I have 10 electrical components that carries a total of 350 watts inside a sealed .075" thk. steel box of 24"Hx30"Wx8"Deep. What would be the inside temp inside the box before heat starting to dissipate outside the box through convection with outside ambient temp of 50 degrees Centigrade.
Eng-Tips is the largest engineering community on the Internet
Intelligent Work Forums for Engineering Professionals
-
Congratulations waross on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!
Heat rise in a closed system
- Thread starter aqe1
- Start date
You are speaking of unsteady state heat transfer. If it is a sealed box full of liquid, as thermcool insinuates, and depending on the original liquid nature and temperature, thermal expansion of the liquid may rupture the box before any heat starts to dissipate.
If it is air, because of its low thermal conductivity, the electrical elements, being by definition constant heat flux system components, may heat up markedly and be damaged as a result, until the inner steel wall reaches a temperature just above 50[sup]o[/sup]C by conduction and radiation (assuming no air convection currents inside the box). The tabulated thermal conductivity for air being about 0.024 W/(m*[sup]o[/sup]C).
I hope you can estimate the final steel box wall temperature when reaching steady state or equilibrium heat transfer considering external convection and radiation as well.
![[smile]](/data/assets/smilies/smile.gif "[smile] [smile]")
To 25362, greater than 50 deg F because I assume there is fuid inside the box and delta T is the driving force in this case(I am also assuming the box initial temp is 50 deg F). If there is no fluid and just a pure vacuum than heat transfer from the heating element will be by radiation. If the inside of the box is in direct contact with the heating elements that again 50 def F and heat transfer will be by conduction.
- Status
Similar threads
- Question