Performance Analysis of High Temperature Heat Pump Cycle for Industrial Process

Abstract

High-temperature heat pumps (HTHP) that can supply heat at temperatures above 200 °C have a very large potential to enhance the energy efficiency of the industrial sector and reduce its CO2 emissions. In the current work, the thermodynamic performance of three different vapor compression cycles, which use R-718 (water) as a working medium, have been evaluated using a commercial process simulation tool (EBSILON Professional 15). All considered cycles use two-stage vapor compression with different intercooling strategies between the stages and the thermodynamic performances of those cycles have been investigated. The comparison studies on the coefficient of performance (COP) and heat supply temperatures have been conducted for all cycle architectures. With increasing temperature difference between a heat source and heat sink, ∆T, the COP values decreased as expected. The highest COP value was found for the cycle configurations where both compressors have the same pressure ratio (PR). The investigation on the HTHP capacities and exergy efficiency, ηexergy, with optimized PR has also been carried out. Both COP and ηexergy values increased with decreasing ∆T and the intercooler cycles with heat exchanger showed higher COP and ηexergy than the spray injection cycle.