The total infrared transmittance of polymerised vinyl fluoride films for a wide range of radiant source temperature

The current growing interest on the use of polymer films is mainly attributed to their suitability as glazing and construction materials in various fields of contemporary technology. Polymerised vinyl fluoride (Tedlar) films are nowdays considered as very suitable for construction and energy applications. Most polymer films are partly transparent, showing a strongly selective absorbing behaviour at the infrared spectrum. Their total hemispherical infrared transmittance which depends on radiant source temperature and film thickness, is a very useful fundamental property for energy balance and heat transfer calculations. However it is not always possible to locate information about this property in the literature. In the present investigation the calculation of the total infrared transmittance of Tedlar films is presented, based on recent spectral transmittance measurements of commercial tedlar films for the wavelength band between 2.5–42.5 μm and for a broad range of radiant source temperatures between –20 to 500 C. Results from the present analysis were found to be in reasonable agreement with earlier data, derived for a specific film thickness and for a narrow range of radiant source temperatures by Willier.

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