1.0 1. 0 ABSTRAC ABST RACT T
This experiment is fluid mixing. Generally, when we said mixing there is type [A] fluid will mix with type [B] fluid in a tank but in this experiment, we used two types of fluid with different visosity separately separately.. The ob!etive ob!etive of this experiment is to observe the flow patterns that an be ahieved by the use of different impellers with and without the use of baffles. "ext is to show how the power onsumed by a mixer varies with speed,types speed,types of impeller impeller and with the inlusion of baffles. #irst #irst of all, all, we need need to do the the gene general ral start start$up $up proed proedur ures. es. The The powe powerr was was swithed on and tightening srews were fastened. Then, shaft was lifted up and brought down by using lifting hain attahed to the shaft before the experiment was arried out. #or experiment %, we start with filling the tank with &' liters of water. Then, a flat paddle impeller was attahed at the end of the shaft. After that, the angular speed of the impeller was ad!usted to (' rpm, %'' rpm, %(' rpm and )'' rpm and the flow pattern of the water at every ever y angular speed was observed and the tor*ue was reorded. The following step is to replae the flat paddle with turbine impeller and work with same proess. +astly, a baffle were plaed inside the tank with eah flat paddle impeller and turbine impeller and take reading as before.#or experiment ), repeat the steps at experiment % by using hydrauli oil.se the formula fore-tor*ueradius, the fore/"0 fore/"0 value was obtained. By using the formula angular speed ,1 - angula angularr speed )π
/rpm0 x
2'
, the angular speed ,1/rads0 value was obtained. By using the formula
power-tor*ue x angular speed, 1 , the power/30 value was obtained. obtained. 4eondly, the experiment of water without baffles was done. The result obtained for tor*ue value of water using the turbine impeller were '"m for all different angular speed/rpm0 whih were ('rpm, %''rpm, %('rpm, and )''rpm. The result obtained for tor*ue value of water using the flat paddle impeller were '.5"m, %.6"m, ).("m, and 1 &.5 "m for different angular speed/rpm0 whih were ('rpm, %''rpm, %('rpm, and
)''rpm.
4eond experiment onsist of water hydrauli oil with baffle and without baffle. The tank was filled with &' litre of oil. #irstly, the experiment of oil with baffle was done. The result obtained for tor*ue value of oil using the turbine impeller were '.%"m, ).2"m, (.5"m, and %'.7"m for different angular speed/rpm0 whih were %''rpm, )''rpm, &''rpm, and 6''rpm. The result obtained for tor*ue value of oil using flat paddle impeller were 5"m, %2.2"m, )).8"m, and )8.)"m for different angular speed/rpm0 whih were %''rpm, )''rpm, &''rpm and 6''rpm. As onlusion, f or water without baffle using flat paddle, the water moves in irular motion /lokwise0 with high veloity and reated a deep whirlpool at the entre of the tank where the impeller is being inserted in.#or turbine impeller,The water moves in irular motion /lokwise0 with high veloity and reates a whirlpool at the entre of the tank where the impeller is being inserted in. "ext, for the water with baffle by using flat paddle, the water irulates in an uneven lokwise moving in satter with high veloity and for the turbine impeller, the water irulates in an uneven irular motion with high veloity. 9ixing of li*uid$li*uid or solid$li*uid system is a diffiult proess to analy:e and relate to variables[%]. #luid mixing is most easiest mixing proess by rotating an agitator in the li*uid onfined tank. But it is possible to waste muh of input energy if the wrong kind of agitator is used.
2.0 INTRODUCTION
9ixing of li*uid$li*uid or solid$li*uid system is a diffiult proess to analy:e and relate to variables[%]. #luid mixing is most easiest mixing proess by rotating an agitator in the li*uid onfined tank. But it is possible to waste muh of input energy if the wrong kind of agitator is used. Generally, the basi onept of fluid mixing is simply put as mixing fluid ;<= into fluid ;>= where the li*uids are soluble to one another and form a homogeneous mixture. 9ixing impeller speially designed to pump fluid through the impeller and produe turbulene whih this effet is vital in mixing operations. These produes 2
fluid veloity and fluid shear respetively. #luid veloity produes movement throughout the mixing vessel, intermixing material in one part of the tank with another, prevents solids from setting out and produes flows. #luid shear in the form
of turbulent eddies is essential to miro$mixing within the large veloity streams breaking up gas bubbles or immisible li*uids into small droplets. All mixing impellers produe both fluid veloity and fluid shear but different types of impellers produe different degrees of flow turbulene. The impeller flow patterns give impat to the result of mixing proess. The flow pattern depends on the impeller type whih gives variation in flow patterns resulting from different impeller types. The presene of baffle in mixing tank would influene the flow patterns as well. ?t an inrease the amount of top to bottom irulation whih ontributes to turbulene by giving out some obstales for the mixture to swirl as a whole and elimination of vortexes. The two main types of the flow patterns are axial radial. The differenes in the flow patterns an ause variations in distribution of shear rate and energy dissipation rate within the mixing tank. ?n this experiment, not only the fluid patterns of the fluid are determined, but also to show how the power onsume by a mixer varies with speed, type of impeller, and with and without baffle. There are varies type of agitator for example propeller and turbine. They have their own pros and ons. @ropeller is usually used for low to medium visosity of fluid[)]. Turbine operates in low speed and usually used for hemial reations, suspension solid and misible li*uid mixing due to exellent feature in designing the flow pattern where a hange in design an divert the flow pattern of fluid by radial flow or axial flow in the reator vessel[)].
3.0 OBJECTIVES Experiment 1 :
The ob!etive of this experiment is to observe the flow patterns that an be ahieved by the use of different impellers with and without the use of baffles. Experiment 2 : 3
The ob!etive of this experiment is to show how the power onsumed by a mixer varies with speed, types of impeller and with the inlusion of baffles.
4.0 THEORY
Tehnially, matter in li*uid or gas state is known as fluid. ? mpellers in agitated tanks are used to mix fluids or slurry in the tank. This an be used to ombine materials in the form of solids, li*uids and gas [&]. 9any type of impeller were used in this experiment suh as turbine impeller and the flat paddle. ?t is beause to ahieve the ob!etive of fluid mixing experiment whih is$ to observe the flow patterns of two fluids with various visosity when different impellers used with and without baffle in li*uid tank and also to study how power affet the fore, tor*ue, angular speed and flow pattern by hanging the speed of mixer. Turbine impeller is a rotating omponent whih transfer energy from motor to the fluid. The veloity that ahieved by impeller is transfer into pressure when the outward movement of fluid is onfined by the ontainer.[6]. As mention in the ob!etive, various visosity were used whih is water and hydrauli oil. ?n this experiment, we also observe the flow pattern of these various material if we put the baffle inside the stirred tank or without the baffle. 9ost of ommon baffle used are straight flat plate of metal that run along the straight sides of vertially oriented ylindrial tank, are also used in this experiment.
4
#?G %$ Geometri speifiation for a stirred tank Baffles are attahed to the inside vertial walls of the tank by means of welded brakets. #our e*ually spaed baffles are usually suffiient to prevent li*uid swirling and vortex formation. The optimum baffle width 3B# depends on the impeller design and fluid visosity, but is of the order %%' to %%) the tank diameter. #or lean, low$visosity li*uids, baffles are attahed perpendiular to the wall as illustrated in #igure 7.6/a0.[(]. #or the unbaffle tank, tendeny for swirling flow pattern to develop rotating li*uid. [6].
#?G )$ Baffle attahed to the wall for low visosity li*uid 5
?n the laminar flow /eC%'0, the power imparted either baffle or unbaffle tank. 3hile in the turbulent flow /eD%''''0, the power imparted in the baffle tank. @ower
imparted in an unbaffled tank is e*ual to %2 of the power imparted in the same tank withbaffle [2]. @ = k µ n ) D & 3here, @ - power /30 k - impeller onstant E - dynami visosity /"sm)0 F - diameter impeller
5.0 APPARATUS AND MATERIALS
#igure & #luid 9ixing apparatus
6
#igure 6 #lat paddle impeller
#igure 2 ?mpellers holder
#igure 7 Hydrauli oil
#igure ( Turbine impeller
#igure 8 #luid mixing apparatus
#igure 5 3ater inside the tank inside the tank
#igure %' 4peed ontroller and fore indiator
6. 0 PROCEDURE 5.1 Gene!" #$!$%&' '()e*&e 7
%0 The power was swith on. )0 The tightening srews were fastened.
#igure %% Baffle
&0 The shaft was lifted up and down by using lifting hain and attahed it to the shaft before started the experiment. 5.2 E+'e,-en$ 1
%0 )0 &0 60
The general start up proedure was performed. The tank was filled with &' liters of water. A flat paddle impeller was attahed at the end of the shaft. The angular speed of the impeller was set up to (' rpm,%'' rpm,%(' rpm and
)'' rpm. (0 The flow pattern of the water was observed at every angular speeds and the tor*ue was reorded. 20 4tep 6 and ( was repeated by replaing the flat paddle impeller with turbine impeller. 80 4tep & to ( was also 70 repeated by replaing baffles inside the tank with eah flat paddle impeller and turbine impeller. 50 The angular speed,fore and power onsumed for eah speed were alulated. 5.3 E+'e,-en$ 2
%0 )0 &0 60
The general start up proedure was performed. The tank was filled with &' liters of hydrauli oil. A flat paddle impeller was attahed at the end of the shaft. The angular speed of the impeller was set up to 8' rpm,%6' rpm,)%' rpm and
)7' rpm. (0 The flow pattern of the water was observed at every angular speeds and the tor*ue was reorded. 20 4tep 6 and ( was repeated by replaing the flat paddle impeller with turbine impeller. 80 4tep & to ( was also repeated by replaing baffles inside the tank with eah flat paddle impeller and turbine impeller. 70 The angular speed,fore and power onsumed for eah speed were alulated. 5.4 Gene!" #&$%*(/n '()e*&e.
%0 +i*uid inside the tank was removed through the outlet valve. )0 The tank was washed and rinsed several times until no oil residue left in the 8
tank. &0 The impeller was removed,washed and plaed at the right plae after used it. 60 The power was shut down.
.0 RESULTS E+'e,-en$ 1 A !$e "(/ '!$$en /,$(&$ !"e ,n#,*e $e $!n.
Types of impeller
#low pattern
Ibservations •
The water moves in irular motion
#lat paddle
/lokwise0 with high veloity and reated a deep whirlpool at the entre of the tank where the impeller is being inserted in. •
The water moves in irular motion /lokwise0 with high
Turbine impeller
veloity and reates a whirlpool at the entre of the tank where the impeller is being inserted in.
Table % the water flow pattern without baffle inside the tank. 9
B !$e "(/ '!$$en /,$ !"e ,n#,*e $e $!n.
Types of impeller
#low pattern
Ibservations •
The water irulates in an
•
uneven lokwise 9oving in satter with high veloity
#lat paddle
•
The water irulates in an uneven irular motion with high veloity.
Turbine impeller
Table ) shows the water flow pattern with baffle inside the tank. 10
E+'e,-en$ 2
Table & 3ater with baffle inside the tank. Type of impeller
Turbine ?mpeller
#lat paddle ?mpeller
Angular speed /rpm0
#ore /"0
Tor*ue /".m0
@ower /watts0
('
Angular speed, 1 /rads0 (.)6
6.((
'.(
).2)
%''
%'.6)
%5.'5
).%
)%.77
%(' )'' (' %'' %(' )''
%(.8% )'.56 (.)6 %'.68 %(.8% )'.56
&%.7) 68.)8 &2.&2 7&.26 %6).8& %8'.5%
&.( (.) 6.' 5.) %(.8 %7.7
(6.55 %'7.7% )'.52 52.&) )62.2( &5&.28
Graph % @ower against speed with baffle by using water
11
Table 6 3ater without baffle inside the tank. Type of impeller
Angular speed /rpm0
Angular speed, 1
#ore /"0
Tor*ue /".m0
@ower /watts0
Turbine ?mpeller
#lat paddle ?mpeller
('
/rads0 (.)6
'.''
'.''
'.''
%''
%'.6)
'.''
'.''
'.''
%(' )'' (' %'' %(' )''
%(.8% )'.56 (.)6 %'.68 %(.8% )'.56
'.'' '.'' %'.5% &%.7) 68.)8 (7.%7
'.'' '.'' %.) &.( (.) 2.6
'.'' '.'' 2.)5 &2.2( 7%.25 %&6.')
Graph ) @ower against speed without baffle by using water.
Table ( Iil with baffle inside the tank. 12
Type of impeller
Angular speed /rpm0 8'
Angular speed, 1 /rads0 8.&&
#ore /"0
Tor*ue /".m0
@ower /watts0
6.((
'.(
&.28
Turbine ?mpeller
#lat paddle ?mpeller
%6'
%6.22
%(.6(
%.8
)6.5)
)%' )7' 8' %6' )%' )7'
)%.55 )5.&) 8.&& %6.22 )%.55 )5.&)
2%.7) 7&.26 6'.5% %''.'' %8'.5% ))).8&
2.7 5.) 6.( %%.' %7.7 )6.(
%65.(& )25.86 &).55 %2%.)2 6%&.6% 8%7.&6
Graph & @ower against speed with baffle by using oil.
Table 2 Iil without baffle inside the tank.
13
Type of impeller
Angular speed /rpm0 8'
Angular speed, 1 /rads0 8.&&
#ore /"0
Tor*ue /".m0
@ower /watts0
'.''
'.''
'.''
Turbine ?mpeller
#lat paddle ?mpeller
%6'
%6.22
%&.26
%.(
)).''
)%' )7' 8' %6' )%' )7'
)%.55 )5.&) 8.&& %6.22 )%.55 )5.&)
)5.'5 &2.&2 %%.7) 67.%7 %)&.26 )'6.((
&.) 6.' %.& (.& %&.2 )).(
8'.&8 %%8.)7 5.(& 88.8' )55.'2 2(5.8
Graph 6 @ower against speed without baffle by using oil.
7.0 CALCULATION 8.0 DISCUSSION 14
?n this fluid mixing experiment, onsists two part of experiments % and ). #or experiment %, the material used is hydrauli oil and the manipulated variable is the mixing tank with baffle or without baffle. The tank were filled with &.' liter oil.
#irstly, for the oil using flat paddle and with baffle experiment, the result of tor*ue,T /"m$)0 value were 6.(, %%, %7.7, and )6.( when the angular speed /rpm0 was 8', %6', )%' and )7' respetively. The value of fore,# were obtained by alulating using #= formula
T d , where T is tor*ue and d is diameter impeller whih is '.%%m.
Therefore, the value of fore,# /"0 were 6'.5%, %'', %8' and ))).8& when the angular speed /rpm0 8', %6', )%', and )7' respetively. The value of power,@ were obtained by alulating using formula @ = T × ω ,where T is tor*ue and ω is angular speed in /rads0. #or the onvetion unit angular speed from /rpm0 to /rads0 by using this ω / rad.s0
formula
=
/rpm0 ×
)π 2' . Therefore, the value of power,@ /30 were &).55,
%2%.)2, 6%&.6% and 8%7.&6 when the angular speed, ω /rads0 is 8.&&, %6.22, )%.55 and )5.&) respetively. #or the oil using flat paddle and without baffle experiment, the result of tor*ue,T /"m$)0 value were %.&, (.&, %&.2 and )).( when the angular speed /rpm0 is 8', %6', )%' and )7' respetively. The value of fore,# /"0 that have been alulated were %%.7), 67.%7, %)&.26 and )'6.(( when the angular speed /rpm0 8', %6', )%', and )7' respetively. Then, the value of power,@ /30 that have been alulated were 5.(&, 88.8', )55.'2 and 2(5.8' when the angular speed, ω /rads0 is 8.&&, %6.22, )%.55 and )5.&) respetively.
4eondly, experiment oil using turbine impeller and with baffle was done. The resulting tor*ue,T /"m $)0 were obtained as '.(, %.8, 2.7 and 5.) when the angular speed /rpm0 was 8', %6', )%' and )7' respetively. "ext, the value of fore,# /"0 were obtained by alulation as 6.((, %(.6(, 2%.7) and 7&.26 when the angular speed /rpm0 8', %6', )%', and )7' respetively. Then, the value of power,@ /30 that have been alulated were &.28, )6.5), %65.(& and )25.86 when the angular speed, ω /rads0 is 8.&&, %6.22, )%.55 and )5.&) respetively. #or the oil using turbine impeller and without baffle experiment, the result of tor*ue,T /"m $)0 value were ', %.(, &.) and 6.' when the angular speed /rpm0 is 8', %6', )%' and )7' respetively. The value of 15 fore,# /"0 that have been alulated were ', %&.26, )5.'5 and &2.&2 when the angular speed /rpm0 8', %6', )%', and )7' respetively. "ext, the value of power,@ /30 that have been alulated were ', )), 8'.&8 and %%8.)7 when the angular speed, ω /rads0
is 8.&&, %6.22, )%.55 and )5.&) respetively. The graph of power /30 against speed /rads0 is also plotted to give a learer understanding of all of the relationships involved. #rom the results and the graph obtained, it an be seen that the power onsumed inreases as the speed inreases. ?t also an be seen that the power onsumed in a baffled tank is higher than without using baffled tank. This is beause with the use of baffles in an agitation proess, vortex does not our thus proper mixing is ahieved. ?n the experiment part ), material that has been used is water. #or experiment using flat paddle and with baffle, the result of tor*ue,T /"m $)0 were 6, 5.), %(.8 and %7.7 when the angular speed /rpm0 is (', %'', %(' and )'' respetively. The value of fore,# /"0 that have been alulated were &2.&2, 7&.26, %6).8& and %8'.5% when the angular speed /rpm0 (', %'', %(' and )'' respetively. Then, the value of power,@ /30 that have been alulated were )'.52, 52.&), )62.2( and &5&.28 when the angular speed, ω /rads0 is (.)6, %'.68, %(.8% and )'.56 respetively. #or the water using flat paddle and without baffle experiment, the result of tor*ue,T /"m $)0 value were %.), &.(, (.) and 2.6 when the angular speed /rpm0 is (', %'', %(' and )'' respetively. The value of fore,# /"0 that have been alulated were %'.5%, &%.7), 68.)8 and (7.%7 when the angular speed /rpm0 (', %'', %(' and )'' respetively. Then, the value of power,@ /30 that have been alulated were 2.)5, &2.2(, 7%.25 and %&6.') when the angular speed, ω /rads0 is (.)6, %'.68, %(.8% and )'.56 respetively. #or experiment using turbine impeller and with baffle, the result of tor*ue,T /"m $)0 were '.(, ).%, &.( and (.) when the angular speed /rpm0 is (', %'', %(' and )'' respetively. The value of fore,# /"0 that have been alulated were 6.((, %5.'5, &%.7) and 68.)8 when the angular speed /rpm0 (', %'', %(' and )'' respetively. Then, the value of power,@ /30 that have been alulated were ).2), )%.77, (6.55 and %'7.75 when the angular speed, ω /rads0 is (.)6, %'.68, %(.8% and )'.56 respetively. The graph of power /30 against speed, ω /rads0 is also plotted to give a learer understanding of all of the relationships involved. #rom the results and the graph obtained, it an be seen that the power onsumed inreases as the speed inreases. 9oreover ,for the water using turbine impeller and without baffle experiment, the 16 result of tor*ue,T /"m $)0 value was all :ero value when the angular speed /rpm0 is (', %'', %(' and )'' respetively. The value of fore,# /"0 also give :ero value when the angular speed /rpm0 (', %'', %(' and )'' respetively. Then, the value of power,@
/30 also give :ero value when the angular speed, ω /rads0 is (.)6, %'.68, %(.8% and )'.56 respetively. Therefore, from the plotted graph power,@ /30 against angular speed, ω /rads0 it an seen that when the power inrease, the value angular speed are onstant at :ero.
The flow patterns of water with different types of impeller are observed. #our set of flow patterns are shown in Se)$,(n .0 with the use of two different impellers with and without the baffle. Based on the observation, we an know that flow pattern of the water is depend on the type of impeller used. This experiment has been onduted using the same speed whih is )'' rpm. Therefore, we an see that the flow patterns produed are irular pattern and rotary motion when using two types of impellers without the inlusion of baffles. Another observation that an be seen is the prodution of the deep vortex in the without inlusion baffled tank. By using flat paddle, it reated a deeper whirlpool than turbine impeller at the enter of the tank. 3ith the inlusion of baffle, the use of flat paddle and turbine impeller produed the same flow pattern whih is uneven. By omparing all the result that obtained, the effetiveness of different impeller,with or without baffle and low or high visosity material, based on observation and alulation, the effetive is by using turbine impeller beause re*uired low power, with baffle beause an limit the vortex produed and low visosity beause if ompare by using turbine impeller and with baffle, the power re*uired are lower beause water is less visous that the hydrauli oil. Then, it an easy to mix.
10.0 CONCLUSION 17
?n this experiment,the first ob!etive is to observe the flow patterns that an be ahieved by the use of different impellers with and without baffles.The flow of fluid
when baffle is inserted in the tank is the fluid flow in random motion espeially in hydrauli oil and the fluid flow smoothly in irular motion when baffle is not inserted in the tank.3ater has low visosity ompared to oil.The higher the visosity of fluid,the more uneven irular motion of the flow.The flow of oil also slow when the visosity is higher. The seond ob!etive is to show the power onsumed by a mixer varies with speed,types of impeller and with the inlusion of baffles.3hen water is used as the fluid in the tank,the values of fore,tor*ue and power alulated is higher with baffle ompared to water without baffle.4ame goes to the hydrauli oil,the values of fore,tor*ue and power alulated is higher with baffle ompared to hydrauli oil without baffle.This experiment is suess beause the ob!etives stated are ahieved.
11.0 RECOMMENDATIONS
Fue to the experiment that has been done, there are few reommendations that should be onsidered to get the best results needed throughout in this experiment. #irst and the foremost, ensure that the e*uipment is in a proper operating good ondition. ?t is suggested to repair and always do some maintenane for this e*uipment when the unit has been used at many times. 4ine this experiment should be done with water soure and oagulant or oil as a fluid, the tank should be leaned thoroughly espeially after onduting the experiment with oil. This is beause to prevent the high onentration of oagulant or oil to be attahed the wall of the tank. This is also to prevent the oil and water from mixing. Therefore, the tank an be used again when onduting the next experiment. Ither than that, it is neessary to make sure the balane is operating in a good ondition. ?f the balane is not operating very well, it will affet the reading for the fore balane regarding to eah speed of impellers. ?t is not the right way to measure the fore by operating the tension spring manually, it is muh better to use the tension spring that operated by omputer itself. ?ndiretly, the aurate readings an be 18 obtained as the best results needed.
#urthermore, ensure that the eyes must be perpendiular to the sale of the tank during refill the tank with water to avoid parallax error. Besides that, always make sure that the water does not spill over the side of the tank by inreasing the speed too muh. ?n addition, several different olors of plasti pallets an be used, so the flow pattern an be deteted easily. Beause of that, the movement of the plasti pellets an be seen learly. +ast but not least, it is muh better to suggest that two tanks should be provided by the laboratory. Ine of them is for water and the remaining one for oagulant or oil. This is to ensure that the water and oil an be prevented from mixing. The mixture between water and oil an be happened if only one tank provided and used the same tank to ondut the experiment. This will affet the data as well as inaurate readings when onduting this experiment.
12.0 RE9ERENCES
%.
httpswww.oursehero.omfile765%%27+7$#luid$9ixing. etrieved on )5th
).
Itober )'%2 httpenggyd.blogspot.my)'%%'2types$of$agitators$used$in$hemial.html.
&. 6. (.
etrieved on )5th Itober )'%2. httpsen.wikipedia.orgwiki?mpeller. etrieved on )6 th Itober )'%2 httpdoslide.usJthermofluids$lab$fluid$mixing. etrieved on )6th Itober )'%2 httphe!ri.iau*.a.irassetssubdomainshe!rifilesBooksmixing.pdf.etrieved
2.
on )6th Itober )'%2 httpmimo:a.marmara.edu.trKbilge.alpaslanenve&'%+eturesLhpJ2.pdf. etrieved on )6th Itober )'%2
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