Large scale Heat Pumps for district heating with R-744 [19]

Local district heating networks are available in different designs and temperature levels.

The third- and fourth-generation of local district heating networks are particularly suitable for retrofitting a Heat Pump systems due to their supply and return temperatures. Due to the often existing buffer tanks, a large amount of heat can be stored. This makes it possible to operate the Heat Pumps in phases when a lot of energy is available, so large heat pumps can contribute to grid stabilization.

System capacities of 1 MW up to 16 MW are typically realized. The most popular refrigerants are R-717 and R-744. For special systems also synthetic refrigerants are used. 

The refrigerant R-744 is very well suited for systems with low return temperatures up to approx. 45 °C. Systems and compressors must meet high requirements in terms of efficiency, operational reliability and durability. The focus of the presentation is about the refrigerant R-744, compressors and the systems which operate in the  field. The large scale compressors are designed to meet the demands for Heat Pump systems. Important measures are the application envelope, the efficiency level, and the serviceability of the compressor.