Convective heat transfer in building energy and thermal load calculations

Valid enclosure film coefficients, required by hourly energy and thermal load programs, were experimentally determined for ventilative flow rates below 12 air changes per hour (ACH). Forty-eight experiments were performed in a full-scale room in order to determine film coefficients at low ventilativ...

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Bibliographic Details
Main Authors: Fisher, D.E., Pedersen, C.O.
Format: Conference Proceeding
Language:English
Subjects:
B CODES
BUILDINGS
CONVECTION
COOLING LOAD
ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ENERGY DEMAND
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Summary:Valid enclosure film coefficients, required by hourly energy and thermal load programs, were experimentally determined for ventilative flow rates below 12 air changes per hour (ACH). Forty-eight experiments were performed in a full-scale room in order to determine film coefficients at low ventilative flow rates. The experiments, which were performed over a range of conditions from 3 to 12 ACH, showed that for most room configurations, natural convection film coefficients significantly underpredict the rate of surface convective heat transfer. The new film coefficients were implemented in the BLAST program, an hourly heat-balance-based building energy simulation. The significance of the error incurred by using natural convection film coefficients in a ventilated space was estimated by comparing BLAST results obtained with both natural convection and the new film coefficients. For the case of space cooling, where surface-to-air temperature differences are relatively small, errors in calculated space cooling loads were typically on the order of 10%.
ISSN:0001-2505