ABSTRACT
This chapter mainly introduces the basic control principle and the implementation method of the variable volume ratio two-stage compression air source heat pump system. For the throttling function module of the two-stage compression cycle with interstage incomplete cooling, the phenomenon of vapor injection with liquid, normal vapor injection and backflow are analyzed and a bivariate control method is proposed. For the compression function module, the start-up control and operation control methods of the two-stage compressor with variable volume ratio are introduced, and the defrost and oil return control strategies of the variable volume ratio two-stage compression air source heat pump system are proposed.
