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An aluminium sphere weighning 5.5 kg and initially at a temperature of 290°C is suddenly immersed in a fluid at 15°C. The convective heat transfer coefficient is 58 W/m²K.
An aluminium sphere weighning 5.5 kg and initially at a temperature of 290°C is suddenly immersed in a fluid at …
fluids

heat and mass transfer

Mech_59 Asked on 29th September 2023 in Mechanical engineering.
- 1K views
- 1 answers
- 0 votes
A metallic rod (k = 32 W/m°C), 10 mm in diameter and 80 mm long, with an insulated end is to be used as spine. It is expossed to sourrounding with a temperature of 80°C and a heat transfer coefficient 55 W/m²°C.
A metallic rod (k = 32 W/m°C), 10 mm in diameter and 80 mm long, with an insulated end is …
fluids

heat and mass transfer

Mech_59 Asked on 29th September 2023 in Mechanical engineering.
- 594 views
- 1 answers
- 0 votes
What is the efficciency of a plate fin of length L = 1.5 cm and thickness 2 mm, (if k = 210 W/m-K, h = 285 W/m²k).
What is the efficciency of a plate fin of length L = 1.5 cm and thickness 2 mm, (if k …
fluids

heat and mass transfer

Mech_59 Asked on 28th September 2023 in Mechanical engineering.
- 2K views
- 1 answers
- 0 votes
It is required to heat oil to about 500°C for quenching purpose. A ladder is used in the furnace. The section of ladder is (10 x 20) mm². The sourroundings are at 27°C.
It is required to heat oil to about 500°C for quenching purpose. A ladder is used in the furnace. The …
fluids

heat and mass transfer

Mech_59 Asked on 28th September 2023 in Mechanical engineering.
- 2K views
- 1 answers
- 0 votes
A fin has 5 mm diameter and 100 mm length. The thermal conductivity of fin material is 400 Wm^-1K^-1.
A fin has 5 mm diameter and 100 mm length. The thermal conductivity of fin material is 400 Wm^-1K^-1. One …
fluids

heat and mass transfer

Mech_59 Asked on 28th September 2023 in Mechanical engineering.
- 1K views
- 1 answers
- 0 votes
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.
- 2K 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.
- 2K 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.
- 550 views
- 1 answers
- 0 votes

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