Thermodynamic analysis of an absorption heat transformer based on experimental measurements

A prototype of an absorption heat transformer with a nominal capacity of 40 kW recovered heat has been investigated and compared with another prototype which measurements have been presented in a previous work (Cudok et al., 2017). The new prototype has been designed for upgrading industrial waste heat by recovering it at a temperature between 80 and 100°C and boosting it to a temperature level between 120 and 150°C. External heat balances obtained from measured external temperatures and flow rates combined with internal balances from enthalpy calculations of liquid and vapor flows have been used to get more insight into the internal process as occuring in real operation. The amount of adiabatic absorption in the absorber has been assessed (amounts up to 30% of the total referigerant absorbed), explaining the resulting heat flows in the main heat exchangers. Moreover, an observed malfunction consisting of liquid refrigerant carry over from evaporator to absorber could be quantified with the results of the energy balances, explaining the deviation between measured coefficients of performance and expected ones.