Competitive technology analysis of a double stage kinetic compressor for 0.5 MW heat pumps for industrial and residential heating

Presently, most heat demands globally are covered by burning fossil fuels, e.g., by using coal, which results in harmful emissions. For example, when burning oil, carbon dioxide emissions alone are estimated to be 3.2 times the mass of fuel (oil) burned. Other harmful emissions include those associated with increased health risks, e.g., sulfur dioxide and indirect climate gases. With new regulations following political initiatives such as a decarbonized Europe, the use of fossils is under pressure. Heat pumps provide clean heat production with efficient use of electricity. With the deployment of high-speed kinetic compressors, more applications with heat pumps become viable. The high-speed kinetic turbo compressors have a higher efficiency and better reliability than reciprocating oil-lubricated compressors. Oil-free compressor technology enables the use of the most efficient and ultra-low global warming potential working fluids, which in most cases are sensitive or unsuitable for bearing lubricants. In this work, the technology alternatives for high-speed oil-free compressors are analyzed. Based on the working conditions of 500 kW residential heat pump modules, a case study comparison between bearingless technology and a surface permanent magnet motor having a rotor with two active magnetic bearings is presented.