16-67E A 2-in-diameter spherical ball whose surface ismaintained at a temperature of 170°F is suspended in the middleof a room at 70°F. If the convection heat transfer coefficient is15 Btu/h-ft².°F and the emissivity of the surface is 0.8, deter-mine the total rate of heat transfer from the ball.16-68 An 800-W iron is left on the iron board with itsbase exposed to the air at 20°C. The convection heat trans-fer coefficient between the base surface and the surround-ing air is 35 W/m².K. If the base has an emissivity of0.6 and a surface area of 0.02 m², determine the temperatureof the base of the iron. Answer: 601°CIron800 WFIGURE P16-6820°C

“Since you have posted multiple questions, we will provide the solution only to the first question…

16-67E A 2-in-diameter spherical ball whose surface is maintained at a temperature of 170°F is suspended in the middle of a room at 70°F. If the convection heat transfer coefficient is 15 Btu/h ft².°F and the emissivity of the surface is 0.8, deter- mine the total rate of heat transfer from the ball.

16-67E A 2-in-diameter spherical ball whose surface is maintained at a temperature of 170°F is suspended in the middle of a room at 70°F. If the convection heat transfer coefficient is 15 Btu/h ft².°F and the emissivity of the surface is 0.8, deter- mine the total rate of heat transfer from the ball.

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

16.- Consider a person standing in a breezy room at 22°C. Determine the total rate of heat transfer from this person if the exposed surface area and the average outer surface temperature of the person are 1.6 m2 and 29°C, respectively, and the convection heat transfer coefficient is 10 W/m2.K.: (* l
16-22 The inner and outer surfaces of a 0.5-cm thick 2-m X 2-m window glass in winter are 10°C and 3°C, respectively. If the thermal conductivity of the glass is 0.78 W/m-K, determine the amount of heat loss through the glass over a period of 5 h. What would your answer be if the glass were 1 cm thick? Answers: 78.6 MJ, 39.3 MJ 16-23 Reconsider Prob. 16-22. Using an appropriate software, plot the amount of heat loss through the glass as a function of the window glass thickness in the range of 0.1 cm to 1.0 cm. Discuss the results.
H.W1 Consider a person standing in a room. Determine the total rate of heat transfer from this person if the exposed surface area and temperature are 1.6m² and 29°C, respectively. Assume that the convection heat transfer coefficient is 6W/m².K and the emissivity of a person is 0.95. The air temperature in the room is maintained at 22°C at all times of the year. In summer, the wall and ceiling temperatures are observed to be 25°C, while in winter, they are 10°C. Ans: Qrotal =104.4 W In Summer Qrotal =231.3 W In Winter
Question 1 An electric current of 6.4 A passing through a resistor has a measured voltage of 9V across the resistor. The resistor is cylindrical with a diameter of 2.5 cm and length of 15 cm. The resistor has a uniform temperature of 115°C and the room air temperature is 23°C. Assuming that heat transfer by radiation is negligible, determine the heat transfer coefficient by convection.
An uninsulated steam pipe passes through a room in which the air and walls are at 25°C. The outside diameter of the pipe is 88 mm, and its surface temperature and emissivity are 200°C and 0.80 respectively. If the coefficient associated with free convection heat transfer from the surface to the air is 15W/m2-k, what is the rate of heat loss for a 5 meter pipe? Round your answer to 2 decimal places.
The composite wall of an oven consists of three materials, with thermal conductivity, KA = 20 W/ m. kg = 30 W/ m. K, kc = 50 W/m. K, and known thickness, LA =30 cm,, LB =20 cm and Lc = 15 cm. Under steady- state operating conditions, measurements reveal an outer surface temperature of Tso =20°C, an inner surface temperature of Tsi = 600°C. The inside and outside convection coefficients are 25 W/m2. K and 15 W/m2. K. The wall repeats itself every 25 cm distance in the vertical direction and if the wall is 1-m deep and 0.25-m high, then assume an area of 0.25m2 for all your calculations. Find the total resistance. T- 600°c T 20°c Air T, h Select one: O a. 10.525°C/W O b. 5.526°C/W O c. 0.526°C/W
The diagram below illustrates a simplified version of the Jet Propulsion Laboratory's 25-ft space simulator chamber. Within it, tests are run for deep space probes and their components. In this particular experiment, a sensor assembly with its housing is placed inside. The sensor-housing electronics create heat such that q=3181.0 W exits the assembly's top surface into the chamber. The chamber itself is under vacuum, and its walls are at cryogenic temperatures to simulate conditions in space. Surfaces 1 and 2 are flat. Assume they are flush. The top surface of the chamber, Surface 4, can be approximated as a perfectly insulated, flat ceiling. The exposed surface of the floor, Surface 2, is a black, donut- shaped surface. Additional surface information can be seen below, including various parameters and dimensions. Assume all surfaces are opaque and diffuse, and conditions are at steady-state. PARAMETERS & DIMENSIONS Surface 1: A = 7.07 m²; diameter d; = 3 m; &₁ = 0.5; Surface 2: A₂ =…
Question 11 Not yet answered Marked out of 2.50 P Flag question A cylindrical resistor element on a circuit board dissipates 0.23 W of power in an environment at 28°C. The resistor is 1.3 cm long, and has a diameter of 3 mm. Assuming heat to be transferred uniformly from all surfaces. What is the surface temperature of the resistor for a combined convection and radiation heat transfer coefficient of 13 W/m .°C? Select one: A. 157.46 B. 190.22 C. 168.73 D. 130.79 E. 143.48
Ton
The thermal conductivities of human tissues vary greatly. “Fat” and “skin” have conductivities of approximately 0.200 W /m 0K and 0.0200 W /m 0K, respectively, while other “tissues” inside the body have conductivities of approximately 0.500 W /m 0 Assume that between the core region of the body and the skin surface lies a “skin” layer of 1.00mm, a “fat” layer of 0.500 cm., and 3.20 cm. layer of other “tissues”. A)Find the R-factor for each of these three layers, and the R-factor for all layers taken together
= A processing plant is convectively heating a solid half-sphere of radius of 12 cm made of pure aluminum (k 237 W/m-K) by placing it on an insulated surface as shown in Fig. 1. It is exposed to hot exhaust gas at 300°C with a convection coefficient of 180 W/m².K. Is the lumped capacitance approximation valid? Figure 1: Half-sphere
The inner and outer surface temperatures of a 1-D slab of material, with a thickness of 4.2 inches, are 180.0°F and 63.0°F respectively. Determine the heat flux through the material in units of BTU/(hr-ft2) if the material is: a) Stainless steel, k = 8.95 BTU/(hr-ft-°F) b) Aluminum, k = 131 BTU/(hr-ft-°F) c) Soil, k = .30 BTU/(hr-ft-°F)