vapor injection, wet vapor injection, reversible heat pump
Extensive use of Heat Pumps is essential to meet European 20-20-20. Reversible air-to-water heat pump systems have to operate at high efficiency levels on a wide operating range to be an economical alternative to the traditional heating and cooling systems. This paper presents the advantages, the control and the implementation of multi vapor injected scroll compressors systems in commercial heat pump water heater application. Enhanced Vapor Injection (EVI) technology allows both performance and reliability improvement across the compressors operating area, especially at low ambient temperatures. Wet Vapor Injection allows extending compressors operating range at very low ambient and high condensing temperatures. The development of a solution integrating injection capable scroll compressors, expansion valves and wet/vapor injection control system is presented in this paper.