Question

To reduce building heating costs, modern building codes in many parts of the country require the use of double-pane windows (sometimes, called "double-glazed" or "thermopane" windows). Ivpically, a double-pane window consists of two panes of glass separated by a space that contains trapped stagnant air. In one design of a double-pane window, each glass layer is 0.7 cm thick, the stagnant air layer is 2 cm thick, and the area is 4 m2 In the living room of a large suburban house, 10 of these windows are installed. In the six months of winter, the room is heated by a bank of electric resistance heaters, which maintains the moving air temperature inside the living room at 22 °C when the moving air temperature outside the room is -5 °C Calculate the savings that are obtained when double-pane windows are used, instead of single-pane windows. GIVE YOUR ANSWER IN DOLLARS A single-pane window contains one layer of glass, 0.7 cm thick Thermal conductivity of the glass 0.81 (w(m.K) Thermal conductivity of stagnant air 0.024 W/(m.K) Mean convective heat transfer coefficient between the moving air inside a room and a glass layer 4 W/(m2.K) Mean convective heat transfer coefficient between the moving air outside a room and a glass layer 15 W(m2.K) Take each month to comprise 30.4 days and assume that the heating bank runs continuously every day. In the suburb, electricity costs $0.10/kWh PROBLEM ON TWo-DIMENSIONAL STEADY-STATE CONDUCTION: Use the finite difference method to determine T1, T2, T3, and Ta

Answer 1

inge pane gh eot transfer rate AT tnge Reg 3--5 KA -332 0216 W ing'e oR132 5 double pane glass Tat tranfer Heat AT A T 6 deusle h,A0 ZA aa-1-5 2 hahta hri 0-5124 1529 deutk = 332.0216 -92:529 heat lost per sec Saving's 39.492 GmonBS 2. 39 H92 6 tmnfer in xGx 20240 Savings af hent Total eloctricity cest avngs is Sav ings