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Cylindrical dry-bulb and wet-bulb thermometers are installed in a large-diameter duct to obtain the temperature
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Fundamentals of Heat and Mass Transfer
- Air at 20oC (density = 1.204 kg/m3) flows towards a rotating cylinder of diameter 1.50 m. If the velocity of the air is 100 km/h and the cylinder rotates clockwise at 220 rpm, determine (c) the maximum velocity of the air around the rotor, and (d) the pressure coefficient at the location corresponding to the maximum velocity.arrow_forwardDetermine the temperature of 0.25kg/s of air after passing through an electrical resistor whose power is 20kW. The initial temperature of the air is 20 degrees Celsius.arrow_forwardApply the conservation of mass principle to various systems including steady- and unsteadyflow control volumes.arrow_forward
- A diffuser is used to increase the pressure of a stream of air circulating at 6500 kg / h. The initial conditions of the inlet are 82 kPa and 197 ° C, and it exits at 115 kPa. The air speed decreases from 245 to 37 m / s as it passes through the diffuser. Calculate: a) The air temperature at the outlet: b) The cross-sectional area at the outlet of the diffuser:arrow_forwardWater enters the cooling tower at 50°C. The approximate leaving water temperature is 30°C. If the atmospheric condition is 25 degrees C wet bulb, determine the cooling effectiveness of the cooling tower?arrow_forwardA U-tube open at both ends is partially filled with water. Oil having a density of 750 kg/m3 is then poured into the right arm and forms a column L = 10.00 cm high. The density of air is 1.29 kg/m3.The right arm is then shielded from any air motion while air is blown across the top of the left arm until the surfaces of the two liquids are at the same height. (d) Determine the pressure difference between the water and oil columns(e) Determine the speed of the air being blown across the left arm.arrow_forward
- Consider a case in which the air inside the pressurized cabin of a jet transport flying at some altitude is at a pressure of 0.9 atm and a temperature of 15°C. The total volume of air at any instant inside the cabin is 1800 m^3. If the air in the cabin is completely recirculated through the air conditioning system every 20 min, calculate the mass flow of air in kg/s through the system.arrow_forwardThe local atmospheric pressure in Denver, Colorado (elevation 1610 m), is 83.4 kPa. Air at this pressure and 20°C flows with a velocity of 8 m/s over a 1.5 m * 6 m flat plate whose temperature is 140°C. Determine the rate of heat transfer from the plate if the air flows parallel to the (a) 6-m-long side and (b) the 1.5 m side.arrow_forwardIn which medium does a sound wave travel faster: in air at 20°C and 1 atm or in air at 20°C and 5 atm?arrow_forward
- A transistor with a height of 0.25 in and a diameter of 0.22 in is mounted on a circuit board. The transistor is cooled by air flowing over it at a velocity of 500 ft/min. If the air temperature is 120°F and the transistor case temperature is not to exceed 180°F, determine the amount of power this transistor can dissipate safely.arrow_forwardA horizontal axis wind turbine with a 20-m diameter rotor is 30% efficient at 10 m/s winds and at 1 atm of pressure and 15° C. (a) How much power would it produce at these conditions? (b) What would the air density be on top of a mountain at an elevation of 2500 m at 10° C? (c) Determine the power the wind turbine would produce on the mountain with the same wind speed. Assume that the efficiency of the turbine is not affected by density. Is it beneficial to build the turbine on top of the mountain? Explain your answer.arrow_forwardIn Rizal province, one of its power plants has been thoroughly monitored for possible conversion into a wind power plant. A propeller wind turbine is to be used. Survey showed that Rizal Province at a height of 10 meters above the ground has a minimum wind speed of 7.1 miles per hour duringthe month of June and a maximum wind speed of 12.9 miles per hour during the month of January. The minimum temperature is at 75 degree Fahrenheit during the month of January and maximum temperature is at 89 degree Fahrenheit during the month of May. The existing power plant has an output of 54MW. For the proposed wind power, the power coefficient of turbine is 35% and the generator efficiency is 95%. Theimpeller diameter is assumed not to exceed 90m. Determine the following:a. Theoretical Wind Power Outputb. Electrical Power Outputc. Number of turbines to be installedarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning