Model and Algorithm for Simulation of a Novel Dry-Type Shell-Tube Evaporator Used in Sewage Source Heat Pump

Aiming at the issue of de-fouling in sewage source heat pump systems for sewage-side heat exchanger, a dry-type shell-tube sewage heat exchanger with auto-de-fouling function outside tubes was firstly developed. Based on reasonable assumptions, a steady-state and two-dimensional model for the dry-type shell-tube sewage evaporator is presented, according to the theory of two-phase flow and thermodynamics of refrigeration systems and the flow pattern of concurrent flow, counter flow, vertically crossed flow and oblique crossed flow in the side of sewage. Section division of the dry-type shell-tube sewage evaporator is setup, then, an new algorithm for the steady-state simulation of this evaporator is presented, which combines the idea of solving in temporal sequence and in spatial sequence, in the method of iterating flows' parameters on both sides until convergence to a certain precision. In order to validate the developed algorithm, simulation results were compared with experimental data. Due to the good agreement verified in the presented results, the developed algorithm was considered validated.