Two-stage compression cycle for water heatersin air source heat pumps

Based on a comprehensive analysis, applies the two-stage compression cycle with two stage throttling and midway incomplete cooling to air-source heat pump in order to fit to the low temperature environment. The calculation results of a case show that the exhaust temperature and the compression ratio of the two-stage system are better than those of the single-stage system, and that the performance coefficient of the two-stage system is higher, and that the cold-adaptability of the system is well to a certain extent.