Questions and Answers of Fundamentals Momentum Heat

A grain dryer consists of a long semicircular duct of radius R = 1 m. One-half of the base surface consists of an electrically heated plate of emissivity ɛp = 0.8, while the other half supports the
Consider two very large metal parallel plates. The top plate is at a temperature Tt = 400 K while the bottom plate is at Tb = 300 K. The desired net radiation heat flux between the two plates is q" =
Consider parallel planes of infinite extent normal to the page as shown in the sketch. (a) Determine F12 using the results of Figure 13.4. (b) Determine F12 using the first case of Table
Consider the two parallel, coaxial, ring-shaped disks shown schematically. Show that Fiz can be expressed as where all view factors on the right-hand side of the equation can be evaluated
Derive expressions for the view factor F12 associated with the following arrangements. Express your results in terms of A1, A2, and any appropriate hypothetical surface area, as well as the view
A solar panel mounted on a spacecraft has an area of 1 m2 and a solar-to-electrical power conversion efficiency of 12%. The side of the panel with the photovoltaic array has an emissivity of 0.8 and
A spherical capsule of 3-m radius is fired from a space platform in earth orbit, such that it travels toward the center of the sun at 16,000 km/s. Assume that the capsule is a lumped capacitance body
A rectangular plate of thickness t, length L, and width W is proposed for use as a radiator in a spacecraft application. The plate material has a thermal conductivity of 300 W/m. K, a solar
The oxidized-aluminum wing of an aircraft has a chord length of Lc = 4 m and a spectral, hemispherical emissivity characterized by the following distribution. (a) Consider conditions for which
Solar irradiation of 1100 W/m2 is incident on a large, flat, horizontal metal roof on a day when the wind blowing over the roof causes a convection heat transfer coefficient of 25 W/m2. K. The
A thin-walled plate separates the interior of a large furnace from surroundings at 300 K. The plate is fabricated from a ceramic material for which diffuse surface behavior may be assumed and the
A spherical niobium droplet of diameter D = 3 mm is levitated by an acoustical technique in a vacuum chamber having walls that are diffuse and gray with an emissivity of ɛw =0.8 and a temperature of
A cylinder of 30-mm diameter and 150-mm length is heated in a large furnace having walls at 1000 K, while air at 400 K is circulating at 3 m/s. Estimate the steady-state cylinder temperature under
A two-color pyrometer is a device that is used to mea sure the temperature of a diffuse surface, Ts. The device measures the spectral, directional intensity emitted by the surface at two
A small anodized aluminum block at 35°C is heated in a large oven whose walls are diffuse and gray with ɛ = 0.85 and maintained at a uniform temperature of 175°C. The anodized coating is also
A small anodized aluminum block at 35°C is heated in a large oven whose walls are diffuse and gray with ɛ = 0.85 and maintained at a uniform temperature of 175°C. The anodized coating is also
A small anodized aluminum block at 35°C is heated in a large oven whose walls are diffuse and gray with ɛ = 0.85 and maintained at a uniform temperature of 175°C. The anodized coating is also
A small anodized aluminum block at 35°C is heated in a large oven whose walls are diffuse and gray with ɛ = 0.85 and maintained at a uniform temperature of 175°C. The anodized coating is also
A small anodized aluminum block at 35°C is heated in a large oven whose walls are diffuse and gray with ɛ = 0.85 and maintained at a uniform temperature of 175°C. The anodized coating is also
A small anodized aluminum block at 35°C is heated in a large oven whose walls are diffuse and gray with ɛ = 0.85 and maintained at a uniform temperature of 175°C. The anodized coating is also
A small anodized aluminum block at 35°C is heated in a large oven whose walls are diffuse and gray with ɛ = 0.85 and maintained at a uniform temperature of 175°C. The anodized coating is also
A small anodized aluminum block at 35°C is heated in a large oven whose walls are diffuse and gray with ɛ = 0.85 and maintained at a uniform temperature of 175°C. The anodized coating is also
A small anodized aluminum block at 35°C is heated in a large oven whose walls are diffuse and gray with ɛ = 0.85 and maintained at a uniform temperature of 175°C. The anodized coating is also
A temperature sensor imbedded in the tip of a small tube having a diffuse, gray surface with an emissivity of 0.8 is centrally positioned within a large air-conditioned room whose walls and air
A thermocouple inserted in a 4-mm-diameter stainless steel tube having a diffuse, gray surface with an emissivity of 0.4 is positioned horizontally in a large airconditioned room whose walls and air
A thermocouple whose surface is diffuse and gray with an emissivity of 0.6 indicates a temperature of 180°C when used to measure the temperature of a gas flowing through a large duct whose walls
A special diffuse glass with prescribed spectral radiative properties is heated in a large oven. The walls of the oven are lined with a diffuse, gray refractory brick having an emissivity of 0.75 and
A diffuse surface having the following spectral characteristics is maintained at 500 K when situated in a large furnace enclosure whose walls are maintained at 1500 K: (a) Sketch the spectral
A diffuse surface having the following spectral characteristics is maintained at 500 K when situated in a large furnace enclosure whose walls are maintained at 1500 K: (a) Sketch the spectral
A diffuse, opaque surface at 700 K has spectral emissivities of ɛλ = 0 for 0 < λ < 3 λm, ɛλ = 0.5 for 3 μm < λ < 10 μm, and ɛλ = 0.9
The spectral reflectivity distribution for white paint (Figure 12.22) can be approximated by the following stair-step function:A small flat plate coated with this paint is suspended inside a large
The spectral reflectivity distribution for white paint (Figure 12.22) can be approximated by the following stair-step function:A small flat plate coated with this paint is suspended inside a large
A small, opaque, diffuse object at Ts = 400 K is suspended in a large furnace whose interior walls are at Tf = 2000 K. The walls are diffuse and gray and have an emissivity of 0.20. The
A radiation thermometer is a device that responds to a radiant flux within a prescribed spectral interval and is calibrated to indicate the temperature of a blackbody that produces the same
A proposed proximity meter is based on the physical arrangement of Problem 12.14. The sensing area of a meter that is installed on a vehicle, A2 is irradiated by a stationary warm object, A1.
Isothermal furnaces with small apertures approximating a blackbody are frequently used to calibrate heat flux gages, radiation thermometers, and other radiometric devices. In such applications, it is
Thermal imagers have radiation detectors that are sensitive to a spectral region and provide white black or color images with shading to indicate relative temperature differences in the scene. The
A small flat plate is positioned just beyond the earth's atmosphere and is oriented such that the normal to the plate passes through the center of the sun. Refer to Problem 12.20 for pertinent
The dark surface of a ceramic stove top may be approximated as a blackbody. The "burners," which are integral with the stove top, are heated from below by electric resistance heaters. (a)
During radiant heat treatment of a thin-film material, its shape, which may be hemispherical (a) or spherical (b), is maintained by a relatively low air pressure (as in the case of a rubber balloon).
The spectral distribution of the radiation emitted by a diffuse surface may be approximated as follows. (a) What is the total emissive power? (b) What is the total intensity of the
Consider a small surface of area A1 = 10-4 m2, which emits diffusely with a total, hemispherical emissive power of E1 = 5 x 104 W/m2. (a) At what rate is this emission intercepted by a
It has been proposed that the very hot air trapped inside the attic of a house in the summer may be used as the energy source for a passive water heater installed in the attic. Energy costs
Fuel cells similar to the PEM cell of Example 1.4 operate with a mixture of liquid water and methanol instead of hydrogen; the anode is placed in direct contact with the liquid fuel. Oxygen (species
At the end of its manufacturing process, a silicon wafer of diameter D = 150 mm, thickness ð = 1 mm, and emissivity ɛ =0.65 is at an initial temperature of Ti = 325°C and is allowed to cool
A thin-walled container with a hot process fluid at 50°C is placed in a quiescent, cold water bath at 10°C. Heat transfer at the inner and outer surfaces of the container may be approximated by
A thin-walled container with a hot process fluid at 50°C is placed in a quiescent, cold water bath at 10°C. Heat transfer at the inner and outer surfaces of the container may be approximated by
The final step of a manufacturing process in which a protective coating is applied to the inner surface of a circular tube involves passage of dry, atmosphere air through the tube to remove a
A humidifier consists of a bundle of vertical tubes, each of 20-mm diameter, through which dry atmospheric air is in fully developed flow at 103 kg/s and 298 K. The inner tube surface is welted with
Air at 25°C and 1 atm is in fully developed flow at m = 103 kg/s through a 10-mm-diameter circular tube whose inner surface is wetted with water. Determine the tube length required for the
Air at 25°C and 1 atm is in fully developed flow at m = 103 kg/s through a 10-mm-diameter circular tube whose inner surface is wetted with water. Determine the tube length required for the
Air at 25°C and 1 atm is in fully developed flow at m = 103 kg/s through a 10-mm-diameter circular tube whose inner surface is wetted with water. Determine the tube length required for the
Air at 25°C and 1 atm is in fully developed flow at m = 103 kg/s through a 10-mm-diameter circular tube whose inner surface is wetted with water. Determine the tube length required for the
Air at 25°C and 1 atm is in fully developed flow at m = 103 kg/s through a 10-mm-diameter circular tube whose inner surface is wetted with water. Determine the tube length required for the
Air at 25°C and 1 atm is in fully developed flow at m = 103 kg/s through a 10-mm-diameter circular tube whose inner surface is wetted with water. Determine the tube length required for the water
The mold used in an injection molding process consists of a top half and a bottom half. Each half is 60 mm × 60 mm × 20 mm and is constructed of metal (ρ = 7800 kg/m3, c = 450 J/kg. K). The cold
In a paper-drying process, the paper moves on a conveyor belt at 0.2 m/s, while dry air from an array of slot jets (Figure 7.16) impinges normal to its surface. The nozzle width and pitch are W = 10
Consider an air conditioning system composed of a bank of tubes arranged normal to air flowing in a duct at a mass rate of mo (kg/s). A coolant flowing through the tubes is able to maintain the
A flat plate coated with a volatile substance (species A) is exposed to dry, atmospheric air in parallel flow with T∞ = 20°C and u∞ = 8 m/s. The plate is maintained at a constant temperature of
A circular transistor of 10-mm diameter is cooled by impingement of an air jet exiting a 2-mm diameter round nozzle with a velocity of 20 m/s and a temperature of 15°C. The jet exit and the exposed
Tissue engineering involves the development of biological substitutes that restore or improve tissue function, Once manufactured, engineered organs can be implanted and grow within the patient,
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Steel (AISI 1010) plates of thickness ð = 6 mm and length L = 1 m on a side are conveyed from a heat treatment process and are concurrently cooled by atmospheric air of velocity u∞ = 10 m/s
Consider heat transfer in a forearm, which can be approximated as a cylinder of muscle of radius 50 mm (neglecting the presence of bones), with an outer layer of skin and fat of thickness 3 mm. There
Consider the conditions of Example 3.12 for an air environment, except now the air and surroundings temperatures are both 15°C. Humans respond to cold by shivering, which increases the metabolic
Heat transfer from a transistor may be enhanced by inserting it in an aluminum sleeve (k = 200 W/ m. K ) having 12 integrally machined longitudinal fins on its outer surface. The transistor radius
One method that is used to grow nanowires (nanotubes with solid cores) is to initially deposit a small droplet of a liquid catalyst onto a flat surface. The surface and catalyst are heated and
Consider a rod of diameter D, thermal conductivity k, and length 2L that is perfectly insulated over one portion of its length, -L < x < 0, and experiences convection with a fluid (T∞, h)
Copper tubing is joined to a solar collector plate of thickness t, and the working fluid maintains the temperature of the plate above the tubes at To. There is a uniform net radiation heat flux q"rad
Most of the energy we consume as food is converted to thermal energy in the process of performing all our bodily functions and is ultimately lost as heat from our bodies. Consider a person who
A hair dryer may be idealized as a circular duct through which a small fan draws ambient air and within which the air is heated as it flows over a coiled electric resistance wire.(a) If a dryer is
A blood warmer is to be used during the transfusion of blood to a patient. This device is to heat blood taken from the blood bank at 10°C to 37°C at a flow rate of 200 ml/min. The blood passes
Chips of width L = 15 mm on a side are mounted to a substrate that is installed in an enclosure whose walls and air are maintained at a temperature of Tsur = T∞ = 25°C. The chips have an
Chips of width L = 15 mm on a side are mounted to a substrate that is installed in an enclosure whose walls and air are maintained at a temperature of Tsur = T∞ = 25°C. The chips have an
A glass window of width W = 1 m and height H = 2 m is 5 mm thick and has a thermal conductivity of k, = 1.4 W/ m.K . If the inner and outer surface temperatures of the glass are 15°C and -20°C,
A wetted-wall column of 2.0-cm inner diameter and 50-cm wetted length is used to oxygenate blood as a continuous, steady-state process, as shown in the figure below. Blood containing 1.0
Often aerobatic fermentations give off CO2 gas because the respiring cells produce CO2 as glucose nutrient is converted to chemical energy. The conditions used to set kLa for O2 transfer in the
Please refer to Problem 30.22. Now consider that a “packed column” containing 3/8-inch rings will be used instead of the wetted-wall column.a. What is kLa, the volumetric mass-transfer
Ozone (O3) dissolved in water is used in many wastewater treatment applications. Pure, 100% ozone gas at 1.0 atm and 20°C is continuously bubbled into a tank of liquid water. The rising bubbles
A pond containing a suspension of microorganisms is used to biologically degrade dissolved organic materials in wastewater, as shown in the figure (right column). The pond contains 1000 m3 of liquid.
A horizontal chemical vapor deposition (CVD) reactor for growth of gallium arsenide (GaAs) thin films is shown in the figure. In this process, arsine (AsH3), trimethyl gallium, Ga(CH3)3, and H2gases

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