Heat leak and pressure drop measurements of the 1000 m class superconducting DC power transmission system in Ishikari

Iizuka²,

Kato³

et al. 2022

Self Cite

The measurements of the heat leak variation with the surface temperature of a cryogenic pipe of the superconducting power transmission were performed in the range of 23.7 °C–36.4 °C. The cryogenic pipe which was an object of the present study was that used in the project of the superconducting DC power transmission conducted in Ishikari, Japan (Ishikari project). This cryogenic pipe has two inner pipes in one outer pipe, with a radiation shield used to conceal the inner pipe installing the cable from the outer pipe, which is at room temperature, to reduce heat leakage. A test pipe with the length of 12 m was used for the measurements. The liquid nitrogen was filled in the test pipe and the evaporated nitrogen gas rate was measured to obtain the heat leak. The heat leak to the inner pipe installing the cable was almost constant at around 0.04 W/m, whereas the heat leak to the other inner pipe used to return liquid nitrogen for circulation was around 1.3 W/m at surface temperatures ranging from 23.7 °C to 36.4 °C. The latter, with previous measurements, was well fitted by a function considering radiative heat transfer and conductive heat transfer. Portions of the radiative heat transfer and the conductive heat transfer were separated with this function. This information can be used to improve the cryogenic pipe in the future.

Section: Resultsmentioning

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Iizuka²,

Kato³

et al. 2022

Self Cite

Heat load to the cryogenic system in the 1000 m class superconducting DC power transmission system

Ivanov

Chikumoto

et al. 2019

Long-term circulation and load cycle tests of the cooling of the 1000 m class superconducting DC power transmission system in Ishikari, Japan were performed to measure the heat load delivered to and the power consumption of the cryogenic system. The average heat load and power consumption during these tests was about 2.5 and 120 kW, respectively. To increase the efficiency of superconducting power transmission systems, the selection and composition of constituent devices of the cooling system should be optimized.

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

Takeuchi

Miyake

et al. 2020

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.