Natural Convection Suppression in Solar Collectors PDF Download

Author: Stephanus Johannes Maria Linthorst
Publisher:
ISBN: 9789062311385
Category : Heat
Languages : en
Pages : 217

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Author: K. G. T. Hollands
Publisher: University of Waterloo Research Institute
ISBN:
Category : Heat
Languages : en
Pages : 129

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Book Description
Improvements to flat plate solar collectors for heating and cooling of buildings have been evaluated through three parallel studies. The first study has demonstrated suppression of free convection by a honeycomb at all angles of inclination. Reductions by a factor of 5 in the free convective heat loss are reported, and equations and charts permitting the rational design of honeycombs for convection suppression in solar collectors are presented. The second study has resulted in a precise, easily programmable set of equations for the free convective heat loss through the air gaps in flat plate solar collectors, for any angle of tilt. The third study has theoretically and experimentally demonstrated that the solar transmittance of a flat transparent cover for a solar collector can be very substantially increased by V-corrugating. Since V-corrugating should also decrease the free convective and radiant losses, substantial improvements in collector efficiency are predicted.

Author: Francis DeWinter
Publisher: MIT Press
ISBN: 9780262041041
Category : Science
Languages : en
Pages : 1116

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Book Description
Solar Collectors, Energy Storage, and Materials covers the materials and basic components needed for solar thermal energy systems. Using thermal performance and durability as the major criteria, the twenty six chapters emphasize the modeling and assessment of devices rather than their application or cost. Each part begins with an overview and concludes with an assessment of current issues and opportunities. The contributors have been careful to document failures as well as successes in materials research. This is the fifth volume in a series that distills the results of the intensive research on and development of solar thermal energy conversion technologies from 1975 to 1986. Francis de Winter is President of the Altas Corporation, Santa Cruz, California and a member of the Santa Cruz Energy Advisory Committee. Contents: Solar Collectors. Collector Concepts and Designs. Optical Theory and Modeling of Solar Collectors. Thermal Theory and Modeling of Solar Collectors. Testing and Evaluation of Stationary Collectors. Testing and Evaluation of Tracking Collectors. Optical Research and Development. Collector Thermal Research and Development. Collector Engineering Research and Development. Solar Pond Research and Development. Reliability and Durability of Solar Collectors. Environmental Degradation of Low-Cost Solar Collectors. Energy Storage for Solar Systems. Storage Concepts and Design. Analytical and Numerical Modeling of Thermal Conversion Systems. Testing and Evaluation of Thermal Energy Storage Systems. Storage Research and Development. Materials for Solar Technologies. Materials for Solar Collector Concepts and Designs. Theory and Modeling of Solar Materials. Testing and Evaluation of Solar Materials. Exposure Testing and Evaluation of Performance Degradation. Solar Materials Research and Development.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Improvements to flat plate solar collectors for heating and cooling of buildings have been evaluated through three parallel studies. The first study has demonstrated suppression of free convection by a honeycomb at all angles of inclination. Reductions by a factor of 5 in the free convective heat loss are reported, and equations and charts permitting the rational design of honeycombs for convection suppression in solar collectors are presented. The second study has resulted in a precise, easily programmable set of equations for the free convective heat loss through the air gaps in flat plate solar collectors, for any angle of tilt. The third study has theoretically and experimentally demonstrated that the solar transmittance of a flat transparent cover for a solar collector can be very substantially increased by V-corrugating. Since V-corrugating should also decrease the free convective and radiant losses, substantial improvements in collector efficiency are predicted.

Author:
Publisher:
ISBN:
Category : Solar collectors
Languages : en
Pages : 568

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Improvements to flat plate solar collectors for heating and cooling of buildings were investigated through two parallel studies. The first study, which deals with the free convective heat loss from V-corrugated absorber plate to a plane glass cover, has shown that, for the same average spacing, the free convective heat loss is greater for a V-corrugated absorber plate than for a plane absorber plate. However, provided the average spacing is large enough, the amount of increase is slight. The second study, which deals with the free convective heat loss in a honeycomb solar collector in which the honeycomb consists of a set of horizontal partitions, or slits, has shown that provided the solar collector is tilted to near vertical, such a honeycomb gives equivalent or superior free convective loss suppression than does a square-celled honeycomb having the same amount of material. Correlation equations for the free convective heat loss are given for both studies.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The present study extends earlier studies by examining the effect of the emissivities of both the absorber plate and the glass cover on the honeycomb's ability to suppress free convection, and on the radiative and conductive heat transfer which takes place across the honeycomb in the absence of free convection. By means of heat transfer measurements on ten Mylar honeycombs, this study has shown that the effect of the above emissivities on the suppression of convection by the honeycomb is slight, and can probably be ignored. On the other hand, the measurements also showed that the effect of these emissivities on the non-convective heat transfer is substantial, but not nearly so large as would have been predicted by existing theories. To explain this latter result theories were developed which take into account the important coupling (ignored by previous theories) between the conductive and radiative modes of heat transfer. These new theories predict the measured heat transfer rates to with about +-15%, depending on the emissivities. The results of this study have direct application to evaluating solar collectors which combine a selective surface with a honeycomb.

Author: Joseph T. Pearson
Publisher:
ISBN:
Category :
Languages : en
Pages : 120

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Author: Jeff G. Symons
Publisher:
ISBN:
Category : Heat
Languages : en
Pages :

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Author: Alan William Dickerson
Publisher:
ISBN:
Category : Heat
Languages : en
Pages :

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