Thermodynamic analysis of absorption heat transformers using [mmim]DMP/H2O and [mmim]DMP/CH3OH as working fluids

The thermodynamic performances of absorption heat transformers (AHTs) using [mmim]DMP/H2O and [mmim]DMP/CH3OH as working fluids were numerically analyzed. Variations in coefficients of performance (COPs), exergy efficiencies, and circulation ratios of the [mmim]DMP/H2O and [mmim]DMP/CH3OH AHTs with varying operating temperatures were simulated and compared with those of the LiBr/H2O system. COPs and exergy efficiencies of the [mmim]DMP/H2O and [mmim]DMP/CH3OH AHTs were slightly lower than those of the LiBr/H2O system. But the properties of GTL for [mmim]DMP/H2O and [mmim]DMP/CH3OH systems are superior to the LiBr/H2O system. The exergy losses of each component and the entire system for the three working fluids were calculated and compared. Changes in exergy losses with varying absorption, generation, and evaporation temperatures were analyzed. For the [mmim]DMP/H2O and LiBr/H2O systems, the largest exergy losses were produced in generator and evaporator. For the [mmim]DMP/CH3OH system, the largest exergy losses were produced in generator and absorber.