If
where
(a) Consider a surface of either polished aluminum
(b) Consider initial conditions associated with placing a workpiece at
Want to see the full answer?
Check out a sample textbook solutionChapter 1 Solutions
Fundamentals of Heat and Mass Transfer
- The amount of radiation received per unit time by a person working near a radioactive source, commonly called the dose rate, is measured in rem hr-1. The safety regulations forbid dose rates in excess of 7.5 × 10-4 rem hr-1. The γ dose rate from the 4219K source is found to be 3 × 10-3 rem hr-1 at a distance of 1 m. What is the minimum distance from this source at which itis safe to work? After how long will it be safe to work at a distance of 1 m from the source?arrow_forwardWhat happens when T < T0. That is, what if we have a medium that is at a lower temperature than the environment?arrow_forward% Power T 53.8 T2 D= 5cm D= 7cm D = 9cm 28 50% 46 27.5 41.1 27 D= 1lem 40.6 21.9 D = 5cm 78 31.5 69 70% D= 7cm D= 9cm 30.1 67 29.8 D= 1lcm 63 28.1 е. Calculations: Determine heat exchange between two black plates Q by using: q= T1: temperature of the first black plate (K). T2: temperature of the second black plate (K). A: area of plate= 0.026 m And then plot the heat exchange between two black plates versus distance between these plates at different power: Darrow_forward
- A ll zain IQ Gmail > محمد مسفر quizidotx A radiation flux of 1000W/m' is incident upon a surface that absorbs 80 percent of the incident radiation. Calculate the amount of radiation energy absorbed by a 4-m area of the surface over a period of 2h.arrow_forwardFind the total heat flux of the composite wall when: B F KA = KC = KF = 15 т. К A E KB = KD = 10 т. К KE = KG = 20 т. К D. Height of B = C = D 4 cm 3 cm 4 cm 6 cm Height of F = G AT = 30 K て)arrow_forwardThe surface area of an unclothed person is 1.5m ^2 and thier skin tempature is 33 degree celcius. This ideal person is located in a room with a tempature of 65 dregrees F. and has an emissivity of e=0.95 suppose the room has dimensions 4mx9mx18m a) suppose you and your closest 10 friends come into this room and heat it up. suppose your clothes are in equilibium with your skin and have the same tempature and emissivity. Further suppose that your net power into the room remains constant . How long does it take before the room to get to hot say 95 degreesarrow_forward
- The image shows a plane wall of thicknessΔx = 21 cm with a thermal conductivity k=0.7 W/(mK). Given that the temperature at point 2 is 283 K and that the heat flux from points 1 to 2 is 154 W/m2 calculate the temperature at point 1 in Kelvin to 1dp (decimal placearrow_forwardGive three reasons why the neutron energy distribution in a thermal homogeneous reactor is not Maxwellian. What specific physical effects cause deviations at high energies and what physical effects give rise to deviations at low energies?arrow_forwardA small sphere (emissivity = 0.745, radius = r1) is located at the center of a spherical asbestos shell (thickness = 1.72 cm, outer radius = r2; thermal conductivity of asbestos is 0.090 J/(s m Co)). The thickness of the shell is small compared to the inner and outer radii of the shell. The temperature of the small sphere is 727 °C, while the temperature of the inner surface of the shell is 406 °C, both temperatures remaining constant. Assuming that r2/r1 = 6.54 and ignoring any air inside the shell, find the temperature in degrees Celsius of the outer surface of the shell.arrow_forward
- Q2:- Light from the sun arrives at the earth, an average of 1.48 x 101' m away, at the rate of 1.4 kW/m2 of area perpendicular to the direction of the light. Assume that sunlight is monochromatic with a frequency of 4.95 x 1014 Hz. (a) How many photons fall per second on each square meter of the earths surface directly facing the sun? (b) What is the power output of the sun, and how many photons per second does it emit?arrow_forwardConsider a shielding wall for a nuclear reactor. The wall receives a gamma-ray flux such that heat is generated within the wall according to the relation - 9:56 ax ġ = ġoe %3D e 9:57 Varrow_forward(a) A wire carrying a 20.5 A current passes between the poles of a strong magnet that is perpendicular to its field and experiences a 2.46 N force on the 3.75 cm of wire in the field. What is the average field strength? Average field strength in tesla = (b) A spherical surface of area 0.7m2, emissivity 0.85 and temperature 134°C is placed in a large, evacuated chamber whose walls are maintained at a fixed temperature. Find the rate at which radiation is emitted by the surface?( Stefan's constant σ = 5.67 x 10-8 W/m2T4 ) Energy radiated per second in watts =arrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY