Heat transfer Question 1 A double window called thermopane is one in which two layers of glasses are separated by a laye

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Heat Transfer Question 1 A Double Window Called Thermopane Is One In Which Two Layers Of Glasses Are Separated By A Laye 1 (33.35 KiB) Viewed 45 times

Heat transfer Question 1 A double window called thermopane is one in which two layers of glasses are separated by a layer of dry, stagnant air. In a given window, each of the glass layers is 6 mm thick separated by a 6 mm space of stagnant air. The thermal conductivity of the glass is 0.869 W/m.K and that of air is 0.026 W/m.K over the temperature range used. A convective coefficient of h=11.35 W/m².K on one outside surface of one side of the window and h = 11.35 W/m².K on the other side surface. For a temperature drop of 27 K over the system, calculate the heat loss for a window 0.9 m x 1.8 and calculate the overall U. (Note: this calculation neglects the convection inside the window) Question 2 ((103.9 W; 2.38 W/m².K) A double pipe heat exchanger passes heats 2.52 kg/s of water from 21.1 to 54.4 °C by using hot water under pressure flows countercurrently entering at 115.6 °C and leaving at 48.9 °C. The outside surface area of the tubes in the exchanger is A. = 9.30 m². Calculate the mean temperature different ATm in the exchanger and the overall heat transfer coefficient, U. Given the specific heat of water = 4187 J/kg.K (42.3 °C; 893 W/m².K)