Wind-chill-equivalent temperatures: regarding the impact due to the variability of the environmental convective heat transfer coefficient |
| |
Authors: | Avraham Shitzer |
| |
Institution: | (1) Department of Mechanical Engineering, Technion, Israel Institute of Technology, 32000 Haifa, Israel |
| |
Abstract: | The wind-chill index (WCI), developed in Antarctica in the 1940s and recently updated by the weather services in the USA and
Canada, expresses the enhancement of heat loss in cold climates from exposed body parts, e.g., face, due to wind. The index
provides a simple and practical means for assessing the thermal effects of wind on humans outdoors. It is also used for indicating
weather conditions that may pose adverse risks of freezing at subfreezing environmental temperatures. Values of the WCI depend
on a number of parameters, i.e, temperatures, physical properties of the air, wind speed, etc., and on insolation and evaporation.
This paper focuses on the effects of various empirical correlations used in the literature for calculating the convective
heat transfer coefficients between humans and their environment. Insolation and evaporation are not included in the presentation.
Large differences in calculated values among these correlations are demonstrated and quantified. Steady-state wind-chill-equivalent
temperatures (WCETs) are estimated by a simple, one-dimensional heat-conducting hollow-cylindrical model using these empirical
correlations. Partial comparison of these values with the published “new” WCETs is presented. The variability of the estimated
WCETs, due to different correlations employed to calculate them, is clearly demonstrated. The results of this study clearly
suggest the need for establishing a “gold standard” for estimating convective heat exchange between exposed body elements
and the cold and windy environment. This should be done prior to the introduction and adoption of further modifications to
WCETs and indices. Correlations to estimate the convective heat transfer coefficients between exposed body parts of humans
in windy and cold environments influence the WCETs and need to be standardized. |
| |
Keywords: | Wind chill Cold environments Convective heat transfer Empirical correlations Model |
本文献已被 PubMed SpringerLink 等数据库收录! |
|