On the heat transfer coefficients between heated/cooled radiant ceiling and room

Cholewa, Tomasz; Anasiewicz, Rafał; Siuta-Olcha, Alicja; Skwarczyński, M.

doi:10.1016/j.applthermaleng.2017.02.019

Cited by 43 publications

(27 citation statements)

References 30 publications

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“…A smaller hydraulic diameter will result in a larger temperature dependency, and a more stable convective heat transfer coefficient with a larger hydraulic diameter. This relationship was observed in the two articles, as previously stated [10,15].…”

Section: Dimensionssupporting

confidence: 74%

“…For the total heat transfer coefficient, the values proposed by Andrés-Chicote et al [13] and Yuan et al [19] were able to keep the predicted values equal to or less than the measured values. For the convective heat transfer, the equation proposed by Cholewa et al [15] had all the errors on the negative side, which correspond to their argument that most convective heat transfer in literature are over evaluated. Table 3 lists the measurement and calculation conditions for each researcher that performed experiments.…”

Section: Prediction Accuracymentioning

confidence: 78%

“…The calculated hydraulic diameters ranged between 1.6-3.4 m. Out of the measurement cases plotted in Fig. 1, the lowest and highest values were seen in the test chambers of Cholewa et al [15] and Yuan et al [10], respectively. In the detailed calculation suggested by ASHRAE [8], the differences in the hydraulic diameters resulted in an error of about 1 W/m 2 K at ∆T=8 K in the resulting convective heat transfer coefficient.…”

Section: Dimensionsmentioning

confidence: 89%

“…The same deviation can be seen in the total heat transfer coefficient as well. Overall, the total heat transfer coefficients showed a constant value between 8-10 W/m 2 K, except for the cases of Causone et al [14], which had a value between 12-14 W/m 2 K. The convective heat transfer coefficients, on the other hand, had larger differences within and between articles, ranging from 2-6 W/m 2 K. Results from Cholewa et al [15] had the largest deviation within the measurements, due to the use of multiple reference temperatures for the same measurements. Calculation within a small band of ∆T may have had an effect as well.…”

Section: Standard/guidelinementioning

confidence: 90%

“…In the articles reviewed in this study, the former approach was more commonly taken. However, Cholewa et al [15,16] argues that the latter approach should be taken, since calculations based on the radiant system input and outputs do not necessarily represent the heat flux towards the room, due to the heat loss towards the other side of the cooled/heated surface. Some articles indicate that heat loss was taken into account, however the calculation method of heat loss was not specified in most cases.…”

Section: Prediction Accuracymentioning

confidence: 99%

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Review on the Surface Heat Transfer Coefficients of Radiant Systems

et al. 2019

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Heat transfer coefficients are often used to describe the thermal behaviour of radiant systems and how it transfers heat between the cooled/heated surface and the room. In addition to current standards, numerous studies have been conducted to obtain the heat transfer coefficients through experiments and simulations. However, inconsistency is evident in the values or expressions suggested. Thus, this study investigated possible sources of discrepancy through an extensive literature review on articles and standards that focused on the heat transfer coefficients at the cooled/heated surface. Measurement data provided by different authors were extracted to compare both the amount of heat transfer and the actual heat transfer coefficients. Consequently, suggested values and expressions were used to predict the measurement data in other articles to examine their accuracy. Comparison of the results showed that the radiant heat transfer coefficients had a consistent value throughout the literature and had prediction error within ±20%. However, larger deviations and prediction errors were seen in the total and convective heat transfer. It was suggested that some of the sources of error may have been the calculation procedure of each heat transfer mechanism, choice of reference temperature and its measurement height/position, and room dimensions.

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Section: Dimensionssupporting

confidence: 74%

Section: Prediction Accuracymentioning

confidence: 78%