Interntonl Journl of Applton or Innovton n Engneerng & Mngement (IJAIEM) Web Ste: www.jem.org Eml: edtor@jem.org Effetveness nd Effeny Anlyss of Prllel Flow nd Counter Flow Het Exngers oopes wr 1, Dr.Govnd Meswr 1 Assstnt Professor, Deprtment of Menl Engneerng, Sgr Insttute of eser nd enology, Indore-4500 INDIA Assote Professor, Deprtment of Menl Engneerng, Insttute of Engneerng & enology, DAVV, Indore- 45017 INDIA Abstrt s pper provdes teoretl nlyss of et exnger to detere te mxmum effetveness of et exnger orrespondng to te et pty rte rto. Moreover, terml effeny for et exnger bsed on te seond lw of termodynms s been norported n te desgn. Also te effeny bsed on fn nlogy number w resembles te effeny of fn of onstnt re wt tp nsulted s been utlzed. Key words: Het exnger, Effetveness, erml effeny, et pty rte. 1. INODUCION Het exngers ve wde ppltons n modern ndustres. Het exngers re deves tt fltte te exnge of et between two fluds wt g effetveness nd low nvestment nd low mntenne ost. Optmzng te performne of te et exnger results n effent utlzton of energy wt reduton n totl volume nd te wegt of te et exnger. us, et exnger s lwys been one of te mn reser tops n termodynms. Severl metods nd teores ve been developed to optmze te et exnger performne. Generlly te performne of et exnger s mesured by ts effetveness, but effetveness does not provde ny nformton bout te effeny of et exnge tt tkes ple n et exnger [1], nd te mesure of rreversblty s entropy generton [-3].In order to tke nto ount te rreversblty, te onept of et exnger effeny bsed on te seond lw of termodynms s been ntrodued [4-8] nd te relton between effetveness nd effeny s been derved. e mn objetve of ts work s to detere te et pty rte rto ountng for bot effeny nd effetveness of te et exnger.. MEHODOLOGY Consderng et exnger wt neglgble flud flow pressure drop, te et exnger effetveness n te NU ppro s defned s te rto of tul mount of et trnsfer rte to te mxmum possble et trnsfer rte, Q C C Q C C tul o o mx Were s te ot flud nlet temperture, outlet tempertures respetvely. C nd Volume 6, Issue 6, June 017 Pge 314 o s te ot flud outlet temperture, nd C re te et pty rtes of ot nd old flud respetvely (1) o re old flud nlet nd C s te mum et pty rte. e ε-nu metod s generlly used wen te nlet tempertures nd te sze of te et exnger re known nd flud outlet tempertures nd te et trnsfer rte re requred to be found out. Now te et exnger effeny s defned s te rto of te tul et trnsfer rte to te optmum et trnsfer rte, C Q C tul o o () Qopt UA UA
Interntonl Journl of Applton or Innovton n Engneerng & Mngement (IJAIEM) Web Ste: www.jem.org Eml: edtor@jem.org e optmum et trnsfer s te produt of overll et trnsfer oeffent (U), et exnger surfe re (A) nd rtmet men temperture dfferene (AMD). AMD s te dfferene between te verge tempertures of ot nd old fluds. Het exnger effeny [4] s lso been defned on te bss of effeny of fn of onstnt re wt ts tp nsulted, s Were F tn(f ) F (3) F s te et exnger number nd s expressed s, NU( 1 ) for ounter flow et exnger nd for prllel flow were NU s te number of trnsfer unts. F NU ( 1 ) s te rto of mum et pty rte ( C ) nd mxmum ( C mx ) et pty rtes. From equtons () nd (3) te equton for et trnsfer n be wrtten s, tn( F ) Qtul UA( ) F On substtutng te vlue of F for ounter flow nd prllel flow rrngement te equtons for et for ounter flow nd prllel flow et exnger re obtned respetvely s, trnsfer rte Q tul C UA tn 1 C 1 (4) nd Q tul C UA tn 1 C 1 (5) Now fndng te relton between nd, We know tt, o o Were o C C nd C On substtutng te vlues of o nd o o we get, C 1 1 (6) Volume 6, Issue 6, June 017 Pge 315
Interntonl Journl of Applton or Innovton n Engneerng & Mngement (IJAIEM) Web Ste: www.jem.org Eml: edtor@jem.org Wrtng te equton (6) n terms of, 1 1. NU1 (7) On ombnng equton () n d equton (7) we get, Q tul. C 1 1. NU (8) Now te reltonsp between ε nd η n be obtned usng equton (1) nd () s, Combnng equtons (7) nd (9) we get, UA C. (9) 1 1. NU 1 (10) 3. ESULS Usng te equton 3, te vrton of effeny s plotted for ounter flow rrngement for dfferent vlues of et pty rto wt smultneously vryng te vlues of number of trnsfer unts. e result s s sown n fgure 1. 1.1 NU= NU=3 NU=4 NU=5 0.4 0.3 0. 0. 0.4 Fgure 1 Vrton of η wt for dfferent vlues of NU for ounter flow rrngement. Volume 6, Issue 6, June 017 Pge 316
Interntonl Journl of Applton or Innovton n Engneerng & Mngement (IJAIEM) Web Ste: www.jem.org Eml: edtor@jem.org Smlrly vrton of effeny s plotted for prllel flow rrngement for dfferent vlues of et pty rto wt smultneously vryng te vlues of number of trnsfer unts. e result s s sown n fgure. NU= NU=3 NU=4 NU=5 0.4 0.3 0. 0. 0.4 Fgure Vrton of η wt for dfferent vlues of NU for prllel flow rrngement. Also omprson s mde of vrton of effeny for ounter flow rrngement nd prllel flow rrngement for dfferent vlues of et pty rto s depted n fgure 3. p t NU=5 t NU=5 p t NU= t NU= 0.4 0.3 0. 0. 0.4 Fgure 3 Comprson of vrton of η wt for dfferent vlues of NU, for prllel flow nd ounter flow rrngement. By pplyng te relton between effetveness nd effeny s gven by equton 10, nd usng te vlues of effeny s lulted bove, te vrton of effetveness s plotted for ounter flow rrngement s well s prllel flow rrngement. e vlues of NU long wt et pty rto re lso vred.e result plotted s s sown n fgure 4. Volume 6, Issue 6, June 017 Pge 317
Interntonl Journl of Applton or Innovton n Engneerng & Mngement (IJAIEM) Web Ste: www.jem.org Eml: edtor@jem.org p t NU=5 t NU=5 p t NU= t NU= 0. 0.4 Fgure 4 Vrton of ε wt for dfferent vlues of NU, for prllel flow nd ounter flow rrngement. 4. DISCUSSION Fgure 1 sows te vrton of effeny, η for dfferent vlues of NU for ounter flow rrngement. From fgure 1 t n be seen tt η of ounter flow rrngement nreses wt nrese n vlues of et pty rto,. Fgure 1 lso sows tt for ounter flow rrngement effeny, η s ger for lower vlues of NU. Fgure sows te vrton of effeny, η for dfferent vlues of NU for prllel flow rrngement. It sows tt η dereses wt nrese n for prllel flow rrngement nd rees mum t =1 for dfferent vlues of NU. e derese n effeny s mxmum for lower vlue of NU. Fgure 3 sows te vrton of effeny η, for dfferent vlues of NU for prllel flow nd ounter flow rrngements. From fgure 3 t n be seen tt η of ounter flow rrngement nreses nd tt of prllel flow rrngement dereses wt nrese n vlues of. Fgure 3 lso sows tt η s ger for lower vlues of NU for bot prllel flow nd ounter flow rrngements. Fgure 4 sows tt ε dereses wt nrese n for bot prllel flow nd ounter flow rrngement nd rees mum t =1.Fgure 4 lso sows tt te derese n ε s greter for prllel rrngement s nreses nd t n lso be seen tt te ε s ger for ger vlues of NU for bot prllel nd ounter flow s nreses. 5. CONCLUSIONS 1. In order to ve te optmum performne of te et exnger n terms of effetveness nd effeny, for prllel flow rrngement, te et exnger must operte t lower vlues of et pty rto.. e et pty rto round = gves te optmum performne of ounter flow rrngement bsed on effetveness nd effeny. FUUE SCOPE e onept of entropy generton nlyss n lso be ppled n te bove nlyss. e bove work s been rred out wtout onsderng te pressure drop nd te et loss, te sme nlyss n be done by tkng nto ount te pressure drop nd te et loss. e bove nlyss s been done for ounter flow nd prllel flow rrngements, te sme nlyss n be performed for te ross flow rrngement. Volume 6, Issue 6, June 017 Pge 318
Interntonl Journl of Applton or Innovton n Engneerng & Mngement (IJAIEM) Web Ste: www.jem.org Eml: edtor@jem.org EFEENCES [1] M.EI Hj Assd, Effet of mxmum nd mum et pty rte on entropy generton n et exnger, Interntonl Journl of Energy eser 010; 34:130-1308. [] Ordonez JC, Bejn A. Entropy generton mzton n prllel-pltes ounter flow et exngers. Interntonl Journl of Energy eser 000;4:843-864 [3] Srng S, Cowdury K. On te generton of entropy n ounter flow et exnger. Cryogens 198; :63-65 [4] Amd Fker, Het Exnger effeny, ASME 007;19: 168-176 [5] Fker, A., 003, Artmet Men emperture Dfferene nd te Conept of Het Exnger Effeny, Proeedngs of te 003 ASME Summer Het rnsfer Conferene, July 1-3 Pper No. H003-47360 [6] Fker, A., 003, An lterntve Appro for Deterng Log Men emperture Dfferene Correton Ftor nd Number os Sell nd ube Het Exngers, J. Enned Het rnsfer, 10(4), pp. 407-40. [7] Fker, A., 003, e Sell nd ube Het Exnger Effeny nd ts elton to Effetveness. Proeedngs of te 003 ASME Interntonl Menl Engneerng Congress nd Exposton, November 16-1. [8] Fker, A., 006, erml Effeny of e Cross Flow Het Exnger, Proeedngs of te 006 ASME Interntonl Menl Engneerng Congress nd Exposton, November 5-10. AUHO Mr.oopes wr presently ssoted wt Sgr Insttute of eser nd enology, SAGE Unversty, Indore,s ssstnt professor n Menl Engneerng Deprtment vng 1 yers of teng experene. Completed BE from Orentl Insttute of Sene & enology, Bopl nd ME from Insttute of Engneerng & enology, DAVV, Indore.Pursung PD under supervson of Dr.Govnd Meswr, Assote Professor,IE,DAVV,Indore Volume 6, Issue 6, June 017 Pge 319