Heat transfer through a low-pressure gas enclosure as a thermal insulator: Design considerations
✍ Scribed by Y. DEMİREL; S. C. SAXENA
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 711 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0363-907X
No coin nor oath required. For personal study only.
✦ Synopsis
Heat transfer through gases at low pressures, rarefied media, plays a very significant role in the design of solar receivers and low-temperature cooling equipment. It is shown here that low-pressure and transition regimes of heat transfer prevail in such applications. State-of-the-art procedures for estimating these heat-transfer rates are presented together with an improved expression for the thermal accommodation coefficient for monatomic gases on engineering surfaces. The latter are characterized with values of thermal accommodation and reflection coefficients. Numerical calculations relevant to design engineers interested in these industrial applications are presented and the same are discussed for the dependencies of the heat-transfer rates on different design and operating parameters. It is shown that the values of surface reflectivity coefficient have a pronounced contribution in low density heat-transfer calculations at low gas temperatures, and are negligibly small for the temperatures greater than 900 K.