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A Calorimeter for Determining Heat Transmission Characteristics of Windows Pages: 15 Published: Jan 1987
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View License Agreement Heat loss through windows is receiving an increasing amount of attention from consumers, manufacturers, and building designers. The technology is changing and should lead to substantial improvements in thermal performance. To assist in the evaluation of existing as well as new products, the Division of Building Research, National Research Council of Canada (DBR/NRCC), has designed and built a new calorimeter for use in their Environmental Test Facility. This paper presents an approach for determining the heat transmission characteristics of windows using the radiative and convective components of heat transfer from the calorimeter to the specimen surface. Through calibration tests using materials of known conductance, expressions for the radiation exchange between the calorimeter surfaces and the specimen and the calorimeter air to the specimen can be determined. These expressions are then used when testing a window to calculate an equivalent surface temperature for the window. This approach is necessary because of the difficulty in determining an average surface temperature on glass. Although the approach can be used with conventional calorimeter designs, uncertainties are introduced because of the changing calorimeter characteristics for different sizes of specimens. To reduce the uncertainties, the new calorimeter was designed to have a constant convection coefficient and uniform temperature radiation field. The calibration program is discussed, and some preliminary results are given. | ||
