Towards the definition of a reference ideal radiator for the assessment of heat emission efficiency in buildings

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IOP Conference Series: Materials Science and Engineering, Volume 415, issue 1
Radiators, as the primary devices used in space heating, cover a fundamental role in the energy efficient use of buildings. In the search of an optimal configuration, from both energy consumption and thermal comfort viewpoints, comparison of different types and emitter size is crucial. However, an ideal heater with the highest maximum heat emission efficiency that can be used as a baseline still needs to be defined. This study contributes to the development of the heat emission standard EN 15316-2-1:2007. We perform an analysis of heat transfer in enclosures with a 21- and 10-type panel radiators, using an ideal convector as a reference heater. Accounting for room side effects of thermal radiation, we compute the induced operative temperature both analytically and numerically. The numerical simulations are carried out for a European reference room specified in the CEN TC130 standardisation committee, introducing a number of assumptions for defining the benchmark radiator. For instance, back wall losses are neglected for ideally isolated emitters. First we find that, contrary to what might be expected, the convector is the worst performing heater. On the other hand, studying analytically the operative temperature as a function of radiator type and size, we identify the most performing heater in the 10-type. Furthermore, our analytical solution highlights a simple predictive method for computing the operative temperature for any panel size, in complete generality. As an example, we provide a series of analytical formulas for calculating the operative temperature of the radiators addressed in this study. The results of this work therefore provide a useful background for a precise and rigorous definition of an ideal radiator.
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Ferrantelli , A , Võsa , K V & Kurnitski , J 2018 , ' Towards the definition of a reference ideal radiator for the assessment of heat emission efficiency in buildings ' , IOP Conference Series: Materials Science and Engineering , vol. 415 , no. 1 , 012034 .