Consider a pond whose energy budget is dominated by radiation. The pond is disk-shaped, with a radius r and a depth H. The pond receives radiation in two forms: (i) sunlight, which has an average intensity of S [W/m²]; (ii) emission from the greenhouse gas layer with temperature Ta. Assume the pond absorbs all incoming radiation. Remember that the pond must also emit radiation. (a) Construct the energy budget for the pond. (b) If we assume S and Ta are constant, find an equation that relates temperature and time. Note that this equation is probably easier to express as t(T) rather than T(t) [weird but true]! (c) Let's imagine that the pond has just lost all its ice after the winter, and we want to know how long it will be until the pond is reasonable for swimming. Assuming S = 250 W/m², H is 3 m, and Ta is 255 K, and an appropriate swimming temperature is T =20°C. Make a spreadsheet with columns T and t. You might want to actually do the spreadsheet "backwards" of normal if it's easier to get numbers this way.

Consider a pond whose energy budget is dominated by radiation. The pond is disk-shaped, with a radius r and a depth H. The pond receives radiation in two forms: (i) sunlight, which has an average intensity of S [W/m²]; (ii) emission from the greenhouse gas layer with temperature Ta. Assume the pond absorbs all incoming radiation. Remember that the pond must also emit radiation. (a) Construct the energy budget for the pond. (b) If we assume S and Ta are constant, find an equation that relates temperature and time. Note that this equation is probably easier to express as t(T) rather than T(t) [weird but true]! (c) Let's imagine that the pond has just lost all its ice after the winter, and we want to know how long it will be until the pond is reasonable for swimming. Assuming S = 250 W/m², H is 3 m, and Ta is 255 K, and an appropriate swimming temperature is T =20°C. Make a spreadsheet with columns T and t. You might want to actually do the spreadsheet "backwards" of normal if it's easier to get numbers this way.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.25P: 1.25 A spherical vessel, 0.3 m in diameter, is located in a large room whose walls are at 27°C (see...

See similar textbooks

Similar questions

1.71 The thermal conductivity of silver at 212°F is 238 Btu/h ft °F. What is the conductivity in SI units?
Figure 3 shows cross section of a duct. If each wall is 100 cm, surface C is insulated, and duct is very long. Evaluate; a) net radiation per meter of duct for surface A, b) temperature of surface C, and c) effect of changing in the value of ɛ, on the results. C,T3, ɛ3 = 0.8 Figure 3 B,T2 = 700 K, ɛ2 = 0.5 A,T, = 1000 K,ɛ, = 0.33
b) Two parallel square plates having 5 mm separation with each plate having 2 m2 area. One of the plates has a surface temperature of 800 K and surface emissivity of 0.6, while the other has a temperature of 300 K and surface emissivity of 0.9. Find the net energy exchange by radiations between the plates
The 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 degrees
1. Solar Collector Problem: From the diameter of the sun and the earth and the mean distance of sun from earth, estimate (a) the amount of energy emitted from the sun, (b) the amount of energy received by the earth, and (c) the solar constant for a sun temperature of 5700K. If the distance of Planet-Y from the sun is 7.0 astronomical unit, estimate, (c) the solar constant for Planet-Y for a sun temperature of 5700K. (Stefan-Boltzmann constant, o = 5.67 x 10-8 W/m2-K4). Diameter of the sun = 1,392,000 km; DiaPlanet-y = 340,800 km; Mean distance of the sun from the earth = 149,600,000 km r Sun R 0₂ m Aa ||A₂ Ar Concentrator
Radiators are used in most of the houses’ heating. If we happen to place a sofa justin front of our heating radiator, how will the heating of the room be affected? Explain.
Molten metal at 2000 C is poured using crucible. The liquid metal jet has a diameter of 3 mm with an insulation shield of 5 cm diameter. There is a slit of 30 degrees around the insulation shield. The temperature inside the room is 30 C and the shield is 700 C. Assuming black bodies, find the net heat transfer between jet and shield, jet and room, shield and the room. One of the steps is wrong A) Resistance network is required to be built B) To find the view factor between metal and shield , ratio of the angles is used C) View factors are one of the most important steps to solve the problem D) None of the above E) Slit doesnot participate in radiation
Q2: A person of skin temp. of 30 K and body surface area 1.75 cm2, find: (a): net total power if he receives radioactive power from the surrounding walls 22 °C would be about 735 w. (6 = 5.7 x 10 12 w/cm) (b): The emissivity of surrounding walls. Good luck
The figure below shows the energy balance for a planet with an atmosphere. The atmosphere is fully transparent to solar radiation and fully absorbing of infra-red radiation. Fill in values for the arrows in the figure assuming Ein=100 W/m?. Doing arrows in the order labeled should help. Enter the values for 1-4 in the text box. What is the temperature of this planet (use E = 2 = oTª , o = = 5.67 x 10-8 W )? m K4 5. K 6. °C 7. °F Sun 2. 1. 3. 4.
SUPPOSE THE AMBIENT TEMPERATURE IS 20degrees CELSIUS, AND THE HOT RESERVOIR CONSISTS OF A SPHERICAL TANK WITH A RADIUS OF 4.00 m, THAT ACTS AS AN IDEAL EMITTER OF RADIATION. IF ALL THE RADIANT ENERGY EMITTED BY THE TANK COULD BE CAPTURED, WHAT IS THE AVERAGE AMOUNT OF WORK THAT COULD BE DONE EACH SECOND? ( please only answer if your 100% correct) (show work)
QUESTION 7 ´ Flat-plate solar collectors are often tilted up toward the sun in order to intercept a greater amount of direct solar radiation, as shown in Figure Q2. The tilt angle from the horizontal also affects the rate of heat loss from the collector. Consider a 2 m (height) and 3 m (width) solar collector that is tilted at an angle 0 from the horizontal. The back side of the absorber is insulated. The absorber plate and the glass cover, which are spaced 2.0 cm from each other, are maintained at temperatures of 75°C and 35°C, respectively. Analyse the solar collector for different angle, 0 = 0°, 20°, and 90° to select which O gives the lowest rate of heat loss from the absorber plate by natural convection. Absorber | || Plate 750 cm Solar radiation, Glass Insulation Cover, Figure Q2
A 20-çm diameter sphere has a surface temperature of 500 K. The sphere is suspended in 300 K still air. Find the heat transfer from the sphere. Neglect radiation.