08 August 2007

R744 System for Heating and Cooling of Automobiles – Analysis of Heat Pumps and Hot Gas Cycle


This paper describes the analysis of an air/air heat pump, a coolant/air heat pump and a hot gas cycle by
means of experimental investigations and numerical simulations. All systems are based on the R744 refrigerant
circuit of the air conditioning system, and they are therefore suitable for heating and cooling of the
passenger cabin. It has been shown that quite large heating capacities of more than 2.4 kW can be achieved
with the heat pump systems, even under unfavourable operating conditions (low compressor speed and low
air fl ow rate). For the hot gas cycle, a maximum heating capacity of 1.1 kW was obtained at the investigated
conditions.