Phase II Testing of Liquid Cooling Garments Using a Sweating Manikin, Controlled by a Human Physiological Model

Abstract

An ADvanced Automotive Manikin (ADAM) developed at the National Renewable Energy Laboratory (NREL) is used to evaluate NASA's liquid cooling garments (LCGs) used in advanced spacesuits. The manikin has 120 separate heated/sweating zones and is controlled by a finite-element physiological model of the human thermoregulatory system. Previous testing showed the thermal sensation and comfort followed expected trends as the LCG inlet fluid temperature was changed. The Phase II test data demonstrates the repeatability of ADAM by retesting the baseline LCG. Skin and core temperature predictions using ADAM in an LCG/arctic suit combination are compared to NASA physiological data to validate the manikin/model. An additional Orlan LCG configuration is assessed using the manikin and compared to the baseline LCG.

Comparison of Thermal Manikin Modeling and Human Subjects’ Response During Use of Cooling Devices Under Personal Protective Ensembles in the Heat

“…Interestingly, the current results disagree with the conclusion that the model may under-predict T sk in higher ambient temperature conditions. Additional research was done using thermal modeling with a PCD which showed that T sk responded as expected over time; however, the absolute magnitude of T sk was inconsistent 22 . This result is in agreement with the current findings as the manikin showed a similar pattern of T sk over time compared to the humans; however, the magnitude of the T sk was over-estimated in the current data.…”

“…The over-estimation of T sk when using thermal manikin modeling has been previously reported in an ambient condition of 23.2°C with a maximum temperature deviation of 4.2°C 28 . However, in a higher ambient temperature of 30°C, the manikin thermal model under-estimated T sk 28 . The current data are in agreement with the conclusions in an ambient condition of 23.2°C; however, the current data show a more mild maximum temperature deviation of 1.88°C.…”

“…Previous conclusions suggest that higher temperature and humidity environments cause greater variability in T c estimation by the manikin 28 . These variations in the manikin data may exist due to either a delay in evaporative cooling compared to the programmed sweat rate or a software artifact caused by an irregularly rapid change in skin heat loss 28 …”

“…This result is in agreement with the current findings as the manikin showed a similar pattern of T sk over time compared to the humans; however, the magnitude of the T sk was over-estimated in the current data. A previous publication has suggested that T sk may be over-estimated in a thermal manikin model because the manikin is not walking, thus not creating wind while walking, as the humans were 22 …”

“…Heat production is translated as estimated core temperature (T c ) and skin temperatures (T sk ) of the manikin and is averaged every minute. Global heat sensation (HS) is calculated as a function of the local T sk and T c 28 29 Maximum sweating rate of the manikin is set at 30 g/min (1.8L/h), which is approximately the same as the maximum sweating capacity for a human body exercising at light-intensity while wearing impermeable PPE 30 …”