Abstract
Current cost-effective solar collectors are mainly used for low-temperature heating, such as building
heating and other domestic low-temperature purposes, and cannot supply in the range of 180 – 200 °C
needed for industrial purposes. The EU-funded FRIENDSHIP project has the proposed solution of
combining a solar heating system with a high-temperature heat pump (HTHP) based on water (R-718)
as a working fluid to upgrade the temperature to be used for both heating and cooling (achieved by
absorption chillers). The work presented here is the further development and evaluation of steam
compression performance using a two-stage turbo compressor configuration at inlet pressures of 1 – 2
bara. A maximum second-stage discharge pressure of 5.3 bar has been achieved, corresponding to a
condensation temperature of 154°C. A novel shaft seal purge system has shown satisfactory
performance in preventing steam leakage into the gearbox oil system.
Keywords: Refrigeration, Carbon Dioxide, Compressors, COP, Evaporators, Energy Efficiency, Solar
Assisted Heat Supply
heating and other domestic low-temperature purposes, and cannot supply in the range of 180 – 200 °C
needed for industrial purposes. The EU-funded FRIENDSHIP project has the proposed solution of
combining a solar heating system with a high-temperature heat pump (HTHP) based on water (R-718)
as a working fluid to upgrade the temperature to be used for both heating and cooling (achieved by
absorption chillers). The work presented here is the further development and evaluation of steam
compression performance using a two-stage turbo compressor configuration at inlet pressures of 1 – 2
bara. A maximum second-stage discharge pressure of 5.3 bar has been achieved, corresponding to a
condensation temperature of 154°C. A novel shaft seal purge system has shown satisfactory
performance in preventing steam leakage into the gearbox oil system.
Keywords: Refrigeration, Carbon Dioxide, Compressors, COP, Evaporators, Energy Efficiency, Solar
Assisted Heat Supply
