Conference Year

2016

Keywords

gas ejector, isobutane, CFD

Abstract

Individual residential air conditioning consumes over 11% of electric energy used for household purposes. For buildings with applied central air conditioning systems it comprises a substantially larger share, even one-third of electric energy consumption. Moreover, air-conditioning creates two sources of environmental pollution: 1) direct emission of greenhouse gases, especially for working fluids belonging to HFC group, and 2) emission of the greenhouse gases during generation of electric power to drive the system. Both sources are contributing signicantly to the global warming effect. Additionally, with energy cost rising constantly, industry is looking for reduction of electric energy expenses as a means of lowering their ixed costs in order to stay competitive. Paper presents development of air-conditioning technology that reduces the greenhouse gases emission by using natural refrigerants and also dramatically reduces the need for the electric power. This is accomplished by using free or inexpensive low temperature heat source, either solar or waste heat, as the main source of energy instead of electricity by means of ejection systems. These systems can be thought as a real alternative to compression devices in air-conditioning technologies. Ejection system can effectively compete with absorption system under temperature of the motive heat source lower than 80°C. The paper deals with CFD numerical simulation along with experimental investigations carried out on a specially constructed prototype/stand for the case of isobutane as a working fluid under motive vapour temperature below 75°C. The numerical and experimental results of entrainment ratio were compared. A good accuracy between numerical and experimental results is observed. The divergent of the results are lower than 20% for tested series. The exemplary pressure and velocity field were presented. The first results of LES (Lagre Eddy Simulation) modelling for isobutane vapour ejector are presented.

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