24 June 2014
Low-grade heat losses in the form of liquid effluents at temperatures of up to 45°C represent more than 24% of total heat losses in the Canadian manufacturing industry. On the
other hand, process or domestic hot water up to 85°C is simultaneously or intermittently required in many industrial plants. By recovering low-grade heat from process fluids or waste
liquid or gas effluents, incoming fresh or recycled water can be heated up to relatively hightemperatures by using supercritical CO2 heat pumps. This paper presents the process integration procedure and the main energy performance achieved with two supercritical CO2 heat pumps. The first one has been implemented in a Canadian dairy plant to provide
process cooling and heating simultaneously. The second one has been laboratory tested over an extensive range of waste heat temperatures to heat cold city water directly. Both the cooling and heating thermodynamic parameters as well as the overall energy performance
achieved are presented and briefly discussed.