A 7.5 cm thickside wall of an oven is primarily made of insulation with a thermalconductivity of 0.04 W/m K. Conditions on theinsideof wall fixthe temperature of that sideat 420K.The electriccoils within theoven dissiplate 36.5 watts of electrical energy to make upfor the heatloss through the wall . Calculatethe wall surfacearea.perpendicularto heat flow, so that tempera - ture on the othersideof the wall does not exceed 310 K.

A 7.5 cm thickside wall of an oven is primarily made of insulation wit

1.	A 7.5 cm thickside wall of an oven is primarily made of insulation with a thermalconductivity of 0.04 W/m K. Conditions on theinsideof wall fixthe temperature of that sideat 420K.The electriccoils within theoven dissiplate 36.5 watts of electrical energy to make upfor the heatloss through the wall . Calculatethe wall surfacearea.perpendicularto heat flow, so that tempera - ture on the othersideof the wall does not exceed 310 K.
Answer» Solution :Under thestipulations of one - dimensionalsteadyheat CONDUCTION , theelectrical ENERGY dissipationrate within the oven must EQUAL the conductionheatransfer rateacross the wall . That is `Q = (KA(t_(1) - t_(2)))/(delta) , 36.5 = (0.04A (420 - 310))/(0.75) = 5.87 A` Hence, the requiredwall surface area `rArr A = (36.5)/(5.87) = 6.218 m^(2)`