Investigations on Boiling Heat Transfer during Flow in Mini-Channels: Error Analysis with the Use of Monte Carlo Method
Current Perspective to Physical Science Research Vol. 1,
20 September 2023
,
Page 142-173
https://doi.org/10.9734/bpi/cppsr/v1/7307A
Abstract
Numerous applications for compact mini-channel heat exchangers have been broadened in recent years, especially in applications with phase change. The advantages of using such devices are that they allow one to remove large heat fluxes, retaining small dimensions of the heat exchange system and provide effectiveness of cooling or thermoregulation. The authors of this chapter described current research which aims to establish heat transfer calculations of flow boiling in mini-channels. The model mini-channel heat exchanger was proposed as the test section with five parallel mini-channels 1 mm deep, asymmetrically heated. The working fluid was Fluorinert FC-770 that laminarly flowed in the circulation loop. The temperature of the common heated wall of the mini-channels was measured by infrared thermography while fluid temperature at the inlet and outlet to the test section was controlled due to K-type thermoelements. Investigations of heat transfer related to the subcooled boiling region. The main objective was to determine local heat transfer coefficients on the contact surface between the working fluid and the heated wall from the Robin boundary condition. The mathematical model described by the heat equation in the mini-channel wall and by the Fourier-Kirchhoff equation in a flowing fluid leads to an inverse heat transfer problem. This problem was solved using the FEM with the Trefftz-type basis functions. As temperature measurement is crucial during heat transfer research, an additional experiment was conducted for the estimation of the temperature measurement uncertainty. During such an experiment, temperature measurement was performed with the use of K-type thermoelements and an infrared camera in two mini-channels simultaneously. Since the uncertainty components are not approximately the same magnitude, the Monte Carlo method was indicated to estimate the uncertainty of the surface temperature measurement. The results obtained from this simulation method were compared with the results of the computation related to the uncertainty propagation method. Both methods of temperature were found to be consistent. The estimate of the temperature uncertainty measurements included in the final results of the heat transfer coefficient.
- Mini-channel
- flow boiling
- heat transfer coefficient
- Trefftz functions
- temperature measurement uncertainty
- Monte Carlo method