operating pressure and compressor input power. The discharge temperature of R152a was higher than that of R134a by about 14–26 K. TEWI of R152a was about 7% lower than that of R134a. The reported results proved that R152a is an energy-efficient and environment-friendly alternative to phase out R134a in domestic refrigerators.  相似文献   

3.
In this study, performance of R430A is examined numerically and experimentally in an effort to replace HFC134a used in refrigeration system of domestic water purifiers. Even though HFC134a is used predominantly in such a system these days, it needs to be phased out in near future in most of the developed countries due to its high global warming potential. To solve this problem, cycle simulation and experiments are carried out with a new refrigerant mixture of 76%R152a/24%R600a using actual water purifiers. This mixture is numbered and listed as R430A by ASHRAE recently. Test results show that the system performance is greatly influenced by the amount of charge due to the small internal volume of the refrigeration system in water purifiers. With the optimum amount of charge of 21–22 g, about 50% of HFC134a, the energy consumption of R430A is 13.4% lower than that of HFC134a. The compressor dome and discharge temperatures and condenser center temperature of R430A are very similar to those of HFC134a for the optimum charge. Overall, R430A, a new long term environmentally safe refrigerant, is a good alternative for HFC134a in domestic water purifiers requiring no major change in the system.  相似文献   

4.
In this paper the viscosity and thermal conductivity of both the liquid and vapour for the refrigerants R152a and R142b have been estimated and presented. Available properties of liquid thermal conductivity of R142b and R152a and the liquid viscosity of R152a are compared with the estimated values. It is found that the agreement is good. Transport properties of R142b, which is a potential replacement for R114 in medium temperature heat pump applications, is compared with that of R114. Also, the properties of R152a, which is considered as a possible replacement of R12 in refrigeration and low-temperature heat pump applications, is compared with the properties of the other possible replacement of R134a.  相似文献   

5.
The performance of a vapour-compression system was examined with both R12/mineral oil and R134a/mineral oil charges. The mineral oil was then removed from the system using a multiple flushing method and the experiments repeated using a charge of R134a and an ester-based lubricant to establish the effect of the oil on the performance of the system. Results were compared with theoretical data for R134a and R12 refrigerants.  相似文献   

6.
Experiments were conducted for a typical R134a compact European automotive air conditioning system equipped with an internally controlled variable displacement compressor, minichannel condenser, TXV, and minichannel evaporator. A “drop-in” R1234yf system was tested together with two modified R1234yf systems with the primary goal to document some laboratory results and their analyses which could prove useful in aiding manufacturers and researchers by indicating “minor” system modifications which could be implemented in existing air conditioning systems, with the aim to achieve with R1234yf similar capacity and efficiency as modern R134a systems. Since the experimental results indicate that, for a given cooling capacity, R1234yf systems present lower performance than the baseline R134a, numerical simulations were used to investigate the effects of “major” system modifications, such as, the use of an enhanced condenser and/or an enhanced evaporator.  相似文献   

7.
This paper compares the performance of a single-stage triple pressure level (TPL) absorption cycle with different refrigerant–absorbent pairs. Four HFC refrigerants namely: R32, R125, R134a and R152a which are alternative to HCFC, such as R22 and R124, in combination with the absorbent dimethylethylenurea (DMEU) were considered. The highest coefficient of performance (COP) and the lowest circulation ratio (f), were found as a function of the generator temperature for a given evaporating and cooling water temperatures. The sensitivity of the COP and f for evaporator and cooling water temperatures changes at the maximum COP for the best three working fluids were also examined. It was obtained that the preferable pair is R124–DMEU and among working fluids based on HFC the preferable pair is the R125–DMEU.  相似文献   

8.
A mixed refrigerant ejector refrigeration cycle operating with two-stage vapor-liquid separators(MRERC2) is proposed to obtain refrigeration temperature at-40℃. The thermodynamic investigations on performance of MRERC2 using zeotropic mixture refrigerant R23/R134 a are performed, and the comparisons of cycle performance between MRERC2 and MRERC1(MRERC with one-stage vapor-liquid separator) are conducted. The results show that MRERC2 can achieve refrigeration temperature varying between-23.9℃ and-42.0℃ when ejector pressure ratio ranges from 1.6 to 2.3 at the generation temperature of 57.3-84.9℃. The parametric analysis indicates that increasing condensing temperature decreases coefficient of performance(COP) of MRERC2, and increasing ejector pressure ratio and mass fraction of the low boiling point component in the mixed refrigerant can improve COP of MRERC2. The MRERC2 shows its potential in utilizing low grade thermal energy as driving power to obtain low refrigeration temperature for the ejector refrigeration cycle.  相似文献   

9.
A compression–absorption cascade system for refrigeration is simulated with different working fluids. LiBr/H2O is used in the absorption cycle and ammonium, R134a and carbon dioxide are evaluated in the compression cycle. First and second laws of thermodynamic analysis were analyzed with the aim of finding the best working fluid performance and appropriate operation parameters. Coefficient of performance, exergetic efficiency, irreversibility of the main components of the system, total irreversibility of the system and improvement potential were estimated for each one of the systems proposed. The results showed that the highest irreversibilities occurred in the cascade heat exchanger using carbon dioxide or ammonium, but this value decreased by using R134a. The highest value of coefficient of performance is observed by the R134a–LiBr/H2O system when the minimum of irreversibility in the absorber and generator are reached within a range of generator temperature from 339 to 345 K. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

10.
为了考察不同状态方程对摩擦理论黏度模型拟合结果的影响,以制冷剂R134a为例,分别采用工程上常用的PR(Peng-Robinson)方程、MBWR(modified benediet-webbrubin)方程和R134a的专用状态方程Span-Wagner方程建立了R134a的摩擦理论黏度模型.计算结果表明,用这三个方...  相似文献   

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