Details
| Originalsprache | Englisch |
|---|---|
| Titel des Sammelwerks | International Heat Transfer Conference 17 |
| Seitenumfang | 9 |
| ISBN (elektronisch) | 978-1-56700-538-7 |
| Publikationsstatus | Veröffentlicht - 14 Aug. 2023 |
| Veranstaltung | 17th International Heat Transfer Conference, IHTC 2023 - Cape Town, Südafrika Dauer: 14 Aug. 2023 → 18 Aug. 2023 |
Publikationsreihe
| Name | International Heat Transfer Conference |
|---|---|
| Herausgeber (Verlag) | Begell House Inc. |
| ISSN (Print) | 2377-424X |
Abstract
Plate heat exchangers feature flexible designs in combination with outstanding thermohydraulic power density. Therefore, they find application in a wide range of technical processes and are not only used as single-phase heat exchangers but also as evaporators and condensers. The already efficient devices can be improved regarding condensation by functionalizing the condensate facing surface of the plates for example by means of femtosecond laser pulses (FSLP). The surface changes that can be achieved by applying FSLP are on the one hand of a geometric character in the nano- and micrometer range, and on the other hand of a chemical character due to the incorporation of selected foreign atoms. The aim of functionalization is to control the wettability of the surface. By producing a hydrophobic surface, droplet condensation can be forced, which shows significantly higher heat transfer coefficients. In order to investigate the thermal behaviour of such structured surfaces during condensation, an experimental setup is developed to provide direct metrological accessibility to the two-phase heat transfer coefficient. The main part of the experimental setup is a measurement section with a testing surface, on which condensation occurs. The measurement section is instrumented with temperature sensors arranged in several levels so that heat flux density and wall temperature can be measured. By determining these quantities, the heat transfer coefficient can be calculated directly from the defining equation, thus providing the determination with low uncertainties. In the context of this work an investigation of the film condensation of R365mfc on an unmodified smooth surface of copper in a range of Reynolds number from 15 to 200 is performed. Already at a Reynolds number of 20, wave formation occurs on the condensate film. The measured heat transfer coefficient rises from 1.46 kW/m2 K to 3.07 kW/m2 K within the range of Reynolds numbers. Due to the early onset of turbulence, the measurement results show a low agreement with the analytical solution for the heat transfer coefficient. Furthermore, it is shown that the measurement of the heat transfer coefficient can be performed with a comparatively low measurement uncertainty. Within the scope of the measurements performed, the standard measurement uncertainty of the heat transfer coefficient is a maximum of 19 %.
ASJC Scopus Sachgebiete
- Physik und Astronomie (insg.)
- Physik der kondensierten Materie
- Ingenieurwesen (insg.)
- Maschinenbau
- Chemische Verfahrenstechnik (insg.)
- Fließ- und Transferprozesse von Flüssigkeiten
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International Heat Transfer Conference 17 . 2023. (International Heat Transfer Conference).
Publikation: Beitrag in Buch/Bericht/Sammelwerk/Konferenzband › Aufsatz in Konferenzband › Forschung › Peer-Review
}
TY - GEN
T1 - Experimental setup for the measurement of condensation heat transfer coefficients on structured testing surfaces
AU - Wendt, S.
AU - Kabelac, S.
N1 - Publisher Copyright: © 2023 Begell House Inc.. All rights reserved.
PY - 2023/8/14
Y1 - 2023/8/14
N2 - Plate heat exchangers feature flexible designs in combination with outstanding thermohydraulic power density. Therefore, they find application in a wide range of technical processes and are not only used as single-phase heat exchangers but also as evaporators and condensers. The already efficient devices can be improved regarding condensation by functionalizing the condensate facing surface of the plates for example by means of femtosecond laser pulses (FSLP). The surface changes that can be achieved by applying FSLP are on the one hand of a geometric character in the nano- and micrometer range, and on the other hand of a chemical character due to the incorporation of selected foreign atoms. The aim of functionalization is to control the wettability of the surface. By producing a hydrophobic surface, droplet condensation can be forced, which shows significantly higher heat transfer coefficients. In order to investigate the thermal behaviour of such structured surfaces during condensation, an experimental setup is developed to provide direct metrological accessibility to the two-phase heat transfer coefficient. The main part of the experimental setup is a measurement section with a testing surface, on which condensation occurs. The measurement section is instrumented with temperature sensors arranged in several levels so that heat flux density and wall temperature can be measured. By determining these quantities, the heat transfer coefficient can be calculated directly from the defining equation, thus providing the determination with low uncertainties. In the context of this work an investigation of the film condensation of R365mfc on an unmodified smooth surface of copper in a range of Reynolds number from 15 to 200 is performed. Already at a Reynolds number of 20, wave formation occurs on the condensate film. The measured heat transfer coefficient rises from 1.46 kW/m2 K to 3.07 kW/m2 K within the range of Reynolds numbers. Due to the early onset of turbulence, the measurement results show a low agreement with the analytical solution for the heat transfer coefficient. Furthermore, it is shown that the measurement of the heat transfer coefficient can be performed with a comparatively low measurement uncertainty. Within the scope of the measurements performed, the standard measurement uncertainty of the heat transfer coefficient is a maximum of 19 %.
AB - Plate heat exchangers feature flexible designs in combination with outstanding thermohydraulic power density. Therefore, they find application in a wide range of technical processes and are not only used as single-phase heat exchangers but also as evaporators and condensers. The already efficient devices can be improved regarding condensation by functionalizing the condensate facing surface of the plates for example by means of femtosecond laser pulses (FSLP). The surface changes that can be achieved by applying FSLP are on the one hand of a geometric character in the nano- and micrometer range, and on the other hand of a chemical character due to the incorporation of selected foreign atoms. The aim of functionalization is to control the wettability of the surface. By producing a hydrophobic surface, droplet condensation can be forced, which shows significantly higher heat transfer coefficients. In order to investigate the thermal behaviour of such structured surfaces during condensation, an experimental setup is developed to provide direct metrological accessibility to the two-phase heat transfer coefficient. The main part of the experimental setup is a measurement section with a testing surface, on which condensation occurs. The measurement section is instrumented with temperature sensors arranged in several levels so that heat flux density and wall temperature can be measured. By determining these quantities, the heat transfer coefficient can be calculated directly from the defining equation, thus providing the determination with low uncertainties. In the context of this work an investigation of the film condensation of R365mfc on an unmodified smooth surface of copper in a range of Reynolds number from 15 to 200 is performed. Already at a Reynolds number of 20, wave formation occurs on the condensate film. The measured heat transfer coefficient rises from 1.46 kW/m2 K to 3.07 kW/m2 K within the range of Reynolds numbers. Due to the early onset of turbulence, the measurement results show a low agreement with the analytical solution for the heat transfer coefficient. Furthermore, it is shown that the measurement of the heat transfer coefficient can be performed with a comparatively low measurement uncertainty. Within the scope of the measurements performed, the standard measurement uncertainty of the heat transfer coefficient is a maximum of 19 %.
KW - Condensation
KW - Heat Transfer Coefficients
KW - Heat Transfer Enhancement
UR - http://www.scopus.com/inward/record.url?scp=85176546638&partnerID=8YFLogxK
U2 - 10.1615/IHTC17.60-130
DO - 10.1615/IHTC17.60-130
M3 - Conference contribution
AN - SCOPUS:85176546638
SN - 978-1-56700-537-0
T3 - International Heat Transfer Conference
BT - International Heat Transfer Conference 17
T2 - 17th International Heat Transfer Conference, IHTC 2023
Y2 - 14 August 2023 through 18 August 2023
ER -