Comparison of flat plate and cylindrical parabolic focusing solar energy collectors for Oak Ridge (Part 2)
The performance of three solar energy collectors (flat plate-..cap alpha.. = epsilon = 0.98, parabolic focusing--..cap alpha.. = epsilon = 0.98, and flat plate with a selective surface--..cap alpha../epsilon = 10.9) was investigated under Oak Ridge sky conditions at working fluid temperatures above 200/sup 0/F. The optimum orientation of the noncircular receiver on the parabolic focusing collector was found to be collinear with the axis of the parabola. Working fluid temperatures of 227, 228, and 184/sup 0/F were attained in the parabolic, flat plate, and selective surface collectors, respectively. Maximum observed efficiencies (useful heat absorbed by the working fluid divided by the total radiation incident on the collector) were 26, 25, and 47 percent for the flat plate, parabolic, and selective surface collectors, respectively. The performance equations did not always accurately predict the heat losses of the parabolic and flat plate collectors. New models should be developed which accurately describe the system under transient operating conditions. Efficiency should be correlated with meteorological variables and operating conditions. Experiments should be conducted to determine the effect of flow rate, average fluid temperature, outlet temperature, the ratio of direct-to-diffuse radiation and total radiation on collector efficiency. The axial temperature profile of the collectors should be determined to predict more accurately the radiative and convective losses as functions of the aforementioned variables.
- Research Organization:
- Massachusetts Inst. of Tech., Oak Ridge, Tenn. (USA). School of Chemical Engineering Practice
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 7138543
- Report Number(s):
- ORNL/MIT-214
- Country of Publication:
- United States
- Language:
- English
Similar Records
Contact stresses on a thin plate after large displacements to a full parabolic surface
Optimization of coatings for flat plate solar collectors: Phase II. Progress report, 28 June--31 December 1976