Heat Pump, Water Heating, Simulation, Refrigeration, System Design
A computational fluid dynamics (CFD) model is developed in ANSYS Fluent for simulating the heat transfer and fluid dynamics in the water tank of a US-type residential heat pump water heating unit that utilizes a wrap-around coil condenser that transfers heat from refrigerant to water through the tank wall. The linked modelling process involves iteration between the CFD model of the water tank and a vapor compression system model (using EES) in describing quasi-steady warm up of a heat pump water heating system. The models are connected via temperatures and heat transfer at the tank wall. The models and the linking procedure are validated experimentally based upon a quasi-steady approach. A wholesome understanding of heat distribution and fluid dynamics in the water tank can enable design optimizations of coil geometry, placement (pitch), etc. Performance is influenced by profiles of water temperature in the tank and refrigerant in the condenser, assuming constant pressure drop, during various warm-up experiments.