Chapter 1 Basics of Heat Transfer1-32E A paddle wheel in an oxygen tank is rotated until the pressure inside rises to 20 psia while some heat is lost to the surroundings. The paddle wheel work done is to be determined. Assumptions1 Oxygen is an ideal gas since it is at a high temperature and low pressure relative to its critical point values of -181°F and 736 psia. 2 The kinetic and potential energy changes are negligible, . 3 The energy stored in the paddle wheel is negligible. 4 This is a rigid tank and thus its volume remains constant. ΔΔkepe≅≅0Properties The gas constant of oxygen is R = 0.3353 psia.ft3/lbm.R = 0.06206 Btu/lbm.R (Table A-1E). AnalysisWe take the oxygen in the tank as our system. This is a closed systemsince no mass enters or leaves. The energy balance for this system can be expressed as EEEWQUWQmuuQmCTTinoutpw inoutpw inoutoutv−==+−≅+−Net energy transferby heat, work, and masssystemChange in internal, kinetic,potential, etc. energies124344ΔΔ,,()(21O214.7 psia
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This note was uploaded on 01/14/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.