Expressor heat pump for heat production in local combined heat and power plants

The reason is that within the refrigeration industry transcritical CO2 systems are being developed and especially at high temperatures they are more efficient than corresponding systems with traditional refrigerants. The CO2 technology has previously been demonstrated in connection with heat pumps in smaller systems and precisely in heat systems with requirements to relatively high inlet temperatures (>55 deg C) transcritical CO2 is substantially more efficient than other refrigerants. By using a so-called expressor consisting of an integrated compressor and a wet expander it is also possible with advantage to use the expansion work to produce mechanical energy which again can be utilised in the compressor (expressor). In that way it is possible to make the heat pump system even more efficient. In practice and depending on the operation conditions and the chosen expander design efficiency in the size range of minimum 4 to 5 is expected. The project is divided into two main phases and the first phase will comprise fact-finding work concerning the technology and there will be three sub-phases. The second main phase will comprise design, set-up and test of a prototype and know-how dissemination during the entire project