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 1, Problem 1.67P
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
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(b)
Hairdryer is an electromechanical device that blows ambient or hot air over damp hair
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Chapter 1 Solutions
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
Ch. 1 - 1.1 On a cold winter day, the outer surface of a...Ch. 1 - 1.2 The weight of the insulation in a spacecraft...Ch. 1 - 1.3 A furnace wall is to be constructed of brick...Ch. 1 - 1.4 To measure thermal conductivity, two similar...Ch. 1 - To determine the thermal conductivity of a...Ch. 1 - A square silicon chip 7mm7mm in size and 0.5-mm...Ch. 1 - A cooling system is to be designed for a food...Ch. 1 - 1.80 Describe and compare the modes of heat loss...Ch. 1 - Heat is transferred at a rate of 0.1 kW through...Ch. 1 - 1.10 A heat flux meter at the outer (cold) wall of...
Ch. 1 - 1.11 Calculate the heat loss through a glass...Ch. 1 - 1.12 A wall with a thickness is made of a...Ch. 1 - 1.13 If the outer air temperature in Problem is...Ch. 1 - Using Table 1.4 as a guide, prepare a similar...Ch. 1 - 1.15 A thermocouple (0.8-mm-diameter wire) used to...Ch. 1 - Water at a temperature of 77C is to be evaporated...Ch. 1 - The heat transfer rate from hot air by convection...Ch. 1 - The heat transfer coefficient for a gas flowing...Ch. 1 - 1.19 A cryogenic fluid is stored in a...Ch. 1 - A high-speed computer is located in a...Ch. 1 - 1.21 In an experimental set up in a laboratory, a...Ch. 1 - 1.22 In order to prevent frostbite to skiers on...Ch. 1 - Using the information in Problem 1.22, estimate...Ch. 1 - Two large parallel plates with surface conditions...Ch. 1 - 1.25 A spherical vessel, 0.3 m in diameter, is...Ch. 1 - 1.26 Repeat Problem 1.25 but assume that the...Ch. 1 - Determine the rate of radiant heat emission in...Ch. 1 - 1.28 The sun has a radius of and approximates a...Ch. 1 - 1.29 A spherical interplanetary probe with a 30-cm...Ch. 1 - A spherical communications satellite, 2 m in...Ch. 1 - A long wire 0.7 mm in diameter with an emissivity...Ch. 1 - Wearing layers of clothing in cold weather is...Ch. 1 - A section of a composite wall with the dimensions...Ch. 1 - A section of a composite wall with the dimensions...Ch. 1 - Repeat Problem 1.35 but assume that instead of...Ch. 1 - 1.37 Mild steel nails were driven through a solid...Ch. 1 - Prob. 1.38PCh. 1 - 1.39 On a cold winter day, the outside wall of a...Ch. 1 - As a designer working for a major electric...Ch. 1 - 1.41 A heat exchanger wall consists of a copper...Ch. 1 - 1.43 A simple solar heater consists of a flat...Ch. 1 - A composite refrigerator wall is composed of 5 cm...Ch. 1 - An electronic device that internally generates 600...Ch. 1 - 1.47 A flat roof is modeled as a flat plate...Ch. 1 - A horizontal, 3-mm-thick flat-copper plate, 1-m...Ch. 1 - 1.49 A small oven with a surface area of is...Ch. 1 - A steam pipe 200 mm in diameter passes through a...Ch. 1 - 1.51 The inner wall of a rocket motor combustion...Ch. 1 - 1.52 A flat roof of a house absorbs a solar...Ch. 1 - Determine the power requirement of a soldering...Ch. 1 - 1.54 The soldering iron tip in Problem 1.53...Ch. 1 - Prob. 1.55PCh. 1 - A pipe carrying superheated steam in a basement at...Ch. 1 - Draw the thermal circuit for heat transfer through...Ch. 1 - 1.60 Two electric resistance heaters with a 20 cm...Ch. 1 - 1.63 Liquid oxygen (LOX) for the space shuttle is...Ch. 1 - The interior wall of a large, commercial walk-in...Ch. 1 - 1.67 In beauty salons and in homes, a ubiquitous...Ch. 1 - The heat transfer coefficient between a surface...Ch. 1 - The thermal conductivity of fibreglass insulation...Ch. 1 - 1.71 The thermal conductivity of silver at 212°F...Ch. 1 - 1.72 An ice chest (see sketch) is to constructed...Ch. 1 - Estimate the R-values for a 5-cm-thick fiberglass...Ch. 1 - A manufacturer in the United States wants to sell...Ch. 1 - Referring to Problem 1.74, how many kilograms of...Ch. 1 - 1.76 Explain a fundamental characteristic that...Ch. 1 - 1.77 Explain each in your own words. (a) What is...Ch. 1 - What are the important modes of heat transfer for...Ch. 1 - 1.79 Consider the cooling of (a) a personal...Ch. 1 - Describe and compare the modes of heat loss...Ch. 1 - A person wearing a heavy parka is standing in a...Ch. 1 - Discuss the modes of heat transfer that determine...
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- A steam power plant is located in the northern part of the country. Steam in the plant flows steadily through a 0.17-m diameter pipeline from the steam generating unit (SGU) to the steam turbine. At the SGU end, the steam conditions are determined to be P = 4 MPa, t = 400°C, h = 3,247 kJ/kg, and specific volume = 0.181 m³/kg. At the steam turbine end, the conditions are found to be P = 3.5 MPa, t = 392°C, h = 3,178.3 kJ kg, and specific volume = 0.248 m³/kg. Heat loss from the pipeline is 7.86 kJ/kg. Determine the steam mass flow rate in kg/s.arrow_forwardA water tube boiler has a capacity of 1000 kg/hr of steam. The factor of evaporation is 1.3, boiler rating is 200%, boiler efficiency is 5%, heating surface area is 0.91 m2/boiler Hp, and the heating value of fuel is 18,400 Kcal/kg. The total coal available in the bunker is 50,000 kg. Determine total number of hours to consume the available fuel.arrow_forwardA Carnot engine operating on air (k = 1.4) accepts 50 kJ/kg of heat and rejects20 kJ/kg. Calculate the high and low reservoir temperatures if the maximum specificvolume is 10 m3/kg and the pressure after the isothermal expansion is 200 kPa. Assumean ideal gas constant for air of 0.287 kJ/kg-K.arrow_forward
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- Question 4: An insulated room is heated by burning candles. Is this a heat or work interaction? Take the entire room, including the candles, as the system Question 5: Is the energy required to heat air from 295 to 305 K the same as the energy required to heat it from 345 to 355 K? Assume the pressure remains constant in both cases.arrow_forwardSOLVE THE PROBLEM AND SHOW THE DETAILED SOLUTION A steam condenser receives 10 kg per second of steam with an enthalpy of 2,570-kJ/kg. The steam condenses into liquid and leaves with an enthalpy of 160kJ/kg. Cooling water passes through the condenser with temperature increases from 13 to 24 Calculate the cooling water flow rate in kg/s.arrow_forwardAn auditorium is designed to seat 4500 people. The ventilation rate is 1.62 x 107 ft3/hr of outside air. The outside temperature is 0oF dry bulb, and outside pressure is 14.6 psia. Air leaves the auditorium at 70oF dry bulb. There is no recirculation. The furnace has a capacity of 1,250,000 Btu/hr. The temperature at which the air should enter the auditorium is most nearlyarrow_forward
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