Sewage heat pump is using sewage as low-temperature heat source, through heat pump technology to extract and recycle the low-temperature energy of sewage to heating and cooling for buildings. The sewage includes unprocessed raw sewage, treated sewage.

       To deal with the water quality conditions of sewage or surface water, the current system adopts indirect heat pump system. First,The sewage passes the heat to the clean water(intermediate water), and the intermediate water enters the heat pump unit for cold and heat transformation. The sewage heat pump heating and cooling system is composed of three sub circulation systems, namely sewage circulation, intermediate circulation and terminal circulation. There is a heat pump working fluid (such as Freon) in the heat pump unit, which is the working process of heat pump unit, and it doesn't appear macroscopically. The main equipment of the system includes the sewage pump, the dredging heat exchanger, the intermediate pump, the heat pump unit and the terminal pump.

       The working process of the system is as follows:

       (1) Sewage cycle, sewage enters the heat exchanger at 11℃, transfer about 5℃ to the intermediate water, and back to the downstream water source at 6℃.

       (2) Intermediary cycle, intermediate water enters heat pump unit at 9℃，release the heat, then return to heat exchanger at about 4 ℃ to absorb heat again.

       (3) Terminal cycle, terminal water enters the heat pump units at 40 ℃ , absorb heat rise up to 50 ℃ ,then enter the end radiator, release heat to the building space.

       The technical key is the efficient heat exchange cycle of sewage or surface water, and the effective matching of each sub-cycle to realize the low energy consumption operation of the system and achieve the purpose of energy conservation and environmental protection.