Investigation of turbulent flow in square duct with heated foil thermometry

Tiselj, Iztok; Sharma, M. P.; Zajec, Boštjan; Veljanovski, Nikola; Kren, Jan; Cizelj, Leon; Mikuž, Blaž

doi:10.1016/j.ijheatmasstransfer.2021.121381

Cited by 3 publications

(1 citation statement)

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“…Electrical power was supplied to the heater using a direct current (DC) power supply (Matsusada Precision, PK120-3.3). Similar methods using thin-film heating elements with low heat capacity have been studied [28,29]. These methods were employed to clarify the detailed spatial distribution of time-varying h in turbulent flows.…”

Section: Methodsmentioning

confidence: 99%

Measurement of the Convective Heat Transfer Coefficient and Temperature of Vehicle-Integrated Photovoltaic Modules

2022

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To improve the thermal design of vehicle-integrated photovoltaic (VIPV) modules, this study clarifies the characteristics of the convective heat transfer coefficient h between the vehicle roof surface and the surrounding air with respect to vehicle speed. Experiments on two types of vehicles with different body shapes indicate that h is strongly affected by vehicle speed, and it is also affected by body shape depending on the position on the roof. Empirical equations for approximating h as a function of vehicle speed and position on the vehicle roof are derived from the experimental datasets, and the differences between the equations derived herein and traditional equations that have been used for the heat transfer analysis of conventional stationary photovoltaic (PV) modules are clarified. Furthermore, the temperature change characteristics of the VIPV module were measured experimentally, confirming that h is the dominant factor causing the high temperature change rate of the VIPV module under driving conditions. In sunny summer conditions, the measured temperature change rate reaches up to 16.5 °C/min, which is approximately 10 times greater than that in the standard temperature cycle test for conventional stationary PV modules.

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Section: Methodsmentioning

confidence: 99%

Measurement of the Convective Heat Transfer Coefficient and Temperature of Vehicle-Integrated Photovoltaic Modules

2022

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Thermal streak spacing in fully developed duct flow with different Reynolds and Prandtl numbers

et al. 2023

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The present study investigates the behaviour of thermal streaks on a heated foil which is cooled with turbulent flow in a square duct channel. Real-time infrared thermography is used to visualize and measure the spacing between the thermal streaks. A stainless-steel foil with a thickness of 25 microns is cooled by water. The experiments were performed in a range of Reynolds numbers from 5000 to 20000 and Prandtl numbers from 3 to 7. The mean temperature, root-mean-square of temperature and autocorrelation function have been calculated and used to measure the average thermal streak spacing and power spectra in the spanwise and streamwise directions. The root mean square temperature was 0.3 °C to 0.5 °C which corresponds to roughly 10% of the mean temperature difference between foil and water. The uncertainty in mean temperature difference and root mean square temperature was around 5% and 10%, respectively. The measured thermal streak spacing was 100 wall unit to 180 wall unit under the present experimental range. The uncertainty in measured thermal streak spacing was around 2.5%. The effects of Reynolds number, Prandtl number and heat flux on the thermal streak spacing and also on the statistics of the temperature field have been presented and discussed in this paper. A new correlation has been proposed to predict the dimensionless thermal streak spacing. The error in the prediction is estimated within ± 15 %.

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