The Weather Channel reports that it is a hot, muggy day with an air temperature of
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- A spherical communications satellite, 2 m in diameter, is placed in orbit around the earth. The satellite generates 1000 W of internal power from a small nuclear generator. If the surface of the satellite has an emittance of 0.3, and is shaded from solar radiation by the earth, estimate its surface temperature.arrow_forward02. An electronic box that consumes 180 W of power is cooled by a fan blowing air into the box enclosure. The dimensions of the electronic box are 15 cm x 50 cm x 50 cm, and all surfaces of the box are exposed to the ambient except the base surface. Temperature measurements indicate that the box is at an average temperature of 32°C when the ambient temperature and the temperature of the surrounding walls are 25°C. The emissivity of the outer surface is 0.85. Determine: (a) The heat lost from the top surface, (b) The heat lost from the side surfaces, (c) The total heat lost by radiation and (d) the total fraction of the heat lost from the outer surfaces of the electronic box.arrow_forwardConsider a very thin plate that is mounted and attached on a horizontal board. The plate is subject to an infrared lamp providing a uniform thermal radiation of 2000 W/m?. The plate absorbs 80% of the infrared irradiation and has an emissivity of 0.498. The plate is also exposed to an airflow of temperature of 20 °C and large surroundings with a temperature of 30 °C. The surface area of the plate is 1 m2 and it's surface temperature is measured to be at 104 °C. Required: Draw a clear and consistent schematic of the problem and label the operating conditions on the schematic. Perform systematic analysis, state your assumptions and justify the equation used and determine the convection heat transfer coefficient of airflow. (circle your final answer)arrow_forward
- Space is considered a perfect black body with T= - 70 celsius AirDoes not absorb heat radiation from the water in the bowl.Air temperature is considered constant TAir = 15 celsiusHeat transfer coefficient from water to air: hc = 2.6 W/(m2∙celsius) cabbage with waterDepth to the water in the bowl: H = 0.020 mBase area to water layer: A= 0.020 m2Starting temperature: T0 = 15 celsiusEmissivity to water: = 0.98 a) Calculate heat transport by radiation from the water in the bowl to space at initial conditions. b) Calculate net heat transport from the water in the bowl at water temperature T= 0 celsius (beginning of freezing).arrow_forwardAn astronaut performing an extra-vehicular activity(space walk) shaded from the Sun is wearing a spacesuitthat can be approximated as perfectly white (e = 0) exceptfor a 5 cm × 8 cm patch in the form of the astronaut’snational flag. The patch has emissivity 0.300. The spacesuitunder the patch is 0.500 cm thick, with a thermalconductivity k = 0.0600 W/m °C , and its inner surface isat a temperature of 20.0 °C . What is the temperature of thepatch, and what is the rate of heat loss through it? Assumethe patch is so thin that its outer surface is at the sametemperature as the outer surface of the spacesuit under it.Also assume the temperature of outer space is 0 K. You willget an equation that is very hard to solve in closed form,so you can solve it numerically with a graphing calculator,with software, or even by trial and error with a calculator.arrow_forward2 inch OD during a visit to a plastic sheet factory 60 m long section of a horizontal steam pipe passes from one end to the other without insulation is observed. While the temperature of the ambient air and its surfaces is 20 °C, the temperature measurements at several points are the average of the exposed surfaces of the steam pipe. indicates that the temperature is 160 °C. It is seen that the outer surface of the pipe is oxidized and The emissivity can be taken as 0.59. According to this; a) Calculate the heat loss in the steam pipe. b) The steam used is produced in a gas furnace operating with an efficiency of 59%. Factory 105500 It pays $1.10 per kJ of natural gas. If it is assumed that the factory works all year (365 days), for this facility Calculate the annual cost of heat losses in the steam pipe.arrow_forward
- Parvinbhaiarrow_forwardConsider a cylindrical tank with a surface temperature of 44°C which contains water. The height of the tank is 1.1 m and its diameter is 0.4 m. The tank is in a room at 20°C. If the surrounding temperature is also at 20°C, calculate the total rate of heat transfer from all surfaces of the tank by natural convection and radiation. Consider the emissivity to be 0.4. Assumptions: 1 Steady operating conditions exist. 2 Air is an ideal gas. 3 The local atmospheric pressure is 1 atm. Note. Report your solution step by step and clearly.arrow_forwardTwo identical bodies radiate heat to each other. One body is at 30°C and the other at 250°C. The emissivity of both is 0.7. Calculate the net heat transfer per square meter. ANSWER: 2635 Warrow_forward
- A tube carries hot water across a factory in a tube with outer diameter Do = 20 mm. The tube surface is black, and the surroundings are at 20°C. You may neglect convection during your analysis. a) If the outer tube surface is at an average temperature of 450°C, what is the rate of heat transfer out of the tube, per unit length of tube (kW/m)? Shield, D₂ = 60 mm €2,0 E2,i Heated tube, D₁₂ = 20 mm Evacuated Page 3 of 4arrow_forwardNine old 1 m2 windows with U = 7 W/m2.k were replaced with new windows having U = 1.8 W/m2 .k . Calculate the energy savings on a day during a 5 hour period, when T in = 20° C , T outside =−10° C .arrow_forwardA flat-plate solar collector, as shown in Fig. 1, is used to heat water by having water flow through tubes attached at the back of the thin solar absorber plate. The absorber plate has an emissivity and an absorptivity of 0.8. The top surface (* = 0) temperature of the absorber is To = 35 °C, and solar radiat ion is incident on the absorber at 600 W/m? with a surrounding temperature of 0 °C. The convection heat transfer coefficient at the absorber surface as 8 W/m?-K. Assuming constant thermal conductivity and no heat generation in the wall, i express the differential equation and the boundary conditions for steady one- dimensional heat conduct ion through the wall, obtain a relation for the variation of temperature in the wall by solving the differential equation, and ii iii. determine the net heat flux, ġo absorbed by the collector ε, α, Τ. Absorber plate Water tubes Insulation Fig. 1arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning