Optimal match between heat source and absorption refrigeration

- An optimal match between heat source and refrigeration level.
- The reason for the maximum exergy efficiency is analyzed.
- Higher heat source temperature is needed for lower refrigeration temperature level.

In process industries, there is usually a great amount of waste heat available at different temperatures, and at the same time, there are cooling or refrigeration demands at different temperatures. In this paper, a single effect water-lithium bromide absorption refrigeration system is modeled and simulated using the process modeling software Aspen Plus. The optimal matches between heat source temperatures and refrigeration levels of the absorption refrigeration cycle are determined. The performance of the absorption refrigeration cycle is assessed in terms of two indicators: coefficient of performance (COP) and exergy efficiency. At a certain evaporator temperature of the absorption refrigeration cycle, which indicates a certain refrigeration level, the COP of the cycle rises rapidly at first and then gently with increasing heat source temperature because higher temperature generates more refrigerant vapor. The exergy efficiency of the cycle, by contrast, exhibits a maximum value because both the system performance and the system irreversibility increase with increasing heat source temperature. Ensuring a proper match between heat source and absorption refrigeration can lead to efficient use of waste heat and decrease degradation loss of waste heat.