Untreated Sewage Turbulent Characteristics And The Research On Heat Pumps Using Untreated Sewage As The Heat Or Cold Source

The thesis has researched on the untreated sewage turbulent characteristics and the key technology and solutions of using the untreated sewage in a heat pump system.Urban sewage is a good choice used in the heat pump system as the cold or heat source. The thesis discusses its heat energy characteristics and the benefit of sewage source heat pump systems and summarizes the project application and research approach inside and outside our country from clog-proof equipments, heat exchange type and system performance. The present existing problems are pointed out so as to impel the extensive application of untreated sewage source heat pump systems.The flow characteristics is one of the research focuses when using sewage heat energy. The flow is typical solid-liquid two phase flow for the sewage containing the solid particles. The research method consists of solid-liquid and non-Newtonian models. The thesis researches on the turbulent velocity distribution of untreated sewage based on the Prandtl mixing length concept when the pipe is fully filled, and the resistance calculation correlation using non-Newtonian model when the pipe is filled with some gases. The discussed results of change rules can direct the design of pipe and heat exchanger where the untreated sewage flows.The sewage source heat pumps usually adopt indirect heat exchange pattern because of the clogging or corrosion effect probably damaging the units. Sewage heat exchangers play an important role in the system performance especially when untreated sewage is used as heat or cold source. The thesis designs the dimension and establishes the suitable transfer functions of a free-flow-channel heat exchanger. The models are verified according to the collected data from the real system using the heat exchanger. The thesis studies the practical system in Tianjin and evaluates its performance from the exegetic cost. The system COP is close to 4, the actual working cost is 16.77yuan per square meter and the saving is about 0.44million yuan.The exegetic cost of water pump entering the evaporator show the highest. So the thesis establishes the heat pump dynamic control models and analyzes variable frequency, temperature and self-control modulations how affect the energy saving operation.Coating the unit component and especially treating the sewage are essential for a system of direct heat exchange pattern. The evaporator or condenser treatments are also essential but it needs large quantities of experiments to ensure the practical performance. The thesis studies the first level filter's configuration, designs and tests a newly equipment as the second level filter which utilizes ultrasonic treatment technique. At last the thesis suggests the film treating technique at the end of the newly equipment. It can make the sewage at the outlet cleaner and safer to enter the unit components.