Abstract: A natural air conditioning system for a car is characterized in a heat energy accumulator, a car battery, a cooler, and a solar collector panel connected to compressor, fan and condenser assembly, expansion valve, and fan and evaporator assembly that are included in a typical car air conditioning system. When the car air conditioning system is in operation, a part of cold energy produced in the system is stored in the heat energy accumulator and the cooler. And, when the car air conditioning system is in an off state, power provided by the solar collector panel or the car battery drives the fan associated with the evaporator and cold energy previously stored in the heat storage accumulator is released to keep an indoor space of the car at a comfortable temperature. Cold energy stored in the cooler also enables the cooler to serve as a spare car refrigerator.

Abstract: Disclosed is a multipurpose heat pump system including a heat pump unit using air as a heat source, a heat recovery heat exchanger, and a heat storage. Refrigerant in the heat pump unit can be guided to flow through different paths defined by a four-way valve of the heat pump unit, so that the heat pump unit can operate in different modes depending on actual needs to produce cold/hot water for air conditioning and/or hot water for daily use. Heat generated during a refrigerant compression in the heat pump unit can be recovered for heating water in the heat storage. Stratified hot water is stored in the heat storage and can be supplied for daily use.