Isothermal performance of a temperature comparison source using potassium concentric annular heat pipe

Abstract

Summary In the field of measurement, high‐precision thermocouples need higher precision calibration equipment. However, the metal temperature equalizing block used in traditional thermocouple calibration equipment has poor temperature uniformity, and the structure of gas‐controlled heat pipe is complex and expensive, and the concentric annular heat pipes have high isothermal performance and simple structure, which can be used to improve the calibration equipment. In this study, a temperature comparison source based on potassium concentric annular heat pipe was fabricated to replace the metal temperature equalizing block, the temperature stability and temperature uniformity within 0 to 16 cm of the different metering wells at 400°C, 500°C, and 600°C were experimentally studied. The temperature stability was ±0.0026 K and the maximum axial temperature difference within 6 to 10 cm of the metering well was 0.027 K. On the vertical section of concentric annular heat pipe, due to the high specific heat of liquid working fluid, the temperature of the metering well near the bottom is higher.