dead body is found in a room with air temperature of 18 ̊C, and the body’s surface temperature ismeasured to be 30 ̊C at noon. The normal surface temperature of a human body is 37 ̊C and the averagehuman body is more than 70% water so that the body can be assumed to have the same thermophysicalproperties as water (r = 1000 kgm-3 ; k = 0.65 Wm-1 K-1 ; cp = 4200 Jkg-1 K-1 ).a. Modeling the body as a 1.8 m-long cylinder with a diameter of 35 cm that is completely exposed toroom air and exchanges radiation with 18 ̊C surroundings (e = 0.85), use lumped capacity analysis toestimate the time of death based on the body’s surface temperature. You may neglect heat loss from theends of the cylinder. Would you expect the actual time of death to be earlier or later than your estimatedtime? Briefly explain.b. Using an average heat transfer coefficient for the cooling process, obtain a better estimate for the timeof death. You may neglect heat loss from the ends of the cylinder and consider only radial conductionwithin the body.c. Estimate the average temperature of the body when its surface temperature is 30 ̊C.
dead body is found in a room with air temperature of 18 ̊C, and the body’s surface temperature is
measured to be 30 ̊C at noon. The normal surface temperature of a human body is 37 ̊C and the average
human body is more than 70% water so that the body can be assumed to have the same thermophysical
properties as water (
r = 1000 kgm-3 ; k = 0.65 Wm-1 K-1 ; cp = 4200 Jkg-1 K-1 ).
a. Modeling the body as a 1.8 m-long cylinder with a diameter of 35 cm that is completely exposed to
room air and exchanges radiation with 18 ̊C surroundings (
e = 0.85), use lumped capacity analysis to
estimate the time of death based on the body’s surface temperature. You may neglect heat loss from the
ends of the cylinder. Would you expect the actual time of death to be earlier or later than your estimated
time? Briefly explain.
b. Using an average heat transfer coefficient for the cooling process, obtain a better estimate for the time
of death. You may neglect heat loss from the ends of the cylinder and consider only radial conduction
within the body.
c. Estimate the average temperature of the body when its surface temperature is 30 ̊C.
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