Evaporation cold screw water chiller-heater unit with total heat recovery function

The invention discloses an evaporation cold screw water chiller-heater unit with a total heat recovery function. The water chiller-heater unit comprises a screw compressor connected into a refrigeration circulation loop, an oil separator, a four-way valve, an evaporative condenser, an electric valve, a liquid storage device, a drying filter, an electromagnetic valve, a throttling valve, an air conditioner water side heat exchanger, a gas-liquid separator, a one-way valve, a total heat recoverer and a fin heat exchanger. By controlling an on-off state of the electric valve and the electromagnetic valve through the unit, switching among four functions and operation modes of refrigeration, heating, refrigeration + total heat recovery and hot water can be achieved; and meanwhile, the unit mayachieve a component independent defrosting function of the fin heat exchanger through on-off control of the four-way valve. The requirements of refrigeration, heating, sanitation or process hot waterall the year round of a co