U.S. Army Research Institute of Environmental Medicine Natick United States
This study details a technique for comparing the evaporative capacity of fabrics. A Sweating Guarded Hot Plate SGHP was used to measure peak evaporative heat flux. In addition to the method we introduce, two commonly-used moisture transfer tests were performed for comparison, a longitudinal wicking strip test, and ASTM F1868-17 SGHP analysis of evaporative resistance. Thermal resistance was also measured on the SGHP. Results The evaporative heat flux test was able to distinguish heat transfer differences between the six fabrics tested with peak rates ranging from 75 and 143 Wm2. The mean absolute error between observed and expected results was 3.4 5.9 with a coefficient of variation of 4.5 across all tests. The peak heat flux rate was moderately correlated to the evaporative potential, imclo of each fabric R 0.63 but was not correlated with longitudinal wickability as determined by wicking strip test R -0.06. While more research is needed to establish best practices for the evaporative heat flux test, it appears useful for distinguishing unique heat transfer properties of fabrics.