Experimental and numerical analysis of an air-cooled double-lift NH3–H2O absorption refrigeration system

• A prototype air-cooled double-lift NH3–H2O absorption chiller is presented.
• Both experimental performance data and model based P-T-X cycles are shown.
• Capacity is 2.5 kW, thermal COP 0.3 and electrical COP 10 with 7 °C chilled water.
• The self-adjusting split behavior and possible design improvements are discussed.

The prototype of an air-cooled double-lift NH3–H2O absorption chiller driven by hot water at low temperature is presented. The main objective of the study is to illustrate the experimental performances of the prototype under different operating conditions. A mathematical model of the cycle is developed, along with a procedure for the identification of otherwise difficult to measure data, with the purpose of providing the complete picture of the internal thermodynamic cycle. The combined experimental and numerical data allowed assessing the effects on the thermodynamic cycle with varying operating conditions. The unit operated steadily with chilled water inlet 12 °C, outlet 7 °C, air temperature between 22 °C and 38 °C, and hot water driving temperatures between 80 °C and 90 °C. The reference cooling capacity at air temperature of 30 °C is 2.5 kW, with thermal COP about 0.3 and electrical COP about 10.