90% of the total energy in the vapour compression cycle is used by the compressor. In order to save electricity in this project a modified form of vapour compression cycle is used. In this cycle the compressor is eliminated completely, & instead renewable energy sources such as solar energy is brought into use with the help of Parabolic trough collector through which the refrigerant is heated. Also a Steam ejector is used for rising the pressure in the system. The steam ejector is designed as per the capacity of the system which is 1 TR and considering the Indian weather conditions, A 0.5 HP pump is used for circulation. The modified vapour compression cycle can be explained as follows: The initial point is the pump which handles the refrigerant in liquid phase, from the pump the refrigerant flows to the parabolic trough collector which gets heated to 115°C with the ambient temperature conditions being 35°C. The R22 refrigerant gets vapourised at 60°C, the vapourised refrigerant then flows to the primary inlet of the steam ejector. In the steam ejector a secondary flow entering from the evaporator is mixed in the the throat section with the primary flow, which attains supersonic speed in the primary nozzle, After mixing in the throat the refrigerant passes through the convergent nozzle which increases its pressure . This high temperature and pressure refrigerant is cooled in the condenser where it attains liquid phase and at the outlet of the condenser the refrigerant is divided, a part of the liquid refrigerant flows to the expansion device and the remaining refrigerant goes back to the pump for recirculation. After expanding in the expansion device the low temperature refrigerant flows through the evaporator absorbing heat from the space to be cooled. After absorbing the heat the refrigerant flows back to the steam ejector as the secondary flow where again mixing of high and low pressure refrigerant takes place.
The main advantage of this system is the power consumption which is only 0.5KW compared to the traditional air conditioning units which consume 2KW therefore there is saving of 75% of energy in the system.
Apart from solar energy, waste heat from various other sources like heat from automobile, Diesel generator, Steel manufacturing process, Waste stream from air conditioning unit, Steam boiler exhaust, Gas turbine exhaust, Heat treating furnaces can also be used.