Consider a spherical shell satellite with outer diameter of 4 m and shell thickness of 10 mm that is reentering the atmosphere. The shell satellite is made of stainless steel with properties of
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Heat and Mass Transfer: Fundamentals and Applications
- A 6 cm diameter cylinder is initially at a temperature of 10 °C. Later, this cylinder was thrown into water at 80°C. Calculate how long it will take for the center temperature of the cylinder to reach 50 °C by taking the convection heat transfer coefficient as 80W //m?K. Thermal properties of the cylinder material k=0,587 W/m°C a = 0,13x10-m² /sarrow_forwardThe top surface of the passenger car of a train moving at a velocity of 70 km/h is 2.8 m wide and 8 m long. The top surface is absorbing solar radiation at a rate of 200 W/m?, and the temperature of the ambient air is 30°C. Assuming the roof of the car to be perfectly insulated and the radiation heat ex- change with the surroundings to be small relative to convec- tion, determine the equilibrium temperature of the top surface of the car. Answer: 35.1°C 200 W/m2 Air 30°C 70 km/harrow_forwardPlease do it Urgentlyarrow_forward
- The boiling temperature of nitrogen at atmospheric pressure at sea level (1 atm) is -196°C. Therefore, nitrogen is commonly used in low temperature scientific studies since the temperature of liquid nitrogen in a tank open to the atmosphere will remain constant at -196°C until the liquid nitrogen in the tank is depleted. Any heat transfer to the tank will result in the evaporation of some liquid nitrogen, which has a heat of vaporization of 198 kJ/kg and a density of 810 kg/m3 at 1 atm. Consider a 3-m-diameter spherical tank initially filled with liquid nitrogen at 1 atm and 196°C. The tank is exposed to 22°C ambient air with a heat transfer coefficient of 22 W/m2 · °C. The temperature of the thin-shelled spherical tank is observed to be almost the same as the temperature of the nitrogen inside. Disregarding any radiation heat exchange, determine the rate of evaporation of the liquid nitrogen in the tank as a result of the heat transfer from the ambient air in kg/sec. Answer in…arrow_forwardConsider a thin suspended hotplate that measures 0.4 mx 0.4 m. The isothermal plate has a mass of 3.75 kg, a specific heat of 2770 J/kg-K, and a temperature of 200°C. The ambient air temperature is 25°C and the surroundings temperature is 25°C. If the convection coefficient is 6.4 W/m²-K and the emissivity of the plate is = 0.42, determine the time rate of change of the plate temperature, dT/dt, when the plate temperature is 200°C. Evaluate the magnitude of the heat losses by convection and by radiation. dT/dt = i 19radl = i 19conv = i K/s W Warrow_forwardA plate heated with a heat flux of 5 kW/m^2 and has an emissivity of 0.3. the air is over the plate has a temperature of 313 K and the heat transfer coefficient is 15 W/m^2K. the surrounding temperature is also the same as the air temperature. *Determine the surface temperature of the plate.arrow_forward
- kindly help me with this question. Thank you, I am having a hard time solving thisarrow_forwardConvection. A thin 100 cm long and 10 cm wide horizontal plate is placed in a large tank full of water at 60°C. At what uniform temperature, in °C, should be maintained in the plate if the rate of heat supplied to the plate is 2 kW as heat is dissipated from either side? The convection heat transfer coefficient at the lower side is h, = 384.5 W/m²K and h,= 3215.5 W/m²K at the upper side.arrow_forwardConvection 2. For a boiling process such as shown in Figure below, the ambient temperature Tin Newton's law of cooling is replaced by the saturation temperature of the fluid Tsat. Consider a situation where the heat flux from the hot plate is q=20 x 105 W/m². If the fluid is water at atmospheric pressure and the convection heat transfer coefficient is hw=20 x 103 W/m2 K, determine the upper surface temperature of the plate, Ts, w. In an effort to minimize the surface temperature, a technician proposes replacing the water with a dielectric fluid whose saturation temperature is Teat, d=52 °C. If the heat transfer coefficient associated with the dielectric fluid is h = 3 x 103 W/m2 K, will the technician's plan work?arrow_forward
- A 5.0-cm-diameter cylinder is heated to a temperature of 200 oC, and air at 30 oC forced across it at a velocity of 50 m/s (h = 180 W/m2K). If the surface emissivity is 0.7, calculate the total heat loss per unit length if the walls of the enclosing room are at 10 oC. Comment on your calculation. COMPLETE SOLUTIONarrow_forwardHi, can you help me to answer this question using the first law of thermodynamics formula to explain this event? On a hot summer day, a student turns his fan on when he leaves his room in themorning. When he returns in the evening will the room be warmer or cooler than theneighborouing rooms ? Explain your answer using the first law of thermodynamics.Assume ALL doors and windows are kept closed.arrow_forwardEstimate the rate of heat transfer (J/s) from a 50.6°C sphere which has an emissivity of 0.2 if it is suspended in a cold volume maintained at -10.7°C. The sphere has a diameter of 0.2m. Reduce your answer in to two decimal point.arrow_forward
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