Urban sewage delivery heat-transfer system （1）: analysis of flow resistance and energy consumption

The thimble delivery heat-transfer (TDHT) system is one of the primary modes to utilize the energy from urban sewage. Explicates the schematic diagram of TDHT system, and based on the definition of equivalent fouling roughness height expounds the calculation method of the flow resistance of the thimble by Nikuradse semi-empirical resistance coefficient formula in the rough region. Compares the resistance of sewage and pure mediate water, concluding that the mediate water sub-system should be emphasized in design of TDHT system. Determines the economical ratios of flow and velocity by an optimization analysis of investment and operation costs in the technically practicable range.