Concept explainers
The extremely high temperatures needed to trigger nuclear fusion are proposed to be generated by laser- irradiating a spherical pellet of deuterium and tritium fuel of diameter
(a) Determine the maximum fuel temperature that can be achieved by irradiating the pellet with 200 lasers, each producing a power of
(b) The pellet is placed inside a cylindrical enclosure. Two laser entrance holes are located at either end of Salt the enclosure and have a diameter of
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Fundamentals of Heat and Mass Transfer
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- 11.68 Two infinitely large, black, plane surfaces are 0.3 m apart, and the space between them is filled by an isothermal gas mixture at 811 K and atmospheric pressure. The gas mixture consists of by volume. If one of the surfaces is maintained at 278 K and the other at 1390 K, calculate (a) the effective emissivity of the gas at its temperature, (b) the effective absorptivity of the gas to radiation from the 1390 K surface, (c) the effective absorptivity of the gas to radiation from the 278 K surface, and (d) the net rate of heat transfer to the gas per square meter of surface area.arrow_forwardA 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 (0.4to0.75m)? Assume that the filament radiates as a graybody.arrow_forward1.26 Repeat Problem 1.25 but assume that the surface of the storage vessel has an absorbance (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 oxygen at –183°C is .arrow_forward
- 1.54 The soldering iron tip in Problem 1.53 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.arrow_forward(a) Calculate the mass and linear absorption coefficients of air for Cr Ka radiation.Assume that air contains 80 percent nitrogen and 20 percent oxygen by weight and has adensity of1.29 x g/cm3. (b) Plot the transmission factor of air for Cr Ka radiationand a path length of 0 to 20 cm.Please use any table or data from the Elements of X-ray Diffraction by Cullityarrow_forwardA typical person can detect light with a minimum intensity of 4.0 x10-11 W/m2. For light of this intensity and λ = 550 nm, how many photons enter the eye each second if the pupil is open wide with a diameter of 9.0 mm?arrow_forward
- A thin, disk-shaped silicon wafer of diameter D=20 cm on a production line must be maintained at a temperature of 100 deg C. The wafer loses heat to the room by convection and radiation from its upper surface, while heat is supplied at a constant flux from below. The surrounding air is at 20 deg C, while all surrounding surfaces (which can be treated as blackbodies) can be approximated to be isothermal at a temperature of 15 deg C. The wafer-to-air heat transfer coefficient is 30 W/m2-K and the emissivity of the wafer’s surface (which can be approximated to be gray) is 0.85. How much heat (in W) must be supplied to the wafer?arrow_forwardTaking the sun as a black body with a radius of 6.92 x 108 m having a maximum intensity of emission at a wavelength of 0.5 μm, estimate the sun's surface temperature and emissive power. If the distance between the earth and the sun is 1.5 x 10¹¹ m, estimate the solar energy radiation flux at the earth's surface. a. 1.36W/m2 O b. 1.36KW/m² O c. 63.99W/m² O d. 63.99 KW/m²arrow_forward4. The filament of a 75 W light bulb may be considered as a black body radiating into a black enclosure at 70° C. the filament diameter is 0.10 mm and length is 5 em. considering the radiation, determine the filament temperature .arrow_forward
- 4. The blackbody emission from the surface can be linearized about some reference temperature To. oT -oT + 40 T (T, – T)+……. And the sensible cooling of the surface can be written as SH = c,pC,U(T, - T,)+…. Calculate and compare the rates at which longwave emission and sensible heat flux vary with surface temperature, T,. In other words, if the surface temperature rises by 1°C, by how much will the longwave and sensible cooling increase? Assume that To = 288 K, T, is fixed, p = 1.2 kg m3, Cp = 1004 J kgK, Cp = 2 x 10-3, and U = 5 ms.arrow_forwardConsider an ideal gas enclosed in a spectral tube. When a high voltage is placed across the tube, many atoms are excited, and all excited atoms emit electromagnetic radiation at characteristic frequencies. According to the Doppler effect, the frequencies observed in the laboratory depend on the velocity of the emitting atom. The nonrelativistic Doppler shift of radiation emitted in the x direction is f = f0(1 + vx / c). The resulting wavelengths observed in the spectroscope are spread to higher and lower values because of the (respectively) lower and higher frequencies, corresponding to negative and positive values of vx. We say that the spectral line has been Doppler broadened. This is what allows us to see the lines easily in the spectroscope, because the Heisenberg uncertainty principle does not cause signifi cant line broadening in atomic transitions. (a) What is the mean frequency of the radiation observed in the spectroscope? (b) To get an idea of how much the spectral line is…arrow_forwardIn a biprism experiment, the slit is illuminated by the light of wavelength 5890A.the distance between the slit and eye piece is 0.8m.the two virtual images of the slit are formed 0.2cm apart. Calculate the change in fringe width if the eye piece is displaced 10cm away from the slit.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning