Abstract
A cascade high-temperature heat pump applying propane as working fluid in the lower vapor
compression cycle and butane as working fluid in the upper vapor compression cycle has been proposed.
The task for the heat pumps was to heat up water from 95°C to 115°C while evaporating temperatures
between 0°C and 50°C were analyzed to find at which temperature the combined cascade heat pump
would be preferable versus a single working fluid system. The cascade system has been numerically
analyzed, and COP's as high as 2.6 were possible to achieve with an evaporating temperature of only
20°C. The heating capacity of the heat pump was calculated based on the commercially available
compressor units and was found to be approximately 370 kW at an evaporating temperature of 20°C.
compression cycle and butane as working fluid in the upper vapor compression cycle has been proposed.
The task for the heat pumps was to heat up water from 95°C to 115°C while evaporating temperatures
between 0°C and 50°C were analyzed to find at which temperature the combined cascade heat pump
would be preferable versus a single working fluid system. The cascade system has been numerically
analyzed, and COP's as high as 2.6 were possible to achieve with an evaporating temperature of only
20°C. The heating capacity of the heat pump was calculated based on the commercially available
compressor units and was found to be approximately 370 kW at an evaporating temperature of 20°C.