Development of a cold climate heat pump using two-stage compression.

This paper presents a simulation study using the ORNL Heat Pump Design Model to investigate the effectiveness of two-stage economizing cycle for cold climate heat pump applications that uses two variable-speed compressors. The high stage compressor was modelled using a compressor map, while the performance of the low stage compressor was evaluated experimentally using calorimeter testing. A single-stage heat pump system was also modelled as the baseline case. The simulated performance of the two-stage system was compared with the single-stage baseline system. Special considerations for designing a cold climate heat pump were addressed at both the system and component levels.