Consider a 320 mm x 320 mm window in an aircraft. For a temperature difference of 80°C from the inner to the outer surface of the window, calculate the heat loss through L = 10-mm-thick polycarbonate, soda lime glass, and aerogel windows, respectively. The thermal conductivities of the aerogel and polycarbonate are kag = 0.014 W/m-K and k pc = 0.21 W/m-K, respectively. Evaluate the thermal conductivity of the soda lime glass at 300 K. If the aircraft has 110 windows and the cost to heat the cabin air is $1/kW-h, compare the costs associated with the heat loss through the windows for an 8-hour intercontinental flight.

Consider a 320 mm x 320 mm window in an aircraft. For a temperature difference of 80°C from the inner to the outer surface of the window, calculate the heat loss through L = 10-mm-thick polycarbonate, soda lime glass, and aerogel windows, respectively. The thermal conductivities of the aerogel and polycarbonate are kag = 0.014 W/m-K and k pc = 0.21 W/m-K, respectively. Evaluate the thermal conductivity of the soda lime glass at 300 K. If the aircraft has 110 windows and the cost to heat the cabin air is $1/kW-h, compare the costs associated with the heat loss through the windows for an 8-hour intercontinental flight.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter7: Forced Convection Inside Tubes And Ducts

Section: Chapter Questions

Problem 7.53P

See similar textbooks

Similar questions

1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus shown in the accompanying sketch. Electric current is supplied to the guard heater, and a wattmeter shows that the power dissipation is 10 W. Thermocouples attached to the warmer and to the cooler surfaces show temperatures of 322 and 300 K, respectively. Calculate the thermal conductivity of the material at the mean temperature in W/m K. Problem 1.4
The heat transfer coefficient for a gas flowing over a thin float plate 3-m long and 0.3-m wide varies with distance from the leading edge according to hc(x)=10x1/4Wm2K If the plate temperature is 170C and the gas temperature is 30C, calculate (a) the average heat transfer coefficient, (b) the rate of heat transfer between the plate and the gas, and (c) the local heat flux 2 m from the leading edge. Problem 1.18
One end of a 0.3-m-long steel rod is connected to a wall at 204C. The other end is connected to a wall that is maintained at 93C. Air is blown across the rod so that a heat transfer coefficient of 17W/m2 K is maintained over the entire surface. If the diameter of the rod is 5 cm and the temperature of the air is 38C, what is the net rate of heat loss to the air?
Determine the rate of heat transfer per meter length from a 5-cm-OD pipe at 150C placed eccentrically within a larger cylinder of 85 magnesia wool as shown in the sketch. The outside diameter of the larger cylinder is 15 cm and the surface temperature is 50C.
Question 1:A glass window of width W = 1 m and height H = 2 m is 5 mm thick and has a thermal conductivity of kg=1.4 W/m.K. If the inner and outer surface temperatures of the glass are 15oC and -20oC, respectively, ona cold winter day, what is the rate of heat loss throughthe glass? To reduce heat loss through windows, it iscustomary to use a double pane construction in whichadjoining panes are separated by an air space. If thespacing is 10 mm and the glass surfaces in contact withthe air have temperatures of (last two digit of your Registration number) oC and -15oC, what isthe rate of heat loss from a 1 m x 2 m window? Thethermal conductivity of air is ka=0.024 W/m.K.
Consider 469 mm × 447 mm window in an aircraft. For a temperature difference of 98°C from the inner to the outer surface of the window, calculate the heat loss rate through L = 15-mm-thick polycarbonate, soda lime glass, and aerogel windows, respectively. The thermal conductivities of the soda lime glass, aerogel and polycarbonate are ksl = 1.960 W/m, kag = 0.011 W/m · K and kpc = 0.201 W/m · K, respectively. If the aircraft has 110 windows and the cost to heat the cabin air is $1.8/kW · h, compare the costs associated with the heat loss through the windows for an 10-hour intercontinental flight.
The window in my office is 2 metres by 3 metres. Assuming all other walls are well insulated and that heat loss only occurs through the window, calculate what size of heater I need in my office to maintain the temperature, if the inside surface of the glass is at 11 °C and the outside surface at 6 °C. Sketch the temperature profile through the glass. Data: Thickness of glass = 4 mm Thermal conductivity of glass 0.78 W/m K.
Thermal treatment of a steel cube, of 10 cm side length, L, requires a two step cooling process. In the first step, the cube at the uniform temperature of 500°C is placed in air where it is cooled to 250°C. In the second step, it is moved to large oil bath of temperature 20°C where the heat transfer coefficient at all surfaces is the same and equal to h = 50 W m-2 K-1. %3D Calculate the total amount of energy lost by the cube and show that the lumped capacitance method can be used to calculate the temperature during the second step of cooling. Calculate the time necessary to reduce the cube temperature to 50°C. Thermal properties Density = 8000 kg m-3 Cp= 480 J kg-1 K-1 k = 30 W m-1 K-1. %3D
Example 1.4 length. It is lined inside with 3 cm of insulating material of k = 0.042 W/mK. It is flying at a height where the average outside temperature is - 30°C. To find: The rate of heating required to maintain the compartment at 20°C for passenger comfort. Given: A jet aircraft compartment is assumed to be a cylindrical tube of 3-m diameter and 20-m
Calculate the quantity of heat conducted per minute through a duralumin circular disc 127 mm diameter and 19 mm thick when the temperature drop across the thickness of the plate is 5 degrees Celsius. Take the coefficient of thermal conductivity of duralumin as 150 W/(m-K).
AN PIPE LOCATED WHERE THE AMBIENT TEMPERATURE IS 32 DEG C, HAS AN INSIDE DIAMETER OF 50 mm WITH 10 mm INSULATION. THE OUTSIDE DIAMETER OF THE CORRUGATED ASBESTOS INSULATION IS 125 mm AND THE SURFACE COEFFICIENT OF STILL AIR (H, = 12- M2-K INSIDE THE PIPE IS STEAM HAVING A TEMPERATURE OF 150 DEG C WITH FILM COEFFICIENT H; = 6000 M2-K THE THERMAL CONDUCTIVITY OF PIPE AND ASBESTOS INSULATION ARE 45 AND 0.12 DETERMINE THE HEAT LOSS PER UNIT M-K LENGTH OF THE PIPE.
A glass with an area of 0.625 m² is fit in the wooden outside wall of a room. The dimension of wall is 25 x 3.05 m , The wood has a thermal conductivity of 0.151W/m.K and is 3.05 cm thick. The glass has a thermal conductivity of 0.692W/m.K and is 5.0 mm thick. The temperature of the inside room is 27°C and outside air temperature is 268K. calculate ,What is the heat loss through wooden wall and glass window? What are the total heat loss?