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Heat is generated in a 8 cm diameter spherical radioactive material whose thermal conductivity is 25 W/m.°C uniformly at a rate of 15×10^6 W/m³.
Heat is generated in a 8 cm diameter spherical radioactive material whose thermal conductivity is 25 W/m.°C uniformly at a …
fluids

heat and mass transfer

Mech_59 Asked on 8th September 2023 in Mechanical engineering.
- 1K views
- 1 answers
- 0 votes
A 2 kW resistance heater wire whose thermal conductivity is k = 15 W/m.K has a diameter of D = 4 mm and a length of L = 0.5 m, and is used to boil water. If the outer surface temperature of the resistance wire is T_s = 105°C, What is the temperature at the center of the wire?
A 2 kW resistance heater wire whose thermal conductivity is k = 15 W/m.K has a diameter of D = …
fluids

heat and mass transfer

Mech_59 Asked on 8th September 2023 in Mechanical engineering.
- 1K views
- 1 answers
- 0 votes
The average heat produced by orange ripening is estimated to be 300W/m². Taking the average size of an orange to be 8 cm and assuming it to be a sphere with K = 0.15 W/m K, calculate the temperature at the center of the orange if its surface temperature is 10°C.
The average heat produced by orange ripening is estimated to be 300W/m². Taking the average size of an orange to …
fluids

heat and mass transfer

Mech_59 Asked on 7th September 2023 in Mechanical engineering.
- 1K views
- 1 answers
- 0 votes
For the three-dimensonal object shown in the figure below, five faces are insulated. The sixth face (PQRS), which is not insulated, interacts thermally with the ambient, with a convective heat transfer coefficcient of 10 W/m²K.
For the three-dimensonal object shown in the figure below, five faces are insulated. The sixth face (PQRS), which is not …
fluids

heat and mass transfer

Mech_59 Asked on 7th September 2023 in Mechanical engineering.
- 1K views
- 1 answers
- 0 votes
Nichrome, having a resistivity of 100 µΩ cm is to be used as a heating element in a 10 kW heater. The Nichrome surface temperature should not exceed 1220°C.
Nichrome, having a resistivity of 100 µΩ cm is to be used as a heating element in a 10 kW …
fluids

heat and mass transfer

Mech_59 Asked on 7th September 2023 in Mechanical engineering.
- 413 views
- 1 answers
- 0 votes
Heat is being transferred connotatively from a cylindrical nuclear reactor fuel rod of 50 mm diamater to water at 75°C, under steady state condition, the rate of heat generation within the fuel element is 10^6 W/m³ and the convective heat transfer coefficient is 1 kW/m²K.
Heat is being transferred connotatively from a cylindrical nuclear reactor fuel rod of 50 mm diamater to water at 75°C, …
fluids

heat and mass transfer

Mech_59 Asked on 14th August 2023 in Mechanical engineering.
- 405 views
- 1 answers
- 0 votes
An electrical transmission line made of a 25mm annealed copper wire carries 200 A and has a resistance of 0.4 x 10^-4 Ω/cm length. Determine the heat tansfer coeffficient between the wire surface and the ambient air and the maximum temperature in the wire.
An electrical transmission line made of a 25mm annealed copper wire carries 200 A and has a resistance of 0.4 …
fluids

heat and mass transfer

Mech_59 Asked on 14th August 2023 in Mechanical engineering.
- 954 views
- 1 answers
- 0 votes
A plane wall 10 cm thick generates heat at the rate of 4×10^4 W/m³ when an electric current is passed through it. Determine: (a) the surface temperaure (b) the maximum temperatrure in the wall.
A plane wall 10 cm thick generates heat at the rate of 4×10^4 W/m³ when an electric current is passed …
fluids

heat and mass transfer

Mech_59 Asked on 14th August 2023 in Mechanical engineering.
- 805 views
- 1 answers
- 0 votes
The variation of temperature in a plane wall is determined to be T(x) = 65x + 25 where x is in m and T is in °C. What is the thickness of the wall for a 13 °C temp drop?
The variation of temperature in a plane wall is determined to be T(x) = 65x + 25 where x is …
fluids

heat and mass transfer

Mech_59 Asked on 14th August 2023 in Mechanical engineering.
- 473 views
- 1 answers
- 0 votes
A 30 mm OD pipe is to be insulated with asbestos having a thermal conductivity of 0.1 W/mK. The convective heat transfer coefficient is 5W/m²K. What is the critical radius of insulation for this pipe?
A 30 mm OD pipe is to be insulated with asbestos having a thermal conductivity of 0.1 W/mK. The convective …
fluids

heat and mass transfer

Mech_59 Asked on 14th August 2023 in Mechanical engineering.
- 757 views
- 1 answers
- 0 votes

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