Numerical Simulation of the Heat Transfer in the Cryoprobe of an Innovative Apparatus for Cryosurgery

Abstract

Cryosurgery is a rapidly developing discipline, alternative to conventional surgical techniques, used to destroy cancer cells by the action of low temperatures. Currently, the refrigeration is obtained via the adiabatic expansion of gases in probes used for surgeries, with the need of inherently dangerous pressurized vessels. The proposed innovative prototypal apparatus aims to reach the cryosurgical temperatures exploiting a closed-loop refrigeration system, avoiding the hazardous presence of pressurized vessels in the operating room. This study preliminarily examines the technical feasibility of the cryoablation with this machine focusing the attention on the cryoprobe design. Cryoprobe geometry and materials are assessed and the related heat transfer taking place during the cryoablation process is simulated with the aid of the computational fluid dynamics software ANSYS®Fluent. Parametric analyses are carried out varying the length of the collecting tubes and the inlet velocity of the cold carrier fluid in the cryoprobe. The values obtained for physical quantities such as the temperature reached in the treated tissue, the width of the obtained cold front, and the maximum pressure required for the cold carrier fluid are calculated and discussed in order to prove the effectiveness of the experimental apparatus and develop the machine further.

Numerical thermal simulation of cryoexposure using Ansys

“…The first is the most detailed numerical simulation of cryoexposure and on its basis, the second is the development of express planning programs. The prospect of using modern software to solve such problems [1][2][3][4][5] is based on increasing of the calculation power, which allows to make more and more complex calculations using FEA, including the use of increasingly sophisticated geometric models (finite element meshes consist of millions of elements). FEA software are becoming more sophisticated every year: turbulence models are being refined, the speed and quality of mesh generators are being improved, parallelization processes are being optimized, that is especially important in the context of increasing of the number of CPU cores.…”