Fundamentals of Thermal-Fluid Sciences
5th Edition
ISBN: 9780078027680
Author: Yunus A. Cengel Dr., Robert H. Turner, John M. Cimbala
Publisher: McGraw-Hill Education
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Chapter 20, Problem 81P
To determine
The rate of heat transfer between the inner sphere and the outer sphere.
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A counter flow double pipe heat exchanger is being used to cool hot oil from 320°F to 285°F
using cold water. The water, which flows through the inner tube, enters the heat exchanger at 70°F
and leaves at 175°F. The inner tube is ¾-std type L copper. The overall heat transfer coefficient
based on the outside diameter of the inner tube is 140 Btu/hr-ft2-°F. Design conditions call for a
total heat transfer duty (heat transfer rate between the two fluids) of 20,000 Btu/hr. Determine the
required length of this heat exchanger (ft).
!
Required information
A one-shell-pass and eight-tube-passes heat exchanger is used to heat glycerin (cp=0.60 Btu/lbm.°F) from 80°F to 140°F
by hot water (Cp = 1.0 Btu/lbm-°F) that enters the thin-walled 0.5-in-diameter tubes at 175°F and leaves at 120°F. The total
length of the tubes in the heat exchanger is 400 ft. The convection heat transfer coefficient is 4 Btu/h-ft²°F on the glycerin
(shell) side and 70 Btu/h-ft²°F on the water (tube) side.
NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part.
Determine the rate of heat transfer in the heat exchanger before any fouling occurs.
Correction factor F
1.0
10
0.9
0.8
R=4.0 3.0 2.0.15 1.0 0.8.0.6 0.4 0.2
0.7
0.6
R=
T1-T2
12-11
0.5
12-11
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
(a) One-shell pass and 2, 4, 6, etc. (any multiple of 2), tube passes
P=
T₁-11
The rate of heat transfer in the heat exchanger is
Btu/h.
!
Required information
Air at 25°C (cp=1006 J/kg.K) is to be heated to 58°C by hot oil at 80°C (cp = 2150 J/kg.K) in a cross-flow heat exchanger
with air mixed and oil unmixed. The product of heat transfer surface area and the overall heat transfer coefficient is 750
W/K and the mass flow rate of air is twice that of oil.
NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part.
Air
Oil
80°C
Determine the effectiveness of the heat exchanger.
Chapter 20 Solutions
Fundamentals of Thermal-Fluid Sciences
Ch. 20 - Prob. 1PCh. 20 - In which mode of heat transfer is the convection...Ch. 20 - Consider a hot boiled egg in a spacecraft that is...Ch. 20 - Prob. 4PCh. 20 - Prob. 5PCh. 20 - Prob. 6PCh. 20 - Prob. 7PCh. 20 - Prob. 8PCh. 20 - Prob. 9PCh. 20 - The density of liquid water can be correlated as...
Ch. 20 - A 10 cm × 10 cm plate has a constant surface...Ch. 20 - Prob. 12PCh. 20 - Prob. 13PCh. 20 - Prob. 14PCh. 20 - Prob. 15PCh. 20 - A 0.2-m-long and 25-mm-thick vertical plate (k =...Ch. 20 - A 0.2-m-long and 25-mm-thick vertical plate (k =...Ch. 20 - A 0.5-m-long thin vertical plate is subjected to...Ch. 20 - Prob. 21PCh. 20 - Prob. 22PCh. 20 - Prob. 24PCh. 20 - Consider a 2-ft × 2-ft thin square plate in a room...Ch. 20 - Prob. 27PCh. 20 - A 50-cm × 50-cm circuit board that contains 121...Ch. 20 - Prob. 29PCh. 20 - Prob. 30PCh. 20 - Prob. 32PCh. 20 - Consider a thin 16-cm-long and 20-cm-wide...Ch. 20 - Prob. 34PCh. 20 - Prob. 35PCh. 20 - Prob. 36PCh. 20 - Prob. 37PCh. 20 - Flue gases from an incinerator are released to...Ch. 20 - In a plant that manufactures canned aerosol...Ch. 20 - Reconsider Prob. 20–39. In order to reduce the...Ch. 20 - Prob. 41PCh. 20 - Prob. 42PCh. 20 - Prob. 43PCh. 20 - Prob. 44PCh. 20 - A 10-m-long section of a 6-cm-diameter horizontal...Ch. 20 - Prob. 46PCh. 20 - Prob. 47PCh. 20 - Prob. 48PCh. 20 - Prob. 49PCh. 20 - Prob. 50PCh. 20 - Prob. 52PCh. 20 - Prob. 53PCh. 20 - Prob. 54PCh. 20 - Prob. 55PCh. 20 - Prob. 57PCh. 20 - Prob. 58PCh. 20 - Prob. 59PCh. 20 - Prob. 60PCh. 20 - Prob. 61PCh. 20 - Prob. 62PCh. 20 - Prob. 63PCh. 20 - Prob. 64PCh. 20 - Prob. 65PCh. 20 - Prob. 66PCh. 20 - Prob. 67PCh. 20 - Prob. 68PCh. 20 - Prob. 69PCh. 20 - Prob. 70PCh. 20 - Prob. 71PCh. 20 - Prob. 72PCh. 20 - Prob. 73PCh. 20 - Prob. 75PCh. 20 - Prob. 77PCh. 20 - Prob. 78PCh. 20 - Prob. 79PCh. 20 - Prob. 81PCh. 20 - An electric resistance space heater is designed...Ch. 20 - Prob. 83RQCh. 20 - A plate (0.5 m × 0.5 m) is inclined at an angle of...Ch. 20 - A group of 25 power transistors, dissipating 1.5 W...Ch. 20 - Prob. 86RQCh. 20 - Prob. 87RQCh. 20 - Consider a flat-plate solar collector placed...Ch. 20 - Prob. 89RQCh. 20 - Prob. 90RQCh. 20 - Prob. 91RQCh. 20 - Prob. 92RQCh. 20 - Prob. 93RQCh. 20 - Prob. 94RQCh. 20 - Prob. 95RQCh. 20 - Prob. 96RQCh. 20 - Prob. 97RQCh. 20 - Prob. 98RQCh. 20 - Prob. 99RQCh. 20 - Prob. 100RQCh. 20 - Prob. 101RQCh. 20 - A solar collector consists of a horizontal copper...Ch. 20 - Prob. 103RQCh. 20 - Prob. 104RQ
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