Determination of the distribution of incident solar radiation in cavity receivers with approximately real parabolic dish collectors

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Journal of Solar Energy Engineering; (USA)

DOI:https://doi.org/10.1115/1.2929929· OSTI ID:5783115

Bammert, K; Lange, H ^[1]; Hegazy, A ^[2]

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1. Inst. for Turbomachinery, Univ. of Hannover, Hannover (DE)
2. El Menoufia Univ., Shebin El Kom (EG)

The absorption of solar heat and the attendant thermal and mechanical loadings on the tubes of cavity receivers depend predominantly on the flux distribution of the incident solar radiation. For an axially symmetric cavity receiver with a parabolic dish collector, it is simple to determine the insolation pattern on the receiver internal surfaces if the system is ideal. In such a system the surface of the dish is perfectly parabolic (no contour flaws are present), and the sun's central ray impinges on the dish surface parallel to the focal axis (no sun tracking flaws are present). These two conditions cannot be achieved in practice, and therefore the feasible parabolic dish system is referred to as a real system although, in actual fact, it is only an approximation to any actual system. The purpose of this paper is to devise calculation principles which permit analysis of a receiver designed for ideal conditions to verify its structural adequacy under the nonideal conditions to be expected in reality. Of the many possible imperfections in real collectors, two were selected which increase the loadings sustained. The first case concerns flaws in the contour of the dish surface. These locally increase the radiation concentration on the receiver inside walls and tubing. In the second case, sun-tracking errors give rise to axially asymmetric radiation distributions. In both examples, greater than design basis loadings will occur in the receiver tubing. Both kinds of flaws considered in this paper are of a purely deterministic nature.

• OSTI ID: 5783115
• Journal Information: Journal of Solar Energy Engineering; (USA), Vol. 112:4; ISSN 0199-6231
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
CAVITY RECEIVERS
SHAPE
SOLAR TRACKING
ABSORPTION
CALCULATION METHODS
DESIGN
DISTRIBUTION
PARABOLIC DISH COLLECTORS
SOLAR COLLECTORS
SOLAR RADIATION
CONCENTRATING COLLECTORS
EQUIPMENT
PARABOLIC COLLECTORS
RADIATIONS
SOLAR EQUIPMENT
SOLAR RECEIVERS
STELLAR RADIATION
141000* - Solar Collectors & Concentrators