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engineering
mechanical engineering

Principles of heat transfer 7th Edition Frank Kreith, Raj M. Manglik, Mark S. Bohn - Solutions

A vertical rectangular water duct 1 m high and 0.1 m deep is placed in an environment of saturated steam at atmospheric pressure. If the outer surface of the duct is about 50?C, estimate the rate of steam condensation per unit length.GIVENWater-cooled rectangular duct, 1 m high, 0.1 m deepDuct
A 1 m long tube-within-a-tube heat exchanger, as shown in the sketch, is used to condense steam at 2 atmospheres in the annulus, and water flows in the inner tube, entering at 90?C. The inner tube is made of copper with an OD of 1.27 cm and an ID of 1.0 cm.(a) Estimate the water flow rate required
A one-pass condenser-heat exchanger, shown in the sketch, has 64 tubes arranged in a square array with 8 tubes per line. The tubes are 4 feet long, made of copper with an outside diameter of 0.50 in., in a shell at atmospheric pressure. Water flows inside the tubes whose outside wall temperature is
Show that the dimensionless equation for ice formation at the outside of a tube of radius ro is where Assume that the water is initially at the freezing temperature Tf, that the cooling medium inside the tube surface is below the freezing temperature at a uniform temperature T??, and that ho is
In the manufacture of can ice, cans having inside dimensions of 11 by 22 by 50 in. with 1- in. inside taper are filled with water and immersed in brine at a temperature of 10?F.[For details of the process see (81).] For the purpose of a preliminary analysis, the actual ice can be considered as an
Estimate the time required to freeze vegetables in thin, tin cylindrical containers 15 cm in diameter. Air at ??12?C is blowing at 4 m/s over the cans, which are stacked to form one long cylinder. The physical properties of the vegetables before and after freezing may be taken as those of water and
Estimate the time required to freeze a 3 cm thickness of water due to nocturnal radiation with ambient air and initial water temperature at 4?C. Neglect evaporation effects.GIVENWater exposed to nocturnal radiation and airInitial water temperature (Twi) and ambient air temperature (T??) =
The temperature of a round cooling pond, 100 m in diameter, is 7?C on a winter day. If the air temperature suddenly drops to ??7?C, calculate the thickness of ice formed after three hours.GIVENA round cooling pond on a winter dayInitial temperature (Tl) = 7?CAir temperature (T??) drops to ??7?CPond
On a rainy Monday afternoon, Sherlock Holmes gets a call from a wealthy banker to arrange a breakfast appointment for the following day to discuss the collection of a loan from farmer Joe. When Holmes arrives at the home of the banker at 9 a.m. Tuesday, he finds the body of the banker in his
Estimate the cross-sectional area required for a 30 cm long methanol-nickel heat pipe to transport 100 Btu/hr at atmospheric pressure.GIVENMethanol-nickel heat pipe30 cm longAtmospheric pressureASSUMPTIONSThe type of wick to be used is a threaded artery wick100°C operation
Design a heat pipe cooling system for a spherical satellite that dissipates 5000 W/m3, has a surface area of 5 m2, and cannot exceed a temperature of 120°C. All the heat must be dissipated by radiation into space. State all your assumptions.GIVENSpherical satellite, 5 m2 surface areaDissipates
Compare the axial heat flux achievable by a heat pipe using water as the working fluid with that of a silver rod. Assume that both are 20 cm long, that the temperature difference for the rod from end to end is 100°C and that the heat pipe operates at atmospheric pressure. State your other
The outer surface of a 0.2m-thick concrete wall is kept at a temperature of ??5?C, while the inner surface is kept at 20?C. The thermal conductivity of the concrete is 1.2 W/(m K). Determine the heat loss through a wall 10 m long and 3 m high.GIVEN10 m long, 3 m high, and 0.2 m thick concrete
The weight of the insulation in a spacecraft may be more important than the space required. Show analytically that the lightest insulation for a plane wall with a specified thermal resistance is that insulation which has the smallest product of density times thermal conductivity.GIVENInsulating a
A furnace wall is to be constructed of brick having standard dimensions 9 by 4.5 by 3 in. Two kinds of material are available. One has a maximum usable temperature of 1900?F and a thermal conductivity of 1 Btu/(h ft?F), and the other has a maximum temperature limit of 1600?F and a thermal
To measure thermal conductivity, two similar 1-cm-thick specimens are placed in an apparatus shown in the accompanying sketch. Electric current is supplied to the 6-cm by 6-cm guarded heater, and a wattmeter shows that the power dissipation is 10 watts (W). Thermocouples attached to the warmer and
To determine the thermal conductivity of a structural material, a large 6-in-thick slab of the material was subjected to a uniform heat flux of 800 Btu/(h ft2), while thermocouples embedded in the wall 2 in. apart were read over a period of time. After the system had reached equilibrium, an
A square silicone chip 7 mm by 7 mm in size and 0.5 mm thick is mounted on a plastic substrate with its front surface cooled by a synthetic liquid flowing over it. Electronic circuits in the back of the chip generate heat at a rate of 5 watts that have to be transferred through the chip. Estimate
A warehouse is to be designed for keeping perishable foods cool prior to transportation to grocery stores. The warehouse has an effective surface area of 20,000 ft2 exposed to an ambient air temperature of 90?F. The warehouse wall insulation (k = 0.1 Btu/(h ft?F)) is 3 in. thick. Determine the rate
With increasing emphasis on energy conservation, the heat loss from buildings has become a major concern. For a small tract house the typical exterior surface areas and R-factors (area × thermal resistance) are listed below (a) Calculate the rate of heat loss from the house when the interior
Heat is transferred at a rate of 0.1 kW through glass wool insulation (density = 100 kg/m3) of 5 cm thickness and 2 m2 area. If the hot surface is at 70?C, determine the temperature of the cooler surface.GIVENGlass wool insulation with a density (ρ) = 100 kg/m3Thickness (L) = 5 cm = 0.05 mArea (A)
A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10 cm thickness is 20 W/m2. If a thermocouple at the inner surface of the wall indicates a temperature of 22?C while another at the outer surface shows 6?C, calculate the thermal
Calculate the heat loss through a 1-m by 3-m glass window 7 mm thick if the inner surface temperature is 20?C and the outer surface temperature is 17?C. Comment on the possible effect of radiation on your answer.GIVENWindow: 1 m by 3 mThickness (L) = 7 mm = 0.007 mSurface temperatureInner (Ti) =
If in Problem 1.11 the outer air temperature is ??2?C, calculate the convective heat transfer coefficient between the outer surface of the window and the air assuming radiation is negligible. Problem 1.11: Calculate the heat loss through a 1 m by 3 m glass window 7 mm thick if the inner surface
Using Table 1.4 as a guide, prepare a similar table showing the order of magnitudes of the thermal resistances of a unit area for convection between a surface and various fluids.GIVENTable 1.4??The order of magnitude of convective heat transfer coefficient ( hc)
A thermocouple (0.8-mm-OD wire) is used to measure the temperature of quiescent gas in a furnace. The thermocouple reading is 165?C. 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 convective heat
Water at a temperature of 77?C is to be evaporated slowly in a vessel. The water is in a low pressure container which is surrounded by steam. The steam is condensing at 107?C. The overall heat transfer coefficient between the water and the steam is 1100 W/(m2 K). Calculate the surface area of the
The heat transfer rate from hot air at 100?C flowing over one side of a flat plate with dimensions 0.1 m by 0.5 m is determined to be 125 W when the surface of the plate is kept at 30?C. What is the average convective heat transfer coefficient between the plate and the air?GIVENFlat plate, 0.1 m by
The heat transfer coefficient for a gas flowing over a thin flat plate 3 m long and 0.3 m wide varies with distance from the leading edge according to hc (x) = 10 ?? ???1/4 W/(m2K) If the plate temperature is 170°C and the gas temperature is 30°C, calculate (a) The average heat transfer
A cryogenic fluid is stored in a 0.3 m diameter spherical container in still air. If the convective heat transfer coefficient between the outer surface of the container and the air is 6.8 W/(m2 K), the temperature of the air is 27?C and the temperature of the surface of the sphere is ??183?C,
A high-speed computer is located in a temperature controlled room of 26?C. When the machine is operating its internal heat generation rate is estimated to be 800 W. The external surface temperature is to be maintained below 85?C. The heat transfer coefficient for the surface of the computer is
In order to prevent frostbite to skiers on chair lifts, the weather report at most ski areas gives both an air temperature and the wind chill temperature. The air temperature is measured with a thermometer that is not affected by the wind. However, the rate of heat loss from the skier increases
Using the information in Problem 1.20, estimate the ambient air temperature that could cause frostbite on a calm day on the ski slopes. From Problem 1.20Suppose that the inner temperature of a 3 mm thick layer of skin with a thermal conductivity of 0.35 W/(m K) is a temperature of 35?C. Under calm
Two large parallel plates with surface conditions approximating those of a blackbody are maintained at 1500 and 500?F, respectively. Determine the rate of heat transfer by radiation between the plates in Btu/(h ft2) and the radiative heat transfer coefficient in Btu/(h ft2 ?F) and in W/(m2
A spherical vessel 0.3 m in diameter is located in a large room whose walls are at 27?C (see sketch). If the vessel is used to store liquid oxygen at ??183?C and the surface of the storage vessel as well as the walls of the room are black, calculate the rate of heat transfer by radiation to the
Repeat Problem 1.23 but assume that the surface of the storage vessel has an absorptance (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
Determine the rate of radiant heat emission in watts per square meter from a blackbody at(a) 150°C,(b) 600°C,(c) 5700°C.GIVENA blackbody
The sun has a radius of 7 × 108 m and approximates a blackbody with a surface temperature of about 5800 K. Calculate the total rate of radiation from the sun and the emitted radiation flux per square meter of surface area.GIVENThe sun approximates a blackbodySurface temperature (Ts) = 5800 KRadius
A small gray sphere having an emissivity of 0.5 and a surface temperature of 1000°F is located in a blackbody enclosure having a temperature of 100°F. Calculate for this system: (a) The net rate of heat transfer by radiation per unit of surface area of the sphere, (b) The radiative thermal
A spherical communications satellite 2 m in diameter is placed in orbit around the earth. The satellite generates 1000 W of internal power from a small nuclear generator. If the surface of the satellite has an emittance of 0.3 and is shaded from solar radiation by the earth, estimate the surface
A long wire 0.03 inches in diameter with an emissivity of 0.9 is placed in a large quiescent air space at 20?F. If the wire is at 1000?F, calculate the net rate of heat loss. Discuss your assumptions.GIVENLong wire in still airWire diameter (D) = 0.03 in.Wire temperature (Ts) = 1000?F = 1460
Wearing layers of clothing in cold weather is often recommended because dead-air spaces between the layers keep the body warm. The explanation for this is that the heat loss from the body is less. Compare the rate of heat loss for single 3/4-in-thick layer of wool [k = 0.020 Btu/(hr ft ?F)] with
A section of a composite wall with the dimensions shown below has uniform temperatures of 200°C and 50°C over the left and right surfaces, respectively. If the thermal conductivities of the wall materials are: kA = 70 W/(m K), kB = 60 W/(m K), kc = 40 W/(m K) and kD = 20 W/(m K), determine the
Repeat the Problem 1.31 including a contact resistance of 0.1 K/W at each of the interfaces. Problem 1.31: A section of a composite wall with the dimensions shown in the schematic diagram below has uniform temperatures of 200°C and 50°C over the left and right surfaces, respectively. If the
Repeat the Problem 1.32 but assume that instead of surface temperatures, the given temperatures are those of air on the left and right sides of the wall and that the convective heat transfer coefficients on the left and right surfaces are 6 and 10 W/(m2 K), respectively. Problem 1.32: Repeat the
Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5 cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that
Calculate the rate of heat transfer through the composite wall in Problem 1.34 if the temperature difference is 25?C and the contact resistance between the sheets of wood is 0.005 m2 K/W.Problem 1.34: To reinforce a solid wall consisting of two layers, each 2.5 cm thick, mild steel nails were
Heat is transferred through a plane wall from the inside of a room at 22?C to the outside air at ??2?C. The convective heat transfer coefficients at the inside and outside surfaces are 12 and 28 W/(m2 K), respectively. The thermal resistance of a unit area of the wall is 0.5 m2 K/W. Determining the
How much fiberglass insulation [k = 0.035 W/(m K)] is needed to guarantee that the outside temperature of a kitchen oven will not exceed 43?C? The maximum oven temperature to be maintained by the convectional type of thermostatic control is 290?C, the kitchen temperature may vary from 15?C to 33?C
A heat exchanger wall consists of a copper plate 3/8 in. thick. The heat transfer coefficients on the two sides of the plate are 480 and 1250 Btu/(h ft2 ?F), corresponding to fluid temperatures of 200 and 90?F, respectively. Assuming that the thermal conductivity of the wall is 220 Btu/(h ft
A submarine is to be designed to provide a comfortable temperature for the crew of no less than 70?F. The submarine can be idealized by a cylinder 30 ft in diameter and 200 ft in length. The combined heat transfer coefficient on the interior is about 2.5 Btu/(h ft2 ?F), while on the outside the
A simple solar heater consists of a flat plate of glass below which is located a shallow pan filled with water, so that the water is in contact with the glass plate above it. Solar radiation is passing through the glass at the rate of 156 Btu/(h ft2). The water is at 200?F and the surrounding air
A composite refrigerator wall is composed of 2 in. of corkboard sandwiched between a? in. thick layer of oak and a 1/32 in. thickness of aluminum lining on the inner surface. The average convective heat transfer coefficients at the interior and exterior wall are 2 and 1.5 Btu/(h ft2 ?F),
An electronic device that internally generates 600 mW of heat has a maximum permissible operating temperature of 70?C. It is to be cooled in 25?C air by attaching aluminum fins with a total surface area of 12 cm2. The convective heat transfer coefficient between the fins and the air is 20 W/(m2 K).
To reduce the home heating requirements, modern building codes in many parts of the country require the use of double-glazed or double-pane windows, i.e., windows with two panes of glass. Some of these so called thermopane windows have an evacuated space between the two glass panes while others
A flat roof can be modeled as a flat plate insulated on the bottom and placed in the sunlight. If the radiant heat that the roof receives from the sun is 600 W/m2, the convection heat transfer coefficient between the roof and the air is 12 W/(m2 K), and the air temperature is 27?C, determine the
A horizontal 3-mm-thick flat copper plate, 1 m long and 0.5 m wide, is exposed in air at 27?C to radiation from the sun. If the total rate of solar radiation absorbed is 300 W and the combined radiative and convective heat transfer coefficients on the upper and lower surfaces are 20 and 15 W/(m2
A small oven with a surface area of 3 ft2 is located in a room in which the walls and the air are at a temperature of 80?F. The exterior surface of the oven is at 300?F and the net heat transfer by radiation between the oven??s surface and the surroundings is 2000 Btu/h. If the average convective
A steam pipe 200 mm in diameter passes through a large basement room. The temperature of the pipe wall is 500?C, while that of the ambient air in the room is 20?C. Determine the heat transfer rate by convection and radiation per unit length of steam pipe if the emissivity of the pipe surface is 0.8
The inner wall of a rocket motor combustion chamber receives 50,000 Btu/(h ft2) by radiation from a gas at 5000? F. The convective heat transfer coefficient between the gas and the wall is 20 Btu/(h ft2 ?F). If the inner wall of the combustion chamber is at a temperature of 1000? F, determine the
A flat roof of a house absorbs a solar radiation flux of 600 W/m2. The backside of the roof is well insulated, while the outside loses heat by radiation and convection to ambient air at 20?C. If the emittance of the roof is 0.80 and the convective heat transfer coefficient between the roof and the
Determine the power requirement of a soldering iron in which the tip is maintained at 400?C. The tip is a cylinder 3 mm in diameter and 10 mm long. Surrounding air temperature is 20?C and the average convective heat transfer coefficient over the tip is 20 W/(m2 K). Initially, the tip is highly
The soldering iron tip in Problem 1.50 becomes oxidized with age and its gray-body emittance increases to 0.8. Assuming that the surroundings are at 20?C determine the power requirement for the soldering iron. Problem 1.50:Determine the power requirement of a soldering iron in which the tip is
Some automobile manufacturers are currently working on a ceramic engine block that could operate without a cooling system. Idealize such an engine as a rectangular solid, 45 cm by 30 cm by 30 cm. Suppose that under maximum power output the engine consumes 5.7 liters of fuel per hour, the heat
A pipe carrying superheated steam in a basement at 10?C has a surface temperature of 150?C. Heat loss from the pipe occurs by radiation (ε = 0.6) and natural convection [ hc = 25 W/(m2 K)]. Determine the percentage of the total heat loss by these two mechanisms.GIVENPipe in a basementPipe surface
For a furnace wall, draw the thermal circuit, determine the rate of heat flow per unit area, and estimate the exterior surface temperature under the following conditions: the convective heat transfer coefficient at the interior surface is 15 W/(m2 K); rate of heat flow by radiation from hot gases
Draw the thermal circuit for heat transfer through a double-glazed window. Include solar energy gain to the window and the interior space. Identify each of the circuit elements. Include solar radiation to the window and interior space.GIVENDouble-glazedwindow
The ceiling of a tract house is constructed of wooden studs with fiberglass insulation between them. On the interior of the ceiling is plaster and on the exterior is a thin layer of sheet metal. A cross section of the ceiling with dimensions is shown below.(a) The R-factor describes the thermal
A homeowner wants to replace an electric hot-water heater. There are two models in the store. The inexpensive model costs $280 and has no insulation between the inner and outer walls. Due to natural convection, the space between the inner and outer walls has an effective conductivity of 3 times
Liquid oxygen (LOX) for the Space Shuttle can be stored at 90 K prior to launch in a spherical container 4 m in diameter. To reduce the loss of oxygen, the sphere is insulated with superinsulation developed at the U.S. Institute of Standards and Technology??s Cryogenic Division that has an
The heat transfer coefficient between a surface and a liquid is 10 Btu/(h ft2 ?F). How many watts per square meter will be transferred in this system if the temperature difference is 10?C?GIVENThe heat transfer coefficient between a surface and a liquid (hc) = 10 Btu/(h ft2 ?F)Temperature
The thermal conductivity of fiberglass insulation at 68°F is 0.02 Btu/(h ft °F). What is its value in SI units?GIVENThermal conductivity (k) = 0.02 Btu/(h ft °F)
The thermal conductivity of silver at 212°F is 238 Btu/(h ft °F). What is the conductivity in SI units?GIVENThermal conductivity of silver (k) = 238 Btu/(h ft °F)
An ice chest (see sketch) is to be constructed from Styrofoam [k = 0.033 W/(m K)]. If the wall of the chest is 5 cm thick, calculate its R-value in (hr ft2 ?F)/(Btu in).GIVENIce chest constructed of Styrofoam, k = 0.0333 W/(m K)Wall thickness 5 cmASSUMPTIONS(a) One-dimensional, steadyconduction
Estimate the R-values for a 2-inch-thick fiberglass board and a 1-inch-thick polyurethane foam layer. Then compare their respective conductivity-times-density products if the density for fiberglass is 50 kg/m3 and the density of polyurethane is 30 kg/m3. Use the units given in Figure
A manufacturer in the U.S. wants to sell a refrigeration system to a customer in Germany. The standard measure of refrigeration capacity used in the United States is the ‘ton’; a one-ton capacity means that the unit is capable of making about one ton of ice per day or has a heat removal rate of
Referring to Problem 1.65, how many kilograms of ice can a 3-ton refrigeration unit produce in a 24-hour period? The heat of fusion of water is 330 kJ/kg. From Problem 1.65: A manufacturer in the U.S. wants to sell a refrigeration system to a customer in Germany. The standard measure of
Explain a fundamental characteristic that differentiates conduction from convection and radiation.
Explain in your own words:(a) What is the mode of heat transfer through a large steel plate that has its surfaces at specified temperatures?(b) What are the modes when the temperature on one surface of the steel plate is not specified, but the surface is exposed to a fluid at a specified
What are the important modes of heat transfer for a person sitting quietly in a room? What if the person is sitting near a roaring fireplace?GIVENPerson sitting quietly in a roomPerson sitting in a room with a fireplaceASSUMPTIONSThe person is clothed
Consider the cooling of(a) A personal computer with a separate CPU, and(b) A laptop computer. The reliable functioning of these machines depends upon their effective cooling. Identify and briefly explain all modes of heat transfer that are involved in the cooling process.GIVENA personal computer
Describe and compare the modes of heat loss through the single-pane and double-pane window assemblies shown in the sketch below.GIVENA single-pane and a double-pane window assemblyASSUMPTIONSThe window assembly wood casing is a goodinsulator
A person wearing a heavy parka is standing in a cold wind. Describe the modes of heat transfer determining heat loss from the person??s body.GIVENPerson standing in a cold wind, wearing a heavyparka
Discuss the modes of heat transfer that determine the equilibrium temperature of the space shuttle Endeavor when it is in orbit. What happens when it reenters the earth??s atmosphere?GIVENSpace shuttle Endeavor in orbitSpace shuttle Endeavor duringreentry
The heat conduction equation in cylindrical coordinates is (a) Simplify this equation by eliminating terms equal to zero for the case of steady ??state heat flow without sources or sinks around a right-angle corner such as the one in the accompanying sketch. It may be assumed that the corner
Write Equation (2.20) in a dimensionless form similar to Equation (2.17).GIVENEquation(2.20)
Calculate the rate of heat loss per foot and the thermal resistance for a 6 in. schedule 40 steel pipe covered with a 3 in. thick layer of 85% magnesia. Superheated steam at 300?F flows inside the pipe [ hc = 30 Btu/(h ft2 ?F)] and still air at 60?F is on the outside [ hc = 5 Btu/(h ft2
Suppose that a pipe carrying a hot fluid with an external temperature of Ti and outer radius ri is to be insulated with an insulation material of thermal conductivity k and outer radius ro. Show that if the convective heat transfer coefficient on the outside of the insulation is h and the
A solution with a boiling point of 180?F boils on the outside of a 1-in. tube with a No. 14 BWG gauge wall. On the inside of the tube flows saturated steam at 60 psia. The convective heat transfer coefficients are 1500 Btu/(h ft2 ?F) on the steam side and 1100 Btu/(h ft2 ?F) on the exterior
Steam having a quality of 98% at a pressure of 1.37 × 105 N/m2 is flowing at a velocity of 1 m/s through a steel pipe of 2.7 cm OD and 2.1 cm ID. The heat transfer coefficient at the inner surface, where condensation occurs, is 567 W/(m2 K). A dirt film at the inner surface adds a unit thermal
Estimate the rate of heat loss per unit length from a 2 in. ID, 23/8 in. OD steel pipe covered with high temperature insulation having a thermal conductivity of 0.065 Btu/(h ft) and a thickness of 0.5 in. Steam flows in the pipe. It has a quality of 99% and is at 300?F. The unit thermal resistance
The rate of heat flow per unit length q/L through a hollow cylinder of inside radius ri and outside radius ro isq/L = ( A k ??T)/(ro ?? ri)where A = 2π (ro ?? ri)/ln(ro/ri). Determine the percent error in the rate of heat flow if the arithmetic mean area π (ro + ri) is used instead of the
A 2.5-cm-OD, 2-cm-ID copper pipe carriers liquid oxygen to the storage site of a space shuttle at ??183?C and 0.04 m3/min. The ambient air is at 21?C and has a dew point of 10?C. How much insulation with a thermal conductivity of 0.02 W/(m K) is needed to prevent condensation on the exterior of the
A salesman for insulation material claims that insulating exposed steam pipes in the basement of a large hotel will be cost effective. Suppose saturated steam at 5.7 bars flows through a 30 cm OD steel pipe with a 3 cm wall thickness. The pipe is surrounded by air at 20?C. The convective heat
A hollow sphere with inner and outer radii of R1 and R2, respectively, is covered with a layer of insulation having an outer radius of R3. Derive an expression for the rate of heat transfer through the insulated sphere in terms of the radii, the thermal conductivities, the heat transfer
The thermal conductivity of a material may be determined in the following manner. Saturated steam 2.41 × 105 N/m2 is condensed at the rate of 0.68 kg/h inside a hollow iron sphere that is 1.3 cm thick and has an internal diameter of 51 cm. The sphere is coated with the material whose thermal
A cylindrical liquid oxygen (LOX) tank has a diameter of 4 ft, a length of 20 ft, and hemispherical ends. The boiling point of LOX is ?? 297?F. An insulation is sought which will reduce the boil-off rate in the steady state to no more than 25 lb/h. The heat of vaporization of LOX is 92 Btu/lb. If
The addition of insulation to a cylindrical surface, such as a wire, may increase the rate of heat dissipation to the surroundings (see Problem 2.4). (a) For a No. 10 wire (0.26 cm in diameter), what is the thickness of rubber insulation [k = 0.16 W/(m K)] that will maximize the rate of heat loss
For the system outlined in Problem 2.11, determine an expression for the critical radius of the insulation in terms of the thermal conductivity of the insulation and the surface coefficient between the exterior surface of the insulation and the surrounding fluid. Assume that the temperature

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