![Introduction to Heat Transfer](https://www.bartleby.com/isbn_cover_images/9780470501962/9780470501962_largeCoverImage.gif)
The emissivity of galvanized steel sheet, a common roofing material, is
![Check Mark](/static/check-mark.png)
Want to see the full answer?
Check out a sample textbook solution![Blurred answer](/static/blurred-answer.jpg)
Chapter 1 Solutions
Introduction to Heat Transfer
- 1.11 Calculate the heat loss through a glass window 7-mm thick if the inner surface temperature is 20°C and the outer surface temperature is 17°C. Comment on the possible effect of radiation on your answer.arrow_forward1.26 Repeat Problem 1.25 but assume that the surface of the storage vessel has an absorbance (equal to the emittance) of 0.1. Then determine the rate of evaporation of the liquid oxygen in kilograms per second and pounds per hour, assuming that convection can be neglected. The heat of vaporization of oxygen at –183°C is .arrow_forwardA small sphere (emissivity = 0.745, radius = r1) is located at the center of a spherical asbestos shell (thickness = 1.72 cm, outer radius = r2; thermal conductivity of asbestos is 0.090 J/(s m Co)). The thickness of the shell is small compared to the inner and outer radii of the shell. The temperature of the small sphere is 727 °C, while the temperature of the inner surface of the shell is 406 °C, both temperatures remaining constant. Assuming that r2/r1 = 6.54 and ignoring any air inside the shell, find the temperature in degrees Celsius of the outer surface of the shell.arrow_forward
- A furnace wall is constructed of an inner layer of 12.7 mm of refracter material, a middle layer of 101.6 mm of insulation material and outer layer of 76.2 mm of steel. The wall surface temperature is 1370 °C inside the refracter material (T0) and 37.8 °C at the outside surface of the steel (T3). Use thermal conductivity for refractor kref = 6.64 W/mK, for insulation, kins= 2.34 W/mK and for steel kste = 45 W/mK. Calculate the heat loss in W for 1 m2 (heat flux)? The temperature at the inter face between the insulation material and steel board?arrow_forwardA flat-plate solar collector, as shown in Fig. 1, is used to heat water by having water flow through tubes attached at the back of the thin solar absorber plate. The absorber plate has an emissivity and an absorptivity of 0.8. The top surface (* = 0) temperature of the absorber is To = 35 °C, and solar radiat ion is incident on the absorber at 600 W/m? with a surrounding temperature of 0 °C. The convection heat transfer coefficient at the absorber surface as 8 W/m?-K. Assuming constant thermal conductivity and no heat generation in the wall, i express the differential equation and the boundary conditions for steady one- dimensional heat conduct ion through the wall, obtain a relation for the variation of temperature in the wall by solving the differential equation, and ii iii. determine the net heat flux, ġo absorbed by the collector ε, α, Τ. Absorber plate Water tubes Insulation Fig. 1arrow_forward2 inch OD during a visit to a plastic sheet factory 60 m long section of a horizontal steam pipe passes from one end to the other without insulation is observed. While the temperature of the ambient air and its surfaces is 20 °C, the temperature measurements at several points are the average of the exposed surfaces of the steam pipe. indicates that the temperature is 160 °C. It is seen that the outer surface of the pipe is oxidized and The emissivity can be taken as 0.59. According to this; a) Calculate the heat loss in the steam pipe. b) The steam used is produced in a gas furnace operating with an efficiency of 59%. Factory 105500 It pays $1.10 per kJ of natural gas. If it is assumed that the factory works all year (365 days), for this facility Calculate the annual cost of heat losses in the steam pipe.arrow_forward
- A wood stove is used to heat a single room. The stove is cylindrical in shape, with a diameter of D = 0.400 m and a length of L = 0.500 m, and operates at a temperature of T, = 200 °C. (a) If the temperature of the room is T, = 20°C, determine the amount of radiant energy delivered to the room by the stove each second if the emissivity of the stove is e = 0.920. (b) By definition, the R-value of a conducting slab is given by Atot(Th – To) Poond R = where Atot is the total surface area, Pcond is the power loss by conduction through the slab, Th and Te are the temperatures on the hotter and cooler sides of the slab. If the room has a square shape with walls of height H = 2.40 m and width W = 7.60 m, determine the R-value of the walls and ceiling required to maintain the room temperature at T = 20°C if the outside temperature is T, = 0°C. Note that we are ignoring any heat conveyed by the stove via convection and any energy lost through the walls and windows via convection or radiation.arrow_forwardDetermine the heat transfer between the platesarrow_forwardA one-dimensional plane wall is exposed to convective and radiative conditions at x = 0. The ambient and surrounding temperatures are T = 15C and Tsur = 80C, respectively. The convection heat transfer coefficient is h = 40 W/(m2K) and the absorptivity of the exposed surface is = 0.8. Determine the convective and radiative heat fluxes to the wall at x = 0 in W/m2, if the wall surface temperature is 24C. Assume the exposed wall surface is gray (meaning = ) and the surroundings are much larger than the wall surface.arrow_forward
- Heat lossarrow_forwardDetermine the heat transfer that occurs by radiation between two surfaces that are co-axial and parallel to each other, full and semicircular. Assume that the surfaces only exchange radiation with each other. T1 = 700 °C; ɛ1 = 0.8; T2 = 20 °C; e2 = 0.4. фб ст (2) to 4 cm 6 8 cm (1 t.arrow_forwardConsider a small house with walls 3.7 m high and each of four walls is 12.2 m long. A total of eight windows areplaced in these walls, each with dimensions 0.9 m by 1.2 m. The windows are single paned with k = 0.78 W/m∙K and0.6 cm thick. The walls have an RSI value of 3.4, which means they have RA = L/K = 3.4 m2K/W resisting heat flow.The heat transfer coefficients on the inside and outside of the house are 3 and 6 W/m2K, respectively. Whatpercentage of total heat loss leaves through the windows? Neglect radiative heat loss.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
![Text book image](https://www.bartleby.com/isbn_cover_images/9781305387102/9781305387102_smallCoverImage.gif)