Question 1 (1 of 1) A Styrofoam box has a surface of 0.8 m2 and a wall thickness
ID: 1608554 • Letter: Q
Question
Question 1 (1 of 1) A Styrofoam box has a surface of 0.8 m2 and a wall thickness of 22 cm. The temperature of the inner surface is 1.1C, and that outside is 11C. If it takes 10.1 h for 3.2 kg of ice to melt in the container, determine the thermal con- ductivity of the Styrofoam. The latent heat of fusion of water is 4186 J/kg/C . Answer in units of W/m/C. Question 2 (1 of 2) A Thermopane window consists of two glass panes, each 0.79 cm thick, with a 0.6 cm thick sealed layer of air between. If the inside surface temperature is 24C and the outside surface temperature is 1C, determine the rate of energy transfer through 4.7 m2 of the window. Answer in units of W. Answer = 391.7Question 3 (2 of 2) What is the rate of energy transfer through 4.7 m2 of a single 0.6 cm thick pane of glass? Answer in units of kW.
Question 1 (1 of 1) A Styrofoam box has a surface of 0.8 m2 and a wall thickness of 22 cm. The temperature of the inner surface is 1.1C, and that outside is 11C. If it takes 10.1 h for 3.2 kg of ice to melt in the container, determine the thermal con- ductivity of the Styrofoam. The latent heat of fusion of water is 4186 J/kg/C . Answer in units of W/m/C. Question 2 (1 of 2) A Thermopane window consists of two glass panes, each 0.79 cm thick, with a 0.6 cm thick sealed layer of air between. If the inside surface temperature is 24C and the outside surface temperature is 1C, determine the rate of energy transfer through 4.7 m2 of the window. Answer in units of W. Answer = 391.7
Question 3 (2 of 2) What is the rate of energy transfer through 4.7 m2 of a single 0.6 cm thick pane of glass? Answer in units of kW.
Question 1 (1 of 1) A Styrofoam box has a surface of 0.8 m2 and a wall thickness of 22 cm. The temperature of the inner surface is 1.1C, and that outside is 11C. If it takes 10.1 h for 3.2 kg of ice to melt in the container, determine the thermal con- ductivity of the Styrofoam. The latent heat of fusion of water is 4186 J/kg/C . Answer in units of W/m/C. Question 2 (1 of 2) A Thermopane window consists of two glass panes, each 0.79 cm thick, with a 0.6 cm thick sealed layer of air between. If the inside surface temperature is 24C and the outside surface temperature is 1C, determine the rate of energy transfer through 4.7 m2 of the window. Answer in units of W. Question 2 (1 of 2) A Thermopane window consists of two glass panes, each 0.79 cm thick, with a 0.6 cm thick sealed layer of air between. If the inside surface temperature is 24C and the outside surface temperature is 1C, determine the rate of energy transfer through 4.7 m2 of the window. Answer in units of W. Answer = 391.7
Question 3 (2 of 2) What is the rate of energy transfer through 4.7 m2 of a single 0.6 cm thick pane of glass? Answer in units of kW.
Explanation / Answer
1.Thermal conductivity, k = Q*x/A*t*T , where Q is heat transfer, x is the thickness, A is area, t is time, and T is temperature
Q = m*f (ice) = 3.2kg*4186J/kg = 13395.2J
t = 10.1h = 36,360s
T = 11C – 1.1C = 9.9C
K = 13395.2J*0.22m/0.8m^2*36,360s*9.9C
K = 0.01023 J/m-s-C
2. xGlass = .0079; kGlass = 0.84; xAir = .0060; kAir = 0.0234; T = 24 - 1; WindowArea = 4.7; HeatLossPerSecond =[(WindowArea * T) / {(xGlass/kGlass) +( xAir/kAir) + (xGlass/kGlass)}]
Heat loss per sec through thermopane glass :-
= [(WindowArea * T) / {(xGlass/kGlass) +( xAir/kAir) + (xGlass/kGlass)}]
= [(4.7*23)/{(0.0079/.84) + (.0060/.0234) + (0.0079/.84)}] =108.1/0.2752 = 392.8 Watts
Heat loss per second through double-thick glass :-
HeatLossPerSecond =[(WindowArea * T) / {(xGlass/kGlass) + (xGlass/kGlass)}]
= [(4.7*23)/{(0.0079/.84) + (0.0079/.84)}] =108.1/0.0188 = 5750 Watts