For an ideal radiator (hohlraum) with a 10-cm- diameter opening, located in black surroundings at 16°C, calculate (a) the net radiant heat transfer rate for hohlraum temperatures of 100°C and 560°C, (b) the wavelength at which the emission is a maxi- mum, (c) the monochromatic emission at lmax, and (d) the wavelengths at which the monochromatic emission is 1% of the maximum value.
> What role did the relationship between Vale and TUV SUD play in the dam disaster? Did TUV SUD have a conflict of interest, and if so, what was the conflict?
> What additional ethical safeguards were needed at Vale that could have prevented, or mitigated the harms from, the dam collapse?
> What ethical safeguards were present at Vale at the time of the dam collapse? Why did they not prevent the dam collapse?
> Using Figure 6.1, how would you classify the ethical climate at Vale? In what way did it contribute to the mine collapse? What ethical climate might have prevented the dam collapse?
> If you were Mike Roman, what would you do to make an ethical decision?
> Which of the several types of moral intensity are relevant in the case?
> Considering the stages of moral development outlined in Figure 5.4, at what stage would you classify a decision to give priority to U.S. customers? Why?
> Considering the four methods of ethical analysis presented in this chapter: a. Would directing N95 respirators first to U.S. customers be consistent with 3M values, as stated in their code of ethics? b. What would be the costs and benefits to key stakeho
> Do you believe it was right for the Administration to ask 3M to direct its N95 respirators first to U.S. customers? Why or why not?
> What further steps could be taken by governments, NGOs, and companies to strengthen the process to exclude conflict minerals from the global supply chain?
> List the four kinds of tipping mentioned in this case. If you worked in a restaurant, which kind of tipping would you support, and why? If you were a customer in a restaurant, which kind of tipping would you support, and why?
> In what ways did Intel collaborate with other sectors (governments and civil society) in its efforts to eliminate conflict minerals from its products? What strengths and weaknesses did each sector bring to the task?
> Why was Intel unable to eliminate conflict minerals from its supply chain unilaterally, that is, without the help of others?
> Consider the three sectors discussed in this chapter (business, government, and civil society). What were the interests of each, with respect to conflict coltan, and in what ways did their interests converge?
> How do conflict minerals, and in particular, conflict coltan get their name? What groups benefited from the trade in conflict minerals? What groups were hurt by it?
> What stage of global corporate citizenship (using Figure 3.5) is Gravity Payments operating at, and why do you think so?
> Is Price acting like an executive of a firm that could be certified as a B corporation?
> What arguments in support of, or concerns about, corporate social responsibility (referring to Figure 3.3) are relevant to this case?
> What principles of global corporate citizenship (using Exhibit 3.A) are evident in this case?
> Is Price demonstrating elements of corporate social responsibility by his actions in this case, or not? Are his actions creating shared value at Gravity Payments?
> Apply the issue management life cycle process model to this case. Which stages of the process can you identify?
> What is the focal organization in this case, and what decision did it make?
> A 15-cm-black disk is placed halfway between two black 3-m-diameter disks that are 7 m apart with all disk surfaces parallel to each other. If the surroundings are at 0 K, determine the temperature of the two larger disks required to maintain the smaller
> A large slab of steel 0.1 m thick contains a 0.1-m-diameter circular hole whose axis is normal to the surface. Considering the sides of the hole to be black, specify the rate of radiative heat loss from the hole. The plate is at 811 K, and the surroundi
> A radiation source is to be built as shown in the diagram for an experimental study of radiation. The base of the hemisphere is to be covered by a circular plate having a centered hole of radius R/2. The underside of the plate is to be held at 555 K by
> Determine the total average hemispherical emissivity and the emissive power of a surface that has a spectral hemispherical emissivity of 0.8 at wave- lengths less than 1.5 m, 0.6 at wavelengths from 1.5 to 2.5 m, and 0.4 at wavelengths longer than 2.5
> In the construction of a space platform, two structural members of equal size with surfaces that are considered black are placed relative to each other as shown in the figure. Assuming that the left member attached to the platform is at 500 K, the other
> Show that the temperature of the reradiating sur- face Tr in Fig. 11.41 is
> A laser beam sends a uniform radiation beam towards the hemispherical opening in a solid housing with dimensions as shown. The surface of the cavity is black and essentially insulated from the surrounding housing material. The hemispherical cavity is a
> A 4-cm-diameter cylindrical enclosure with black surfaces, as shown in the accompanying sketch, has a 2-cm hole in the top cover. Assuming the walls of the enclosure are all at the same temperature, determine the percentage of the total radiation emitted
> Two electric resistance heaters with a 20 cm length and a 2 cm diameter are inserted into a well-insulated 40-L tank of water that is initially at 300 K. If each heater dissipates 500 W, what is the time required for bringing the water temperature in the
> A square silicon chip 7 mm * 7 mm in size and 0.5-mm thick is mounted on a plastic substrate as shown in the sketch below. The top surface of the chip is cooled by a synthetic liquid flowing over it. Electronic circuits on the bottom of the chip generate
> In thermal management or cooling of microchip modules for high-powered computer systems, very high heat fluxes have to be accommodated in the design of the cooling method. For many such cases, immersion cooling via pool boiling in a dielectric fluid is o
> Two coaxial parallel plate discs are situated relative to each other as shown in the sketch. The diameter of the upper plate is 20 cm, and that of the lower plate is 40 cm. The lower plate is maintained at a uniform temperature of 500 K and the upper tem
> Using basic shape-factor definitions, estimate the equilibrium temperature of the planet Mars, which has a diameter of 6600 km and revolves around the sun at a distance of 225 * 106 km. The diameter of the sun is 1,384,000 km. Assume that both the planet
> Two parallel plates of infinite extent perpendicular to the page are situated relative to each other as shown in the figure. The upper plate is at 300°C and the lower plate is at 100°C. Determine the net rate of radiation heat tran
> A circular ice skating rink, 20m in diameter, is enclosed by a large hemispherical dome of diameter 30 m. Assuming that the ice is 2 cm thick, estimate the time it takes for the ice to melt if the refrigeration system of the rink fails. Make this calcula
> Determine the view factors F12 and F21 for the following geometries (as shown in the figure): (a) a sphere of diameter, D, inside a cubic box of length L = D, (b) one side of a diagonal partition in a long square duct if side L, and (c) the end and si
> Determine the shape factor F1–2 for the geometrical configuration shown in the figure.
> A tungsten filament is heated to 2700 K. At what wavelength is the maximum amount of radiation emitted? What fraction of the total energy is in the visible range (0.4 to 0.75 m)? Assume that the filament radiates as a graybody.
> Determine the shape factor F1–4 for the geometrical configuration shown in the figure.
> Derive an expression for the geometric shape factor F1–2 for the rectangular surface A1 shown in the figure. A1 is 1-m * 20-m and is placed parallel to and centered 5 m above a 20-m square surface A2.
> Estimate the rate at which heat needs to be supplied to an astronaut repairing the Hubble telescope in space. Assume that the emissivity of the spacesuit is 0.5. Describe your model with a simple sketch and clearly state your assumptions.
> On a rainy Monday afternoon, a wealthy banker calls Sherlock Holmes 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 th
> 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 bel
> A hypothetical PV solar cell in space can utilize solar radiation between 0.8 and 1.1 mm in wavelength. Estimate the maximum theoretical efficiency for this solar cell facing the sun using the ideal black- body curve of the sun as the source. Supposing t
> As a result of the atmosphere surrounding the Earth trapping some of the incoming solar radiation, the average temperature of the Earth is approximately 15°C. Estimate the amount of radiation that is trapped by the atmosphere, including CO2 and methane,
> The diameter of the sun is 1.39 * 109 m. Estimate the percentage of the total radiation emitted by the sun, which approximates a blackbody at 5760 K, that is actually intercepted by the Earth. Of the total radiation falling on the Earth, about 70% f
> The glass cover for a flat plate solar collector has a spectral transmissivity that may be approximated as shown in the figure. Determine the total effective transmissivity of the glass cover to solar radiation assuming the sun emits that of a blackbody
> In a shell-and-tube heat exchanger with /W/M2 K and negligible wall resistance, by what percent would the overall heat transfer coefficient (based on the outside area) change if the number of tubes were doubled? The tubes have an outside diameter of 2.5
> The heat transfer coefficient of a copper tube (1.9-cm ID and 2.3-cm OD) is 500 W/m2 K on the inside and 120 W/m2 K on the outside, but a deposit with a fouling factor of 0.009 m2 K/W (based on the tube outside diameter) has built up over time. Estimate
> Repeat Problem 10.6, but assume that a fouling factor of 0.173 m2 K/kW based on the tube outside diameter has developed over time.
> Hot water is used to heat air in a double-pipe heat exchanger as shown in the following sketch. If the heat transfer coefficients on the water side and on the air side are 550 W/m2 K and 55 W/m2 K respectively, calculate the overall heat transfer coeffi
> The temperature of a 100-m-diameter cooling pond is 7oC on a winter day. If the air temperature suddenly drops to -7 °C, calculate the thickness of ice formed after three hours.
> Microchannel compact heat exchangers can be used to cool high heat flux microelectronic devices. The accompanying sketch on the next page shows a schematic view of a typical microchannel heat sink. Microfabrication techniques can be used to mass produce
> Draw the thermal circuit for heat transfer through a double-glazed or a double-paned window. Identify each of the circuit elements. Include solar radiation to the window and interior space.
> An air-to-water compact heat exchanger is to be designed to serve as an intercooler for a 3.7 MW gas turbine plant. The exchanger is to meet the following heat transfer and pressure drop performance specifications: Air-side operating conditions: The exch
> Calculate the water-side heat transfer coefficient and the coolant pressure drop per unit length of tube for the core of a compact air-to-water inter- cooler for a 3.7 MW gas turbine plant. The water flows inside a flattened aluminum tube having the cros
> Saturated steam at 137 kPa condenses on the outside of a 2.6-m length of copper tubing, heating 5 kg/h of water flowing in the tube. The water temperatures measured at 10 equally spaced stations along the tube length (see the sketch) are: Calculate (a)
> While flowing at the rate of 1.25 kg/s in a simple counterflow heat exchanger, dry air is cooled from 65°C to 38°C by means of cold air that enters at 15°C and flows at a rate of 1.6 kg/s. It is planned to lengthen the heat exchanger so that 1.25 kg/s of
> Water flowing in a long, aluminum tube is to be heated by air flowing perpendicular to the exterior of the tube. The ID of the tube is 1.85 cm, and its OD is 2.3 cm. The mass flow rate of the water through the tube is 0.65 kg/s, and the temperature of th
> An oil having a specific heat of 2100 J/kg K enters an oil cooler at 82°C at the rate of 2.5 kg/s. The cooler is a counterflow unit with water as the cool- ant; the transfer area is 28 m2, and the overall heat transfer coefficient is 570 W/m2 K. The wate
> Calculate the overall heat transfer coefficient and the rate of heat flow from the hot gases to the cold air in the cross-flow tube bank of the heat exchanger shown in the accompanying illustration on the next page. The following operating conditions are
> Liquid benzene 1 specific gravity 5 0.862 is to be heated in a counterflow concentric-pipe heat exchanger from 30°C to 90°C. For a tentative design, the velocity of the benzene through the inside pipe (ID = 2.7 cm, OD = 3.3 cm ) can be taken as 8
> Determine the excess temperature at one-half of the maximum heat flux for the fluid-surface combinations in Problem 9.3.
> In an industrial plant a shell-and-tube heat exchanger is heating pressurized dirty water at the rate of 38 kg/s from 60°C to 110°C by means of steam condensing at 115°C on the outside of the tubes. The heat exchanger has 500 steel tubes (ID = 1.6 cm, OD
> A shell-and-tube heat exchanger in an ammonia plant is preheating 1132 m3 of atmospheric pressure nitrogen per hour from 21°C to 65°C using steam condensing at 138,000 N/m2. The tubes in the heat exchanger have an inside diameter of 2.5 cm. In order to c
> The walls of a typical industrial furnace used for the heat treating of metals are usually a composite structure made up of layers of firebrick, high-temperature insulation, steel plates, and outer surface cladding. Radiant tubes/beams and/or combustion
> A shell-and-tube counterflow heat exchanger is to be designed for heating an oil from 27°C to 82°C. The heat exchanger has two tube passes and one shell pass. The oil is to pass through 3.8 cm schedule 40 pipes at a velocity of 1 m/
> A one-tube pass cross-flow heat exchanger is being considered for recovering energy from the exhaust gases of a turbine-driven engine. The heat exchanger is constructed of flat plates forming an egg-crate pattern as shown in the following sketch. The ve
> A small space heater is constructed of 1.25 cm, 18-gauge brass tubes that are 60 cm. The tubes are arranged in equilateral, staggered triangles on 3.6 cm centers with four rows of 15 tubes each. A fan blows 0.95 m3/s of atmospheric pressure air at 21
> Determine the heat-transfer area requirements of Problem 10.41 if (a) a 1–2 shell-and-tube, (b) an unmixed cross-flow, and (c) a parallel flow heat exchanger are used.
> A counterflow regenerator is used in a gas tur- bine power plant to preheat the air before it enters the combustor. The air leaves the compressor at a temperature of 350°C. Exhaust gas leaves the turbine at 700°C. The mass flow rates of air and gas ar
> Repeat Problem 10.3, but assume that fouling factors of 0.0009 m2 K/W and 0.0004 m2 K/W have developed on the inside and on the outside, respectively.
> Determine the appropriate size of a shell-and-tube heat exchanger with two tube passes and one shell pass to heat 8.82 kg/s of pure ethanol from 15.6°C to 60°C. The heating medium is saturated steam at 152 kPa condensing on the outside of the tubes with
> Estimate the time required for nocturnal radiation to freeze a 3-cm thickness of water with ambient air and initial water temperatures at 4oC. Neglect evaporation effects.
> A shell-and-tube heat exchanger with the characteristics given below is to be used to heat 27,000 kg/h of water before it is sent to a reaction system. Saturated steam at 239 kPa absolute pressure is available as the heating medium and will be condensed
> A shell-and-tube heat exchanger is to be used to cool 25.2 kg/s of water from 38°C to 32°C. The exchanger has one shell-side pass and two tube-side passes. The hot water flows through the tubes, and the cooling water flows through the shell. The cooling
> A horizontal shell-and-tube heat exchanger is used to condense organic vapors. The organic vapors condense on the outside of the tubes, while water is used as the cooling medium on the inside of the tubes. The condenser tubes are 1.9-cm OD, 1.6-cm- ID co
> 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 and natural convection / Determine the percentage of the total heat loss by these two
> Two engineers are having an argument about the efficiency of a tube-side multipass heat exchanger compared to a similar exchanger with a single tube- side pass. Smith claims that for a given number of tubes and rate of heat transfer, more area is require
> Design (i.e., determine the overall area and a suit- able arrangement of shell and tube passes) a tubular feed-water heater capable of heating 2300 kg/h of water from 21°C to 90°C. The following specifications are given: (a) saturated steam at 920 kPa a
> An air-cooled low-pressure steam condenser is shown in the following figure. The tube bank is four rows deep in the direction of air flow, and there are a total of 80 tubes. The tubes have a 2.2-cm ID and a 2.5-cm OD and are 9 m long with circular fins o
> Water flowing at a rate of 10 kg/s through a 50-tube double-pass shell-and-tube heat exchanger heats air that flows through the shell side. The length of the brass tubes is 6.7 m, and they have an outside diameter of 2.6 cm and an inside diameter of 2.3
> Water flowing at a rate of 12.6 kg/s is to be cooled from 90°C to 65°C by means of an equal flow rate of cold water entering at 40°C. The water velocity will be such that the overall coefficient of heat transfer U is 2300 W/m2 K. Calculate the heat-excha
> Hot water is to be heated from 10°C to 30°C at the rate of 300 kg/s by atmospheric pressure steam in a single-pass shell-and-tube heat exchanger consisting of 1-in. schedule 40 steel pipe. The surface coefficient on the steam side is estimated to be 11,3
> Estimate the time required to freeze vegetables in thin, tin cylindrical containers 15 cm in diameter. Air at 212°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
> A light oil flows through a copper tube of 2.6-cm ID and 3.2-cm OD. Air flows perpendicular over the exterior of the tube as shown in the following sketch. The convection heat transfer coefficient for the oil is 120 W/m2 K and for the air is 35 W/m2 K. C
> It is proposed to preheat the water for a boiler using flue gases from the boiler stack. The flue gases are available at the rate of 0.25 kg/s at 150°C, with a specific heat of 1000 J/kg K. The water entering the exchanger at 15°C at the rate of 0.05 kg/
> Water at a rate of 0.32 L/s and a temperature of 27°C enters a No. 18 BWG 1.6 cm condenser tube made of nickel chromium steel (k = 26 W/m K ) . The tube is 3 m long, and its outside is heated by steam condensing at 50°C. Under these conditions the avera
> Water flowing through a pipe is heated by steam condensing on the outside of the pipe. (a) Assuming a uniform overall heat transfer coefficient along the pipe, derive an expression for the water temperature as a function of distance from the entrance.
> 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 * 30 cm * 30 cm. Suppose that under maximum power output the engine consumes
> An economizer is to be purchased for a power plant. The unit is to be large enough to heat 7.5 kg/s of pressurized water from 71°C to 182°C. There are 26 kg/s of flue gases (cp = 1000 J/kg K ) available at 426°C. Estimate (a) the outlet temperature of t
> Carbon dioxide at 427°C is to be used to heat 12.6 kg/s of pressurized water from 37°C to 148°C while the gas temperature drops 204°C. For an overall heat transfer coefficient of 57 W/m2 K, compute the required area of the exchanger in square feet for (a
> Determine the outlet temperature of the oil in Problem 10.24 for the same initial fluid temperatures if the flow arrangement is one shell pass and two tube passes. The total area and average overall heat transfer coefficient are the same as those for the
> In a single-pass counterflow heat exchanger, 1.25 kg/s of water enters at 15°C and cools 2.5 kg/s of an oil having a specific heat of 2093 J/kg K from 95°C to 65°C. If the overall heat transfer coefficient is 280 W/m2 K, determine the surface area requir
> For safety reasons, a heat exchanger performs as shown in (a) of the accompanying figure. An engineer suggests that it would be wise to double the heat transfer area so as to double the heat transfer rate. The suggestion is made to add a second, identic
> In the manufacture of can ice, cans having inside dimensions of 27.5 * 55 * 125 cm with 2.5 cm inside taper are filled with water and immersed in brine at a temperature of –12oC. For the purpose of a preliminary analysis, the actual ice can be considered
> A steam-heated, single-pass tubular preheater is designed to raise 5.6 kg/s of air from 20°C to 75°C, using saturated steam at 2.6 MPa (abs). It is pro- posed to double the flow rate of air, and in order to be able to use the same heat exchanger and achi
> In a single-pass counter flow heat exchanger, 4536 kg/h of water enter at 15°C and cool 9071 kg/h of an oil having a specific heat of 2093 J/kg K from 93°C to 65°C. If the overall heat transfer coefficient is 284 W/m2 K, determine the surface area requ
