chapter  4
30 Pages

Infrared Absorption Characteristics of Fabrics

I. Introduction 93

II. 95 95

Background A. Thermal radiation B. Infrared emitters 96

III. 97 97 99

Methodology A. Measurements of spectral absorptivities B. Calculation of integrated average absorptivities C. Calculation of overall radiant efficiencies 99

IV. 100 100 101 112

Fabric IR Absorption A. Parameters influencing IR absorption B. Spectral characteristics C. Average absorptivity D. Overall radiant efficiency 119

References 121

I. INTRODUCTION For many years, the textile industry has used infrared (IR) radiation for predrying, drying, and curing of various textile products. Until recently, most of the heating applications have used IR sources with emissions in the medium to long infrared

regions of the spectrum. Improvements in electric-based IR equipment, particu­ larly in emitter materials and controls, have allowed the adjustment of the region (short, medium, or long wavelength) in which peak emission occurs. Because there are several types of IR emitters available for heating textiles, the type of emitter that should be used for a given application is often an issue. The interac­ tion of IR energy with fabrics and the effect of emitter type on the efficiency of heating fabrics is discussed in this chapter. The material presented here is based on research conducted at Georgia Tech [1,2]. Although the efficiency of IR heat­ ing may depend on factors such as oven design and the interaction of convective and conductive modes of heat transfer with infrared heating, only the interaction of IR energy with fabrics is considered in this chapter.