The human body is adaptable to extreme climatic conditions and keeps the body core and skin temperatures within the comfort zone by regulating the metabolic heat generation rate. For example. in extreme cold conditions, the human body will maintain the body temperature by increasing metabolic heat generation, while in very hot conditions, the body will sweat and release heat. To understand this effect of ambient conditions on the human body, repeat Example 3-14 in the text and consider a case where climatic conditions change from -20°C and 20°C. For this change in ambient air temperature, calculate the metabolic heat generation rate required with skin/fat thicknesses of 0.0075, 0.005, and 0.0025 m to maintain the skin temperature at page 238 34°C. Assume that in spite of the change in ambient air temperature. the perspiration rate remains constant at 0.0005 s − 1 . Plot a graph of metabolic heat generation rate against the ambient temperature with temperature increments of 5°C.
The human body is adaptable to extreme climatic conditions and keeps the body core and skin temperatures within the comfort zone by regulating the metabolic heat generation rate. For example. in extreme cold conditions, the human body will maintain the body temperature by increasing metabolic heat generation, while in very hot conditions, the body will sweat and release heat. To understand this effect of ambient conditions on the human body, repeat Example 3-14 in the text and consider a case where climatic conditions change from -20°C and 20°C. For this change in ambient air temperature, calculate the metabolic heat generation rate required with skin/fat thicknesses of 0.0075, 0.005, and 0.0025 m to maintain the skin temperature at page 238 34°C. Assume that in spite of the change in ambient air temperature. the perspiration rate remains constant at 0.0005 s − 1 . Plot a graph of metabolic heat generation rate against the ambient temperature with temperature increments of 5°C.
Solution Summary: The author analyzes the metabolic heat generation rate against the ambient temperature with temperature increment of 5°C. A human with lesser skin layer thickness will have higher metabolism to maintain interface temperature.
The human body is adaptable to extreme climatic conditions and keeps the body core and skin temperatures within the comfort zone by regulating the metabolic heat generation rate. For example. in extreme cold conditions, the human body will maintain the body temperature by increasing metabolic heat generation, while in very hot conditions, the body will sweat and release heat. To understand this effect of ambient conditions on the human body, repeat Example 3-14 in the text and consider a case where climatic conditions change from -20°C and 20°C. For this change in ambient air temperature, calculate the metabolic heat generation rate required with skin/fat thicknesses of 0.0075, 0.005, and 0.0025 m to maintain the skin temperature at page 238 34°C. Assume that in spite of the change in ambient air temperature. the perspiration rate remains constant at
0.0005
s
−
1
. Plot a graph of metabolic heat generation rate against the ambient temperature with temperature increments of 5°C.
The boiling temperature of nitrogen at atmospheric pressure at sea level (1 atm pressure) is -196 °C. Therefore, nitrogen is commonly used in low-temperature scientific studies since the temperature of liquid nitrogen in a tank open to the atmosphere will remain constant at -196 °C until it is depleted. Any heat transfer to the tank will result in the evaporation of some liquid nitrogen, which has a heat of vaporization of 198 kJ/kg and a density of 810 kg/m3 at 1 atm.
Consider a 3-m-diameter spherical tank that is initially filled with liquid nitrogen at 1 atm and -196 °C. The tank is exposed to ambient air at 15° C, with a combined convection and radiation heat transfer coefficient of 35 W/m2⋅K. The temperature of the thin-shelled spherical tank is observed to be almost the same as the temperature of the nitrogen inside. Determine the rate of evaporation (in kg/s) of the liquid nitrogen in the tank as a result of the heat transfer from the ambient air if the tank is insulated with…
Hi, can you help me to answer this question using the first law of thermodynamics?
On a hot summer day a student turns his fan on when he leaves his room in themorning. When he returns in the evening will the room be warmer or cooler than theneighborouing rooms ? Explain your answer using the first law of thermodynamics.Assume ALL doors and windows are kept closed.
The boiling temperature of nitrogen at atmospheric pressure at sea level (1 atm) is -196°C. Therefore, nitrogen is commonly used in low temperature scientific studies since the temperature of liquid nitrogen in a tank open to the atmosphere will remain constant at -196°C until the liquid nitrogen in the tank is depleted. Any heat transfer to the tank will result in the evaporation of some liquid nitrogen, which has a heat of vaporization of 198 kJ/kg and a density of 810 kg/m3 at 1 atm. Consider a 3-m-diameter spherical tank initially filled with liquid nitrogen at 1 atm and 196°C. The tank is exposed to 22°C ambient air with a heat transfer coefficient of 22 W/m2 · °C. The temperature of the thin-shelled spherical tank is observed to be almost the same as the temperature of the nitrogen inside. Disregarding any radiation heat exchange, determine the rate of evaporation of the liquid nitrogen in the tank as a result of the heat transfer from the ambient air in kg/sec. Answer in…
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