Validation of heat transfer coefficients on interior building surfaces using a real-sized indoor test cell

Khalifa, Abdul Jabbar N.; Marshall, R. H.

doi:10.1016/0017-9310(90)90122-b

Cited by 194 publications

(59 citation statements)

References 3 publications

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“…To compare a heated window with radiator heating, it is necessary to use a higher convective heat transfer coefficient, one which is caused by the convection airflow of a radiator. Khalifa and Marshall [7] give the following equation for a window surface with radiator heating…”

Section: Comparison To Convective or Radiator Heatingmentioning

confidence: 99%

05/00791 Efficiency of electrically heated windows

2005

Fuel and Energy Abstracts

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This study defined, derived and calculated the efficiency of electrical energy use in electrically heated windows which may be used for improving thermal comfort near glazing. In a cold climate, a warm glass surface is a unique possibility for thermal conditioning. The effects of surface and outdoor temperatures and the U-value of the window on the efficiency of a heated window were analyzed. The calculated results were compared to previously measured ones. The efficiency of a common heated window with a U-value of 1.1 W/m 2 K was about 78% at an outdoor temperature of −10 • C. The highest efficiency of 89% was calculated for a highly insulated window. Efficiency was proportional to the outdoor temperature and practically independent of the inner surface temperature of the window, the effect of which was less than 1%. The correlation of the calculated efficiencies shows that efficiency is primarily dependent on the U-value of the unheated window and can be expressed with very good accuracy for engineering purposes by a simple linear equation of the U-value. The results show that heated glazing is an efficient method for thermal conditioning when properly used.

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Section: Comparison To Convective or Radiator Heatingmentioning

confidence: 99%

05/00791 Efficiency of electrically heated windows

2005

Fuel and Energy Abstracts

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“…As yearly simulations are required to analyze the building energy use, detailed analysis of the flow around and in the building is not possible and the calculation of convective heat transfer has to be simplified using correlations. Since the past 50 years, many researchers have studied experimentally convective heat transfer coefficients (CHTC) in order to improve the accuracy of simulations [1][2][3][4][5][6][7][8][9]. The first correlations were derived from flat plate experiments [1,2].…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless these correlations are not always applicable to buildings due to the scale effect and different flow characteristics: Awbi and Hatton [3] showed that the CHTC for a heated wall tends to be higher than that of isolated plates with free edges. Therefore full-scale measurements have also been performed under different conditions [3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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Experimental investigation of convective heat transfer during night cooling with different ventilation systems and surface emissivities

Dréau

Heiselberg

Jensen

2013

Energy and Buildings

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a b s t r a c tNight-time ventilation is a promising approach to reduce the energy needed for cooling buildings without reducing thermal comfort. Nevertheless actual building simulation tools have showed their limits in predicting accurately the efficiency of night-time ventilation, mainly due to inappropriate models for convection. In a full-scale test room, the heat transfer was investigated during 12 h of discharge by nighttime ventilation. A total of 34 experiments have been performed, with different ventilation types (mixing and displacement), air change rates, temperature differences between the inlet air and the room, and floor emissivities. This extensive experimental study enabled a detailed analysis of the convective and radiative flow at the different surfaces of the room. The experimentally derived convective heat transfer coefficients (CHTC) have been compared to existing correlations. For mixing ventilation, existing correlations did not predict accurately the convective heat transfer at the ceiling due to differences in the experimental conditions. But the use of local parameters of the air flow showed interesting results to obtain more adaptive CHTC correlations. For displacement ventilation, the convective heat transfer was well predicted by existing correlations. Nevertheless the change of floor emissivity influenced the CHTC at the surface of interest.

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“…To calculate CHTCs for all surfaces in an enclosure, Khalifa and Marshall [5] utilized an experimental enclosure that had dimensions similar to those of a real-size room. Sixty-five aluminium thermistors were used to measure air and surface temperatures in the enclosure.…”

Section: Introductionmentioning

confidence: 99%

Numerical Determination of Effects of Wall Temperatures on Nusselt Number and Convective Heat Transfer Coefficient in Real-Size Rooms

Açıkgöz

Kıncay

2013

Advances in Mechanical Engineering

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A modeled room was numerically heated from a wall and cooled from the opposite wall in order to create a real-room simulation. The cooled wall simulated heat loss of the room, and the heated wall simulated the heat source of enclosure. The effects of heated and cooled wall temperatures on convective heat transfer coefficient (CHTC) and Nusselt number in the enclosure were investigated numerically for two-(2D) and three-dimensional (3D) modeling states. Different hot wall and cold wall temperatures were applied in order to obtain correlations that contained characteristic length in Rayleigh numbers. Results were compared with the results of previously reported correlations that have been suggested for vertical room surfaces in enclosures. In addition, new correlations for Nusselt number and average CHTC for enclosures for isothermal boundary conditions within indicated Rayleigh number ranges were derived through solutions. Average deviations of new correlations obtained for CHTC and Nusselt number from the numerical data were found 0.73% and 1.76% for 2D study, 3.01% and 0.49% for 3D study. It was observed that the difference between the 2D and 3D solutions in terms of CHTC and Nusselt number was approximately 10%.

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Validation of heat transfer coefficients on interior building surfaces using a real-sized indoor test cell

Cited by 194 publications

References 3 publications

05/00791 Efficiency of electrically heated windows

05/00791 Efficiency of electrically heated windows

Experimental investigation of convective heat transfer during night cooling with different ventilation systems and surface emissivities

Numerical Determination of Effects of Wall Temperatures on Nusselt Number and Convective Heat Transfer Coefficient in Real-Size Rooms

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