A house has a composite wall of plywood, fiberglass insulation, and plaster board, as indicated in Fig. On a cold winter day the convection heat transfer coefficients are ho 60 W/m2.K and h= 30 W/m².K. The total wall surface area is 350 m2. If Kp= 0.17 W/m.K, K = 0.036 W/m.K, and K,= 0.12 W/m.K. Glass fiber blanket (28 kg/m), k Plaster board, k, Plywood siding, k, Inside Outside h, Ti = 20°C h, T = -15°c 11 10 mm 100 mm -20 mm A. What are the main assumptions? B. Draw the thermal circuit representing conduction through the composite wall ? C. Drive an expression in symbol form for the total thermal resistance of the composite wall, including inside and outside convection effects for the prescribed conditions. D.Determine the total heat rate through the wall. E. What is the controlling resistance that determines the heat rate through the wall?

A house has a composite wall of plywood, fiberglass insulation, and plaster board, as indicated in Fig. On a cold winter day the convection heat transfer coefficients are ho 60 W/m2.K and h= 30 W/m².K. The total wall surface area is 350 m2. If Kp= 0.17 W/m.K, K = 0.036 W/m.K, and K,= 0.12 W/m.K. Glass fiber blanket (28 kg/m), k Plaster board, k, Plywood siding, k, Inside Outside h, Ti = 20°C h, T = -15°c 11 10 mm 100 mm -20 mm A. What are the main assumptions? B. Draw the thermal circuit representing conduction through the composite wall ? C. Drive an expression in symbol form for the total thermal resistance of the composite wall, including inside and outside convection effects for the prescribed conditions. D.Determine the total heat rate through the wall. E. What is the controlling resistance that determines the heat rate through the wall?

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 1.57P

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A house has a composite wall of plywood, fiberglass insulation, and plaster board, as indicated in Fig. On a cold winter day the convection heat transfer coefficients are ho= 60 W/m?.K and h= 30 W/m2.K. The total wall surface area is 350 m2 . If Kp= 0.17 W/m.K, K= 0.036 W/m.K, and K, = 0.12 W/m.K. Glass fiber blanket (28 kg/m), k Plaster board, k Plywood siding, k, Inside Outside h;, Tmi = 20°C h T = -15°C 111 11 10 mm 100 mm -20 mm A. What are the main assumptions? B. Draw the thermal circuit representing conduction through the composite wall ? C. Drive an expression in symbol form for the total thermal resistance of the composite wall, including inside and outside convection effects for the prescribed conditions. D.Determine the total heat rate through the wall. E. What is the controlling resistance that determines the heat rate through the wall?
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Heat Transfer
Q3/ A house has a composite wall of wood, fiberglass insulation, and plaster board, as indicated in the sketch. On a cold winter day, Plaster board, k Glass fiber blanket (28 kglm'), k Plywood siding, k, the convection heat transfer coefficients are Inside Outside h, = 60 W/m? K and hi = 30 W/m² K. The total wall surface area is 350 m2. Determine the total heat loss through the wall. If the wind were blowing violently, raising ho to 300 W/m? K, determine the percentage increase in the heat loss. The thermal conductivity of A, T - 20°C A, Ta =-15°C 11 11 10 mm 100 mm 4 -20 mm (kb = 0.038 W/m-K, ks = 0.12 W/m-K, kp = 0.17 W/m-K.)
Heat transfer
Requested questions: Q1: A house has a composite wall of wood, fiberglass insula- tion, and plaster board, as indicated in the sketch. On a cold winter day, the convection heat transfer coefficients are h, = 60 W/m K and h, = 30 W/m2 K. The total wall surface area is 350 m'. Glass fiber blanket (28 kg/m'), A Plaster board, - Plywood siding. k, (a) Determine a symbolic expression for the total thermal resistance of the wall, including inside and outside convection effects for the prescribed conditions. Inside Outside A, T20°c T-15°C 111 (b) Determine the total heat loss through the wall. (c) If the wind were blowing violently, raising h, to 300 W/m K, determine the percentage increase in 10 mm 100 mm- - 20 mm the heat loss. Q2: The walls of a refrigerator are typically constructed by sand- wiching a layer of insulation between sheet metal panels. Consider a wall made from fiberglass insulation of thermal conductivity k, = 0.046 W/m K and thickness L, = 50 mm and steel panels. each of…
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