Performance of flat-plate solar collector in a closed-loop thermosiphon using refrigerant-11
Thesis/Dissertation
·
OSTI ID:5922957
The performance of a refrigerant charged flat-plate solar collector in a closed-thermosiphon loop was analyzed. The analysis resulted in a generalized form of the Hottel-Whillier-Bliss equation, which allows for the consideration for full (Z* = 0) or partial (0.0 less than or equal to Z* less than or equal to 1.0) boiling in the collector tube and for both (or either) thermosiphon flow or forced flow. In the limit of no-boiling (Z* = 1.0) the developed equation was identical to the Hottel-Whillier-Bliss equation. The refrigerant charged systems showed superiority in performance over identical hydronic flat-plate solar collector systems under the same weather conditions because they are utilizing latent heat transfer (phase change) rather than sensible heat. Those systems operate at the highest possible efficiency if the collector tubes are full of refrigerant (100% submergence) and the inlet fluid is saturated (T/sub in/ = T/sub sat/) with normal incidence of solar beam radiation. The circulation rate was found to depend primarily, in a complex manner, on solar irradiance, system geometry, weather conditions, physical properties of the working fluid, and operating conditions. A relationship was developed and tested for predicting the flow rate at any operating conditions. It showed good agreement with experimental measurements. The collector performance was analyzed for transient operation. The analysis indicated that those systems have a spontaneous response to perturbations in weather conditions. The system is self-regulating after any changes in solar irradiance.
- OSTI ID:
- 5922957
- Country of Publication:
- United States
- Language:
- English
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