R134a In Domestic Refrigerators Research Articles

Thermodynamic analysis of a linear compressor vapour compression system

Linear compressors are advantageous in terms of miniaturization, high efficiency, and continuous operation without a crank mechanism. The drop-in replacement for R134a in domestic refrigerators is R1234yf. This study aims to investigate the linear compressor thermodynamic performance in vapour compression system with R1234yf by modelling and measuring key parameters such as pressure-volume (P-V) diagram, refrigerant distribution, mass flow rate, volumetric efficiency, cooling capacity, and coefficient of performance (COP). Results show that at 40 °C condenser temperature and 2 pressure ratio, the linear compressor vapour compression system achieved a maximum 299.1 W cooling capacity, which gives 4.12 COP. The thermodynamic analysis calculations are in good agreement to the results of experimental measurements, verifying the accuracy of the model.

Energy and Thermal Conductivity Assessment of Dimethyl-Ether and its Azeotropic Mixtures as Alternative Low Global Warming Potential Refrigerants in a Refrigeration System

Abstract Substituting Hydrofluorocarbons with natural refrigerants in domestic refrigerators will significantly reduce the direct contributions of fluorinated gases to global warming which will be of great environmental benefit. In this study, the performances of dimethyl-ether (RE170) and its azeotropic mixtures (R510A and R511A) in a refrigeration system were assessed theoretically and compare with that of conventional refrigerant. The study revealed that the three investigated alternative refrigerants exhibited significantly good heat transfer characteristics, low pressure ratio, high latent heat in the liquid phase which resulted in their high thermal conductivity and Volumetric Cooling Capacity (VCC). The thermal conductivity of the refrigerants reduces while the evaporating temperature rises and the value obtained for RE170 was the highest among the four refrigerants studied. The Coefficient of Performance (COP) for RE170, R510A and R511A were higher than that of R134a by 6.20, 10.06 and 3.02 % respectively while their power consumptions per ton of refrigeration were lower than that of R134a by 6.99, 11.04 and 1.47 % respectively. In conclusion, dimethyl-ether and its azeotropic mixtures performed better than R134a in that they have higher thermal conductivity, refrigerating effect, VCC, COP, lower power consumption per ton of refrigeration and hence, they can be considered as suitable replacements for R134a in domestic refrigerator.

Theoretical assessment of new low global warming potential refrigerant mixtures as eco-friendly alternatives in domestic refrigeration systems

Refrigerants of low global warming potentials (GWPs) of ≤ 150 are required by regulations as working fluids in domestic refrigeration systems. Therefore, this study theoretically investigated the performance of five new refrigerant mixtures (R440A, R441A, R444A, R445A and R451A) with zero ODP and GWPs of less than 150. The results showed that all the investigated refrigerants exhibited very low pressure ratios and discharge temperatures in comparison with R134a with average discharge temperatures of R451A and R440A lower by 8 and 7% respectively, than that of R134a. R451A and R440A have similar vapour specific volume and pressure-temperature characteristics with those of R134a which confirmed that they could be used as replacement for R134a. R440A and R451A have advantages of better COPs and volumetric cooling capacity (VCC) in comparison with R134a. Their average COPs are higher by 14 and 5% respectively, than that of R134a. The specific power consumptions (SPCs) of R441A and R445A are significantly higher by average of 57 and 44% respectively; while those of R440A and R451A are lower by average of 8 and 4% respectively, in comparison with R134a. In general, in terms of all the performance parameters considered, R441A and R445A consistently performed poorly, while R440A and R451A achieved better performance than R134a in all aspects. Beside the flammability of these two refrigerants, in which their use require following the established rules and regulations for the safety precautions, they can serve as long term eco-friendly substitute refrigerants for R134a in domestic refrigerators.

Hydrocarbons as Alternate Refrigerants to Replace R134a in Domestic Refrigerators

Hydrocarbons as Alternate Refrigerants to Replace R134a in Domestic Refrigerators

Comparative study on energy efficiency of low GWP refrigerants in domestic refrigerators with capacity modulation

The ever rapid rise in the number of refrigerators causes a dramatic increase in energy demand and emissions, which represents a small but growing contribution to overall global warming. To mitigate the greenhouse gas emission and energy efficiency, high efficiency linear compressor with capacity modulation and low global warming potential (GWP) refrigerants can be considered for use in refrigerators. This paper presents a comparative study on energy efficiency of R717 (ammonia), R600a (iso-butane), R1234yf and R134a in domestic refrigerators using an oil-free linear compressor. The results show that for given operation conditions, R717 has the highest resonant frequency, power input, cooling capacity while R600a has the lowest. R717 has the potential to be used the proposed linear compressor where there is no contact between the corrosive refrigerant with copper windings. This can significantly improve the energy efficiency ratio (EER) with low cost and minimal environmental impact compared with R134a. R600a requires a larger capacity compressor to achieve the same cooling capacity as R717, R1234yf, and R134a. R1234yf can be considered as an ideal drop-in alternative to R134a for an existing refrigerator because of the similar system performance to R134a.

R-152a as an alternative refrigerant to R-134a in domestic refrigerators: An experimental analysis

Among all sectors of refrigeration, one of the most affected by the latest international regulations is the domestic refrigeration. Although for it has been suggested some solutions, such as the construction of household refrigerator operating with the hydrocarbons, there remains the need to find a substitute for R-134a. With the aim of finding a simple implementation solution, in the present work, it is reported an experimental investigation carried out on a domestic no-frost refrigerator designed and built to operate with R-134a and for which a drop-in with R-152a has been realised. Different tests have been performed with the aim to identify the right charge of R-152a too. In line with the standard ISO 15502:2005 (2005), pull-down and 24 h energy consumption experiments have been run to evaluate the performance of R-152a as the drop-in replacement of R-134a in a domestic refrigerator. Also, a theoretical model has been proposed with the aim to give support to the observed energy change.

Experimental investigations on R430A as a drop-in substitute for R134a in domestic refrigerators

In this work, the energy performance of a domestic refrigerator has been experimentally investigated using R430A as a possible drop-in substitute to replace R134a. Experiments have been carried out in an R134a-based single evaporator domestic refrigerator of total volume 190 L. The pull-down and ON/OFF cycle performance tests were carried out at 32 ± 0.3 ℃ ambient temperature. The continuous running performance test was carried out for wide range of ambient temperatures between 24 ℃ and 43 ℃ by maintaining evaporator temperature at −12 ± 0.2 ℃. The experimental results showed that the R430A has 3.9% lower energy consumption with 3.8%–6.4% higher coefficient of performance when compared to R134a. However, the compressor discharge temperature of R430A was observed to be 2 ℃–4 ℃ higher when compared to R134a. The lubricant used in R134a compressors is physically stable and retains its lubricant property at 4 ℃ elevated temperature when operating with R430A. The total equivalent warming impact of R430A was found to be 4%–5% lower when compared to R134a due to its higher energy efficiency and lower global warming potential. The results confirmed that R430A is found to be a good drop-in substitute to phase out R134a in domestic refrigerator servicing sectors.

HFO1234ze as Drop-in Replacement for R134a in Domestic Refrigerators: An Environmental Impact Analysis

Abstract In this paper are reported the results of an experimental comparative analysis between R134a and HFO1234ze, when they are employed as refrigerants in a domestic refrigerator. Under sub-tropical conditions, it have been measured the energy consumptions in accordance with the UNI-EN-ISO15502. For each experiment it have been estimated both the TEWI and the Life Cycle Climate Performance indexes to assess the environmental impact due to HFO1234ze when used in place of R134a.

HFO1234yf as a Drop-in Replacement for R134a in Domestic Refrigerators: A Life Cycle Climate Performance Analysis

HFO1234yf as a Drop-in Replacement for R134a in Domestic Refrigerators: A Life Cycle Climate Performance Analysis

HFO1234yf as a drop-in replacement for R134a in domestic refrigerators: a life cycle climate performance analysis

HFO1234yf as a drop-in replacement for R134a in domestic refrigerators: a life cycle climate performance analysis

Energy and exergy analysis of LPG (liquefied petroleum gas) as a drop in replacement for R134a in domestic refrigerators

This study presents a comparison of energetic and exergetic performance of a vapour compression refrigeration system using pure HC (hydrocarbon) refrigerants. In this study, three different pure HCs propane (R290), butane (R600) and commercial LPG (liquefied petroleum gas) are used in the theoretical analysis. R134a is also used in the analysis as a reference refrigerant. The evaporator temperature ranges from −30 to 0 °C while the condenser ranges from 30 to 50 °C. MATLAB software is used for solving the thermodynamic equations, while the thermo-physical properties are calculated using REFPROP software. The results show that R600 has the highest COPc and exergetic efficiency, while LPG has the lowest. When compared to R134a, the COPc for R134a is higher than that for LPG by 10%. Also, the exergetic efficiency is higher by 5%. However, LPG has the advantage of being not expensive, available in large amounts and zero ozone depletion potential and low global warming potential.

EXPERIMENTAL STUDY OF LPG AND R134a REFRIGERANTS IN VAPOR COMPRESSION REFRIGERATION

Natural refrigerants, such as hydrocarbons, have been renewed in recent years as a result of the environmental problems associated with chlorofluorocarbon (CFC) and hydro-chlorofluorocarbon (HCFC) refrigerants. Due to the depletion of the ozone layer and global warming effects, synthetic refrigerants are being gradually phased out in accordance with the international protocols that aim to protect the environment. A refrigerator designed to work with R134a was used for this experiment, liquefied petroleum gas (LPG) which consists of 60% propane (R290) and 40% butane (R600) was compared with R134a refrigerant in a vapor compression refrigerator with a total volume of 62 L. The experiments were carried out using different charges of 40, 60, 80, and 100 g for R134a and LPG refrigerants, the charges were measured with a digital charging scale. The K-type thermocouples were used to measure the temperatures at the inlet and outlet of the four major components (evaporator, compressor, condenser, and expansion device) of the refrigeration system. The system was instrumented with two pressure gauges at the inlet and outlet of the compressor for measuring the suction and discharge pressures. The results obtained were used to determine the thermodynamic properties of the refrigerants using Refprop, version 9. The results obtained showed that the design temperature and pull-down time set by the International Standard Organisation (ISO) for a refrigerator were achieved with LPG earlier than with R134a. The coefficient of performance (COP) of the system increases by 9.5% and the power consumption is reduced by 12%, when compared with R134a. Therefore, LPG can successfully substitute R134a in domestic refrigerators.

Energy performance assessment of R430A as a possible alternative refrigerant to R134a in domestic refrigerators

In this work, the energy performance of a domestic refrigerator has been assessed theoretically with R134a and R430A as alternative refrigerant. The performance has been assessed for three different condensing temperatures, specifically, 40, 50 and 60°C with a wide range of evaporator temperatures between −30 and 0°C. The performance of the domestic refrigerator was compared in terms of volumetric cooling capacity, coefficient of performance, compressor power consumption and compressor discharge temperature. Total equivalent global warming impact of the refrigerator was assessed for a 15-year life time. The results showed that volumetric cooling capacities of R430A and R134a are similar, so that R134a compressor can be used for R430A without modifications. The coefficient of performance of R430A was found to be higher than that of R134a by about 2.6–7.5% with 1–9% lower compressor power consumption at all operating temperatures. The compressor discharge temperature of R430A was observed to be 3–10°C higher than that of R134a. Total equivalent global warming impact of R430A was found to be lower than that of R134a by about 7% due to its higher energy efficiency. The results confirmed that R430A is an energy efficient and environment-friendly alternative to R134a in domestic refrigerators.

ASSESSMENT OF PROPANE/COMMERCIAL BUTANE MIXTURES AS POSSIBLE ALTERNATIVES TO R134a IN DOMESTIC REFRIGERATORS

The possibility of using hydrocarbon mixtures as working fluids to replace R134a in domestic refrigerators has been evaluated through a simulation analysis in the present work. Performance characteristics of domestic refrigerators were predicted over a wide range of evaporation temperatures (-35 to -10°C) and condensation temperatures (40 to 60°C) for various working fluids such as R134a, propane, commercial butane and propane/iso-butane/n-butane mixture with various propane mass fractions. Performance characteristics of the considered domestic refrigerator was identified by the coefficient of performance (COP), volumetric cooling capacity, cooling capacity, condenser capacity, input power to the compressor, discharge temperature, pressure ratio and the refrigerant mass flow rate. Results showed that pure propane could not be used as a drop-in replacement for R134a in domestic refrigerators because of its high operating pressures and low COP. Commercial butane yields many desrirable characteristics, but requires compressor change. Coefficient of performance of the domestic refrigerator using a ternary hydrocarbon mixture with propane mass fraction from 0.5 to 0.7 is higher than that of R134a. Comparison among the considered working fluids confirmed that average refrigerant mass flow rate of propoane/commercial butane mixture is 50% lqwer than that of R134a. Also, results indicated that R134a and propoane/commercial butane mixture of 60% propane mass concentration have approximately the same values of saturation pressure, compressor discharge temperature, condenser heat load, input power, cooling capacity and volumetric cooling capacity. However, the pressure ratio of the hydrocarbon mixture with 60% propane is lower than that of R134a by about 11.1%. Finally, the reported results confirmed that the propane/iso-butane/n-butane mixture with 60% propane is the best drop-in replacement for R134a in domestic refrigerators under normal, subtropical and tropical operating conditions.

Experimental study of R152a and R32 to replace R134a in a domestic refrigerator

This paper presents an experimental study of R152a and R32, environment-friendly refrigerants with zero ozone depletion potential (ODP) and low global warming potential (GWP), to replace R134a in domestic refrigerator. A refrigerator designed and developed to work with R134a was tested, and its performance using R152a and R32 was evaluated and compared with its performance when R134a was used. The results obtained showed that the design temperature and pull-down time set by International Standard Organisation (ISO) for small refrigerator were achieved earlier using refrigerant R152a and R134a than using R32. The average coefficient of performance (COP) obtained using R152a is 4.7% higher than that of R134a while average COP of R32 is 8.5% lower than that of R134a. The system consumed less energy when R152a was used. The performance of R152a in the domestic refrigerator was constantly better than those of R134a and R32 throughout all the operating conditions, which shows that R152a can be used as replacement for R134a in domestic refrigerator.

Comparative assessment of environment-friendly alternatives to R134a in domestic refrigerators

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.

Assessment of propane/commercial butane mixtures as possible alternatives to R134a in domestic refrigerators

Abstract The possibility of using hydrocarbon mixtures as working fluids to replace R134a in domestic refrigerators has been evaluated through a simulation analysis in the present work. The performance characteristics of domestic refrigerators were predicted over a wide range of evaporation temperatures (−35 to −10 °C) and condensation temperatures (40–60 °C) for various working fluids such as R134a, propane, commercial butane and propane/iso-butane/ n -butane mixtures with various propane mass fractions. The performance characteristics of the considered domestic refrigerator were identified by the coefficient of performance (COP), volumetric cooling capacity, cooling capacity, condenser capacity, input power to compressor, discharge temperature, pressure ratio and refrigerant mass flow rate. The results showed that pure propane could not be used as a drop in replacement for R134a in domestic refrigerators because of its high operating pressures and low COP. Commercial butane yields many desirable characteristics but requires a compressor change. The coefficient of performance of the domestic refrigerator using a ternary hydrocarbon mixture with propane mass fractions from 0.5 to 0.7 is higher than that of R134a. Comparison among the considered working fluids confirmed that the average refrigerant mass flow rate of the propoane/commercial butane mixture is 50% lower than that of R134a. Also, the results indicated that R134a and the propoane/commercial butane mixture with 60% propane mass concentration have approximately the same values of saturation pressure, compressor discharge temperature, condenser heat load, input power, cooling capacity and volumetric cooling capacity. However, the pressure ratio of the hydrocarbon mixture with 60% propane is lower than that of R134a by about 11.1%. Finally, the reported results confirmed that the propane/iso-butane/ n -butane mixture with 60% propane is the best drop in replacement for R134a in domestic refrigerators under normal, subtropical and tropical operating conditions.