(a) Differentiate between free and forced convection with examples. (b) Define Nusselt (Nu), Prandtl (Pr), Reynolds (Re) and Grashof (Gr) dimensionless numbers. State which numbers are used in free and forced convection to determine the heat transfer coefficient. (c) A vertical pipe 90 mm diameter and 2.5 m height is maintained at a constant temperature of 125 °C, The pipe is surrounded by still atmospheric air at 25 °C, Find heat loss by natural convection. Properties of water at 75 °C: Density = 1.0145 kg/m³ Kinematic viscosity = 20.55 x10-6 m²/s Prandtl number (Pr) = 0.693 %3D Thermal conductivity (k) = 30.06 x 10-3 W/m K g ×ß x L³ × AT V2 Grashof number, Gr = Nu = 0.10(GrPr)0.333

(a) Differentiate between free and forced convection with examples. (b) Define Nusselt (Nu), Prandtl (Pr), Reynolds (Re) and Grashof (Gr) dimensionless numbers. State which numbers are used in free and forced convection to determine the heat transfer coefficient. (c) A vertical pipe 90 mm diameter and 2.5 m height is maintained at a constant temperature of 125 °C, The pipe is surrounded by still atmospheric air at 25 °C, Find heat loss by natural convection. Properties of water at 75 °C: Density = 1.0145 kg/m³ Kinematic viscosity = 20.55 x10-6 m²/s Prandtl number (Pr) = 0.693 %3D Thermal conductivity (k) = 30.06 x 10-3 W/m K g ×ß x L³ × AT V2 Grashof number, Gr = Nu = 0.10(GrPr)0.333

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

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Question

Q1
(a) Differentiate between free and forced convection with examples.
(b) Define Nusselt (Nu), Prandtl (Pr), Reynolds (Re) and Grashof (Gr)
dimensionless numbers. State which numbers are used in free and forced
convection to determine the heat transfer coefficient.
(c) A vertical pipe 90 mm diameter and 2.5 m height is maintained at a
constant temperature of 125 °C, The pipe is surrounded by still
atmospheric air at 25 °C. Find heat loss by natural convection.
Properties of water at 75 °C:
Density =
1.0145 kg/m³
Kinematic viscosity = 20.55 x10-6 m²/s
Prandtl number (Pr) = 0.693
Thermal conductivity (k) = 30.06 x 10-3 W/m K
g × ß x L³ × AT
Grashof number, Gr =
V²
Nu =
0.10(GrPr)0.333

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