Air source heat pump with multiple slide rotary screw compressor/expander

摘要

An air source heat pump system includes in a primary refrigeration circuit a hermetic screw compressor and a helical screw rotary expander selectively clutchable to the permanently coupled helical screw compressor and electric induction drive motor. A solar/reclaim evaporator alternately functions as an expander boiler to feed refrigerant vapor to the compressor injection slide valve or to the feed port of the helical rotary screw expander to cause the expander to drive the compressor under compressor load or to drive the electric induction motor as a generator with the compressor unloaded. The solar/reclaim evaporator and expander boiler may be selectively fluid connected to the injection slide valve or to the suction port of the compressor. The hydronic system heating condenser and water chilling evaporator coil may form basic input and rejection heat exchangers to cascaded building zone heat pumps. Additional heat input to the primary circuit may be provided by a fossil fueled combustion heater feeding through the expander of the hydronic system heating condenser.