Thermodynamics HW Solutions 13

Thermodynamics HW Solutions 13 - Chapter 1 Basics of Heat...

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Chapter 1 Basics of Heat Transfer 1-32E 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. Assumptions 1 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. ΔΔ ke pe ≅≅ 0 Properties The gas constant of oxygen is R = 0.3353 psia.ft 3 /lbm.R = 0.06206 Btu/lbm.R (Table A-1E). Analysis We take the oxygen in the tank as our system. This is a closed system since no mass enters or leaves. The energy balance for this system can be expressed as EE E WQU WQ m u u Q m C T T in out pw in out pw in out out v −= =+ ≅+ Net energy transfer by heat, work, and mass system Change in internal, kinetic, potential, etc. energies 12 43 4 4 Δ Δ , , () ( 21 O 2 14.7 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.

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