VALIDATION OF LOCAL THERMAL EQUILIBRIUM ASSUMPTION IN A VASCULAR TISSUE DURING INTERSTITIAL HYPERTHERMIA TREATMENT

In this paper, the validity of local thermal equilibrium assumption in a tissue-like porous medium is investigated numerically, with an interstitial heat source. The study is based on comparison between two three-equation local thermal nonequilibrium (LTNE) model and one-equation local thermal equilibrium (LTE) model. The LTNE model is validated by an steady-state 1D analytical solution which is presented for first time. The presented results indicate the small temperature difference between fluid and solid phases in heat-affected region, which leads to considerable errors in prediction of tissue thermal behavior. According to records, increasing perfusion rate or intensity of heat source increases the differences between LTE and LTNE models. It is found that in a counter-current vascular tissue if the perfusion rate of blood into tissue becomes higher, the prediction error of LTE model will be more considerable. Moreover, the higher the intensity of heat source is, the greater the difference between LTE and LTNE models is. These findings could be extended to heat transfer modeling of actual tissue during various interstitial hyperthermia treatments.