Thermal Conductivity Of Cryogenic Liquids By Transient Hot Wire Method

Thermal conductivity,as an inherent property of materials,reflects the heat transfer speed of different materials in the process of heat conduction.Since Franklin first proposed the concept of thermal conductivity in 1753,the research results obtained by scholars on the thermal conductivity of liquids have greatly promoted the improvement of scientific research and industrial production.The thermal conductivity of nanofluids is closely related to the development of microchannel heat exchangers.The development of new heat transfer working fluids and refrigerants is inseparable from the experimental research on thermal conductivity.Liquid hydrogen and liquid oxygen are used as fuels in the aerospace field.Conductivity data is an indispensable physical parameter for the study of flow combustion characteristics and structural optimization in the engine.The main purpose of this paper is to provide basic thermal conductivity experimental data and associated equations for the study of low temperature liquid thermal conductivity,improve the accuracy and reliability of thermal conductivity measurement,and provide a basis for future experimental research on liquid thermal conductivity in the liquid helium temperature zone.In this paper,the measurement principle of transient single hot wire method for liquid thermal conductivity and various corrections for deviation from the ideal model are analyzed in detail.The structure of the liquid sensor is improved to make it suitable for low temperature measurement,and the performance of the data acquisition system is improved.Self-developed and built A set of constant temperature system suitable for the experimental study of thermal conductivity of cryogenic liquid was developed,and an adaptive PID temperature control algorithm was introduced,so that the temperature fluctuation of the low temperature constant temperature environment was less than 10 m K.Using this experimental system,the thermal conductivity of saturated liquid phase of propane(100～200K,normal pressure)and argon(90～140K,0.2～4MPa)was experimentally studied,and the fitting equations of thermal conductivity were obtained respectively.The minimum deviation between the experimental results of liquid R290 thermal conductivity and the calculated value of the fitting equation is-0.00%,the maximum deviation is2.98%,and the average deviation is-0.00%.The minimum deviation between the existing literature data and the calculated value of the fitting equation is-0.05%,the maximum deviation is 6.39%,and the average deviation is-0.33%.The minimum deviation between the experimental results of the thermal conductivity of liquid argon and the calculated value of the fitting equation is-0.01%,the maximum deviation is 3.17%,and the average deviation is 0.06%.The minimum deviation between the existing literature data and the calculated value of the fitting equation is-0.01%,the maximum deviation is 11.37%,and the average deviation is 2.41%.