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Title: Techniques for reducing thermal conduction and natural convection heat losses in annular receiver geometries

Abstract

Analytical and experimental work has been undertaken to analyze thermal conduction and natural convection heat losses in annular receiver geometries. Techniques studied for reducing conduction heat loss include evacuation of the annulus gas, oversizing of the annular space while maintaining slight vacuum levels, and use of gases other than air in the annular space. For the geometry considered, total heat loss reductions of 10 percent to 50 percent may be obtained depending on the means by which the conduction heat loss is limited. In addition, natural convection studies considering the effects of nonuniform temperature distributions and eccentric cylinders are discussed. The numerical analysis performed indicates that highly nonuniform temperature distributions are required to appreciably affect the natural convection process between concentric cylinders and that rather large eccentricities cause only a slight increase in natural convection heat transfer.

Authors:
; ;
Publication Date:
Research Org.:
Fluid Mechanics and Heat Transfer Division, Sandia Laboratories, Albuquerque, N. M. 87185
OSTI Identifier:
6049489
Resource Type:
Journal Article
Journal Name:
J. Heat Transfer; (United States)
Additional Journal Information:
Journal Volume: 101:1
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; EVACUATED TUBE COLLECTORS; HEAT LOSSES; ANNULAR SPACE; HIGH TEMPERATURE; LOW PRESSURE; MEDIUM PRESSURE; MEDIUM TEMPERATURE; MEDIUM VACUUM; NATURAL CONVECTION; PRESSURE DEPENDENCE; TEMPERATURE DISTRIBUTION; THERMAL CONDUCTION; CONFIGURATION; CONVECTION; ENERGY LOSSES; ENERGY TRANSFER; EVACUATED COLLECTORS; HEAT TRANSFER; LOSSES; SOLAR COLLECTORS; 141000* - Solar Collectors & Concentrators

Citation Formats

Ratzel, A.C., Hickox, C.E., and Gartling, D.K. Techniques for reducing thermal conduction and natural convection heat losses in annular receiver geometries. United States: N. p., 1979. Web. doi:10.1115/1.3450899.
Ratzel, A.C., Hickox, C.E., & Gartling, D.K. Techniques for reducing thermal conduction and natural convection heat losses in annular receiver geometries. United States. doi:10.1115/1.3450899.
Ratzel, A.C., Hickox, C.E., and Gartling, D.K. Thu . "Techniques for reducing thermal conduction and natural convection heat losses in annular receiver geometries". United States. doi:10.1115/1.3450899.
@article{osti_6049489,
title = {Techniques for reducing thermal conduction and natural convection heat losses in annular receiver geometries},
author = {Ratzel, A.C. and Hickox, C.E. and Gartling, D.K.},
abstractNote = {Analytical and experimental work has been undertaken to analyze thermal conduction and natural convection heat losses in annular receiver geometries. Techniques studied for reducing conduction heat loss include evacuation of the annulus gas, oversizing of the annular space while maintaining slight vacuum levels, and use of gases other than air in the annular space. For the geometry considered, total heat loss reductions of 10 percent to 50 percent may be obtained depending on the means by which the conduction heat loss is limited. In addition, natural convection studies considering the effects of nonuniform temperature distributions and eccentric cylinders are discussed. The numerical analysis performed indicates that highly nonuniform temperature distributions are required to appreciably affect the natural convection process between concentric cylinders and that rather large eccentricities cause only a slight increase in natural convection heat transfer.},
doi = {10.1115/1.3450899},
journal = {J. Heat Transfer; (United States)},
number = ,
volume = 101:1,
place = {United States},
year = {1979},
month = {2}
}