An Experimental Study for Mixed Convection through a Circular Tube Filled with Porous Media and Fixed Horizontally and Inclined

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1 Mdern Applied Science Vl., N. ; April 0 An Experimental Study fr Mixed Cnvectin thrugh a Circular Tube Filled with Pru Media and Fixed Hrizntally and Inclined Taheen Ahmad Taheen Mechanical Engineering, Cllege f Engineering, Tikrit Univerity, Iraq Received: December, 0 Accepted: December 17, 0 di:./ma.vnp1 Abtract The pru media have a great influence n the heat tranfer and traging it characteritic. In thi tudy an experimental wrk ha been cnducted t meaure the mixed cnvectin thugh the filled circular tube. Firt, the tet apparatu ha been manufactured; filled circular tube with a pru media and fixed hrizntally firt then tilted with different angle. Secndly, the circular tube i heated with a cntant heat flux and, thermcuple have been tickled in prper pitin. Then many reading, fr temperature, have been regitered fr each thermcuple with different peed f the utlet air (frm the circular tube) and the inclinatin angle f the tube ha been changed many time t be 0, 0,4 &. Thee experiment have been cnducted fr the range (.4 Ra 7.7) f Rayleigh number and fr the range (.1 1.4) f clet number. Three tet fr the heat flux have been cnducted, fr each five clet number ha been ued. Finally, the experimental reult hw that the urface temperature f pipe ha a prprtinal relatin with the tube length fr all value f the heat flux and clet number. In additin, the heat tranfer i achieved by free cnvectin fr mall clet number, by frced cnvectin fr large clet number and by mixed cnvectin fr medium value f clet number. Keywrd: Mixed cnvectin, Cntant heat flux, Pru media, Inclined Hrizntal circular tube Nmenclature A tube urface area (m ) C pecific heat (J.kg -1. K -1 ) D tube diameter (m) d grain diameter (m) g acceleratin due t gravity (m/ ) Gr Grahf number h heat tranfer cefficient (W.m -. C -1 ) I electrical current (ampere) K permeability (m ) k thermal cnductivity (W.m -1. C -1 ) L tube length (m) m ma flw rate (kg. -1 ) Nu Nuelt number clet number Ra Rayleigh number Re Reynld number Ri Richardn number Q heat input (W) q heat flux (W. m - ) T temperature ( C) u velcity f air (m. -1 ) 1 ISSN E-ISSN 1-1

2 Mdern Applied Science Vl., N. ; April 0 V heater vltage (vlt) Greek ymbl tube angle f inclinatin Prity kinematic vicity ( m. -1 ) dynamic vicity (kg.m ) denity (kg.m - ) percentage f heat l Subcript av average b bulk e effective f fluid (air) i inlet utlet urface p grain (gla phere) z lcal 1. Intrductin Over the lat three decade Heat tranfer thugh pru media ha received cniderable attentin in many ther field earching fr alternative energy. The analytical treatment fr cnvective heat tranfer thrugh pru lk fr the firt time cmplicated. Depending n the fluid prpertie, the temperature will effect the fluid flw in the internal and external flw and will cmplicate the aumptin f heat tranfer particularly laminar flw at lw Reynld number, the effect f the buncy can t be neglected and free cnvectin cnvicted by frced cnvectin in heat tranfer will caue a new field fr tudy called mixed cnvectin. It i difficult t knw it whle nature(dnald A. Nield and Adrian Bejan, 1)( Al- Daher M.. 000). The cmbined frced and free cnvectin in an inclined urface and aturated in a pru medium, in the cae f tream line and urface temperature ditributin will be in harmnic with ditance. The parameter (Gr/Re) i the ne wh will decide the type f the effective cnvectin, when it value i very mall the frced cnvectin i the dminant, and when it value very large the free cnvectin i dminant(ping Cheng, 00). Analytical tudy and invetigating the influence f permeability f the cmbined frce and free cnvectin arund inclined buried urface in aturated pru media wa preented by (chandraeekhara& P.M. S, 1). The reearcher had tudied tw cae, unifrm urface temperature and linearly variable with ditance meaured frm the frnt edge f the plate with aitance and pping flw. They fund that the nn-dimeninle parameter (Gr/Re ) and ( /Re) will cnduct the flw behavir, al they nticed that the permeability change will increae heat tranfer fr all ( /Re) value. (W.L etal. 1) cnducted an experiment n a mixed cnvectin heat tranfer in a vertical packed channel with a ymmetric heating f pping wall. The experiment were carried ut in the range f <<00 and 0<Ra<. The meaured temperature ditributin indicate the exitence f a ecndary cnvective cell inide the vertical packed channel. A crrelatin equatin fr Nuelt number in term f clet and Rayleigh number wa btained frm experimental data and plt the relatin between them. Three cnvectin regime were exit: frced cnvectin Ra/<1, mixed cnvectin <Ra/< and natural cnvectin </. Mixed cnvectin analyi n a vertical packed plane in tw directin uing unbalanced heat wa tudied by (Nawaf,004). He aumed ne ide i inulated and the ther ne i cled by a cntant temperature media. The tudy wa carried ut fr (0.1- ), Ra (, 0, ), thermal cnductivity rati Kr (0.01- ) and heat tranfer cefficient H (0.01- ). He fund that the net average Nuelt number decreae a H increae at lw clet number, while fr large clet number and H value and when Kr increae the average Nuelt number will increae. Publihed by Canadian Center f Science and Educatin 1

3 Mdern Applied Science Vl., N. ; April 0 (Y.M.F. etal. 00) Studied laminar mixed cnvectin in the entrance regin fr hrizntal emicircular duct with the flat wall at the bttm. They ued mmentum and energy equatin which were lved by cntrl vlume apprach uing finite cntrl vlume by SIMPLER Algrithm. Reult were fr the thermal bundary cnditin f unifrm axially heat flux and with unifrm wall temperature circumferentially t ditribute velcitie temperature and lcal Nuelt number hwed that Nu decreae in mixed cnvectin cae in the entrance regin, and decreae when the entrance length i increaed and increaed with the natural cnvectin effect befre reaching a cntant value (fully develped). While Gr and Nu increae with increaing mean cefficient f frictin fr the wall in fully develped cae. Mixed cnvectin wa tudied experimentally in a circular inclined channel with different angle and vertical fr laminar dwnward flw by (Huein, et al. 007). The ued a cpper pipe (length 0mm) inner diameter (0mm). The uter urface wa heated at cntant heat flux, Re range wa (0- ), Ra (1.7* -.* ). They fund the tune urface temperature increae a lng the tube with dwnward flw extenively increaing cmparing with upward flw. Nu in the dwnward flw i le in the upward cae. A crrelatin wa btained between Nu, Ra and Re in the till and vertical cae in the frm Nu Ra Re.. Experimental Wrk Mixed cnvectin heat tranfer i ne f the mt imprtant cnvectin tranfer we cnduct an experiment mixed cnvectin in a packed aturated pru media heated with a cntant heat flux in the hrizntal pitin and changing the inclinatin tube angle (0, 4, ) repectively. A cpper tube i ued, it internal and external diameter are (4mm) and (47mm) repectively, the length wa (0mm). The active heated length i nly (00mm). The channel wa packed with gla phere, their diameter i (mm) and their thermal cnductivity i (0.1W/m. C). They were fitted between tw permeable dic made f galvanized irn. The tube i prvided with air by a blwer at (00 rpm) and A.V at (0 v). The vltage wa tabilized by a tabilizer. The tube urface temperature wa meaured by (4) thermcuple (T type) were pitin a lng the tet ectin tube, three thermcuple were pitin fr each lcate. The mean read wa ued, thi pitin repreent ne frm 1. One thermcuple i ued t meaure the air temperature at the entrance f the tube which wa lcated in the air flw, anther ne wa lcated after packed t meaure the ut flw air temperature and it wa pitined in the ame perviu way. Anther thermcuple meaure the labratry ambient temperature. The tet ectin wa heated electrically uing cil and an electrical reitance arund tube f (m) in length with a reitance (1 /m). T increae the upplied pwer the tet ectin wa thermally inulated with fiber gla f (mm) in thickne. The tw end f the tube were inulated electrically and thermally uing tw part f tephln made f inulatr and thermal reitr lapanate al it wa ued t reduce the thermal le in the axial directin. The entrance ectr wa packed t be inure t get fully develped befre the tet ectin. The heater wa upplied with an alternative electrical pwer uing cnverter that upplied with a teady vltage thrugh a vltage regulatr (0v). An Ameter wa ued t meaure the current pa thrugh the heater with accuracy ( -4 A). Digital Anemmeter AM400 with an accuracy f (0.1 m/) i ued t meaure the velcity f entering air t the tet ectin, the maximum velcity that the anemmeter can meaure i (0m/). A pht (1) hw the tet ectin, and fig. () illutrate the chematic drawing f the tet ectin.. Calculatin Prcedure The temperature f the in flw air t the tet ectin i within (0-) C. And the tet prcedure can be lited a fllw. 1- Turn n the air blwer in rder t upply the tet ectin with the required air. And the air flw i cntrlled eaily uing the cntrl valve that hwn in pht graph (1). - The tet ectin wa et t the prper temperature and thi wa achieved uing a variable tranfrmer. - After (- 4) minute the ytem wuld reach the teady tate cnditin. And thi technique wa adpted by (Al- Daher M. and A. H. Jaim, 00)(Al-Sammarai A. T. A., 1). Many reading fr the tube urface and al fr the inlet and utlet air and the libratry temperature have been regitered. The diameter f the filler (gla phere) wa meaured and fund t be (d=mm). And the prity f thi filler wa fund practically and fund t be (0.1), were phere rder in the tube i cnider t have randm arrangement and when thi wa cmpared with the value that calculated by uing the fllwing equatin(al- Daher M.. A, 000):- 0 ISSN E-ISSN 1-1

4 Mdern Applied Science Vl., N. ; April 0 dp * D...(1) And thi equal t (0.7), and the deference between the tw value (meaured and calculated) i fund t be negligible. Therefre the permeability wa calculated uing the fllwing equatin(b. Bunm, G. Fglia, O. Manca& S. Nardini, 00):- dp K... () 17(1 ) There are many variable have been calculate me f them i lcally indirectly meaured uch a Nuelt number and heat tranfer cefficient and the ther in between variable have been calculated e.g. clet number (), Rayeigh number (Ra) and Richardn number (Ri). Then the lcal heat tranfer cefficient wa calculated uing the fllwing equatin(huein A. Mhammed and Yain K. Salman, 007):- q hz.. () T T b z Where (q) i the heat flux fr a unit f area and thi i calculated frm the fllwing equatin:- Q q... (4) A. Where A.D.L. () And the bulk temperature fr the air wa calculated uing the fllwing equatin(j. P. Hlman, 177):- Ti T Tb ( ) () The characteritic f the flwing air were calculated thrugh the tet ectin which were variable depending n in the bulk temperature f the flwing air and thi were calculated uing the fllwing empirical equatin(jhn H. Lienhrd IV and Jhn H. Lienhrd V, 00):- f * Tb.1.. (7) * *Tb 4.47* Tb 4 f 1.77* 1.* Tb..() 1.* Tb.* Tb kf * Tb.().7* Tb.* Tb Prf. 1.1* Tb.() 4.7* Tb.* Tb Cpf. 1.7Tb () * Tb.0* Tb Where the quantity f the added heat tranfer (Q) frm the air wa calculated a fllw:- Q m Cpf (T T i). (1) And the generated heat (Pwr in ) in the heater wa fund a flw:- Pwr in I*V () The percentage f the heat tranfer heat l culd calculated a flw:- Q (1 ).(14) Pwrin And the lcal Nuelt number wa calculated uing the fllwing equatin:- Publihed by Canadian Center f Science and Educatin 1

5 Mdern Applied Science Vl., N. ; April 0 h D z Nu z.(1) ke Where k e i the effective cefficient f thermal cnductivity fr the pru media which culd be calculated a fllw(b. Bunm, G. Fglia, O. Manca& S. Nardini, 00)( C. Y. Chi and F. A. Kulacki, 1):- ke kf (1 ) k p.. (1) Where k f and k p i the thermal cnductivity f the air and pru media repectively. The thermal cnductivity f the air wa calculated uing equatin (). Reynld number (Re) wa calculated a fllw(al- Daher M.. A. 000):- f udp Re. (17) f 1 And clet number () wa calculated a fllw:- Re Pr f....(1) And Prandtl number (Pr f ) wa calculated depending n the change f the bulk temperature f the air uing equatin ().Grahf number (Gr) wa calculated a fllw(dnald A. Nield and Adrian Bejan, 1)(B. Bunm, G. Fglia, O. Manca& S. Nardini, 00)( C. Y. Chi and F. A. Kulacki, 1):- g KqD Gr (1) k 1 Where T b Rayleigh number (Ra) wa calculated uing the fllwing equatin:- Ra Gr Pr f...(0) Where Richardn number (Ri) wa calculated uing the fllwing equatin:- Ri Gr Re.. (1) And the average value f Nuelt number wa calculated a fllw:- dz....() L Five tete had been cared ut fr the fllwing rang (.1 1.4) f clet number. And fr each value f thi number the upplied heat wa changed. And thi wa fr three quantitie f the heat flux and al the flw wa (1.4,. and 1.)W/m. And thi wa depending n the upplied electricity vltage that ued fr heating the tet ectin the previu tet had been repeated ne fr each f the fllwing tube pitin (hrizntal and inclined with deferent angle)(0, 4, ). The relatinhip between the change f tube urface temperature and the tube length, fr each tet pitin were pltted. Al the relatin between average Nuelt number and clet number, fr a fixed value f a Rayleigh number were pltted. And a relatin between average Nuelt number and Rayleigh number fr fixed value f a clet number were pltted. 4. Reult and Dicuin Sixty tet had been carried ut fr each f the fllwing variable. 1) The angle ( ) f the tube have been change t have different value. Thee value were (0, 0, 4, ). ) clet number have been varied within the range (. 1.4) and thi wa dne five time. ) Rayleigh number have been varied within the range (.4-7.7) and thi wa dne three time. The relatinhip between f the tube urface temperature and it length fr the hrizntal pitin fr deferent value f heat flux were preented n fig. (). Thi figure hw that the tube urface temperature increae prprtinal with tube length. And thi with a linear manner. Except few pint at the tw end f the tube. And thi exceptin i increaed fr high value f Rayleigh number. And thi i believed i due t that bundary layer tart frm zer at ne end f the tube and it thickne i increaed t reach it peak me were between the tw end. The decreae in the tube urface temperature at the ut flw end i jutified by the heat l at that regin. The ame behavir wuld cntinue fr the fig. (4, and )which are fr the angle (0, 4 and ). And it can L e ISSN E-ISSN 1-1

6 Mdern Applied Science Vl., N. ; April 0 be nte that the tube urface temperature increae with the increae f the angle f the tube inclinatin and thi i due t the decreae f the thickne f the bundary layer, in additin t abrbed heat by the flwing air. The ht air ettle in the upper pace f the pru media and the cld air ettle in the bttm pace f the pru media. The height difference in the tube urface temperature i ( T=4. C). Thi wa regitered fr the firt heat flux and thi wa fr the pitin between ( =0) and ( = ). And the height difference fr the ecnd heat flux wa (( T=1.1 C). And the height difference fr the third heat flux wa ( T=.). Fig. (7,, and ) hw the relatinhip between the urface temperature and the tube length fr different value f clet number. The little difference between clet number value i related t the thermal prpertie which can be calculated fr each value f bulk temperature. And thu wa clarified in previuly (experimental wrk), in the equatin (7,,, and ). And fr thi relatinhip fr the hrizntal pitin and the ther angled pitin. It can be nticed that the tube urface temperature increaed with the increae f the tube length fr the different value f the heat flux. The maximum increae wa fr the maximum value f heat flux. And al the maximum difference fr the tube urface temperature wa regitered fr each tube pitin and they were fund t be: 0, T. C 0, T.1 C 4, T C, T 7.1 C Fig. () hw the ditributin f the tube urface temperature with it length fr all the tube inclinatin angle and fr (=1) and heat flux (q=.w/m ). It i clear frm thi figure that the tube urface temperature increae with the increae f the tube length. And thi increae ha a large tep fr a higher inclinatin angle f the tube. The highet temperature fr the tube urface regiter wa (T=7.4 C). The ame previu temperature ditributin and the ame tube pitin and fr (=0) and heat flux (q=1.w/m ) are preented in fig. (1). The highet temperature that regitered fr the tube urface wa (T=14. C) and thi, fr the tube pitin ( = ). The ditributin f the lcal Nuelt number with the tube length, fr different tube pitin and fr the firt heat flux (q=1.4w/m ) were preented n fig. (, 14, 1 and 1). It can be nticed that at me reading that the lcal Nuelt number i decreaed it thermal fully develped. And the regin thugh t be related t phenmenn f flw and thi i due t the exitence f the gla phere. Al culd be ntice be that the increae f clet number caue an increae in lcal Nuelt number, and thi i becaue f the bundary layer i thin. S the effect f the natural cnvectin increae at lw flw peed. And the height value f Nuelt number wa the hrizntal pitin f the tube and it decreae when the inclinatin angle f the tube increae t reach it maximum value (Nu=7.) at ( = ). The relatinhip between lcal Nuelt number with tube length fr all tube pitin are preented n fig. (17, 1, 1 and 0) at the heat flux (q=1.w/m ). It i clear that lcal Nuelt number behave in the ame manr a in the previu cae. And all it value are cled t each ther. And the rean i becaue cnvergence f the lcal cefficient f the heat tranfer, and thi i a reult frm cnvergence f the difference in the temperature value. The average value f Nuelt number had been calculated by ching the cnvergence value f temperature in the mid ectin f the tube where the air flw wa cnidered thermally fully develped. That becaue the imple difference between the temperature value near t the tube end. The increae f Rayleigh number caue cniderable increae in the average value f Nuelt number a hwn in fig.1, and. And thi wa fr all the tube pitin, except inclinatin with ( ) angle. And thi wa dwn fr different value f clet number which have been teted. Thi i becaue that the effect f natural cnvectin which ha a (parablic relatin) which i the cmmn hape fr all heat tranfer cnditin f thi rt. Publihed by Canadian Center f Science and Educatin

7 Mdern Applied Science Vl., N. ; April 0 The highet Nuelt number i crrepnding t the highet clet number. And thi i fr all tube inclinatin angle. And the average value f Nuelt number crrepnding t the mall Rayleigh number are cnvergence and the difference between the increaed at higher value f Rayleigh number. The relatinhip between Nuelt number and the average clet number fr different Rayleigh number fr all the tube pitin a hwn in fig.4,, and 7). Frm all thee curve, it i clear that the average Nuelt number increae with the increae f clet number and thi fr all cnditin. And the larget Nuelt number i crrepnding t the high value f Rayleigh number. Al frm thee figure it i pible t lcate, the heat tranfer regin (by natural cnvectin) and thi i dived int three regin, the firt i the left end f the curve. It can be een that the value f Nuelt number i ettle and thi cntinue t a certain pint right t the firt pint in the curve. S thi regin i the natural cnvectin zne which han t any effect fr clet number and there i n effect fr Reynld number. And Rayleigh number nly play the mater rle in thi mater. The ecnd regin t the right f the firt ne i the mixed cnvectin zne in thi regin it culd be een that the change f the Nuelt number give a change in the clet and Rayleigh number gather. And the third regin which i the right prtin f the curve, end it culd be een that a large change in Nuelt number value give light change in the value f Rayleigh number, i., e. thi regin i a frced cnvectin zne. Fig. (7,, and 0) give a clear picture t the effect f clet number fr different value f Rayleigh number. It culd be een that the average Nuelt number i increaed with the increae f Rayleigh number and thi i fr all the tube pitin. And the increae f the Nuelt number ha a large tep crrepnding t a large Rayleigh number pecially at the hrizntal tube pitin.. Cncluin Frm thi tudy the fllwing cncluin be deduced:- 1) The tudy urface temperature increae with increae f the heat flux and thi increae with larger tep at higher f the tube inclinatin angle. Thi i becaue the Phenmenn f eparating the cld air t be ettle in the bttm and the ht air t be ettle in the upreme. ) The tube urface temperature fr mall clet number i higher than that fr large value f clet number. And thi i true fr all value f heat flux. ) The value f lcally Nuelt number have it highet value fr the cae f hrizntal pitin f the tube. And thi i large value f Rayleigh number. 4) Lcal Nuelt number increae with the increae f clet number all the tube pitin. ) Thi fr teady we fund that there are three regin f cnvectin thi i depending f the change f Nuelt number and thi depend f clet number. And thi i fr the teted value f Rayleigh number which i hwn in table 1, fr all the teted tube pitin. ) An empirical relatin between the average value f Nuelt number with average clet number and average value f Rayleigh number. And thi fr all tube pitin. Thi empirical frmal:- Nu av Ra av a c1 c b av....() av All the cntant f the previu frmal are hwn in table. Recnditin 1) Studying the effect f the changing the cr ectin f the teted tube (elliptical, quare, triangle, etc..) ectin. ) Studying the effect f the changing the teting tube diameter. ) Studying the effect f the change the grain diameter. 4) Studying the effect f the uing grain with different diameter. ) Studying the effect f the change flwing fluid phae, e. g. uing vapr. Reference Al- Daher M. and A. H. Jaim. (00). A Theretical and Experimental Study n Laminer Frced Cnvectin Heat Tranfer Thrugh a Hrizntal Tube Filled with Pru Media, Scientific Jurnal f Tikrit, 00. c 4 ISSN E-ISSN 1-1

8 Mdern Applied Science Vl., N. ; April 0 Al- Daher M.. A. (000). Heat Tranfer by Mixed Cnvectin Thrugh the Hrizntal Circular Tube Filled with Pru Media, phd. Thei, Univerity f Technlgy, Baghdad, Iraq, 000. Al-Sammarai A. T. A. (1). Experimental tudy f frced cnvectin Heat Tranfer frm a Heated Cylinder in Free and Embedded Hrizntal Cylinder Array in a Pru Medium in Cr Flw, M.Sc. Thei, Univerity f Tikrit, Tikrit, Iraq, 1. B. Bunm, G. Fglia, O. Manca& S. Nardini. (00). Numerical Study n Mixed Cnvectin a Channel with an Open Cavity Filled with Pru Media, th Eurpean Thermal- Science Cnference, Vl., pp 1-, 00. B. C. Chandraekhara and P. M. S. Nambdiri. (00). Influence f Variable rmeability n Cmbine Free and Frced Cnvectin abut Inclined Surface in Pru Media, Internatinal Jurnal f Heat and Ma Tranfer, Vl., Iue, pp 1-0, January 1, Available nline 00. C. Y. Chi and F. A. Kulacki. (1). Mixed Cnvectin Thrugh Vertical Pru Annuli Lcally Heated frm the Inner Cylinder, Jurnal f Heat Ma Tranfer, Vl., pp 14-, 1. Dnald A. Nield and Adrian Bejan. (1). Cnvectin in Pru Media, Secnd Editin, Springer, pp 14-7, pp 1-4, 1. Huein A. Mhammed and Yain K. Salman. (007). Experimental Mixed Cnvectin fr Dwnward Laminar Flw in the Thermal Entrance Regin f Inclined and Vertical Circular Tube, Experimental Thermal and Fluid Science, pp 1-1, February 007, J. P. Hlman. (177). Experimental Methd fr Engineer, McGraw- Hill Bk cmpany th Editin, 177. Jhn H. Lienhrd IV and Jhn H. Lienhrd V. (00). A Heat Tranfer Text Bk, Third editin, Jhn H., pp 714, 00, Lienhrd. Nawaf H. Saeid. (004). Analyi f Mixed Cnvectin in a Vertical Pru Layer uing Nn-Equilibrium Mdel, Internatinal Jurnal f Heat and Ma Tranfer, Vl. 47, pp 1-7, July 004, Ping Cheng. (177). Cmbined Free and Cnvectin Flw abut Inclined urface in pru media, Internatinal Jurnal f Heat and Ma Tranfer, Vl. 0, Iue, pp 07-14, Augut 177, Available nline 00. W. L. Pu., P. Cheng and T. S. ha. (1). An Experimental Study f Mixed Cnvectin Heat Tranfer in Vertical Packed Channel, ALAA Jurnal f Thermphyic and Heat Tranfer, Vl. (4), pp. 17-1, 1 Y. M. F. El. Haadi, I. M. Rutum and A. Abdala. (00). Laminar Mixed Cnvectin in the Entrance Regin f Semicircular with Cntant Heat Flux, th ALAA/ASME/ Jurnal f Thermphyic and Heat Tranfer Cnference, 00. Table 1. Reult f Teting Tube Pitin Natural Frced Mixed cnvectin cnvectin cnvectin Hrizntal (0 ) <1. 1.<<.4 >.4 Inclined (0 ) < <<4.1 >4.1 Inclined (4 ) < <<. >. Inclined ( ).<<7. 7.<<.7 >.7 Publihed by Canadian Center f Science and Educatin

9 Mdern Applied Science Vl., N. ; April 0 Table. cntant f the previu frmal a b c1 c c = = = =0. Figure 1. A pht graph hwing the tet partie 1- Blwer, - Valve, - Tet Sectin, 4- Meter panel, - Vltage regular, - Vltmeter, 7- Ameter, - Thermmeter, - Flw meter Figure. Schematic drawing fr the tet rig including the tet ectin 1- Cncrete bae, - Blwer bae, - Blwer, 4- cnnecting tube, - Air valve, - Flange, 7- Fibber gla, ISSN E-ISSN 1-1

10 Mdern Applied Science Vl., N. ; April 0 T ( C) 4 4 q=1.4 W/m =.7 =1. =71. =. =. T ( C) 4 4 q=1.4 W/m =0. =17.00 =7.0 =4.1 = (A) q=. W/m q=. W/m (A) T ( C) 0 =.4 =1. =.7 =7.0 =4. T ( C) =.1 =14. =4.1 =0. = q=1. W/m =.1 =14. =.0 =04. =41.71 (B) q=1. W/m =0.1 =1. =41. =0. =4.4 (B) 0 T ( C) (C) Figure. The relatin between the tube urface temperature and it length fr many value f heat flux at many value f clet number at the hrizntal pitin f the tube (C) Figure 4. The relatin between the tube urface temperature and it length fr many value f heat flux at many value f clet number at the inclined angle (0 ) Publihed by Canadian Center f Science and Educatin 7

11 Mdern Applied Science Vl., N. ; April q=1.4 W/m =4. =1.4 =74.1 =41.4 = q=1.4 W/m =. =1. =7. =.7 = q=. W/m =. =1. =1.7 =. =4.1 (A) q=. W/m =. =1.00 =. =. =4. (A) q=1. W/m =. =14. =4.4 =00. =4.0 (B) (C) Figure. The relatin between the tube urface temperature and it length fr many value f heat flux at many value f clet number at the inclined angle (4 ) q=1. W/m =. =147. =41. =0. =4.4 (B) (C) Figure. The relatin between the tube urface temperature and it length fr many value f heat flux at many value f clet number at the inclined angle ( ) ISSN E-ISSN 1-1

12 Mdern Applied Science Vl., N. ; April =1. q=1. W/m q=. W/m q=1.4 W/m 10 =1. q=1. W/m q=1.4 W/m q=. W/m Figure 7. The relatin between the tube urface temperature and it length fr many value f heat flux fr =1. and hrizntal pitin f the tube =14.1 q=1. W/m q=. W/m q=1.4 W/m Figure. The relatin between the tube urface temperature and it length fr many value f heat flux fr =14.1 and inclinatin angle (0 ) =1.7 q=1. W/m q=. W/m q=1.4 W/m Figure. The relatin between the tube urface temperature and it length fr many value f heat flux fr =1.7 and inclinatin angle (4 ) Figure. The relatin between the tube urface temperature and it length fr many value f heat flux fr =1. and inclinatin angle ( ) 0 4 =1 q=. W/m Inclined Inclined 4 Inclined 0 Hrizntal Figure. The relatin between the tube urface temperature and it length fr all the tube pitin and fr the minimum value f heat flux q=1. W/m =0.00 Inclined Inclined 4 Inclined 0 Hrizntal Figure 1. The relatin between the tube urface temperature and it length fr all the tube pitin and fr the maximum value f heat flux Publihed by Canadian Center f Science and Educatin

13 Mdern Applied Science Vl., N. ; April 0 0 q=1.4 W/m 1 q=1.4 W/m =. =. =4.4 =0. 1 =71. =1. =.7 =41.1 =147. =. 7 0 Figure. The relatin between lcal Nuelt number and the tube length fr many value f clet number and hrizntal pitin f the tube at minimum heat flux q=1.4 W/m =4.4 =0. =41. =1. = Figure 1. The relatin between lcal Nuelt number and the tube length fr many value f clet number and inclinatin angle ( ) at minimum heat flux q=1. W/m =41.71 =04. =.04 =14. =. 1 Figure 14. The relatin between lcal Nuelt number and the tube length fr many value f clet number and inclinatin angle (0 ) at minimum heat flux q=1.4 W/m =. =41.4 =74.4 =1.4 =4. 1 Figure 1. The relatin between lcal Nuelt number and the tube length fr many value f clet number and inclinatin angle (4 ) at minimum heat flux Figure 17. The relatin between lcal Nuelt number and the tube length fr many value f clet number and hrizntal pitin f the tube at maximum heat flux q=1. W/m =4.4 =0. =41. =1. =0.1 Figure 1. The relatin between lcal Nuelt number and the tube length fr many value f clet number and inclinatin angle (0 ) at maximum heat flux 1 ISSN E-ISSN 1-1

14 Mdern Applied Science Vl., N. ; April q=1. W/m =4.0 =00. =4.4 =14. =. 1 =4.00 =. =.7 =14.1 =.47 1 Figure 1. The relatin between lcal Nuelt number and the tube length fr many value f clet number and inclinatin angle (4 ) at maximum heat flux q=1. W/m =4.4 =0. =41. =147. = Ra Figure. The relatin between average value f Nuelt number and Rayleigh number with changing the value f clet number fr the inclinatin angle (0 ) 1 =41. =. =.7 =1.7 =.0 1 Figure 0. The relatin between lcal Nuelt number and the tube length fr many value f clet number and inclinatin angle ( ) at maximum heat flux 1 1 =4. =. =. =1. = Ra Figure. The relatin between average value f Nuelt number and Rayleigh number with changing the value f clet number fr the inclinatin angle (4 ) 1 Hrizntal 14 1 Ra=01.7 Ra=4. Ra= Ra Figure 1. The relatin between average value f Nuelt number and Rayleigh number with changing the value f clet number fr the hrizntal pitin f tube Figure 4. The relatin between average value f Nuelt number and clet number fr the hrizntal pitin and fr different value f Rayleigh number Publihed by Canadian Center f Science and Educatin 141

15 Mdern Applied Science Vl., N. ; April Inclined 0 Ra=0.1 Ra=. Ra=1.4 1 Ra=. Hrizntal Inclined 0 Inclined 4 Inclined av Nu Figure. The relatin between average value f Nuelt number and clet number fr inclinatin angle (0 ), and fr different value f Rayleigh number Inclined 4 Ra=0.4 Ra=4. Ra= Figure. The relatin between average value f Nuelt number with clet number fr Rayleigh number (Ra=.) fr all tube pitin 1 Ra=4. Hrizntal Inclined 0 Inclined 4 Inclined Figure. The relatin between average value f Nuelt number and clet number fr inclinatin angle (4 ), and fr different value f Rayleigh number 1 Inclined Ra=.4 Ra=4.7 Ra= Figure. The relatin between average value f Nuelt number with clet number fr Rayleigh number (Ra=4.) fr all tube pitin Ra=.4 Hrizntal Inclined 0 Inclined 4 Inclined Figure 7. The relatin between average value f Nuelt number and clet number fr inclinatin angle ( ), and fr different value f Rayleigh number Figure 0. The relatin between average value f Nuelt number with clet number fr Rayleigh number (Ra=.4) fr all tube pitin 14 ISSN E-ISSN 1-1