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This study proposes the experimental evaluation of alternative refrigerants with low global warming potentials (GWPs) such as R1234ze(E), R513A, and the mixture R516A as a drop-in replacement for R134a in a domestic refrigerator with a volumetric capacity of 513 L. Initially, the optimal charge for each refrigerant was defined based on the minimum energy consumption of the refrigerator, then the thermal and energy performance of the refrigerator was evaluated. Finally, a total equivalent warming impact analysis (TEWI) was performed. The main results indicated that the optimal charge of the alternative refrigerants was below that corresponding to R134a (105 g), of which R516A (86 g) presented the greatest charge reduction. Regarding the average temperature of the refrigerator compartments, very adequate thermal conditions were observed; thus, the alternative refrigerants showed very similar conditions to R134a. For the coefficient of performance (COP) and considering R134a as a reference, it was observed that R513A presented the greatest reduction of around 28%, while R1234ze(E) showed an increase of 13% in relation to R134a. Finally, the TEWI analysis showed R1234ze(E) as the refrigerant with the least impact. [ABSTRACT FROM AUTHOR]

• R513A showed a 9% reduction in energy consumption compared to R134a. • The TEWI for R513A presented a reduction of 8.85% with respect to R134a. • The optimal charge of R513A presented a reduction of 16.7% with respect to R134a. Today, hydrofluorocarbons continue to be used as part of a long transition towards the use of fluids with less impact on the environment. In this sense, the present work provides more information on the thermal and energetic performance of a domestic refrigerator using the R513A refrigerant as a direct replacement for R134a. Initially, the effect of the variation of the R513A charge on certain parameters such as operating pressures and temperatures, the superheating degree and subcooling, as well as the cooling capacity, is evaluated. The charge variations were made in increments of 10 g, until the optimal charge was defined for R513A concerning the minimum energy consumption, which was 100 g, representing a reduction of 16.7% compared to R134a (120 g). Once the optimal charge was defined, comparisons were made between both refrigerants under the same test conditions, resulting in a very similar average temperature of the refrigerator compartments; and for a test period of 24 h, R513A showed a 9% reduction in energy consumption compared to R134a. Finally, the analysis of the total equivalent warming impact presented R513A as a fluid with a lesser impact, around 8.85%, relative to R134a. [ABSTRACT FROM AUTHOR]

• First experimental work using R468A in a vapour compression cycle, mounting a low temperature freezing cabinet. • Energy consumption is similar using R404A or R468A • R468A is a proper energy alternative to R404A. • No technical problems arise. • IHX is useful to improve energy consumption when R468A is used as working fluid. This work analyses experimentally the energy behaviour of a centralized commercial refrigeration plant designed to be used with R404A (GWP 100 = 3,943) at low temperatures, when it is replaced with the new low-GWP refrigerant blend R468A (GPW 100 = 148). The tests have been done at a selected product temperature of -20°C, Class III indoor conditions according to ISO 23953-2:2015 and 20, 30 and 40°C of heat sink temperature. The product has been kept at the requested temperature in whichever conditions tested. Respect to R404A, running with R468A presents an increase in compressor discharge temperature, greater compressión operation time, and a reduction in compressor electric comssumption that yields in a very similar total energy consumption of the refrigeration plant. So it has been proved that, from an operational point of view, R468A can be a R404A drop in replacement fluid. Also, it has been measured energy savings when an internal heat exchanger is placed. [ABSTRACT FROM AUTHOR]

Abstract In this work, the use of R1234yf as a drop-in replacement for R134a in an air to water refrigeration system used to produce cool water at 7 °C is studied. This equipment was constructed in our laboratory with a minichannel heat exchanger working as condenser and a plate heat exchanger working as evaporator resulting in a 2.5 kW water chiller, which initially was working with R134a as refrigerant. A brief description of the refrigeration system and the installation used to test its behaviour as well as the uncertainty analysis is presented. Then, the test matrix defined in order to evaluate the effect of the different variables of interest on the performance of the refrigeration cycle is also presented. Air inlet temperature in the condenser was varied in order to analyse the influence of a variation in the ambient temperature. Other variables were varied in order to analyse the influence of different operating conditions as a variation in the compressor frequency or in the condenser fan velocity (by varying air inlet velocity). Finally, the subcooling degree was varied in order to compare a system with refrigerant receiver (no subcooling) and a system without refrigerant receiver and different refrigerant charge (different subcooling). According to the results obtained, R1234yf performs worse than R134a, presenting lower cooling capacity and higher compressor consumption in all tests, with a global efficiency around 25% lower. This can be explained by its lower isentropic and volumetric efficiency, which could be related to the type of lubricant used. [ABSTRACT FROM AUTHOR]

This work analyses experimentally the possibility of using the reduced GWP refrigerant R-407H (HFC family, GWP = 1378) as drop-in substitute of R-404A (HFC family, GWP = 3945) in low temperature centralized direct expansion refrigeration system. The experimental plant and the test methodology are described. It covered top up or partial drop-in and energy consumption tests at −20 °C of product temperature and 25, 35 and 45 °C of condensing temperature using a small-scale supermarket under laboratory conditions. It has been measured that the use of R-407H instead of R-404A is favourable from the point of view of energy efficiency. Reductions in the energy consumption of up to 7.7% (compressor) and 4.0% (whole system) have been measured. However, there is an increment in the compressor's discharge temperature of up to 13.8 K. In addition, the operation of the system with both refrigerants was correct. [ABSTRACT FROM AUTHOR]

The R22 refrigerant widely used in refrigerating and air conditioning devices is invariably released to the atmosphere due to reasons such as breakdown and/or translocation. As the sales of new devices operating with R22 are decreasing gradually, refrigerants of such available devices should be changed with the ones that are not depleting the ozone layer. In this paper, the amount of consumed energy, cooling capacity and COP values of R417A, R422A, R422D and R424A, which can be used as alternatives to R22, were determined experimentally for a split type air conditioning device at the ambient temperatures of 35, 38 and 41 °C. Basically, COP values of all HFC refrigerants were found to be smaller than that of R22. It was noted that the most suitable refrigerating fluid was R424A, which can be used instead of R22, since the COP of R424A was smaller than that of R22 by 2.5% only at an ambient temperature of 41 °C. [ABSTRACT FROM AUTHOR]

Due to the adoption of EU Regulation No 517/2014, R404A is going to be banned in Europe in most of refrigeration applications, in which is typically used, due to its very high GWP value, 3943. In this paper an experimental comparison between R404A and R448A, a non-flammable alternative with GWP of 1390, is presented. The experimental tests are intended to simulate typical freezing and conservation temperatures and different condensing conditions. Despite cooling capacity of R448A is slightly below that of R404A, R448A energy consumption is even smaller; and R448A COP is higher than that obtained using R404A. Hence, it can be concluded that R448A could be an energy efficient alternative to R404A with a GWP reduction of 70%. Compressor discharge temperature remains at non-dangerous levels. [ABSTRACT FROM AUTHOR]

Abstract: R22, the HCFC most widely used in refrigeration and air-conditioning systems in the last years, is phasing-out. R422D, a zero ozone-depleting mixture of R125, R134a and R600a (65.1%/31.5%/3.4% by weight, respectively), has been recently proposed as a drop-in substitute. For energy consumption calculations and temperature control, it is of primary importance to estimate operating conditions after substitution. To determine pressure drop in the evaporator and piping line to the compressor, in this paper the experimental adiabatic pressure gradients during flow boiling of R422D are reported for a circular smooth horizontal tube (3.00mm inner radius) in a range of operating conditions of interest for dry-expansion evaporators. The data are used to establish the best predictive method for calculations and its accuracy: the Moreno-Quibèn and Thome method provided the best predictions for the whole database and also for the segregated data in the annular flow regime. Finally, the experimental data have been compared with the adiabatic pressure gradients of both R22 and its much used alternative R407C available in the literature. [Copyright &y& Elsevier]