Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
8th Edition
ISBN: 9781305387102
Author: Kreith, Frank; Manglik, Raj M.
Publisher: Cengage Learning
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Chapter 3, Problem 3.13P
To determine
Temperatures of the copper wire after 2 s, 10 s, 1 min
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Calculate the heat losses per unit length in a horizontal tube with an outside diameter of 15 cm, if its surface is kept at 400 K AND the surrounding air has a temperature of 300 K and a pressure of 1 bar.The properties of air at a pressure of 1 bar and a film temperature of 350 K are:
In this case, v = 20.76 x 10-6 m2/s , α = 0.2983 x 10-4 m2/s, k = 0.03003 W/mK, Pr = 0.697, β = 2.86 x 10-3 K-1
Oil is flowing through a 45 mm inside diameter iron pipe (k=16 W/mK) at 1.2 m/s. The thickness of pipe is 8 mm. It is being heated by steam outside the pipe, and the steam-film coefficient may be taken as 12 kW/m2 oC. At a particular point along the pipe the oil is at 40 oC, its density is 880 kg/m3, its viscosity is 2.1 cP, its thermal conductivity is 0.135 W/moC and its specific heat is 2.17 J/g oC.
a) What is the overall heat transfer coefficient at this point, based on the inside area of the pipe?
b) If the steam temperature is 120oC, what is the heat transfer rate at this point, based on the outside area of the pipe?
c) Calculate the inside and outside wall temperatures of pipe when the steam temperature is 120oC and bulk temperature of oil is 40o
Hot water is being transported in a horizontal pipe (k = 0.15 W/m∙K, Di = 2.5 cm, Do = 4.5 cm), where the pipe inner surface temperature is at 100°C. A length of 2 m of the pipe outer surface is exposed to cool air at 12°C. Assuming that the properties of air can be evaluated at 40°C and 1 atm pressure, determine the outer surface temperature of the pipe. Is 40°C an appropriate film temperature for evaluation of the air properties?
Chapter 3 Solutions
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
Ch. 3 - Consider a flat plate or a plane wall with a...Ch. 3 - 3.2 High-strength steel is required for use in...Ch. 3 - Prob. 3.3PCh. 3 - 3.5 In a ball-bearing production facility, steel...Ch. 3 - A 0.6-cm diameter mild steel rod at 38C is...Ch. 3 - Prob. 3.7PCh. 3 - Prob. 3.8PCh. 3 - 3.9 The heat transfer coefficients for the flow of...Ch. 3 - 3.10 A spherical shell satellite (3-m-OD,...Ch. 3 - Prob. 3.11P
Ch. 3 - Prob. 3.12PCh. 3 - Prob. 3.13PCh. 3 - 3.14 A thin-wall cylindrical vessel (1 m in...Ch. 3 - A thin-wall jacketed tank heated by condensing...Ch. 3 - 3.16 A large, 2.54-cm.-thick copper plate is...Ch. 3 - 3.17 A 1.4-kg aluminum household iron has a 500-W...Ch. 3 -
3.28 A long wooden rod at with a 2.5-cm-OD is...Ch. 3 - A mild-steel cylindrical billet 25 cm in diameter...Ch. 3 - Prob. 3.37PCh. 3 -
3.38 An egg, which for the purposes of this...
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- Determine the rate of heat transfer per meter length to a light oil flowing through a 2.5-cm-ID, 60-cm-long copper tube at a velocity of 0.03 m/s. The oil enters the tube at 16C, and the tube is heated by steam condensing on its outer surface at atmospheric pressure with a heat transfer coefficient of 11.3 kW/m K. The properties of the oil at various temperatures are listed in the following table: Temperature, T(C) 15 30 40 65 100 (kg/m3) 912 912 896 880 864 c(kJ/kgK) 1.80 1.84 1.925 2.0 2.135 k(W/mK) 0.133 0.133 0.131 0.129 0.128 (kg/ms) 0.089 0.0414 0.023 0.00786 0.0033 Pr 1204 573 338 122 55arrow_forwardConsider the flow of oil (use unused engine oil properties) at 20? in a 30-cm-diameter pipeline at an average velocity of 2 m/s. A 200-m-long section of the pipeline passes through icy waters of a lake at 0?C. Measurements indicate that the surface temperature of the pipe is very nearly 0?C. Disregarding the thermal resistance of the pipe material, determine (a) the temperature of the oil when the pipe leaves the lake, (b) the rate of heat transfer from the oil, and (c) the pumping power required to overcome the pressure losses and to maintain the flow of the oil in the pipe.arrow_forwardWater flows at a rate of 0.8 kg /s in a 2.5 -cm diameter tube whose surface is maintained at a constant temperature of 90°C. If water must be heated from 35°C to 40°C, what is the value of the temperature on which you will base the value of the thermal conductivity that will be used to compute for the convection heat transfer coefficient? Express in Celsus.arrow_forward
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