A group of 25 power transistors, dissipating 1.5 W each, are to be cooled by attaching them to a black-anodized square aluminum plate and mounting the plate on the wall of a room at 30°C. The emissivity of the transistor and the plate surfaces is 0.9. Assuming the heat transfer from the back side of the plate to be negligible and the temperature of the surrounding surfaces to be the same as the air temperature of the room, determine the size of the plate if the average surface temperature of the plate is not to exceed 50°C.

Q: Consider a person whose exposed surface area is 1.7 m², emissivity is 0.7, and surface temperature…

A: (a) Write the given data. A=1.7 m2ε=0.7Ts=32 °C=305 KTw=300 K

Q: Consider a large plane wall of thickness L = 0.8 ft and thermal conductivity K=1.2 Btu/h-ft-*F. The…

A: GivenL=0.8 ftk=1.2 Btu/h ftoFε=0.80α=0.60T1=524 Rq˙solar=300 Btu/h ft2Tsurr=0Kσ=0.1714×10-8 Btu/h…

Q: A 4-mm-diameter sphere at 50°C is covered by a 1-mm-thick plastic insulation (k=0.13 W/m°C). The…

A: Given data as per the question Diameter of sphere =4 mm The thickness of insulation =1 mm k=0.13…

Q: Give the boundaries of the indicated valve 5.5 milliliters

A: Answer: 5.45-5.55

Q: An industrial spherical oven has 2.8 m diameter. It is placed in a factory floor where the air…

A: Given:  D = 2.8 m,    Therefore    R = 1.4 m Ta = 25 oC = 25 +273 = 298 K Qpeak load = 905 kW Ts,…

Q: A man is working in a chamber enclosed with black walls. If the air around the worker is at 20oC,…

A: Given data: Tw=100°C=373 KTair=20°Ch=15 W/m2°Cε=0.8 Need to determine the temperature will the…

Q: A solar collector consists of a long duct through which air is blown; its cross section forms an…

A: Geometry:Length of duct (L) = 1 mSide length of equilateral triangle cross-section (a) = 1 mSurface…

Q: A 50-cm x 50-cm circuit board that contains 121 square chips on one side is to be cooled by combined…

A:

Q: A 2-m-diameter thin-walled stainless steel spherical tank is filled with chemicals undergoing a…

A: Given data as per question Diameter =2 m Surface temperature = 500 c Air temperature  = 200 c…

Q: An asphalt playground is heated in the sun all day; by sundown it reaches a temperature of 45degC.…

A: Emissivity (∈): It is defined as the ratio between total hemispherical emissive power of a non…

Q: A flat-plate collector with one glass cover is placed in horizontal. The absorber plate temperature…

A:

Q: Consider steady heat transfer between two large parallel plates at constant temperatures T1 = 300 K…

A:

Q: A 1.2 m wide and 5.1 m long solar collector is mounted to a roof.  Now the average surface…

A: Given width of solar collector w=1.2 m Length of solar collector l=5.1 m Average surface temperature…

Q: 2. (a) Consider a 25-cm-diameter spherical ball at 700 K suspended in air and assume the…

A: Note - As per our guidelines we are supposed to answeronly one question. Kindly repost other…

Conduction and Convection

When energy travels from one object to another it is said to have undergone heat transfer. Heat transfer is nothing but the transfer of thermal energy or internal energy from one thing to another, like e.g., when a vessel with water, kept on top of a burner, heats up because of the flame underneath it.