Introduction to Heat Transfer
6th Edition
ISBN: 9780470501962
Author: Frank P. Incropera, David P. DeWitt, Theodore L. Bergman, Adrienne S. Lavine
Publisher: Wiley, John & Sons, Incorporated
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Chapter 4, Problem 4.70P
Consider Problem 4.69. An engineer desires to measurethe surface temperature of the thin sheathing by paintingit black
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An infrared camera is used to measure a temperature at a tissue location. The infrared
camera uses the same equation as that in the lecture notes. When the total hemispherical emissivity is
selected as &=1.0, the temperature reading on the camera is 45°C.
(a) Based on the equation given in the notes, please calculate the radiation heat flux received by the
camera qck. The Stefan-Boltzmann's constant ois 5.67*108 W/(m²K¹).
(b) However, you notice that the actual emissivity of the tissue surface should be 0.95. The room
temperature is 20°C. Use the equation again to calculate the temperature of the tissue location, note that
qck should be the same as in (a). What is the absolute error of the measurement if both the room
temperature and deviation from a perfect blackbody surface are not considered?
A spherical interplanetary probe of 0.5 m diameter contains electronics that dissipate 150 W. If the probe surface has an emissivity of 0.9 and the probe does not receive radiation from other surfaces, as, for example, from the sun, what is its surface temperature?
2. A heater is a thin vertical panel 1.0m long and 0.7m high and is used in a warehouse to keep workers warm.
The heater has air circulating on each side. Assume the maximum temperature of the panel is 60°C
(already above the board line that is safe for human hands to touch briefly without getting hurt). Assume
the room air temperature is 18°C but the warehouse wall temperature is 5°C. Model the surface with an
emittance of 0.9 and Vair = 1.57x105 m²/s.
a. Determine the maximum power rating for the heater.
b.
Now if you run the heat by standing on its side (it will be 1.0 m high and 0.7 m long), determine
the surface temperature.
c.
Compare case a and b and explain any differences you see.
Chapter 4 Solutions
Introduction to Heat Transfer
Ch. 4 - In the method of separation of variables (Section...Ch. 4 - A two-dimensional rectangular plate is subjected...Ch. 4 - Consider the two-dimensional rectangular plate...Ch. 4 - A two-dimensional rectangular plate is subjected...Ch. 4 - Prob. 4.5PCh. 4 - Prob. 4.6PCh. 4 - Free convection heat transfer is sometimes...Ch. 4 - Prob. 4.8PCh. 4 - Radioactive wastes are temporarily stored in a...Ch. 4 - Based on the dimensionless conduction heat rates...
Ch. 4 - Prob. 4.11PCh. 4 - A two-dimensional object is subjected to...Ch. 4 - Prob. 4.13PCh. 4 - Two parallel pipelines spaced 0.5 m apart are...Ch. 4 - A small water droplet of diameter D=100m and...Ch. 4 - Prob. 4.16PCh. 4 - Pressurized steam at 450 K flows through a long,...Ch. 4 - Prob. 4.19PCh. 4 - A furnace of cubical shape, with external...Ch. 4 - Prob. 4.21PCh. 4 - Prob. 4.22PCh. 4 - A pipeline, used for the transport of crude oil,...Ch. 4 - A long power transmission cable is buried at a...Ch. 4 - Prob. 4.25PCh. 4 - A cubical glass melting furnace has exterior...Ch. 4 - Prob. 4.27PCh. 4 - An aluminum heat sink k=240W/mK, used to coolan...Ch. 4 - Hot water is transported from a cogeneration power...Ch. 4 - Prob. 4.30PCh. 4 - Prob. 4.31PCh. 4 - Prob. 4.32PCh. 4 - An igloo is built in the shape of a hemisphere,...Ch. 4 - Consider the thin integrated circuit (chip) of...Ch. 4 - Prob. 4.35PCh. 4 - The elemental unit of an air heater consists of a...Ch. 4 - Prob. 4.37PCh. 4 - Prob. 4.38PCh. 4 - Prob. 4.39PCh. 4 - Prob. 4.40PCh. 4 - Prob. 4.41PCh. 4 - Determine expressions for...Ch. 4 - Prob. 4.43PCh. 4 - Prob. 4.44PCh. 4 - Prob. 4.45PCh. 4 - Derive the nodal finite-difference equations for...Ch. 4 - Prob. 4.47PCh. 4 - Prob. 4.48PCh. 4 - Consider a one-dimensional fin of uniform...Ch. 4 - Prob. 4.50PCh. 4 - Prob. 4.52PCh. 4 - Prob. 4.53PCh. 4 - Prob. 4.54PCh. 4 - Prob. 4.55PCh. 4 - Prob. 4.56PCh. 4 - Steady-state temperatures at selected nodal points...Ch. 4 - Prob. 4.58PCh. 4 - Prob. 4.60PCh. 4 - The steady-state temperatures C associated with...Ch. 4 - A steady-state, finite-difference analysis has...Ch. 4 - Prob. 4.64PCh. 4 - Consider a long bar of square cross section (0.8 m...Ch. 4 - Prob. 4.66PCh. 4 - Prob. 4.67PCh. 4 - Prob. 4.68PCh. 4 - Prob. 4.69PCh. 4 - Consider Problem 4.69. An engineer desires to...Ch. 4 - Consider using the experimental methodology of...Ch. 4 - Prob. 4.72PCh. 4 - Prob. 4.73PCh. 4 - Prob. 4.74PCh. 4 - Prob. 4.75PCh. 4 - Prob. 4.76PCh. 4 - Prob. 4.77PCh. 4 - Prob. 4.78PCh. 4 - Prob. 4.79PCh. 4 - Prob. 4.80PCh. 4 - Spheres A and B arc initially at 800 K, and they...Ch. 4 - Spheres of 40-mm diameter heated to a uniform...Ch. 4 - To determine which parts of a spiders brain are...Ch. 4 - Prob. 4.84P
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- Determine the power requirement of a soldering iron in which the tip is maintained at 400C. The tip is a cylinder 3 mm in diameter and 10 mm long. The surrounding air temperature is 20C, and the average convection heat transfer coefficient over the tip is 20W/m2K. The tip is highly polished initially, giving it a very low emittance.arrow_forwardA long wire 0.7 mm in diameter with an emissivity of 0.9 is placed in a large quiescent air space at 270 K. If the wire is at 800 K, calculate the net rate of heat loss. Discuss your assumptions.arrow_forward1.13 If the outer air temperature in Problem is –2°C, calculate the convection heat transfer coefficient between the outer surface of the window and the air, assuming radiation is negligible.arrow_forward
- 1.15 A thermocouple (0.8-mm-diameter wire) used to measure the temperature of the quiescent gas in a furnace gives a reading of . It is known, however, that the rate of radiant heat flow per meter length from the hotter furnace walls to the thermocouple wire is 1.1 W/m and the convection heat transfer coefficient between the wire and the gas is K. With this information, estimate the true gas temperature. State your assumptions and indicate the equations used.arrow_forward1.26 Repeat Problem 1.25 but assume that the surface of the storage vessel has an absorbance (equal to the emittance) of 0.1. Then determine the rate of evaporation of the liquid oxygen in kilograms per second and pounds per hour, assuming that convection can be neglected. The heat of vaporization of oxygen at –183°C is .arrow_forwardHeat transfer problem.The internal surface area is an enclosure is 50 meter square. The surface is black and maintained at constant temperature. A small opening in the enclosure has area 0.05 meter square. The radiant power emitted from the opening is 52W. (A) what’s the temperature of the interior enclosure wall. (B)if the interior surface is maintained in this temperature, but polished so that emissivity is 0.15, what will be the radiant power emitted in the opening.arrow_forward
- Spacecraft must be cooled via radiative mechanisms, and one means of doing this is by using radiation fins. In many instances, these fins are heated rods that protrude from the spacecraft. Assume that the rod is of length, L; cross-sectional are, Ac; and perimeter, Pā. Its base temperature is T, and the rod has thermal conductivity and emissivity, λ and ɛ, respectively. Set up the differential equation describing the temperature profile within the rod assuming that space is a blackbody at Ts.arrow_forwardAbsorptivity, reflectivity and transmissivity are three main properties inradiation heat transfer. With the help of illustration distinguished the differentbetween these three properties and conclude the relationship between them.arrow_forwardUsing a polynomial equation solver, determine the steady-state surface temperature (Ts) of the passive radiative cooler below that is exposed to a windy convective enviroment h=40 W/m2*K and T∞= 25°C. The surrounding atmosphere is fixed at Tsur= 10°C. Set up the energy balance/conservation equation.arrow_forward
- 2 inch OD during a visit to a plastic sheet factory 60 m long section of a horizontal steam pipe passes from one end to the other without insulation is observed. While the temperature of the ambient air and its surfaces is 20 °C, the temperature measurements at several points are the average of the exposed surfaces of the steam pipe. indicates that the temperature is 160 °C. It is seen that the outer surface of the pipe is oxidized and The emissivity can be taken as 0.59. According to this; a) Calculate the heat loss in the steam pipe. b) The steam used is produced in a gas furnace operating with an efficiency of 59%. Factory 105500 It pays $1.10 per kJ of natural gas. If it is assumed that the factory works all year (365 days), for this facility Calculate the annual cost of heat losses in the steam pipe.arrow_forwardPROBLEM 4: A black thermocouple is inside a chamber with black walls. If the air around the thermocouple is at 20°C, the walls are at 100-C, and the heat transfer coefficient between the thermocouple and the air is 75 W/m²K, what temperature will the thermocouple read?arrow_forwardA brass plate has a circular hole whose diameter is slightly smaller than the diameter of an aluminum ball. Ifthe ball and the plate are always kept at the same temperature,(a) should the temperature of the system be increased or decreasedin order for the ball to fit through the hole? (b) Choose the bestexplanation from among the following:I. The aluminum ball changes its diameter more with temperature than the brass plate, and therefore the temperatureshould be decreased.II. Changing the temperature won’t change the fact that the ballis larger than the hole.III. Heating the brass plate makes its hole larger, and that willallow the ball to pass through.arrow_forward
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