Pressure drop simulation and pipe size optimization in ammonia pump feeding refrigeration system

Mathematical models for pressure drop through both the compressor suction pipe and the evaporator returning pipe in ammonia pump feeding refrigeration system are developed. The system cycle's performance parameters are simulated by a computer program, which are developed based on both the pressure drop models and the thermal parameters models of the ammonia refrigerant. The program was used to simulate an ice making refrigeration loop with a capacity of 100 kW, a 102 m long compressor suction pipe and a 152 m long evaporator returning pipe. The simulation results show that, comparing to the traditional pipe selecting method, the pipe size optimized by the program is capable of increasing the system COP by 7.6% which corresponds to an annual energy saving of 9092 kWh. The further analysis shows the cost caused by the optimization can be recalled within two years. The life period of refrigeration compressor can be extended because its discharged temperature reduced evidently after pipe size optimization.