First law analysis of a novel double effect air-cooled non-adiabatic ammonia/salt absorption refrigeration cycle

• We analyze a double effect ammonia/salt absorption refrigeration cycle.
• Double effect system driven by waste heat energy obtains high COP value.
• System works well in high ambient temperature conditions.
• Air-cooled non-adiabatic absorber is implemented for performance improvement.
• Method of optimal LPG temperature calculation is provided.

This paper thermodynamically analyzes an air-cooled type double effect absorption refrigeration system using ammonia/lithium nitrate and ammonia/sodium thiocyanate solutions as working pairs and driven by high temperature heat source such as waste heat energy, innovatively, an air-cooled type non-adiabatic absorber is implemented in the system to improve the cycle performance. Comparing to the single effect absorption refrigeration system, the double effect system is designed not only to directly and efficiently utilize high temperature waste heat energy for cycle performance improvement, but also to greatly extend the application occasion to high ambient temperature condition. Parametric analysis of the present system show that COP of the double effect system is 30–60% higher than the single effect system under air cooling working condition and the high pressure generating temperature of the double effect system can be extended to as high as 220 °C. Influences of high pressure generator temperature, low pressure generator temperature, absorber outlet solution temperature as well as other system working parameters on cycle performance are numerically simulated and parametric optimization is provided in the present model. Cycle performance comparison of NH3/LiNO3 system with NH3/NaSCN system has been carried out. According to the simulation results, COP of NH3/NaSCN system is found to be 10–15% higher than that of NH3/LiNO3 system in evaporating temperature range of -10°C

A novel double effect air-cooled type non-adiabatic absorption refrigeration system using NH3/NaSCN and NH3/LiNO3 as working pairs has been thermodynamically analyzed. The present system is driven by waste heat energy with relatively high temperature. A novel non-adiabatic absorber is implemented in the double effect system for the purpose of performance improvement. Comparing to the single effect absorption refrigeration system, the double effect system is designed not only to directly utilize high temperature waste heat energy to obtain high system COP values, but also to greatly extend the application occasion to high ambient temperature condition.Figure optionsDownload as PowerPoint slide