Modeling the airside dynamic behavior of a heat exchanger under frosting conditions

Abstract

A general distributed model with a non-steady-state heat exchanger model coupled with a frost model was developed to study the dynamic behavior of an airside heat exchanger in an air-to-water heat pump heater/chiller unit. The effects of water vapor diffusion and uneven fin temperature distribution were considered. The model was found to agree well with reported experimental results. Compared with the routine model, the present model has higher precision of frost layer thickness especially on the fin surface. Results include the propagation of frost formation along the tube and its effect on the dynamic characteristics of refrigerant, air, and tube sides. According to the results, the temperature difference between air and tube surface temperature was proposed to be the main driving force of frosting. Tube surface temperature is the most important factor affecting frosting when there is little variation in air humidity. Frost at the fin base was found to be thicker than that at the fin tip due to the fact that the frost layer grows faster with lower tube surface temperature.

How to stabilize the output of a time delay distributed bilinear system and application to regional stabilization

“…There has been growing interest in the study of infinite dimensional bilinear systems, which are a type of nonlinear systems that exhibit nonlinearity as a result of the interaction between the state and control. These systems are widely used in various industrial and natural processes, including heat transfer through conduction-convection, neutron kinetics in nuclear reactors, and dynamic heat exchangers with controlled flow [7], among others. Bilinear systems are also often used as simple approximations for nonlinear systems [11].…”

A Numerical Investigation of Frost Growth on Cold Surfaces Based on the Lattice Boltzmann Method

“…Therefore, to guarantee normal operation of the heat exchanger, a frosting investigation on a cold surface is necessary. Apart from previous experimental studies [1][2][3], theoretical studies on frost growth predictions have been paying more attention.…”