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.
First monthly exam
Gas dynamics
Third stage
Q1/Water at 15° C flow through a 300 mm diameter riveted steel pipe, E-3 mm with a head loss of 6 m in
300 m length. Determine the flow rate in pipe. Use moody chart.
Q2/ Assume a car's exhaust system can be approximated as 14 ft long and 0.125 ft-diameter cast-iron pipe (
= 0.00085 ft) with the equivalent of (6) regular 90° flanged elbows (KL = 0.3) and a muffler. The
muffler acts as a resistor with a loss coefficient of KL= 8.5. Determine the pressure at the beginning of the
exhaust system (pl) if the flowrate is 0.10 cfs, and the exhaust has the same properties as air.(p = 1.74 ×
10-3 slug/ft³, u= 4.7 x 10-7 lb.s/ft²) Use moody chart
(1)
MIDAS
Kel=0.3
Q3/Liquid ammonia at -20°C is flowing through a 30 m long section of a 5 mm diameter copper tube(e =
1.5 × 10-6 m) at a rate of 0.15 kg/s. Determine the pressure drop and the head losses.
.μ= 2.36 × 10-4 kg/m.s)p = 665.1 kg/m³
2/Y
Y+1
2Cp
Q1/ Show that
Cda
Az x
P1
mactual
Cdf
Af
R/T₁
2pf(P1-P2-zxgxpf)
Q2/ A simple jet carburetor has to supply 5 Kg of air per minute. The air is at a pressure of 1.013 bar
and a temperature of 27 °C. Calculate the throat diameter of the choke for air flow velocity of 90 m/sec.
Take velocity coefficient to be 0.8. Assume isentropic flow and the flow to be compressible.
Quiz/ Determine the air-fuel ratio supplied at 5000 m altitude by a carburetor which is adjusted to give
an air-fuel ratio of 14:1 at sea level where air temperature is 27 °C and pressure is 1.013 bar. The
temperature of air decreases with altitude as given by the expression
The air pressure decreases with altitude as per relation h = 19200 log10 (1.013), where P is in bar. State
any assumptions made.
t = ts
P
0.0065h
36
2) Use the method of MEMBERS to determine the true magnitude and
direction of the forces in members1 and 2 of the frame shown below
in Fig 3.2.
300lbs/ft
member-1
member-2
30°
Fig 3.2.
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