Chapter 8 Internal Forced Convection8-65A compressor is connected to the outside through a circular duct. The power used by compressor to overcome the pressure drop, the rate of heat transfer, and the temperature rise of air are to be determined. Assumptions1Steady flow conditions exist. 2The inner surfaces of the duct are smooth. 3The thermal resistance of the duct is negligible. 4Air is an ideal gas with constant properties. PropertiesWe take the bulk mean temperature for air to be 15°C since the mean temperature of air at the inlet will rise somewhat as a result of heat gain through the duct whose surface is exposed to a higher temperature. The properties of air at this temperature and 1 atm pressure are (Table A-15) /sm10568.1CW/m.02476.0kg/m225.125-3×=°==υρk7323.0PrCJ/kg.1007=°=pCThe density and kinematic viscosity at 95 kPa are P==95 kPa101.325 kPaatm0938./sm101.673=)/s)/(0.938m10568.1(kg/m149.1)938.0)(kg/m225.1(25-25-33××===AnalysisThe mean velocity of air is m/s594.8/4m)(0.2/sm27.0
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.