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Radiant Heat Hot Water Radiators

June 8th, 2011 admin No comments

Final this thursday…& I don’t understand these last 4 chapters we did today!?

In an old house, the heating system uses radiators, which are hollow metal devices through which hot water or steam circulates. In one room the radiator has a dark color (emissivity = 0.80). It has a temperature of 79°C. The new owner of the house paints the radiator a lighter color (emissivity = 0.50). Assuming that it emits the same radiant power as it did before being painted, what is the temperature of the newly painted radiator?

I used a ratio to solve this problem and got the wrong answer I used the equation Q=emissivity*constant(5.67*10^-8)*A*T^4
manipulated two emissity equations and set them equal to each other and got 88.85<<

any help will greatly be appreciated

When performing multiplication or division, be sure to use kelvins and not Celsius. Celsius has the problem of division by zero (even though you don’t divide by zero here, the scaling is wrong). Once you convert to kelvin to do the math, and then convert back to Celsius once you have the answer in kelvin, you’ll be ok.

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