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The replacement of HFCs using lower GWP refrigerants in the coming years is a priority to reduce the predicted climate change. The exergy analysis of vapor compression systems can help to identify the feasibility of alternative fluids in existing installations and the potential to improve them. In this sense, this paper presents an exergy analysis of an experimental setup which operates with R134a and the alternative HFO/HFC mixture R513A. The evaporating temperature is ranges between −15 °C and 5 °C, while the condensing temperature is set at 30 °C and 35 °C. In this analysis, the highest amount of exergy destruction rate is obtained at the compressor, followed by the evaporator. The maximum exergy efficiencies are observed at the condenser and the thermostatic expansion device. Finally, the average global exergy efficiency of R513A when replaced R134a in this refrigeration experimental setup is 0.4% higher (absolute difference), and with respect to the components, there is only slight reduction in efficiency in the condenser using R513A. Therefore, the R513A replacement is acceptable according to the second law of thermodynamics., Export Date: 22 October 2018; Article; CODEN: ENEYD; Correspondence Address: Belman-Flores, J.M.; School of Engineering Campus Irapuato-Salamanca, University of Guanajuato, Carretera Salamanca-Valle de Santiago km 3.5+1.8, Comunidad de Palo BlancoMexico; email: jfbelman@ugto.mx; Funding details: Energimyndigheten; Funding details: R513A, SFFA, Svenska Föreningen för Allergologi; Funding details: POSDOC/2016/23, SFFA, Svenska Föreningen för Allergologi; Funding text: This research is done within the Effsys Expand P08 project that is funded by the Swedish Energy Agency with the support of Bosch Thermoteknik AB, Danfoss Värmepumpar AB, Nibe AB, Nowab, Svensk Energi & Kylanalys AB and Svenska Kyltekniska Föreningen. Adrián Mota-Babiloni would like to acknowledge the funding received from the Plan for the promotion of research of the University Jaume I for the year 2016 [Grant number POSDOC/2016/23 ]. Appendix A In this appendix section, the condensing and evaporating experimental temperatures for R134a and R513A is reported. Likewise, the uncertainty of exergy efficiency and exergy destruction rate for the global system and its main four components is also provided. Table A1 Uncertainty of the estimated parameters for R134a and R513A. Table A1 Refrigerant T cond [°C] T evap [°C] Uncertainty (±) Global Compressor Condenser TXV Evaporator η ex [-] E ˙ d [W] η ex [-] E ˙ d [W] η ex [-] E ˙ d [W] η ex [-] E ˙ d [W] η ex [-] E ˙ d [W] R134a 30.0 −15.0 0.0011 1.1 0.0058 2.7 0.0164 0.4 0.0005 0.3 0.0112 2.0 R134a 30.1 −12.4 0.0012 1.2 0.0053 2.6 0.0177 0.4 0.0005 0.3 0.0100 1.9 R134a 30.0 −9.8 0.0013 1.2 0.0050 2.4 0.0194 0.4 0.0004 0.2 0.0086 1.8 R134a 30.0 −7.7 0.0013 1.2 0.0047 2.3 0.0199 0.5 0.0004 0.2 0.0079 1.7 R134a 29.9 −5.3 0.0018 1.3 0.0044 2.2 0.0242 0.5 0.0004 0.2 0.0069 1.6 R134a 30.0 −2.3 0.0019 1.4 0.0039 2.0 0.0240 0.5 0.0003 0.2 0.0059 1.5 R134a 30.1 0.1 0.0021 1.4 0.0037 1.9 0.0250 0.6 0.0003 0.2 0.0052 1.4 R134a 30.0 2.7 0.0022 1.4 0.0034 1.8 0.0266 0

In this paper, an artificial neural network application to model a small refrigeration system is presented. The main objective of this study is an energy comparison of three refrigerants: R134a, R450A and R513A. The application of the artificial neural network was designed to model individually three typical energy parameters: the cooling capacity, the power consumption and the coefficient of performance, as a function of the evaporating temperature and the condensing temperature. Each model was validated using a technique called cross-validation, producing minimum relative errors of 0.15 for the cooling capacity and the coefficient of performance, while 0.05 for the power consumption. Based on the appropriate validation results, computer simulations were performed to build 3D color surfaces. After inspecting these 3D color surfaces, it was concluded that R450A presented a slightly lower cooling capacity than R134a, actually a 10% reduction in the cooling capacity was estimated. Similar results were observed for the power consumption, that is, R450A had about 10% less power consumption than the other two refrigerants. On the other hand, it was observed that R134a and R513A presented very similar energy behaviors. With respect the COP, it was concluded that all three refrigerants showed a very similar behavior. After the analysis performed with the artificial neural networks and the use of 3D surface color, it was concluded that R450A and R513A are appropriate refrigerants to replace R134a in the short term in applications at medium evaporating temperature., QC 20171130

This paper presents an experimental study for three identical domestic refrigerators using R1234yf as a drop-in replacement for R134a. An alternative methodology was proposed to estimate the optimal mass charge for R1234yf; with the use of such methodology, new evidences were sought on the thermal behavior of the refrigerator compartments as well as at the heat exchangers. Additionally, energy performance for both refrigerants was measured, and, finally, a TEWI analysis was conducted. For the type of refrigerator evaluated, results showed that R1234yf presented an average (for the 3 refrigerators) of 0.4 degrees C for the fresh food compartment, and 1.2 degrees C for the freezer, among different charges with respect to R134a. The optimal charge for R1234yf was 92.2 g, which is about 7.8% lower than the one for R134a, which represents a small increase of 4% in energy consumption in comparison to R134a. Finally, the TEWI analysis for the R1234yf was 1.07% higher than the R134a., QC 20170920

This article presents a feasibility study of a new polymer-ceramic composite material applied as a thermal insulator on the surface of a low net volume household refrigerator. This paper describes its manufacture in a succinct manner, and a thermal and energy comparison between the factory refrigerator and the refrigerator with the composite installed. Based on the experiments, it is concluded that when using the composite, the average internal temperature of the fridge is increased by 1°C, for practical and design purposes, the refrigerator still functions below 3°C. It was also found that at stable operating conditions the energy consumption using the composite saves approximately 1.5%. Despite these slight savings,the pyro-expanded perlite composite acts as a thermal isolating material. This material may exhibit better ease of use and thermal, energetic and economic benefits, without omitting the environmental characteristics that they favor., Este artículo presenta un estudio de viabilidad de un nuevo material compuesto polímero-cerámico aplicado como aislante térmico sobre una superficie de un refrigerador doméstico de pequeña capacidad volumétrica. Este trabajo describe de manera sucinta su manufactura así como la comparación energética y térmica entre el refrigerador de referencia (cuando sale de fábrica) y el refrigerador con el composite instalado. Experimentalmente, cuando se usa el composite la temperatura interna promedio del frigobar incrementa alrededor de 1°C, que para propósitos prácticos y de diseño, el refrigerador aún funciona por debajo de los 3°C. Además, para condiciones de operación estables, la energía consumida usando el composite ahorra aproximadamente 1.5% en comparación con el refrigerador de referencia. A pesar de este ligero ahorro, la perlita pyro-expandida actúa como material aislante. Este material puede exhibir mejor facilidad de uso y beneficios térmicos, energéticos y económicos, sin omitir las características ambientales a su favor.