A bank of drying ovens is mounted on a rack in a room with an ambient air temperature of 27°C. The cubical ovens are 500 mm to a side, and the spacing between the ovens is 15 mm
(a) Estimate the heat loss from a facing side of an oven when its surface temperature is 47°C.
(b) Explore the effect of the spacing on the heat loss. At what spacing is the heat loss a maximum? Describe the boundary layer behavior for this condition. Can this condition be analyzed by treating the side of an oven as an isolated vertical plate?
Want to see the full answer?
Check out a sample textbook solutionChapter 9 Solutions
Fundamentals of Heat and Mass Transfer
Additional Engineering Textbook Solutions
Vector Mechanics For Engineers
Machine Elements in Mechanical Design (6th Edition) (What's New in Trades & Technology)
Mechanics of Materials, 7th Edition
Engineering Mechanics: Statics & Dynamics (14th Edition)
Machine Tool Practices (10th Edition)
Degarmo's Materials And Processes In Manufacturing
- A storage tank consists of a cylindrical section that has a length and inner and inner diameter of L=2 m and Di=1 m, respectively, and two hemispherical end sections. The tank is constructed form 20 mm thick glass (pyrex) and is exposed to ambient air for which the temperature is 300 K. The tank is used to store heated oil, which maintains the inner surface at a temperature of 400 K. Determine the electrical power that must be supplied to a heater submerged in the oil if the prescribed conditions are to be maintained. Radiation effects may be neglected, and the pyrex may be assumed to have a thermal conductivity of 1.4 W/m.K.arrow_forwardQuestion: a) We want to increase heat transfer by placing fans to provide forced convection to reduce the length of the pipe necessary (Note that the outside surface temperature of the pipe remains the same at 100oC). What is the rate of heat transfer from pipe to the air per meter length if the air speed over the pipe surface is 5m/s? What is the total length of the pipe necessary? Problem: Consider a rectangular warehouse with the dimensions of 40m long x 20m widex10m height. The overall heat transfer coefficient for all sidewalls is Uwall=0.3 W/m2K (Approx. R=20 hr.ft2.oF/Btu) and for the flat roof, it is Uroof= 0.20W/m2K. The floor can be assumed to be insulated and we can ignore the heat transfer through the doors, etc. We want to maintain the inside air temperature at 15oC while the outside temperature is 0oC by using a thin-walled, 5.0cm diameter copper pipe that carries steam. Steam enters the pipe as saturated vapor at 100oC. So, as it starts losing heat to the inside air, it…arrow_forwardIf I noticed copied solution I will give dislike. In a solar collector 1 m wide by 4 m long, the glass cover plate at an average temperature of 29°C is spaced 40 mm from the absorber plate at an average temperature of 75°C. Estimate the convection heat loss coefficient from the absorber plate to the glass when the collector is positioned horizontally. What is the convection heat loss coefficient if the spacing reduced to 10 mm?arrow_forward
- Calculate the free convection heat transfer coefficient for a plate 6 ft high and 8 ft wide at 120 °F that is exposed to nitrogen at 60 °F. (see attached)arrow_forward1.13 If the outer air temperature in Problem is –2°C, calculate the convection heat transfer coefficient between the outer surface of the window and the air, assuming radiation is negligible.arrow_forwardThe onset of free convection. Plastic shrink wrap can be used to insulate windows by trapping air between your window and the wrapping. Calculate the critical gap width between the plastic and the window at which free convection will occur on an average winter’s day, when the outside temperature is 41°F and the inside temperature is 68°F. Would you expect there to be more or less heat transfer when the spacing is above this gap? Explain.arrow_forward
- A thermal energy storage unit consists of a large rectangular channel, which is wellinsulated on its outer surface and encloses alternating layers of the storage material andthe flow passage.Each layer of the storage material is an aluminum slab of width ? = 0.05 m, which is at aninitial temperature of 25°C. Consider conditions for which the storage unit is charged bypassing a hot gas through the passages, with the gas temperature and the convectioncoefficient assumed to have constant values of ?∞ = 600°C and ℎ = 100 W/m2– Kthroughout the channel. How long will it take to achieve 75% of the maximum possibleenergy storage? What is the temperature of the aluminum at this time?arrow_forwardA cylinder 6”in diameter and 18”long is suspended horizontally in a largeroom. The air and wall surfaces of the room are at a temperature of 60 °Fwhile the surface temperature of the cylinder is 440 °F. Compute (a) thesurface coefficient due to free convection, (b) the heat transferred by freeconvection (neglecting the end areas), (c) the surface coefficient due toradiation if the surface emissivity is 0.75, and (d) the total heattransferred by free convection and radiation (neglecting end areas)arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning