1. Tardigrade
  2. Question
  3. Physics
  4. A double-plane window consists of two glass sheets each of area 1 m2 and thickness 0.01 m separated by a 0.05 m thick stagnant air space. In the steady state, the room glass interface and the glass outdoor interface are at constant temperature of 27°C and 0°C respectively. The rate of heat flow through the window pane is (Given, Kglass = 0.8 W m-1 K-1, Kair= 0.08 W m-1 K-1)

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Q. A double-plane window consists of two glass sheets each of area $1 \,m^2$ and thickness $0.01\, m$ separated by a $0.05\, m$ thick stagnant air space. In the steady state, the room glass interface and the glass outdoor interface are at constant temperature of $27^{\circ}C$ and $0^{\circ}C$ respectively. The rate of heat flow through the window pane is (Given, $K_{glass} = 0.8\, W \,m^{-1}\,K^{-1}$, $K_{air}= 0.08\, W \,m^{-1}\,K^{-1}$)

Thermal Properties of Matter

Solution:

image
Total thermal resistance is
$R=\frac{t_{1}}{K_{1}A_{1}}+\frac{t_{2}}{K_{2}A_{2}}+\frac{.t_{1}}{K_{1}A_{1}}$
$R=2 \times \frac{0.01}{0.8 \times1}+\frac{0.05}{0.08\times1}$
$=0.65\,W^{-1}\,K$
$\therefore $ Heat current, $H=\frac{\Delta T}{R}=\frac{27-0}{0.65}$
$=41.5\,W$