A 22 m x 098 m x 58 cm thick solid wood door has a 05 m squa

A 2.2 m x 0.98 m x 5.8 cm thick solid wood door has a 0.5 m square window. The window has two panes of 0.44 cm thick glass with a 0.2 cm thick space between the glass panes that is filled with argon. Argon is used since it has a thermal conductivity that is 34% lower than that of air. The inside air temperature is 20 °C and the outside temperature is -7 °C. Determine the magnitude of the heat flow through the door.
_wood = 0.10 W/(m°C)
_glass = 0.84 W/(m°C)
_air = 0.026 W/(m°C)

Solution

Most sources indicate the direction not by an arrow but by labeling the left point \"1\" and the right-hand point \"2\". If the expansion were isentropic, the temperature would FALL, so indeed heat must be transferred into the oxygen to bring about the expansion without a decrease in temperature. The heat transfer can be represented by a short but wiggly arrow pointing down through the horizontal line, and labeled \"Q-in\".

W = integral from V1 to V2 of p dV
= integral from V1 to V2 of (nRT/V) dV
Easy to integrate because T is constant