Author : Chetan P. WaykoleȦ and H.M. Dange

It is necessary to modify the simple vapour compression refrigeration systems in order to improve the performance. The coefficient of performance of the system can be increased either by decreasing the work of compression or increasing the refrigerating effect or by the combination of both. The refrigerating effect can be increased by maintaining the condition of refrigerant in lower temperature liquid stage, at the entrance of evaporator. This can be achieved by expanding the refrigerant very close to the liquid line i.e. by sub-cooling the refrigerant and by removing the flashed vapour. The present work describes the design of a VCRS and the design of the liquid suction heat exchanger. A tube in tube type heat exchanger is incorporated in the system, in between the liquid line i.e. pipe joining the condenser and the expansion device and the suction line i.e. pipe joining the evaporator and the compressor. So it is called as Liquid Suction Heat Exchanger (LSHX) or Suction line heat exchanger (SLHX). Effect of reduced flashing was found dominant, compared with the effect of sub-cooling on the refrigeration capacity. The effects of different flow rates of refrigerant and initial temperature of water on COP, work of compression, refrigeration effect of the system, heat exchange capacity of the LSHX, effectiveness of the LSHX & refrigeration capacity of the evaporator are calculated and analyzed. On the basis of experimentation and analysis, it is found that, use of liquid suction heat exchanger in the VCRS, increases the COP of the refrigeration unit for different initial temperatures of water. The power consumption by the compressor gets reduced by using the liquid suction heat exchanger. The optimum effect of the LSHX is seen at different flow rates of the refrigerant for lower initial temperature of water (30 to 35 °C).

Keywords: LSHX, water cooler, VCC, heat exchanger, COP.