Performance comparison of cryogenic refrigeration system using LNG wasted cold and ammonia refrigeration

Abstract

Objective: To compare the performance of cryogenic refrigeration system using LNG wasted cold and ammonia cooling. Methods: The thermodynamic and economic models of the two systems were established by MATLAB. Under the basic parameters, the working medium concentration suitable for LNG low-temperature refrigeration system was selected, and the cold storage temperature and refrigeration capacity were changed respectively. The thermal economy of the two systems was compared and analyzed. Results: With the increase of ethylene glycol concentration, LNG mass flow, system power consumption and cold storage capacity increased, COP decreased, but ethylene glycol mass flow remained unchanged; With the increase of cold storage temperature, the system COP increased, while the working medium mass flow and power consumption decrease. Similarly, with the increase of refrigeration capacity, the mass flow and power consumption increase, while the COP of ammonia low-temperature refrigeration system remained unchanged and the COP of LNG low-temperature refrigeration system increased. In the range of 5~20 kW, the COP of LNG low-temperature refrigeration system was lower than that of ammonia low-temperature refrigeration system, and the opposite was true in the range of 20~30 kW. The comparison of economic performance showed that the investment cost of LNG cryogenic refrigeration system was much lower than that of ammonia cryogenic refrigeration system. Conclusion: Under the same working conditions, the thermodynamic and economic performance of the low-temperature refrigeration system using LNG wasted cold is better than that of the traditional ammonia low-temperature refrigeration system.

Keywords

• refrigeration system
• lng
• ammonia
• thermal performance
• economic performanc