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Unformatted text preview: 412Refrigerant134a in a cylinder is heated at constant pressure until its temperature rises to a specified value. The boundary work done during this process is to be determined. AssumptionsThe process is quasiequilibrium. PropertiesNoting that the pressure remains constant during this process, the specific volumes at the initial and the final states are (Table A11 through A13) [email protected]vTPPfAnalysisThe boundary work is determined from its definition to be kg233.1/kgm0.0008580m0.23311vVmand kJ557133121221out,mkPa1kJ1/kgm0.0008580)413kPa)(0.027kg)(900(233.1)()(vvVVVmPPdPWbDiscussion The positive sign indicates that work is done by the system (work output). 422CO2gas in a cylinder is compressed until the volume drops to a specified value. The pressure changes during the process with volume as 2VaP. The boundary work done during this process is to be determined. AssumptionsThe process is quasiequilibrium. AnalysisThe boundary work done during this process is determined from kJ53.333361221221out,mkPa1kJ1m0.31m0.11)mkPa(811VVVVVadadPWbDiscussion The negative sign indicates that work is done on the system (work input). 434E R134a contained in a rigid vessel is heated. The heat transfer is to be determined. Assumptions1 The system is stationary and thus the kinetic and potential energy changes are zero. 2 There are no work interactions involved 3 The thermal energy stored in the vessel itself is negligible. vP 900 12P V P = aV20.1 0.3 12AnalysisWe take R134a as the system. This is a closed system since no mass enters or leaves. The energy balance for this stationary closed system can be expressed as 0)=PE=KE(since)(12inenergiesetc.potential,kinetic,internal,in Changesystemmassandwork,heat,by nsferenergy traNet outinuumUQEEEThe properties at the initial and final states are (Tables A11E, A13E)...
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This note was uploaded on 09/05/2010 for the course MEEN 315 taught by Professor Ramussen during the Summer '07 term at Texas A&M.
 Summer '07
 RAMUSSEN

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