The key technical and economic indexes of Russian free-piston diesel compressors designed for carbon dioxide heat pumps are given. Use of these compressors allows building of 0.5-5.0 MW heat pumps with improved weight-size and cost parameters. A wide variety of hydrocarbons, such as natural gas, mine methane, associated petroleum gas, biogas, etc., can be used in these installations as the primary fuel, which makes it possible to increase the share of heat pumps substantially in stand-alone and centralized heat supply systems.Thermally driven heat pumps (TDHP) can reduce organic fuel consumption by a half (compared to boiler installations) by drawing into the heat supply system not only low-potential heat of various sources, but also waste heat of internal combustion engines (ICE) [1]. However, because of low cost of organic fuel and expansion of electrification in the USSR, TDHP lacked development [2]. In the current situation, increased cost of electric power and technological addition of equipment to power networks, development and introduction of new-generation TDHP are acquiring urgency [3-6, and others].At present, the major area of application of TDHP is stand-alone heat supply system based on heat sources with capacities ranging from 10 kW to several megawatts. Also, in EC countries, gas-fired heating boilers are being replaced by TDHP within the framework of updating of stand-alone heat supply systems [7, 8].A promising engineering and technological solution to development of this direction is heat pump (Fig. 1) based on free-piston diesel compressor (FPDC) where carbon dioxide is used as the working fluid. This machine was developed by the specialists of EKIP firm and Moscow State University of Mechanical Engineering (MAMI) over the years 2002-2013 [9, 10].The operating principle of the FPDC-based TDHP consists in the following. The fuel (natural gas) is injected into the working diesel chamber where the fuel is mixed with the air flowing in from the scavenge blower (SB). With the blowing and exit ports remaining open, the obtained fuel-air mixture expels the combustion products from the cylinder. As the piston moves from the periphery to the center, the fuel-air mixture is compressed at the expense of the energy stored in the buffer (B) that serves as a pneumatic spring. As the piston approaches the inner dead point (IDP), the fuel-air mixture ignites due to compression (diesel cycle).The absence of limits to severity of the working process in the free-piston engine (FPE) and maximum cycle pressure allow operation with high compression ratios, which ensure higher efficiency compared to the efficiency of crank-type diesel

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