2. Compare the heat loss from insulated and uninsulated copper pipe (k-400 W/m K) under the following conditions. The pipe has an internal diameter of 10 cm and an external diameter of 12 cm. The inside surface temperature of the pipe is at 110°C. The pipe is located in a space where its outside surface temperature was maintained at 30°C. The insulation available to reduce heat losses is 5 cm thick and its conductivity is 0.20 W/m K. If the furnace for heating the fluid in the pipe operating at an efficiency of 85% using natural gas priced at Cg = Php 1.00/MJ, what is the daily cost of heat loss per meter of pipe?

2. Compare the heat loss from insulated and uninsulated copper pipe (k-400 W/m K) under the following conditions. The pipe has an internal diameter of 10 cm and an external diameter of 12 cm. The inside surface temperature of the pipe is at 110°C. The pipe is located in a space where its outside surface temperature was maintained at 30°C. The insulation available to reduce heat losses is 5 cm thick and its conductivity is 0.20 W/m K. If the furnace for heating the fluid in the pipe operating at an efficiency of 85% using natural gas priced at Cg = Php 1.00/MJ, what is the daily cost of heat loss per meter of pipe?

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.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.62P

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3.16 A large, 2.54-cm.-thick copper plate is placed between two air streams. The heat transfer coefficient on one side is and on the other side is . If the temperature of both streams is suddenly changed from 38°C to 93°C, determine how long it takes for the copper plate to reach a temperature of 82°C.
3- Pipes with inner and outer diameter of 50mm and 60mm, respectively, are used for transporting superheated vapor in a manufacturing plant. The pipes with thermal conductivity of 16 W/m.K are connected together by flanges with combined thickness of 20mm and outer diameter of 90mm. Air condition surrounding the pipes has a temperature of 25C and a convection heat transfer coefficient of 10 W/m².K. If the inner surface temperature of the pipe is maintained at a constant temperature of 150C, determine the temperature at the base of the flange and the rate if heat loss through the flange. Air, 25 °C h= 10 W/m².ºC D;= 90 mm D;, = 50 mm T; = 150 °C Pipe, k = 16 W/m•°C D,= 60 mm t= 20 mm
3. A pipe carrying the liquid at -20°C is 10 mm in outer diameter and is exposed to ambient at 25°C with convective heat transfer coefficient of 50 W/m²-K. It is proposed to apply the insulation of material having thermal conductivity of 0.5 W/m-K. Calculate the heat loss for 2.5 mm, 7.5 mm and 15 mm thickness of insulation over 1 m length. Which one is more effective thickness of insulation?
A central heating system from a house consists of 50m of 15mm outside diameter copper pipe with a wall thickness of 1mm. This pipe is used to distribute water at a temperature of 70 degrees C. Calculate the rate of heat loss from the length of pipe if it is fitted with a 15mm radial thickness of insulation. Take the ambient air temperature to be 15 degrees C and the internal and external surface heat transfer coefficients to be 100 W/m².K and 8 W/m?.K respectively. The thermal conductivity of the copper is known to be 400 W/m.K and 0.05 W/m.K for the insulation. State your answer correct to three significant figures in Watts. Assume steady state radial heat transfer.
A central heating system from a house consists of 50m of 15mm outside diameter copper pipe with a wall thickness of 1mm. This pipe is used to distribute water at a temperature of 70 degrees C. Calculate the rate of heat loss from the length of pipe if it is fitted with a 15mm radial thickness of insulation. Take the ambient air temperature to be 15 degrees C and the internal and external surface heat transfer coefficients to be 100 W/m?.K and 8 W/m2.K respectively. The thermal conductivity of the copper is known to be 400 W/m.K and 0.05 W/m.K for the insulation. State your answer correct to three significant figures in Watts. Assume steady state radial heat transfer. Answer: 608 Ensure that you consider the overall effects of radial heat transfer through conduction and convection. Additionally ensure that you consider the overall length of the copper pipe.
A furnace wall is made of composite wall of total thickness 550 mm. The insidelayer of wall is made of refractory material (k = 1.5 W/m°C) and outside layer ofwall is made of an insulating material (k = 0.2 W/m°C). The mean temperature ofthe gases inside the furnace is 900°C and interface temperature is 520°C. Theaverage heat transfer coefficient between the gases and inner surface is 230W/m2-°C and between the outside surface and atmosphere is 46 W/m2-°C. Takingair temperature = 30°C, calculate: (a) Thickness of each layer of wall, (b) Rate ofheat loss per unit area, (c) Temperatures of surfaces exposed to gases andatmosphere.
A central heating system from a house consists of 50m of 15mm outside diameter copper pipe with a wall thickness of 1mm. This pipe is used to distribute water at a temperature of 70 degrees C. Calculate the rate of heat loss from the length of pipe if it is fitted with a 15mm radial thickness of insulation. Take the ambient air temperature to be 15 degrees C and the internal and external surface heat transfer coefficients to be 100 W/m².K and 8 W/m2.K respectively. The thermal conductivity of the copper is known to be 400 W/m.K and 0.05 W/m.K for the insulation. State your answer correct to three significant figures in Watts. Assume steady state radial heat transfer. Answer: Ensure that you consider the overall effects of radial heat transfer through conduction and convection. Additionally ensure that you consider the overall length of the copper pipe.
One side of refrigerated cold chamber is 6 m long by 3.7 m high and consists of 168 mm thickness of cork between outer and inner walls of wood. The outer wood wall is 30 mm thick and its outside face temperature is 20 deg C, the inner wood wall is 35 mm thick and its inside face temperature is -3 deg C. Taking the coefficient of thermal conductivity of cork and wood as 0.042 and 0.20 W/m-K respectively, calculate the heat transfer per second per sq meter of surface area. Select the correct response: 6.318 J 3.318 J 5.318 J 4.318 J
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Calculate the heat transfer rate from a single-pane glass window with aninside surface temperature of approximately 20° C and an outside surfacetemperature of 5° C . The glass is 1 m tall, 1.8 m wide, and 8 mm thick, asshown . The thermal conductivity of the glass is approximatelyk = 1.4 W⁄m ·K .
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