Liquid oxygen, which has a boiling into of 90 K and a latent heat of vaporization of 214 kJ/kg, is stored in a spherical container whose outer surface is of 500-mm diameter and at a temperature of
(a) If the surface emissivity is 0.20 and the heat transfer coefficient associated with free convection at the outer surface of the container is
(b) Moisture in the ambient air will result in frost formation on the container, causing the surface emissivity to increase. Assuming the surface temperature and convection coefficient to remain at
Want to see the full answer?
Check out a sample textbook solutionChapter 1 Solutions
Fundamentals of Heat and Mass Transfer
- 1.13 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_forwardDetermine the power requirement of a soldering iron in which the tip is maintained at 400C. The tip is a cylinder 3 mm in diameter and 10 mm long. The surrounding air temperature is 20C, and the average convection heat transfer coefficient over the tip is 20W/m2K. The tip is highly polished initially, giving it a very low emittance.arrow_forwardA horizontal steam pipe with an outside diameter of 60.0 mm passes through a large room whose walls are at a temperature of 298 K. The outer surface of the pipe wall has a surface temperature of 443 K and an emissivity of 0.8. The air temperature in the room is 303 K. Calculate the rate of heat loss per unit length of the pipe by radiation and natural convection.arrow_forward
- The production line of a special biscuit at 30 ̊C and 1 atm has a 0.8 X 0.8 (m) square plate. One side of the plate is maintained at a temperature of 100 ̊C, while the other side is insulated. Determine the rate of heat transfer from the plate by natural convection if the plate (i) Is horizontal with the hot surface facing down; (ii) Is horizontal with the hot surface facing up; Data: The properties of air at the film temperature are: thermal conductivity, k= 0.0279 W/m.k); kinematic viscosity= 1.815 x 10-5 m2/s; Pr = 0.709arrow_forwardA small, oxidized, horizontal metal tube with an OD of 0.0254 m (1 in.), 0.61 m (2 ft) long, and with a surface temperature at 588 K (600°F) is in a very large furnace enclosure with fire-brick walls and the surrounding air at 1088 K (1500°F). The emissivity of the metal tube is 0.60 at 1088 K and 0.46 at 588 K. Calculate the heat transfer to the tube by radiation using SI units and AES units.arrow_forwardA hot liquid (cp = 1000 J/kg∙K) flows at a flow rate of 0.05 kg/s inside a copper pipe with an inner diameter of 45 mm and a wall thickness of 5 mm. At the pipe exit, the liquid temperature decreases by 10°C from its temperature at the inlet. The outer surface of the 5-m-long copper pipe is black oxidized, which subjects the outer surface to radiation heat transfer. The air temperature surrounding the pipe is 10°C. Assuming that the properties of air can be evaluated at 35°C and 1 atm pressure, determine the outer surface temperature of the pipe. Is 35°C an appropriate film temperature for evaluation of the air properties?arrow_forward
- The small horizontal metal tube with an OD of 0.05 m, 0.1 m long, and with a surface temperature of 25 C is in a very large furnace enclosure with firebrick walls and the surrounding air at 500 C. The emissivity of the metal tube is 0.6. Calculate the net heat transfer to the tube by radiation in Watts.arrow_forwardFor the Convective Heat Transfer experiment, describe the difference in the procedures: Natural or FreeConvection and Forced convection. What makes the FORCED convection experiment as FORCED? Explain which, in your consideration should give the higher heat transfer rate? And REASON why? Did your results support your consideration?arrow_forwardDifferentiate between free and forced convection with examples.arrow_forward
- (a) If the cost of producing the hot water is $0.10 per kWh, what is the representative daily costof heat loss from an uninsulated pipe to the air per meter of pipe length? The convectionresistance associated with water flow in the pipe may be neglected.(b) Determine the savings associated with application of a 10-mm-thick coating of urethaneinsulation (k = 0.026 W/m-K) to the outer surface of the pipe.arrow_forwardCalculate the convection heat loss from the top and bottom of a flat 1 m squarehorizontal restaurant grill heated to 227°C in ambient air at 27°C.arrow_forwardA circular grill of diameter 0.35 m and emissivity 0.7 is maintained at a constant surface temperature of 130 °C in a horizontal position. What electrical power is required when the room air and surroundings are at 24 °C?arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning