Optimal design of wall temperature measurement for microchannel flat tube based on resistance temperature detector

Microchannel heat exchangers are characterized by high heat transfer efficiency and compact volume. The accuracy of microchannel wall temperature measurement directly affects the measurement result of the heat transfer coefficient. The water bath can control the heat flux in the microchannel heat transfer experiment with good uniformity of heat flux distribution and small heat dissipation. However, there is no suitable enough method to accurately measure the wall temperature of the microchannel under the water bath method and bilateral fluid. This paper uses the CFD method to carry out the fluid–solid coupled heat transfer. The measurement errors of six wall temperature measurement schemes in the Reynolds number range from 2400 to 7200 are investigated. The flow field distribution, pressure drop, and turbulent kinetic energy characteristics of different wall temperature measurement schemes are studied. The method of measuring microchannel flat tube wall surface temperature is optimized to solve the problem under a flowing water bath with a traditional resistance temperature detector. The results show that the measurement error of wall temperature caused by the layout method can be reduced to 0.0137 K. The pressure drop and turbulent specific kinetic energy are smaller using the optimal design.