HEAT+MASS TRANSFER (LL)-W/ACCESS
6th Edition
ISBN: 9781265879631
Author: CENGEL
Publisher: MCG CUSTOM
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Textbook Question
Chapter 2, Problem 95EP
Heat is generated uniformly at a rate of 3 kW per ft length in a 0.08-in diameter electric resistance wire made of nickel steel
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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.
In an industrial facility, a counter-flow double-pipe heat exchanger uses superheated steam at a temperature of 155°C to
heat feed water at 30°C. The superheated steam experiences a temperature drop of 70°C as it exits the heat exchanger.
The water to be heated flows through the heat exchanger tube of negligible thickness at a constant rate of 3.47 kg/s. The
convective heat transfer coefficient on the superheated steam and water side is 850 W/m²K and 1250 W/m²K,
respectively. To account for the fouling due to chemical impurities that might be present in the feed water, assume
a fouling factor of 0.00015 m²-K/W for the water side.
The specific heat of water is determined at an average temperature of (30 +70)°C/2 = 50°C and is taken to be
J/kg.K.
Cp=
4181
Water
Steam
What would be the required heat exchanger area in case of parallel-flow arrangement?
The required heat exchanger area in case of parallel-flow arrangement is
1m².
Chapter 2 Solutions
HEAT+MASS TRANSFER (LL)-W/ACCESS
Ch. 2 - How does transient heat transfer from steady heat...Ch. 2 - Is heat transfer a scalar or a vector quantity?...Ch. 2 - Does a hear flux vector at a point P on an...Ch. 2 - From a heat transfer point of view, what is the...Ch. 2 - What is heat generation in a solid? Give examples.Ch. 2 - Heat generation is also referred to as energy...Ch. 2 - In order to size the compressor of a new...Ch. 2 - In order to determine the size of the heating...Ch. 2 - Consider a round potato being baked in an oven....Ch. 2 - Consider an egg being cooked in boiling water in a...
Ch. 2 - Prob. 11CPCh. 2 - Consider the cooking process of a roast beef in an...Ch. 2 - Consider heat loss from a 200-L cylindrical hot...Ch. 2 - Consider a cold canned drink left on a dinner...Ch. 2 - Heat flux meters use a very sensitive device know...Ch. 2 - Prob. 16PCh. 2 - Consider a large 3-cm-thick stainless steel plate...Ch. 2 - In a nuclear reactor, heat is generated uniformly...Ch. 2 - Prob. 19PCh. 2 - Prob. 20EPCh. 2 - Writer down the one-dimensional transient heat...Ch. 2 - Writer down the one-dimensional transient heat...Ch. 2 - Starting with an energy balance on rectangular...Ch. 2 - Prob. 24PCh. 2 - Prob. 25PCh. 2 - Consider a medium in which the heat conduction...Ch. 2 - Consider a medium in which the heat conduction...Ch. 2 - Consider a medium in which the heat conduction...Ch. 2 - Consider a medium in which the heat conduction...Ch. 2 - Consider a medium in which the heat conduction...Ch. 2 - Consider a medium in which the heat conduction...Ch. 2 - Consider a medium in which the heat conduction...Ch. 2 - Starting with an energy balance on a volume...Ch. 2 - Prob. 34PCh. 2 - Prob. 35PCh. 2 - What is a boundary condition? How many boundary...Ch. 2 - What is an initial condition? How many initial...Ch. 2 - What is a thermal symmetry boundary condition? How...Ch. 2 - How is the boundary condition on an insulated...Ch. 2 - It is claimed that the temperature profile in a...Ch. 2 - Why do we try to avoid the radiation boundary...Ch. 2 - Consider an aluminum pan used to cook stew on top...Ch. 2 - Prob. 43PCh. 2 - Prob. 44PCh. 2 - Heat is generated in a long wire of radius ro at a...Ch. 2 - Consider a long pipe of inner radius r1, Outer...Ch. 2 - A 2-kW resistance heater wire whose thermal...Ch. 2 - Prob. 48PCh. 2 - Prob. 49PCh. 2 - Consider a spherical shell of inner radius r1,...Ch. 2 - A container consists of two spherical layers, A...Ch. 2 - A spherical metal ball of radius ro is heated in...Ch. 2 - Prob. 53PCh. 2 - It is stated that the temperature in a plane wall...Ch. 2 - Consider one-dimensional heat conduction through a...Ch. 2 - Consider a solid cylindrical rod whose side...Ch. 2 - Consider a solid cylindrical rod whose ends are...Ch. 2 - Prob. 58PCh. 2 - Prob. 59PCh. 2 - Prob. 60PCh. 2 - Prob. 61PCh. 2 - Consider a 20-cm-thick concrete plane wall...Ch. 2 - Prob. 63PCh. 2 - Prob. 64PCh. 2 - Prob. 65PCh. 2 - Prob. 66PCh. 2 - Prob. 67PCh. 2 - Prob. 68EPCh. 2 - Prob. 69PCh. 2 - Consider a chilled-water pipe of length L, inner...Ch. 2 - Prob. 71EPCh. 2 - Prob. 72PCh. 2 - Prob. 73PCh. 2 - Prob. 74PCh. 2 - Prob. 75PCh. 2 - Prob. 76PCh. 2 - Prob. 77PCh. 2 - Prob. 78PCh. 2 - Prob. 79PCh. 2 - Prob. 80PCh. 2 - Prob. 81PCh. 2 - Prob. 82CPCh. 2 - Does heat generation in a solid violate the first...Ch. 2 - Prob. 84CPCh. 2 - Prob. 85CPCh. 2 - Prob. 86CPCh. 2 - Prob. 87PCh. 2 - Prob. 88PCh. 2 - Consider a large 3-cm thick stainless steel plate...Ch. 2 - Prob. 90PCh. 2 - Prob. 91EPCh. 2 - Prob. 92PCh. 2 - Prob. 93PCh. 2 - Prob. 94PCh. 2 - Heat is generated uniformly at a rate of 3 kW per...Ch. 2 - Prob. 96PCh. 2 - Prob. 97PCh. 2 - Prob. 98PCh. 2 - Prob. 99PCh. 2 - Prob. 100PCh. 2 - Prob. 101PCh. 2 - Prob. 102PCh. 2 - Prob. 103PCh. 2 - Prob. 104PCh. 2 - Prob. 105PCh. 2 - Prob. 106PCh. 2 - Prob. 107PCh. 2 - Prob. 108PCh. 2 - Prob. 109CPCh. 2 - When the thermal conductivity of a medium varies...Ch. 2 - The temperature of a plane wall during steady...Ch. 2 - Consider steady one-dimensional heat conduction in...Ch. 2 - Prob. 113CPCh. 2 - Prob. 114PCh. 2 - Prob. 115PCh. 2 - Prob. 116PCh. 2 - Consider a plane wall of thickness L whose thermal...Ch. 2 - Prob. 118PCh. 2 - Prob. 119PCh. 2 - A pipe is used for transporting boiling water in...Ch. 2 - Prob. 121PCh. 2 - Prob. 122PCh. 2 - Consider a spherical shell of inner radius r1 and...Ch. 2 - Prob. 124PCh. 2 - A spherical tank is filled with ice slurry, where...Ch. 2 - Prob. 126CPCh. 2 - Prob. 127CPCh. 2 - Can a differential equation involve more than one...Ch. 2 - Prob. 129CPCh. 2 - Prob. 130CPCh. 2 - Prob. 131CPCh. 2 - Prob. 132CPCh. 2 - How is integation related to derivation?Ch. 2 - Prob. 134CPCh. 2 - Prob. 135CPCh. 2 - How is the order of a differential equation...Ch. 2 - How do you distinguish a linear differential...Ch. 2 - How do you recognize a linear homogeneous...Ch. 2 - How do differential equations with constant...Ch. 2 - What kinds of differential equations can be solved...Ch. 2 - Consider a third-order linear and homogeneous...Ch. 2 - A large plane wall, with a thickness L and a...Ch. 2 - Prob. 143PCh. 2 - Prob. 144EPCh. 2 - A spherical vessel has an inner radius r1 and an...Ch. 2 - Consider a short cylinder of radius r0 and height...Ch. 2 - Prob. 147PCh. 2 - Consider a 20-cm-thick large concrete plane wall...Ch. 2 - Prob. 149PCh. 2 - Prob. 150PCh. 2 - Prob. 151PCh. 2 - Prob. 152PCh. 2 - Prob. 153PCh. 2 - Prob. 154EPCh. 2 - Prob. 155PCh. 2 - Consider a water pipe of length L=17m, inner...Ch. 2 - Prob. 157PCh. 2 - In a manufacturing plant, a quench hardening...Ch. 2 - Consider a spherical reactor of 5-cm diameter...Ch. 2 - Consider a cylindrical sheel of length L, inner...Ch. 2 - A pipe is used for transporting boiling water in...Ch. 2 - A metal spherical tank is filled with chemicals...Ch. 2 - The heat conduction equation in a medium is given...Ch. 2 - Consider a medium in which the heat conduction...Ch. 2 - Consider a large plane wall of thicness L, thermal...Ch. 2 - A solar heat flux qs is incident on a sidewalk...Ch. 2 - A plane wall of thickness L is subjected to...Ch. 2 - Consider steady one-dimensional heat conduction...Ch. 2 - The conduction eqution boundary condition for an...Ch. 2 - Prob. 170PCh. 2 - Prob. 171PCh. 2 - The temperatures at the inner and outer surfaces...Ch. 2 - The thermal conductivity of a solid depends upon...Ch. 2 - Prob. 174PCh. 2 - Prob. 175PCh. 2 - Prob. 176PCh. 2 - Prob. 177PCh. 2 - Prob. 178PCh. 2 - Write essay on heat generation in nuc1e e1 rods....Ch. 2 - Write an interactive computer program to calculate...Ch. 2 - Prob. 181P
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