Effect of spacers on the thermal performance of an annular multi-layer insulation

Y. Haim, Y. Weiss, R. Letan

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

The current study presents a model and is experimentally conducted in a system of 40 stainless steel coaxial foils, of nitrogen gas, entrapped between the foils, and of spacers, which are zirconia, spherical, 50 μm in size particles, widely dispersed in the gaps between the foils. The model, experimentally verified, relates to radiation between the foils, unobstructed by particles, to conduction in the nitrogen gas, and to conduction across the particles. The study was, in particular, aimed to measure the effective thermal conductivity of the particles and to assess its effect upon the array. At vacuum of 0.092 Pa, the effective thermal conductivity of the particles was 2.13 × 10-4 W/m K, while the effective thermal conductivity of the array was 4.74 × 10-4 W/m K. Thus, the low contribution of the particles conduction at vacuum conditions improves the insulation. It reaches 45% of the heat transfer rate. At atmospheric pressure, the effective thermal conductivity of the array reaches 4.5 × 10-2 W/m K. There, the spacers contribution is negligible.

Original languageEnglish
Pages (from-to)418-421
Number of pages4
JournalApplied Thermal Engineering
Volume65
Issue number1-2
DOIs
StatePublished - 1 Apr 2014

Keywords

  • Effective thermal conductivity
  • Multi-layer
  • Spacers
  • Thermal insulation

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

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