Minimizing convective heat losses in flat plate solar collectors

Solar Energy ◽  
1980 ◽  
Vol 25 (6) ◽  
pp. 521-526 ◽  
Author(s):  
A. Malhotra ◽  
H.P. Garg ◽  
Usha Rani
2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ramadhani Bakari ◽  
Rwaichi J. A. Minja ◽  
Karoli N. Njau

This study aimed at investigating the effect of thickness of glazing material on the performance of flat plate solar collectors. Performance of solar collector is affected by glaze transmittance, absorptance, and reflectance which results into major heat losses in the system. Four solar collector models with different glass thicknesses were designed, constructed, and experimentally tested for their performances. Collectors were both oriented to northsouth direction and tilted to an angle of 10° with the ground toward north direction. The area of each collector model was 0.72 m2with a depth of 0.15 m. Low iron (extra clear) glass of thicknesses 3 mm, 4 mm, 5 mm, and 6 mm was used as glazing materials. As a control, all collector performances were analysed and compared using a glass of 5 mm thickness and then with glass of different thickness. The results showed that change in glass thickness results into variation in collector efficiency. Collector with 4 mm glass thick gave the best efficiency of 35.4% compared to 27.8% for 6 mm glass thick. However, the use of glass of 4 mm thick needs precautions in handling and during placement to the collector to avoid extra costs due to breakage.


1983 ◽  
Vol 105 (1) ◽  
pp. 80-85 ◽  
Author(s):  
R. J. Kind ◽  
D. H. Gladstone ◽  
A. D. Moizer

This paper presents results for convective heat transfer coefficients on the surface of flat-plate solar collectors mounted on a single-family residential building and exposed to the wind. The results were obtained by testing a 1:32 scale model in highly turbulent nonuniform flows which simulated the natural wind. For full-scale conditions, the heat transfer coefficients are two to three times lower than those given by a commonly used correlation. The coefficients show some sensitivity to wind direction but are insensitive to the characteristics of the wind and to architectural details of the building.


2019 ◽  
Vol 24 ◽  
pp. 01009
Author(s):  
Yedilkhan Amirgaliyev ◽  
Murat Kunelbayev ◽  
Aliya Kalizhanova ◽  
Beibut Amirgaliyev ◽  
Ainur Kozbakova ◽  
...  

The paper herein considers the study of convective heat transfer in flat plate solar collectors, as it is seen from the analysis on research of the heat transfer by a circular and flat tubes upon conforming the forced and free convections, placed vertically or horizontally with various liquid flow directions. There have been obtained Nusselt criterion dependencies in circular and flat pipes, which shows that corresponding equations allow defining the heat transfer intensity for all fluids with appropriate accuracy. As well there has been studied Prandtl criterion for fluids, which plays an important role in points spacing as regard to the curve. In each case the lines are with a tip 1/3, as in the research herein only the laminar conditions have been considered.


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