Task 01 An industrial freezer is designed to operate with an internal air temperature of -20 0C when the external air temperature is 25 0C and the internal and external heat transfer coefficients are 12 W/m2K and 8 W/m2K , respectively. The walls of the freezer are composite construction, comprising of an inner layer of plastic ( k=1 W/m.K , and the thickness of 3 mm) , and an outer layer of stainless steel (k=16 W/m.K , and thickness of 1mm). Sandwiched between these two layers is a layer of insulation material with k=0.07 W/m.K and the thickness of 195mm. Find the overall heat transfer coefficient and determine the heat transfer through the industrial freezer.

Task 01 An industrial freezer is designed to operate with an internal air temperature of -20 0C when the external air temperature is 25 0C and the internal and external heat transfer coefficients are 12 W/m2K and 8 W/m2K , respectively. The walls of the freezer are composite construction, comprising of an inner layer of plastic ( k=1 W/m.K , and the thickness of 3 mm) , and an outer layer of stainless steel (k=16 W/m.K , and thickness of 1mm). Sandwiched between these two layers is a layer of insulation material with k=0.07 W/m.K and the thickness of 195mm. Find the overall heat transfer coefficient and determine the heat transfer through the industrial freezer.

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.

Chapter8: Natural Convection

Section: Chapter Questions

Problem 8.1DP

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Concept explainers

Conduction and Convection

When energy travels from one object to another it is said to have undergone heat transfer. Heat transfer is nothing but the transfer of thermal energy or internal energy from one thing to another, like e.g., when a vessel with water, kept on top of a burner, heats up because of the flame underneath it.

Question

Task 01

An industrial freezer is designed to operate with an internal air temperature of -20 ⁰C when the external air temperature is 25 ⁰C and the internal and external heat transfer coefficients are 12 W/m²K and 8 W/m²K , respectively. The walls of the freezer are composite construction, comprising of an inner layer of plastic ( k=1 W/m.K , and the thickness of 3 mm) , and an outer layer of stainless steel (k=16 W/m.K , and thickness of 1mm). Sandwiched between these two layers is a layer of insulation material with k=0.07 W/m.K and the thickness of 195mm. Find the overall heat transfer coefficient and determine the heat transfer through the industrial freezer.

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