Numerical investigation of the heat pump system

Abstract

The purpose of the presented research is to develop an overall mathematical model, which will allow for a more precise simulation of the operation of a water-to-water heat pump system, having in mind its thermodynamics, fluid mechanics and heat transfer processes. The simulation allows the prediction of the parameters of the state at each and every point of the cycle, i.e., of the heat pump. The developed model is deterministic, stationary and with distributed parameters. The shell and tube heat exchangers’ mathematical models are described by coupled differential equations, while the models of the compressor and the expansion valve are described using algebraic equations with lumped parameters. The thermodynamics, fluid mechanics and heat transfer processes are examined as functions of changing mass flow of the cooled water $\dot{m}_{\text{cw}} = 0.28, 0.42, 0.55\,{\text{and }}\,0.69 \left[ {{\text{kg}} {\text{s}}^{ - 1} } \right]$, with a referent mass flow of the refrigerant $\dot{m}_{\text{ref}} = 0.019 \left[ {{\text{kg s}}^{ - 1} } \right]$ and the heated water $\dot{m}_{\text{hw}} = 0.28 \left[ {{\text{kg s}}^{ - 1} } \right]$. The used refrigerant is R134a.