Vapour compression refrigeration is used in almost 80 % of the refrigeration industries in the world for refrigeration, heating, ventilating and air conditioning. The high-grade energy consumption of these devices is very high and the working substance creates environmental problems due to environmental unfriendly refrigerants such as chloroflurocarbons, hydrochloroflurocarbons and hydroflurocarbons. Heating, ventilating, air conditioning and refrigeration industries are searching for ways to increase performance, durability of equipments and energy efficiency in a sustainable way while reducing the cost of manufacturing. With the present refrigerants, environmental problems such as ozone layer depletion, global warming potential, green house gases and carbon emission are increasing day by day. In this paper, the popular refrigerant is thoroughly studied experimentally and recommendations are given for alternatives such as carbon dioxide, ammonia and hydrocarbons and new artificially created fluid, HydroFluoro-Olefin 1234yf by DuPont and Honeywell which exhibit good thermo-physical and environmental properties and will be commercialized in the near future.
An experimental performance study on vapour compression refrigeration system with R134a and drop in substitute R152a with aluminium microchannel condenser was carried out for condensation temperature of 48°C while evaporation temperature varied from -10 to 15°C. Refrigerant charge of R152a was reduced by 40% over R134a with the microchannel condenser. Performance parameters like work input to the compressor, coefficient of performance, refrigerating capacity, condenser capacity and the product of the overall heat transfer coefficient & surface area of the condenser are plotted and results are discussed.
A jet pump or an ejector uses primary fluid flow as motive fluid to entrained secondary fluid. In this paper, the main intention is to find suction flow rate, primary flow rate, secondary flow rate, loss factors and ejector efficiency for an applied pressure. The values of the different loss factors estimated are primary nozzle loss factor (Kp)=0.06, suction loss factor (Ks)=0.04-0.1, mixing loss factor (Km)=0.07-0.1 and diffuser loss factor (Kd)=0.0289. It is found that with the increase in pressure across the ejector, efficiency increases with increase in flow ratio and decrease in pressure ratio.
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