Studies on Methods of Reducing Heat Losses From Flat Plate Solar Collectors - Final Report PDF Download

Author: University of Waterloo. Research Institute
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ISBN:
Category :
Languages : en
Pages : 200

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Author: University of Waterloo. Research Institute
Publisher:
ISBN:
Category :
Languages : en
Pages : 35

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Book Description

Author: University of Waterloo. Research Institute
Publisher:
ISBN:
Category :
Languages : en
Pages : 75

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Author: K. G. T. Hollands
Publisher:
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Category :
Languages : en
Pages : 0

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Author:
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Category :
Languages : en
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Improvements to flat plate solar collectors for heating and cooling of buildings are being 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 better free convective loss suppression than does a square-celled honeycomb having the same amount of material.

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

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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:
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Category :
Languages : en
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Author: Hollands, K. G. T
Publisher: University of Waterloo Research Institute
ISBN:
Category : Solar collectors
Languages : en
Pages : 118

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Book Description
Improvements to flat plate solar collectors for heating and cooling of buildings are being evaluated by three parallel studies. The first study has demonstrated that suppression of convective heat transfer by honeycomb panels is possible even when the panel is inclined from the horizontal. The second study has resulted in a precise, simple equation for the free convective heat transfer through an inclined air layer. The third study has theoretically demonstrated that if an inner cover is V-corrugated, its solar transmittance may be enhanced.

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.