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In: Mechanical Engineering

A double pane window consists of two pieces of glass each of 8 mm thick that...

A double pane window consists of two pieces of glass each of 8 mm thick that enclose an air space of 8 mm thick. The window separates room air at 18°C from outside ambient air at -8°C. The convection coefficient associated with the inner (room-side) surface is 12W/m2 .K. The thermal conductivity of the glass is kg=1.35 W/m. K and that of the air is ka=0.027 W/m. K Q1- If the outside air convection coefficient is ho = 76 W/m2 .K what is the heat loss through a window that is 0.8 m long by 0.5 m wide? Neglecting radiation and assume the air enclosed between the panes to be stagnant. Q2- We consider now that the heat transfer in the air gap is transferred by conduction and radiation and that the radiation coefficient hrad = 3 W/m2 K . Show the thermal circuit representing the steady state situation and define the new heat transfer loss through the window.
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