Analysis of gas heat conduction in evacuated tube solar collectors
- Ludwig-Maximilians-Univ. Muenchen (Germany). Sektion Physik
The authors investigated the gas heat conduction in two types of evacuated tubular solar collectors for a wide range of Knudsen numbers. For tube-in-tube collectors, they generalized a solution of the gas kinetic Boltzmann equation, which has been obtained by the 4-momentum method, to polyatomic gases. The resulting equation coincides with Sherman`s interpolation formula. For a plate-in-tube collector, they measured the stationary heat loss for gas pressures varying between 10{sup {minus}2} and 10{sup 4} Pa. The accuracy of an earlier experiment was improved. For analysis the authors applied the temperature jump method: a heat conduction equation with boundary conditions of the third kind involving the temperature gradient and the pressure was numerically solved. The results with the temperature jump method agree with the experimental values nearly within the error bands. They also applied Sherman`s interpolation formula and found, as expected, that the heat conduction as function of the pressure is too steep. For both types of collectors, the influence of geometric parameters was theoretically studied.
- OSTI ID:
- 438640
- Report Number(s):
- CONF-9603117-; ISBN 0-7918-1765-2; TRN: IM9711%%100
- Resource Relation:
- Conference: 1996 American Society of Mechanical Engineers international solar energy conference, San Antonio, TX (United States), 31 Mar - 3 Apr 1996; Other Information: PBD: 1996; Related Information: Is Part Of Solar engineering 1996; Davidson, J.H. [ed.] [Univ. of Minnesota, Minneapolis, MN (United States)]; Chavez, J. [ed.] [Sandia National Labs., Albuquerque, NM (United States)]; PB: 544 p.
- Country of Publication:
- United States
- Language:
- English
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