Heat and Mass Transfer: Fundamentals and Applications
5th Edition
ISBN: 9780073398181
Author: Yunus A. Cengel Dr., Afshin J. Ghajar
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 1, Problem 123CP
Consider a house in Atlanta, Georgia, that is maintained at
(see Prob. 1-120 for the definition of U-factor). The winter average temperature of Atlanta is
Determine the average rate of heat loss through the windows in winter.
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A person stands in a breezy room whose temperature is 20 °C. The emissivity of
the person is 0.35. Determine the total rate of heat transfer from this person if the
exposed surface area and the average surface temperature of the person are 1.6
m2 and 29 °C respectively. Take the convection heat transfer coefficient to be 6.5
W/m2/K and that the surrounding wall of the room is at a temperature of 20 oC.
Select one:
A 123.7 W
B. 86.4 W
C. 151.7 W
D. 100.5 W
E 43.0 W
q1
A glass window in a storefront has an are of 12m2 and a thickness of 1 cm. The thermal conductivity of the glass is 0.8 W/m-oC. On the cold day, outside surface temperature of the glass is -1oC and the inside surface temperature is 3 oC. Determine the temperature at a plane midway between the inside and outside glass surfaces.
Chapter 1 Solutions
Heat and Mass Transfer: Fundamentals and Applications
Ch. 1 - How does the science of heat transfer differ from...Ch. 1 - What is the driving force for (a) heat transfer,...Ch. 1 - Prob. 3CPCh. 1 - How do rating problems in heat transfer differ...Ch. 1 - What is the difference between the analytical and...Ch. 1 - Prob. 6CPCh. 1 - What is the importance of modeling in engineering?...Ch. 1 - When modeling an engineering process, how is the...Ch. 1 - On a hot summer day, a student turns his fan on...Ch. 1 - Consider two identical rooms, one with a...
Ch. 1 - An ideal gas is heated from 50C to 80C (a) at...Ch. 1 - Prob. 12CPCh. 1 - What is heat flux? How is it related to the heat...Ch. 1 - What are the mechanisms of energy transfer to a...Ch. 1 - A logic chip used in a computer dissipates 3 W of...Ch. 1 - Consider a 150-W incandescent lamp. The filament...Ch. 1 - A 15-cm-diameter aluminum ball is to be heated...Ch. 1 - Prob. 18PCh. 1 - Prob. 19PCh. 1 - A 60-gallon water heated is initially filled with...Ch. 1 - Prob. 21PCh. 1 - Prob. 22PCh. 1 - Prob. 23PCh. 1 - Prob. 24PCh. 1 - Prob. 25PCh. 1 - Prob. 26PCh. 1 - Prob. 27PCh. 1 - Prob. 28PCh. 1 - A 5-m6-m8-m room is to be heated by an electrical...Ch. 1 - Prob. 30PCh. 1 - Prob. 31PCh. 1 - Air enters the duct of an air-conditioning system...Ch. 1 - Define thermal conductivity, and explain its...Ch. 1 - Prob. 34CPCh. 1 - Which is a better heat conductor, diamond or...Ch. 1 - How do the thermal conductivity of gases and...Ch. 1 - Why is the thermal conductivity of superinsulation...Ch. 1 - Why do we characterize the heat conduction ability...Ch. 1 - Prob. 39CPCh. 1 - What are the mechanisms of heat transfer? How are...Ch. 1 - Write down the expression for the physical laws...Ch. 1 - How does heat conduction differ from convection?Ch. 1 - Does any of the energy of the sun reach the earth...Ch. 1 - How does forced convection differ from natural...Ch. 1 - What is the physical mechanism of heat conduction...Ch. 1 - Consider heat transfer a windowless wall of house...Ch. 1 - Consider heat loss through two walls of house on a...Ch. 1 - Consider two houses that are identical except that...Ch. 1 - Consider two walls of a house that are identical...Ch. 1 - Define emissivity and absorptivity. What is...Ch. 1 - What is a blackbody? How do real bodies differ...Ch. 1 - A wood slab with a thickness 0.05 m is subjected...Ch. 1 - Prob. 53PCh. 1 - The inner and outer surfaces of a 0.5-cm thick...Ch. 1 - Prob. 55PCh. 1 - Prob. 56PCh. 1 - The north wall of an electrically heated home is...Ch. 1 - Prob. 58PCh. 1 - Prob. 59PCh. 1 - Prob. 60PCh. 1 - A concreate wall a surface area of 20 m2 and a...Ch. 1 - Prob. 62PCh. 1 - Prob. 63PCh. 1 - Prob. 64EPCh. 1 - Prob. 65EPCh. 1 - Air at 20C with a convection heat transfer...Ch. 1 - Prob. 67PCh. 1 - Prob. 68PCh. 1 - Prob. 69PCh. 1 - Prob. 70PCh. 1 - Prob. 71PCh. 1 - Prob. 72PCh. 1 - Prob. 73PCh. 1 - Prob. 74PCh. 1 - Prob. 75PCh. 1 - Prob. 76EPCh. 1 - Prob. 77EPCh. 1 - Prob. 78PCh. 1 - Prob. 79PCh. 1 - Prob. 80PCh. 1 - Prob. 81PCh. 1 - Prob. 82PCh. 1 - Using the conversion factors between W and Btu/h,...Ch. 1 - The outer surface of a spacecraft in space has an...Ch. 1 - Consider a person whose expose surface are is 1.7...Ch. 1 - Prob. 86PCh. 1 - Two surfaces, one highly polished and the other...Ch. 1 - A spherical interplanetary probe with a diameter...Ch. 1 - Prob. 89PCh. 1 - Can all three modes of heat transfer occur...Ch. 1 - Can a medium involve (a) conduction and...Ch. 1 - The deep human body temperature of a healthy...Ch. 1 - We often turn the fan on in summer to help us...Ch. 1 - Prob. 94PCh. 1 - Prob. 95PCh. 1 - Prob. 96PCh. 1 - An electronic package with a surface area of 1 m2...Ch. 1 - Consider steady heat transfer between two large...Ch. 1 - Prob. 99PCh. 1 - Prob. 100PCh. 1 - A 2-in-diameter spherical ball whose surface is...Ch. 1 - Prob. 102PCh. 1 - A 3-m-internal-diameter spherical tank made of...Ch. 1 - Prob. 104PCh. 1 - Solar radiation is incident on a 5-m2 solar...Ch. 1 - Prob. 106PCh. 1 - Prob. 107PCh. 1 - Prob. 108PCh. 1 - Prob. 109EPCh. 1 - An AISI 304 stainless steel sheet is going through...Ch. 1 - Prob. 111PCh. 1 - Prob. 112CPCh. 1 - Prob. 113PCh. 1 - Prob. 114PCh. 1 - Prob. 115PCh. 1 - Prob. 116PCh. 1 - Prob. 117PCh. 1 - Why is the metabolic rate of women, in general,...Ch. 1 - What is asymmetric thermal radiation How does it...Ch. 1 - How do (a) draft and (b) cold floor surfaces cause...Ch. 1 - Prob. 121CPCh. 1 - Why is it necessary to ventilate buildings? What...Ch. 1 - Consider a house in Atlanta, Georgia, that is...Ch. 1 - Prob. 124PCh. 1 - Prob. 125PCh. 1 - Prob. 126PCh. 1 - A 4m5m6m and room is to be heated by one ton (1000...Ch. 1 - Engine valves (cp=440J/kg.Kandp=7840kg/m3) are to...Ch. 1 - Prob. 129PCh. 1 - Prob. 130PCh. 1 - A 0.3 -cm-thick, 12-cm-high, and 18-cm-long...Ch. 1 - A 40-cm-long, 800-W electric resistance heating...Ch. 1 - It is well known that wind makes the cold air feel...Ch. 1 - An engine block with a surface area measured to be...Ch. 1 - Prob. 135PCh. 1 - Prob. 136PCh. 1 - Prob. 137PCh. 1 - Consider a person standing in a room maintained at...Ch. 1 - Prob. 139PCh. 1 - Prob. 140PCh. 1 - Prob. 141PCh. 1 - Prob. 142PCh. 1 - Prob. 143PCh. 1 - Prob. 144PCh. 1 - Prob. 145PCh. 1 - Prob. 146PCh. 1 - A 2-kW electric resistance heater submerged in...Ch. 1 - Prob. 148PCh. 1 - A cold bottled drink (m=2.5kg,cp=4200J/kg.K) at...Ch. 1 - Prob. 150PCh. 1 - Air enters a 12-m-long, 7-cm-diameter pipe at 50oC...Ch. 1 - Prob. 152PCh. 1 - Steady heat conduction occurs through a...Ch. 1 - Heat is lost through a brick wall (k=0.72W/m.K),...Ch. 1 - Prob. 155PCh. 1 - A 40-cm-long, 0.4-cm-diameter electric resistance...Ch. 1 - Prob. 157PCh. 1 - Over 90 percent of the energy dissipated by an...Ch. 1 - On a still, cleat night, the sky appears to be a...Ch. 1 - Prob. 160PCh. 1 - Prob. 161PCh. 1 - A persons head can be approximated as a...Ch. 1 - A person standing in a room loses heat to the air...Ch. 1 - Prob. 164PCh. 1 - Write an essay on how microwave ovens work, and...Ch. 1 - Using information form the utility bill for the...Ch. 1 - It is well know that at the same outdoor air...
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- A pipe carrying superheated steam in a basement at 10C has a surface temperature of 150C. Heat loss from the pipe occurs by radiation (=0.6) and natural convection (hc=25W/m2K). Determine the percentage of the total heat loss by these two mechanisms.arrow_forward1.29 A spherical interplanetary probe with a 30-cm diameter contains electronic equipment that dissipates 100 W. If the probe surface has an emissivity of 0.8, what is its surface temperature in outer space? State your assumptions in the calculations.arrow_forwardA cooling system is to be designed for a food storage warehouse for keeping perishable foods cool prior to transportation to grocery stores. The warehouse has an effective surface area of 1860 m2 exposed to an ambient air temperature of 32C. The warehouse wall insulation (k=0.17W/(mK)) is 7.5 cm thick. Determine the rate at which heat must be removed (W) from the warehouse to maintain the food at 4C.arrow_forward
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- The heat transfer coefficient between a surface and a liquid is 57 W/(m2K). How many watts per square meter will be transferred in this system if the temperature difference is 10C?arrow_forwardThe heat transfer rate from hot air by convection at 100C flowing over one side of a flat plate with dimensions 0.1m0.5m is determined to be 125 W when the surface of the plate is kept at 30C. What is the average convection heat transfer coefficient between the plate and the air?arrow_forward1.67 In beauty salons and in homes, a ubiquitous device is the hairdryer. The front end of a typical hairdryer is idealized as a thin-walled cylindrical duct with a 6-cm diameter with a fan at the inlet that blows air over an electric heating coil as schematically shown in the figure. The design of this appliance requires two power settings, with which the air blown over the electric heating coil is heated from the ambient temperature of to an outlet temperature of and with exit air velocities of 1.0 m/s and 1.5 m/s. Estimate the electric power required for the heating coil to meet these conditions, assuming that heat loss from the outside of the dryer duct is neglected.arrow_forward
- The outside temperature on a particular winter's day is 0°C. Consider two identical houses, each of external surface area 200 m² and internal temperature 20°C. The walls of the first are constructed of a single layer of brick, of thermal conductivity 1 W m-1 °C-1 and thickness 20 cm. What is the heat flux Q out of this house? What is its rate of heat loss in Watts? The walls of the second house are constructed of two layers of brick, each 10 cm thick, and a layer of insulation, also 10 cm thick. The insulation is made mostly out of air, thermal conductivity 0.01 W m of heat loss from this house? How different would your answer be if you neglected the layers of brick in this calculation? -1 °C-1. what are the heat flux and the ratearrow_forwardA glass window inside storefront has an are of 12m2 and a thickness of 1 cm. The thermal conductivity of the glass is 0.8 W/m-oC. On the cold day, outside surface temperature of the glass is -1oC and the inside surface temperature is 3 oC. Determine the temperature at a plane midway between the inside and outside glass surfaces.arrow_forward1. A 1000-W iron is left on the iron board with its base exposed to the air at 20°C. The convection heat transfer coefficient between the base surface and the surrounding air is 35 W/m². °C. If the base has an emissivity of 0.6 and a surface area of 0.02 m², determine the temperature of the base of the iron. 2. The inner and outer surfaces of a 5-m x 6-m brick wall of thickness 30 cm and thermal conductivity 0.69 W/m °C are maintained at temperatures of 20°C and 5°C, respectively. Determine the rate of heat transfer through the wall, in W.arrow_forward
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