Review on the Surface Heat Transfer Coefficients of Radiant Systems

Abstract

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.

Cooling Capacity and Energy Performance of Open-Type Ceiling Radiant Cooling Panel System with Air Circulators

“…To quantify the impact of air circulators on the cooling capacity, convective heat transfer needs to be distinguished from the total cooling capacity. Although many studies on ceiling radiant cooling systems have suggested radiant/convective heat transfer coefficients [1,6,8,[22][23][24], these studies focused on the ceiling radiant cooling system made of top-insulated panels. Thus, heat transfer at the upper panel surface was not considered to determine the radiant/convective heat transfer coefficients.…”