Heat leak measurement of the cryogenic pipe for the superconducting power transmission at different surface temperatures

Abstract

The heat leak of the cryogenic pipe constituting a transmission line of the superconducting power transmission depends on the surface temperature of the cryogenic pipe, because the heat leak is mainly caused by the radiative and conductive heat transfers. The heat leak of the cryogenic pipe for the superconducting power transmission has been measured with respect to its surface temperature ranging from -3 to 53 °C to investigate the effect of the surface temperature variation and to obtain data for the installation of cables in different places with different environmental conditions. The cryogenic pipe used for the measurements has two inner pipes, called cable pipe and return pipe, in a single outer pipe. For the cable pipe the heat leak of 0.82 W/m at -3 °C increases to 1.27 W/m at 51°C, while for the return pipe the heat leak of 0.46 W/m at -3 °C increases to 0.94 W/m at 51°C. The heat leak increases smoothly with the surface temperature, which can be well reproduced by a formula based on the temperature dependences of the radiative and conductive heat transfers. The heat leak by the conductive heat transfer is discussed based on the experiments and the calculations.

Heat leak variation with the surface temperature of a cryogenic pipe of the superconducting power transmission

“…This function was fitted to all experimental data, including the previous results [4,5,6], and the values of the fitting parameters were obtained. In the previous study, it was shown that this function could well reproduce experimental results [7]. Figure 4 shows that this function also accurately reproduces the data, though the type of the cryogenic pipe in this study differed from that in the previous study [7].…”

“…In the previous study, it was shown that this function could well reproduce experimental results [7]. Figure 4 shows that this function also accurately reproduces the data, though the type of the cryogenic pipe in this study differed from that in the previous study [7]. This function can accurately predict the heat leak variation of the cryogenic pipe with the surface temperature.…”

“…The curve in figure 4 is obtained by the function proposed in previous study [7] of 𝑦 = 𝑎{(𝑇 + 273.15) ! − 77.3 ! }…”

“…In a previous study, it was shown that a simple function which reflects the temperature dependence of radiative heat transfer and conductive heat transfer could accurately reproduce the heat leak variation with the cryogenic pipe's surface temperature, and the function could be used to extract portions of the radiative heat transfer and the conductive heat transfer from the heat leak [7]. The application of this function to the present result was investigated.…”