Simplified calculation method of phase change heat transfer thermal field based on spherical coordinates in cryotherapy

• 1、Key Laboratory of Low-grade Energy Utilization Technologies and Systems, College of power engineering, Chongqing University, Chongqing 400044

Abstract：At present, most of the cryotherapy research can only guide the actual surgical procedure on the qualitative level. For the prediction of thermal field changes, there is no simple and accurate calculation method. In this paper, the calculation method is based on the most commonly used point-type cryotherapy system .The method of moving heat source is used to deal with phase change latent heat and the difference of physical properties between frozen zone and non-freezing zone is considered. This paper used spherical coordinates to analyze the differential equations of bioheat transfer during cryotherapy and obtained the simplified calculation method of temperature distribution under steady state and transient state. By comparing the calculation results with numerical simulations and data from vitro and vivo experiments, the temperature distribution comparison lines are obtained, verifying the accuracy of the calculation method. This simplified calculation method has a direct guiding significance for the actual cryotherapy operation.

Keywords： Engineering thermophysics cryotherapy simplified calculation method biological heat transfer phase change