Consider two rectangular surfaces perpendicular to each other with a common edge which is 1.6 mlong. The horizontal surface is 0.8 m wide and the vertical surface is 1.2 m high. The horizontal surface has anemissivity of 0.75 and is maintained at 400 K. The vertical surface is black and is maintained at 550 K. The backsides of the surfaces are insulated. The surrounding surfaces are at 290 K, and can be considered to have anemissivity of 0.85. Determine the net rate of radiation heat transfers between the two surfaces, and betweenthe horizontal surface and the surroundings.A. 2245 W, 725 WT2 = 275 KE2 = 1T; = 300 KEz = 1%3DB. 1245 W, 725 WC. 1245 W, 825 WD. 2245 W, 825 WDTj = 425 KEj = 1-)

1. Steady operating conditions exist 2. The surfaces are opaque, diffuse, and gray 3. Convection…

Answered: emissivity of 0.85. Determine the net…

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

Two infinite black plates at 500°C and 100°C exchange heat by radiation. If another perfectly black plate is placed between the 500°Cand 100°C plates, what is the temperature of the center plate? K
A 2-m-internal-diameter double-walled spherical tank is used to store iced water at 0°C. Each wall is 0.5 cm thick, and the 1.5-cm-thick air space between the two walls of the tank is evacuated in order to minimize heat transfer. The surfaces surrounding the evacuated space are polished so that each surface has an emissivity of 0.15. The temperature of the outer wall of the tank is measured to be 20°C. Assuming the inner wall of the steel tank to be at 0°C, determine (a) the rate of heat transfer to the iced water in the tank and (b) the amount of ice at 0°C that melts during a 24-h period.
2. Consider steady heat transfer between two large parallel plates at constant temperatures of T1 = 295 K and T2 = 155 K that are L = 2 cm apart. Assuming the surfaces to be black, determine the rate of heat transfer between the plates per unit surface area assuming the gap between the plates is (a) filled with atmospheric air,(k = 0.01979 W/m- o C) (b) evacuated,(c) filled with superinsulation having an apparent thermal conductivity of 0.00015 W/m · °C.
Determine the net heat transferred by radiation from a 9-ft square hot plate to a cold plate of equal size that are parallel to one another, and 20 ft apart if the hot plate is oxidized steel at 700°F and the cold plate is dull brass at 175°F.Ans: 2,863 Btu/hr
This experiment is conducted to determine the emissivity of a certain material. A long cylindrical rod of diameter D₁ = 0.01 m is coated with this new material and is placed in an evacuated long cylindrical enclosure of diameter D₂ = 0.1 m and emissivity 2 = 0.95, which is cooled externally and maintained at a temperature of 200 K at all times. The rod is heated by passing the electric current through it. When steady operating conditions are reached, it is observed that the rod is dissipating electric power at a rate of 16 W per unit of its length, and its surface temperature is 600 K. Based on these measurements, determine the emissivity of the coating on the rod. The emissivity of the coating on the rod is 0.1165
A furnace that has a 40-cm * 40-cm glass window can be considered to be a blackbody at 1200 K. If the transmissivity of the glass is 0.7 for radiation at wavelengths less than 3 mm and zero for radiation at wavelengths greater than 3 mm, determine the fraction and the rate of radiation coming from the furnace and transmitted through the window.
Two surfaces make up an enclosure where surface 1 is flat and has area A1,temperature T1 and emissivity 1. Surface 2 is black and has temperature T2. Showthat the net power transfer rate (net heat flux) in W/m2 at surface 1 is given by
Two parallel discs pf 1m diameter are situated 2m part in surroundings at a temparature 20 C. The inner side of one disc has an emissivity of 0.5 and is manintained at 500 C by electric resistance heating and the outer side of the disc is well insulated. The other disc is Two parallel discs of 1m diameter are situated 2m apart in surroundings at a temperature of 20 oC. The inner side of one disc has an emissivity of 0.5 and is maintained at 500 oC by electric resistance heating and the outer side of the disc is well insulated. The other disc is open to radiation on both sides and reaches an equilibrium temperature. Calculate this equilibrium temperature and the heat flow rate from the first disc, assuming heat transfer is entirely by radiation.
A particular furnace is shaped like a section of a cone. The top surface of the furnace is uniformly heated by a resistance heater. During operation, the top surface is measured to be 800 K and the power supplied to the resistance heater is 1750 W/m². The sidewall of the furnace is perfectly insulated with & = 0.2. If the emissivity of the top and bottom surfaces are ε = 0.5 and ε = 0.7, respectively, determine the temperatures of the sidewall and the bottom surface of the furnace. A₁ A2 A3 →→D₂ = 20 mm D₁ = 40 mm L = 50 mm
Two very large parallel plates are kept at uniform temperatures T1=800 K and T2=500 K, and have emissivities ε1=0.2 y ε2=0.7, respectively, as shown in the figure. Determine the net rate of radiation heat transfer between the two surfaces per unit surface area of the plates.
A one-dimensional plane wall is exposed to convective and radiative conditions at x = 0. The ambient and surrounding temperatures are T. exposed surface is a = 0.78. Determine the convective and radiative heat fluxes to the wall at x = 0, both in W/m2, if the wall surface = 20°C and Tsur = 40°C, respectively. The convection heat transfer coefficient is h = 20 W/m²-K, and the absorptivity of the temperature is T, = 30°C. Assume the exposed wall surface is gray, and the surroundings are large. gbonv i W/m? Tad i W/m2
Determine the heat flow between the roof and floor of 4 x 3 m size of a furnace of 4 m x 4 m x 3 m size when the roof is at 1200 K and the floor is maintained at 600 K, with the other surfaces non absorbing and reradiating. The surface emissivity of the hotter surface is 0.8 and that of the cooler surface 0.6.

SEE MORE QUESTIONS

Recommended textbooks for you

Elements Of Electromagnetics

Mechanical Engineering

ISBN:

9780190698614

Author:

Sadiku, Matthew N. O.

Publisher:

Oxford University Press

Mechanics of Materials (10th Edition)

Mechanical Engineering

ISBN:

9780134319650

Author:

Russell C. Hibbeler

Publisher:

PEARSON

Thermodynamics: An Engineering Approach

Mechanical Engineering

ISBN:

9781259822674

Author:

Yunus A. Cengel Dr., Michael A. Boles

Publisher:

McGraw-Hill Education

Elements Of Electromagnetics

Mechanical Engineering

ISBN:

9780190698614

Author:

Sadiku, Matthew N. O.

Publisher:

Oxford University Press

Mechanics of Materials (10th Edition)

Mechanical Engineering

ISBN:

9780134319650

Author:

Russell C. Hibbeler

Publisher:

PEARSON

Thermodynamics: An Engineering Approach

Mechanical Engineering

ISBN:

9781259822674

Author:

Yunus A. Cengel Dr., Michael A. Boles

Publisher:

McGraw-Hill Education

Control Systems Engineering

Mechanical Engineering

ISBN:

9781118170519

Author:

Norman S. Nise

Publisher:

WILEY

Mechanics of Materials (MindTap Course List)

Mechanical Engineering

ISBN:

9781337093347

Author:

Barry J. Goodno, James M. Gere

Publisher:

Cengage Learning

Engineering Mechanics: Statics

Mechanical Engineering

ISBN:

9781118807330

Author:

James L. Meriam, L. G. Kraige, J. N. Bolton

Publisher:

WILEY

SEE MORE TEXTBOOKS

emissivity of 0.85. Determine the net rate of radiation heat transfers between the two surfaces, and between the horizontal surface and the surroundings.