Problem II.20 The temperature in a room is 30 °C and the atmosphere is at 5 °C. The thickness of the window made of glass is 4.0 mm. The thermal conductivity of glass, λ, is 0.76 W/m K, and the heat-transfer coefficients inside and outside the room, a₁ and a₂, are 10 and 50 W/m² K, respectively. Calculate the heat flux, q, defined as heat flow per unit time and unit area. (Ans: 199.5 J/m² s)

Problem II.20 The temperature in a room is 30 °C and the atmosphere is at 5 °C. The thickness of the window made of glass is 4.0 mm. The thermal conductivity of glass, λ, is 0.76 W/m K, and the heat-transfer coefficients inside and outside the room, a₁ and a₂, are 10 and 50 W/m² K, respectively. Calculate the heat flux, q, defined as heat flow per unit time and unit area. (Ans: 199.5 J/m² s)