Thermodynamics HW Solutions 841

Thermodynamics HW - Chapter 10 Boiling and Condensation 10-57 Saturated refrigerant-134a vapor at a saturation temperature of Tsat = 30C condenses

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Chapter 10 Boiling and Condensation 10-57 Saturated refrigerant-134a vapor at a saturation temperature of T sat = 30 ° C condenses inside a horizontal tube which is maintained at 20 ° C. The fraction of the refrigerant that will condense at the end of the tube is to be determined. Assumptions 1 Steady operating conditions exist. 2 The tube is isothermal. 3 The vapor velocity is low so that Re vapor < 35,000. Properties The properties of refrigerant-134a at the saturation temperature of 30 ° C are h fg = 173.1 × 10 3 J/kg and ρ v = 37.53 kg/m 3 . The properties of liquid R-134a at the film temperature of 20)/2 = 25 ° C are (Table A-10) TT T fs =+ () / sat 2 ( = 30 + C W/m. 08325 . 0 C J/kg. 1427 C /s m 10 1667 . 0 / kg/m.s 10 2.012 kg/m 1207 2 6 4 3 ° = ° = × = = × = = l pl l l l l l k ρμ ν μ ρ Analysis The heat transfer coefficient for condensation inside horizontal tubes is R-134a 30 ° C ondensate 20 ° C C W/m 2 . 509 C 0) 2 C)(30 J/kg 1427 ( 8 3 + J/kg 10 1 . 173 C 0) 2 s)(30 kg/m 10 012 . 2 ( C) W/m 08325 . 0 )( kg/m ) 53 . 37 1207 )( kg/m 1207 )( m/s 81 . 9 ( 555 . 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.

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