Accession Number:

ADA275240

Title:

Validation and Sensitivity Analysis of Texas Human Thermal Model Predictions During Cold Water Immersion

Descriptive Note:

Final rept. Mar-Sep 1992

Corporate Author:

NAVAL AIR WARFARE CENTER AIRCRAFT DIV WARMINSTER PA AIR VEHICLE AND CREW SYSTEMS TECHNOLOGY DEPT

Report Date:

1993-02-01

Pagination or Media Count:

157.0

Abstract:

The Texas Human Thermal Model referred to below as the Model has been used to simulate the effects of thermal stresses on individuals under a variety of conditions. As part of a US Navy effort to develop integrated protection garments, the Model has been modified to predict tolerance to cold water immersion with garments whose CLO values are less than 0.1. Other program modifications have been implemented leading to easier use, enhanced speed and versatility and accuracy of predictions. With these modifications, a validation of Model performance was done using human data obtained from Finnish cold water immersion suit assessments. Limitations in Model performance were found but predictions of rectal temperature Tre were in reasonable agreement to actual results. A sensitivity analysis was also performed to determine which Model parameters were most effected by cold water immersions. The condition tested was head-out immersion in 40 deg F water by 160 lb man with a 10 mm mean skinfold thickness. Based on the thermal end points, the Model was sensitive to body segmental changes in CLO ordered from most to least sensitive chest and abdomen, leg, head, arm, foot and hand. Mean skinfold thickness, basal metabolic rate, body weight and level of exercise metabolic rate up to 100 BTUher were the most important physical parameters affecting Model performance. Lowering the water temperatures to 28 deg F caused a simple shift by in segment temperature predictions with respect to 40 deg F estimates. The overall shapes of the curves at 28 and 40 deg F were essentially the same, though the 28 deg F curves had steeper slopes leading to a faster fall to critical temperatures e.g. Tre 35 deg C. Hypothermia, Mathematical modeling, Anti-exposure protection.

Subject Categories:

  • Stress Physiology
  • Protective Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE