Q1. Double glazed window is made of 2 glass panes of 6 mm thick each with an air gap of 6 mm betweenthem. Assuming that the air layer is stagnant and only conduction is involved, determine the thermalresistance and overall heat transfer coefficient. The inside is exposed to convection with h - 15 W/m?. Kand the outside to 9 W/m'. K. Compare the values with that of a single glass of 12 mm thickness. Theconductivity of the glass - 1.4 W/m. K and that for air is 0.025 W/m. K.h, = 15 Wim'kGlass Air gap Giass14 Wmk=0.025 WimKh Wim'k6 mmQ2. A 2m long, 0.3cm diameter electrical wire extends across a room at 15°C. Heat is generated in thewire as a result of resistance heating, and the surface temperature of the wire is measured to be 152°C insteady operation. Also, the voltage drop and electric current through the wire are measured to be 60 Vand 1.5 A, respectively. Disregarding any heat transfer by radiation, determine the convection heattransfer coefficient for heat transfer between the outer surface of the wire and the air in the room.

as per rule solved 1st question

Q1. Double glazed window is made of 2 glass panes of 6 mm thick each with an air gap of 6 mm between them. Assuming that the air layer is stagnant and only conduction is involved, determine the thermal resistance and overall heat transfer coefficient. The inside is exposed to convection with h-15 W/m. K and the outside to 9 Wim'. K. Compare the values with that of a single glass of 12 mm thickness. The conductivity of the glass - 1.4 Wim. K and that for air is 0.025 Wim. K. I5 Wim gGlass Glass 14 WK 0.025 Wim 6 mm 6 mm

Q1. Double glazed window is made of 2 glass panes of 6 mm thick each with an air gap of 6 mm between them. Assuming that the air layer is stagnant and only conduction is involved, determine the thermal resistance and overall heat transfer coefficient. The inside is exposed to convection with h-15 W/m. K and the outside to 9 Wim'. K. Compare the values with that of a single glass of 12 mm thickness. The conductivity of the glass - 1.4 Wim. K and that for air is 0.025 Wim. K. I5 Wim gGlass Glass 14 WK 0.025 Wim 6 mm 6 mm

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.3P: 1.3 A furnace wall is to be constructed of brick having standard dimensions of Two kinds of...

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Question

Q1. Double glazed window is made of 2 glass panes of 6 mm thick each with an air gap of 6 mm between
them. Assuming that the air layer is stagnant and only conduction is involved, determine the thermal
resistance and overall heat transfer coefficient. The inside is exposed to convection with h - 15 W/m?. K
and the outside to 9 W/m'. K. Compare the values with that of a single glass of 12 mm thickness. The
conductivity of the glass - 1.4 W/m. K and that for air is 0.025 W/m. K.
h, = 15 Wim'k
Glass Air gap Giass
14 Wmk
=0.025 WimK
h Wim'k
6 mm
Q2. A 2m long, 0.3cm diameter electrical wire extends across a room at 15°C. Heat is generated in the
wire as a result of resistance heating, and the surface temperature of the wire is measured to be 152°C in
steady operation. Also, the voltage drop and electric current through the wire are measured to be 60 V
and 1.5 A, respectively. Disregarding any heat transfer by radiation, determine the convection heat
transfer coefficient for heat transfer between the outer surface of the wire and the air in the room.

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Heat transfer