Measurement of Heat Conduction through Stacked Screens

Abstract

This paper describes the experimental apparatus for the measurement of heat conduction through stacked screens as well as some experimental results taken with this apparatus. Screens are stacked in a fiberglass-epoxy cylinder, which is 24.4 mm in diameter and 55 mm in length. The cold end of the stacked screens is cooled by a Gifford-McMahon (GM) cryocooler at cryogenic temperature and the hot end is kept at room temperature. Heat conduction flow is estimated from the temperature gradient in a calibrated heat flow sensor mounted between the cold end of the stacked screens and the GM cryocooler cooling stage. The sample used for these measurements consisted of 400 mesh stainless steel screens with an overall porosity of 66.7 %. The experimental results showed that the helium gas between each screen enhanced the heat conduction through the stacked screens by several orders of magnitude compared to that in vacuum. The conduction degradation factor, which is the ratio of actual heat conduction and heat conduction where the regenerator material is assumed to be a bulk, was about 0.1. This factor was almost constant for the temperature range between 40 K and 80 K at the cold end.

1)Guest researcher from Toshiba Co., Japan

2)Guest researcher from EBARA Research Co., Japan