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originally posted by: AthlonSavage
sun covers half body so use 1m2.
1.361 kilowatts = 1361watts per m2
thats 1361 x3600 = 4899600 joules per hour.
The specific heat of water is 1 calorie/gram °C = 4.186 joule/gram °C
Human body is 80Kg = 80000.
Its body temp interior 37 deg C
therefore 80000 x 4.186 x 37 = 12390560 Joules
12390560 + 4899600 Joules =
Per hour 17290160 Joules of heat energy needs to be managed.
divide by 3600 seconds per hour 4802 watts (Joules/sec)
Presuming human body mainly water
The specific heat capacity of water is 4,200 Joules per kilogram per degree
If the space around suit is perfect insulator will need to rid averge at least 4200 Joules of enery per second to maintin a regular body temp.
The cals do not need to be accurate just in the ball park range to show what is feasible and what is not.
originally posted by: choos
originally posted by: AthlonSavage
sun covers half body so use 1m2.
1.361 kilowatts = 1361watts per m2
thats 1361 x3600 = 4899600 joules per hour.
The specific heat of water is 1 calorie/gram °C = 4.186 joule/gram °C
Human body is 80Kg = 80000.
Its body temp interior 37 deg C
therefore 80000 x 4.186 x 37 = 12390560 Joules
12390560 + 4899600 Joules =
Per hour 17290160 Joules of heat energy needs to be managed.
divide by 3600 seconds per hour 4802 watts (Joules/sec)
Presuming human body mainly water
The specific heat capacity of water is 4,200 Joules per kilogram per degree
If the space around suit is perfect insulator will need to rid averge at least 4200 Joules of enery per second to maintin a regular body temp.
you put in all that effort, but why is the suit white? and why are your calcs assuming a black body object?
You are not considering the latent heat of vaporization.
Energy = mass x change in temperature x specific heat of water.
Starting from what temperature? But isn't the boiling temperature of water dependent upon pressure?
So energy required to boil at 100 Deg C is 50 kg x 65 degrees C * 4184 (joules /kg x deg C) = 13598000 joules.
The only part of cooling that involved battery power was a small pump, used to circulate the water.
Quite incredible however is the longest apollo lunar excursions went for over 7 hours and suits have 279Watt-hour battery (i.e 279 x 60 *60) = 1004500 joules capacity. Seems quite underated for running the suits cooling system.
In fact sunlight hits the moon's surface, the temperature can reach 260 degrees Fahrenheit (127 degrees Celsius).