12-41 Consider a circular grill whose diameter is 0.3 m. The bottom of the grill is covered with hot coal bricks at 1100 K, while the wire mesh on top of the grill is covered with steaks initially at 5°C. The distance between the coal bricks and the steaks is 0.20 m. Treating both the steaks and the coal bricks as blackbodies, determine the initial rate of radiation heat transfer from the coal bricks to the steaks. Also, determine the initial rate of radiation heat transfer to the steaks if the side opening of the grill is covered by aluminum foil, which can be approx-

12-41 Consider a circular grill whose diameter is 0.3 m. The bottom of the grill is covered with hot coal bricks at 1100 K, while the wire mesh on top of the grill is covered with steaks initially at 5°C. The distance between the coal bricks and the steaks is 0.20 m. Treating both the steaks and the coal bricks as blackbodies, determine the initial rate of radiation heat transfer from the coal bricks to the steaks. Also, determine the initial rate of radiation heat transfer to the steaks if the side opening of the grill is covered by aluminum foil, which can be approx-

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.

Chapter11: Heat Transfer By Radiation

Section: Chapter Questions

Problem 11.39P

See similar textbooks

Similar questions

Determine the rate of radiant heat emission in watts per square meter from a blackbody at (a) 15C, (b) 600C, and (c) 5700C.
Three thin sheets of polished aluminum are placed parallel to each other so that the distance between them is very small compared to the size of the sheets. If one of the outer sheets is at 280C and the other outer sheet is at 60C, calculate the temperature of the intermediate sheet and the net rate of heat flow by radiation. Convection can be ignored.
According to an Atomic Energy Commissionreport, a hydrogen bomb can be approximated as a large fireball at a temperature of 7200 K. You are to assess theimpact if such a bomb exploded 5 km above a city. Assumethe diameter of the fireball to be 1 km, and the blast to last15 s. Investigate the level of radiation energy people, plants,and houses will be exposed to and how adversely they will beaffected by the blast.
The basal metabolic rate isthe rate at which energy is produced in the body when a person is at rest.A 75 kg (165 lb) person of height 1.83 m (6 ft) has a body surface areaof approximately 2.0 m2. (a) What is the net amount of heat this personcould radiate per second into a room at 18°C (about 65°F) if his skin’ssurface temperature is 30°C? (At such temperatures, nearly all the heatis infrared radiation, for which the body’s emissivity is 1.0, regardless ofthe amount of pigment.) (b) Normally, 80% of the energy produced bymetabolism goes into heat, while the rest goes into things like pumpingblood and repairing cells. Also normally, a person at rest can get rid ofthis excess heat just through radiation. Use your answer to part (a) to findthis person’s basal metabolic rate.
Two large plates are maintained at a temperature of 910 K and 500 K respectively. Each plate has area of 100cm^2. Compare the net heat exchange between the plates for the following cases. a. Both plates are black b. Plates have an emissivity of 0.5
The furnace water walls of a steam generator having a capacity of 9 kg/s, consist of 130 half radiant tubes of 30 mm diameter spaced by 75 mm center distance and 15 m long each, and a temperature of 450°C. If the latent heat of vaporization of the water is 2200 kJ/kg and 25% of the steam latent heat is carried by radiation. For the fuel, emissivity=0.9, sigma=5.67x10-8 W/m2.K4. Determine the temperature of the flue gases at the outlet of the furnace. Select one: a. 1414 °C b. 735 K c. 1141 K d. 1141 °C
A concentric cylinder with outer and inner radii of 8 cm and 6 cm, respectively, has length of 1 mwith emissivities of the inner and outer radii at 0.4 and 0.6, respectively. Determine the heattransfer from the outer cylinder to the inner cylinder if the inner and outer temperatures are400K and 600K, respectively.
2.A person stands in front of a fire at 650°C in a room where air is at 5°C. Assuming the body temperature to be 37°C and a connection coefficient of 6 W/m²K, the area exposed to convection as 0.6m2, determine the net heat flow from the body. The fraction of radiation from the fire of 1m² are reaching the person is 0.01
Two parallel rectangular black plates 0.5 m by 2.0 m are spaced 1.0 m apart. One plate is maintained at 1000 °C and the other at 2000 °C. What is the net radiant heat exchange between the two plates? show how to get the F12
Explain the following terms related to the radiation mode of heat transfer: Black body, emissive power, monochromatic emissive power, gray body, white body and opaque body.
Sipho’s mother is making a fire in the stove inside a shack using coal. A fan is used to extract the flue gasfrom the fire via a chimney made of zinc material. The wall thickness of Chimney is L=4mm and the walltemperature of the chimney on the flue gas side is T_si=60˚C. Sipho, playing outside next to the chimneyexperiences an ambient temperature of 20˚C. The surrounding temperature is T_sur=35˚C and the emissivityis ε=0.95. Assume the convection coefficient is 20W/m2K and the chimney is grey material.Under these conditions determine the outer surface (air side) temperature T_so=? of the chimney.