Assignment 2 Solutions 2009

Atsteadystatethisreducesto in q d l overallmaterial

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Unformatted text preview: energy balance can be formulated as: [Accumulation of total energy ] = [Input of total energy ] - [Output of total energy ] time time time [Energy supp lied by steam ] + time Or = Fc [ d Hc p , B , av (T - T f ) re dt in p F , av (T - T f ) , re Bc p , B , av (T - T f ) - D p , D , av (T - T f ) + l ] + Q [c re re Assuming T e f = 0 then, R [ d Hc p , B , av T dt = Fc p , F , av Tin - Bc p , B , av T - D[ p , D , av T + l ] + Q c Where, l is the mo lar heat of vaporization and T = T . At steady­state, this reduces to, in Q = D l Overall material balance yields, d ( H M ) = M F - M D - M B d t Where, HM is the mass ho ldup of the unit and Mi are the mass flowrates. We can express the mass flowrate as, for example: M F = MW Fx F + MWC F (1 - x F ) = F [MWC + x F ( W - MWC ) M A ] A Where, MWi is the mo lecular weight of component i This results in the fo llowing material balance (mo lar balance) expressio n: d ( H [MW + x B ( MW A - MW ) ) C C ] = F [MW + x F ( MW A - MW ) C C ] d t [ C - B MW + x B ( MW A - MW ) C ] [ C - D MW + x D ( MW A - MW ) C ] The component balance for component A yields, d ( Hx B MW ) A = Fx F MW - Bx MW - Dx D MW A B A...
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