Since sewage source heat pump air conditioning is a new technology that has been widely developed in recent years, its system design is a new problem for all designers. In the past five years, Xiao Li, a researcher of Reynolds sewage thermal energy, has obtained some valuable design experience through a large number of laboratory research and engineering practice. The new problems inevitably encountered in the design are:

1 Choice of system form What kind of sewage can directly enter the unit (direct system), and what kind of sewage can only exchange heat with intermediate clean water first, and then clean water into the unit (indirect system)? For indirect heat exchange, it is recommended to use centrifugal sewage heat exchangers, which can maximize the avoidance of blockage and subsequent cleaning.

2 Water intake and drainage Considering factors such as the elevation of the water surface of the sewage source, the elevation of the machine room, the water pressure distribution, and the exhaust, the design calculation and equipment selection of the open sewage loop. Material and selection of piping and piping equipment.

3 Working conditions Reasonable determination of the design temperature of each node in the sewage loop, the intermediate water loop, the refrigerant loop and the chilled water loop, the pressure, and the flow rate of the medium in the loop. This work has a great relationship with the operation effect and comprehensive energy consumption of the system.

4 Since the viscosity of sewage heat exchanger is several times larger than that of clean water, in order to prevent clogging and pollution, it is not possible to adopt the usual measures to enhance heat exchange for clean water. The heat exchanger used in heat exchange shall use a centrifugal sewage heat exchanger. The resistance and heat transfer coefficient of the sewage heat exchanger must be calculated from scratch according to the water quality report and the basic calculation formula of resistance and heat exchange. The number of processes and the arrangement of countercurrent are completely new problems.