The effect of the wind conditions on the thermal performance of an unglazed solar thermal collector

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21720%2F23%3A00369046" target="_blank" >RIV/68407700:21720/23:00369046 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1016/j.egyr.2023.09.132" target="_blank" >https://doi.org/10.1016/j.egyr.2023.09.132</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.egyr.2023.09.132" target="_blank" >10.1016/j.egyr.2023.09.132</a>

Result language

angličtina

Original language name

The effect of the wind conditions on the thermal performance of an unglazed solar thermal collector

Original language description

The paper presents a theoretical analysis performed for unglazed liquid solar thermal collectors (USTCs) to demonstrate the magnitude of the thermal performance uncertainty caused by the different wind conditions under the same wind speed. The literature currently comprises more than 90 combined convection heat transfer correlations. The difference between them is primarily caused by the difference in wind characteristics during the experiment (wind turbulence level, wind direction, etc.). A detailed validated theoretical model of a USTC and forty applicable combined convection heat transfer correlations were used to perform the analysis to demonstrate the magnitude of the thermal performance uncertainty caused by the different wind conditions. It was found that, for the low operating temperature, the uncertainties caused by the different wind conditions are ± 4 %, ± 6 %, and ± 8.5 % under wind speeds of 0 m/s, 1.5 m/s, and 3 m/s, respectively. These values are relatively small compared to the obtained average thermal performance values of 78 %, 73 %, and 65 %. In contrast, the uncertainty values are significant for relatively high operation temperatures: ± 11.5 %, ± 16.5 %, and ± 22 %, while the modelled efficiency values for these operating conditions are 15 %, 30 %, and 44 %. The analysis demonstrated that the difference in wind characteristics under the same wind speed significantly affects a USTC’s thermal performance. From a practical standpoint, the USTC’s thermal performance in real wind conditions may exhibit significant disparities compared to its performance tested in controlled laboratory conditions under the same wind speed. Furthermore, notably varied thermal performance can be expected for identical USTCs installed in different locations under the same wind speed due to the different wind characteristics (wind turbulence level, wind direction, etc.).

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

20704 - Energy and fuels

Project

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2023

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Energy Reports

ISSN

2352-4847

e-ISSN

—

Volume of the periodical

10

Issue of the periodical within the volume

November

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

9

Pages from-to

2880-2888

UT code for WoS article

001085973400001

EID of the result in the Scopus database

2-s2.0-85172232916