dc.contributor.author |
Roberts, DE
|
|
dc.date.accessioned |
2015-10-05T07:20:43Z |
|
dc.date.available |
2015-10-05T07:20:43Z |
|
dc.date.issued |
2013-12 |
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dc.identifier.citation |
RobertS, DE. 2013. A figure of merit for selective absorbers in flat plate solar water heaters. Solar Energy, vol. 98(C), pp 503-510 |
en_US |
dc.identifier.issn |
0038-092X |
|
dc.identifier.uri |
http://hdl.handle.net/10204/8142
|
|
dc.description |
Abstract only |
en_US |
dc.description.abstract |
We derive from first principles an analytical expression for a figure of merit (FM) for a selective solar absorber in a single glazed flat plate water heater. We first show that the efficiency of a collector with an absorber with absorptance α and emittance ε, relative to the maximum efficiency for an ideal absorber, can be expressed as ηR=α−Aε−B. The effectiveness of the absorber can then be written as a figure of merit, FM=α−Aε. The larger the value of FM, the better the solar absorber performs in the collector. This is shown to give quite different results from the coating selectivity, α/ε. A is a function of many heater parameters as well as the orientation and geographical location of the heater but, to a good degree of approximation, can be simplified sufficiently to be expressed as a linear function of the inlet water temperature only: Aav=0.0073Tin. For typical average water temperatures between 30°C and 60°C, Aav ranges from 0.22 to 0.44 so the emittance is relatively less important than the absorbtance. In the latter case, for example, the figure of merit is a very simple expression which can be used by developers of solar absorbers without any knowledge of the parameters or location of the HWH: FM=α-0.44εFM=α-0.44ε. |
en_US |
dc.language.iso |
en |
en_US |
dc.relation.ispartofseries |
Worklist;14360 |
|
dc.subject |
Selective solar absorber |
en_US |
dc.subject |
Efficiency |
en_US |
dc.subject |
Figure of merit |
en_US |
dc.subject |
FM |
en_US |
dc.subject |
Flat plate solar heater |
en_US |
dc.title |
A figure of merit for selective absorbers in flat plate solar water heaters |
en_US |
dc.type |
Article |
en_US |
dc.identifier.apacitation |
Roberts, D. (2013). A figure of merit for selective absorbers in flat plate solar water heaters. http://hdl.handle.net/10204/8142 |
en_ZA |
dc.identifier.chicagocitation |
Roberts, DE "A figure of merit for selective absorbers in flat plate solar water heaters." (2013) http://hdl.handle.net/10204/8142 |
en_ZA |
dc.identifier.vancouvercitation |
Roberts D. A figure of merit for selective absorbers in flat plate solar water heaters. 2013; http://hdl.handle.net/10204/8142. |
en_ZA |
dc.identifier.ris |
TY - Article
AU - Roberts, DE
AB - We derive from first principles an analytical expression for a figure of merit (FM) for a selective solar absorber in a single glazed flat plate water heater. We first show that the efficiency of a collector with an absorber with absorptance α and emittance ε, relative to the maximum efficiency for an ideal absorber, can be expressed as ηR=α−Aε−B. The effectiveness of the absorber can then be written as a figure of merit, FM=α−Aε. The larger the value of FM, the better the solar absorber performs in the collector. This is shown to give quite different results from the coating selectivity, α/ε. A is a function of many heater parameters as well as the orientation and geographical location of the heater but, to a good degree of approximation, can be simplified sufficiently to be expressed as a linear function of the inlet water temperature only: Aav=0.0073Tin. For typical average water temperatures between 30°C and 60°C, Aav ranges from 0.22 to 0.44 so the emittance is relatively less important than the absorbtance. In the latter case, for example, the figure of merit is a very simple expression which can be used by developers of solar absorbers without any knowledge of the parameters or location of the HWH: FM=α-0.44εFM=α-0.44ε.
DA - 2013-12
DB - ResearchSpace
DP - CSIR
KW - Selective solar absorber
KW - Efficiency
KW - Figure of merit
KW - FM
KW - Flat plate solar heater
LK - https://researchspace.csir.co.za
PY - 2013
SM - 0038-092X
T1 - A figure of merit for selective absorbers in flat plate solar water heaters
TI - A figure of merit for selective absorbers in flat plate solar water heaters
UR - http://hdl.handle.net/10204/8142
ER -
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en_ZA |