CHAPTER 4: RESULTS AND DISCUSSION
4.4 Results for Polyacrylamide
4.4.2 Polyacrylamide at 200 kg/min
50
Figure 4.28: Graph for Water and Polyacrylamide 0.05 % at 200 kg/min
Figure 4.29: Graph for Water and Polyacrylamide 0.075 % at 200 kg/min
0 20 40 60 80 100 120 140 160 180
0 20 40 60 80 100 120
dP/L (Pascal/m)
XD/D
X
D/D Vs dP/L for Water and PAA 0.05 % @ 200 kg/min
water_200 kg/min
PAA 0.05
%_200 kg/min
Poly.
(water_200 kg/min) Poly. (PAA 0.05 %_200 kg/min)
0 50 100 150 200
0 20 40 60 80 100 120
dP/L (Pascal/m)
XD/D
X
D/D Vs dP/L for Water and PAA 0.075 % @ 200 kg/min
water_200 kg/min
PAA 0.075
%_200 kg/min
Poly.
(water_200 kg/min) Poly. (PAA 0.075 %_200 kg/min)
52
Figure 4.30: Graph for Water and Polyacrylamide 0.1 % at 200 kg/min
Table 4.6: Properties involved for 200 kg/min flow rate of Polyacrylamide concentrations
Fluid Type Entrance Length (m)
Pressure Drop (Pa/m)
Viscosity (Pa.s)
Velocity (m/s)
Reynolds Number
XD/D Polyacrylamide
0.01%
2.7 55.52 0.002244 0.618 22842 35.43 Polyacrylamide
0.025 %
2.7 52.65 0.003016 0.618 16995 35.43 Polyacrylamide
0.05 %
2.7 73.20 0.004462 0.618 11488 35.43 Polyacrylamide
0.075 %
2.7 106.65 0.00609 0.619 8417 35.43
Polyacrylamide 0.1 %
1.8 138.01 0.007563 0.619 6777 23.62
As we can see from the graphs above, for polyacrylamide at 0.01, 0.025, 0.05, 0.075 and 0.01 % against water flowing at 200 kg/min through the test tube, there is a significant difference in the development of the entrance length. The entrance length is reduced as the polyacrylamide polymer percentage increases. Besides that the pressure is also noticed to increase along with the polyacrylamide polymer thickness.
However the overall pressure is at a higher value as the velocity of the fluid is higher compared to 100 kg/min.
0 50 100 150 200 250
0 20 40 60 80 100 120
dP/L (Pascal/m)
XD/D
X
D/D Vs dP/L for Water and PAA 0.1 % @ 200 kg/min
water_200 kg/min
PAA 0.1
%_200 kg/min
Poly.
(water_200 kg/min) Poly. (PAA 0.1
%_200 kg/min)
4.4.3 Polyacrylamide at 300 kg/min
Figure 4.31: Graph for Water and Polyacrylamide 0.01 % at 300 kg/min
Figure 4.32: Graph for Water and Polyacrylamide 0.025 % at 300 kg/min
0 50 100 150 200 250 300 350
0 20 40 60 80 100 120
dP/L (Pascal/m)
XD/D
X
D/D Vs dP/L for Water and PAA 0.01 % @ 300 kg/min
water_300 kg/min
PAA 0.01
%_300 kg/min
Poly.
(water_300 kg/min) Poly. (PAA 0.01 %_300 kg/min)
0 50 100 150 200 250 300 350
0 20 40 60 80 100 120
dP/L (Pascal/m)
XD/D
X
D/D Vs dP/L for Water and PAA 0.025 % @ 300 kg/min
water_300 kg/min
PAA 0.025
%_300 kg/min
Poly.
(water_300 kg/min) Poly. (PAA 0.025 %_300 kg/min)
54
Figure 4.33: Graph for Water and Polyacrylamide 0.05 % at 300 kg/min
Figure 4.34: Graph for Water and Polyacrylamide 0.075 % at 300 kg/min
0 50 100 150 200 250 300 350
0 20 40 60 80 100 120
dP/L (Pascal/m)
XD/D
X
D/D Vs dP/L for Water and PAA 0.05 % @ 300 kg/min
water_300 kg/min
PAA 0.05
%_300 kg/min
Poly.
(water_300 kg/min) Poly. (PAA 0.05 %_300 kg/min)
0 50 100 150 200 250 300 350
0 20 40 60 80 100 120
dP/L (Pascal/m)
XD/D
X
D/D Vs dP/L for Water and PAA 0.075 % @ 300 kg/min
water_300 kg/min
PAA 0.075
%_300 kg/min
Poly.
(water_300 kg/min) Poly. (PAA 0.075 %_300 kg/min)
Figure 4.35: Graph for Water and Polyacrylamide 0.1 % at 300 kg/min
Table 4.7: Properties involved for 300 kg/min flow rate of Polyacrylamide concentrations
Fluid Type Entrance Length (m)
Pressure Drop (Pa/m)
Viscosity (Pa.s)
Velocity (m/s)
Reynolds Number
XD/D Polyacrylamide
0.01%
3.6 99.35 0.002244 0.927 34262 47.24
Polyacrylamide 0.025 %
2.7 101.55 0.003016 0.928 25408 35.43 Polyacrylamide
0.05 %
3.6 113.63 0.004462 0.929 17185 47.24 Polyacrylamide
0.075 %
2.7 141.36 0.00609 0.931 12625 35.43
Polyacrylamide 0.1 %
2.7 174.28 0.007563 0.937 10162 35.43
As we can see from the graphs above, for polyacrylamide at 0.01, 0.025, 0.05, 0.075 and 0.01 % against water flowing at 300 kg/min through the test tube, there is a significant difference in the development of the entrance length. The entrance length is reduced following a pressure change of 15% of 3 consecutive points as the polyacrylamide polymer percentage increases. Besides that the pressure is also noticed to increase along with the polyacrylamide polymer thickness. However the overall pressure is at a higher value as the velocity of the fluid is higher compared to 100 kg/min and 200 kg/min.
0 50 100 150 200 250 300 350
0 20 40 60 80 100 120
dP/L (Pascal/m)
XD/D
X
D/D Vs dP/L for Water and PAA 0.1 % @ 300 kg/min
water_300 kg/min
PAA 0.1
%_300 kg/min
Poly.
(water_300 kg/min) Poly. (PAA 0.1
%_300 kg/min)
56
Furthermore, in order to justify our finding with that of theory which states that the higher the viscosity or percentage concentration polymer added, the shorter the entrance length would become. The data taken was prepared in graphs (Figure 4.35, figure 4.36 and figure 4.37) in the following subsection indicating the influence of the percentage concentration against the entrance length of the flow for water and the two polymers used which are polyacrylamide and xanthan gum.
4.5 Performance Comparison of XG and PAA
Figure 4.36: Graph of Length and % concentration polymer at 100 kg/min
0 0.5 1 1.5 2 2.5 3 3.5
0 0.02 0.04 0.06 0.08 0.1 0.12
Length, XD
% concentration
XD/ % Concentration for 100 kg/min
XG_100 kg/min PAA_100 kg/min
Figure 4.37: Graph of Length and % concentration polymer at 200 kg/min
Figure 4.38: Graph of Length and % concentration polymer at 300 kg/min
As we can see from the graphs above, there is a significant chance in the entrance length as the concentration of the polymers are added respectively, from the common pattern, we can conclude that the higher the concentration the shorter the entrance length would be. Therefore, using data from this experiment we have also proven that viscosity has influence on the entrance length of pipe flow.
0 1 2 3 4 5 6
0 0.02 0.04 0.06 0.08 0.1 0.12
Length, XD
% concentration
XD/ % Concentration for 200 kg/min
XG_200 kg/min PAA_200 kg/min
0 1 2 3 4 5 6 7 8
0 0.02 0.04 0.06 0.08 0.1 0.12
Length, XD
% concentration
XD/ % Concentration for 300 kg/min
XG_300 kg/min PAA_300 kg/min
58
Another consideration done in order to verify the theory stated is to prove that the flow rate which is an important factor in this study also has a great influence on the entrance length. Below are the results of the findings in Figure 4.38 – 4.42.
Figure 4.39: Graph of Length and Flow Rate of 0.01 % polymer concentration
Figure 4.40: Graph of Length and Flow Rate of 0.025 % polymer concentration
0 1 2 3 4 5 6 7 8 9
0 50 100 150 200 250 300 350
Length, Le
Flow Rate, Q
XD/Q for 0.01% Concentration
water XG PAA
0 1 2 3 4 5 6 7 8 9
0 50 100 150 200 250 300 350
Length, Le
Flow Rate, Q
XD/Q for 0.025% Concentration
water XG PAA
Figure 4.41: Graph of Length and Flow Rate of 0.05 % polymer concentration
Figure 4.42: Graph of Length and Flow Rate of 0.075 % polymer concentration
0 1 2 3 4 5 6 7 8 9
0 50 100 150 200 250 300 350
Length, Le
Flow Rate, Q
XD/Q for 0.05% Concetration
water XG PAA
0 1 2 3 4 5 6 7 8 9
0 50 100 150 200 250 300 350
Length, Le
Flow Rate, Q
XD/Q for 0.075% Concentration
water XG PAA
60
Figure 4.43: Graph of Length and Flow Rate of 0.1 % polymer concentration
Based on the results plotted above, it is shown that the flow rate does has an influence on the entrance length where the length keeps increasing with a higher flow rate and the opposite would take place otherwise. Hence, we have proven another theory from the literature studied.
.
0 1 2 3 4 5 6 7 8 9
0 50 100 150 200 250 300 350
Length, Le
Flow Rate, Q
XD/Q for 0.1% Concentration
water XG PAA
4.6 Discussion
From the flow loop experiment conducted throughout this study using water, xanthan gum and polyacrylamide has been used at various mass flow rates of 100 kg/min, 200 kg/min and 300 kg/min. Besides that the concentrations of the polymer also have been varied to 0.01 %, 0.025 %, 0.05 %, 0.075% and 0.1 %. The results that were produced did prove the theory for flow of fluids in a pipe. The objective of the study was to discover the entrance length of the polymer flows and identify the difference in the length whether is reduces or increases the entrance length. From the results of conducting the experiment with tap water, we noticed the difference of the results in terms of flow rate, pressure drop, velocity and the entrance length. All this results do relate to each other. We notice that for water flowing at 100 kg/min at a velocity of 0.3095 m/s the pressure drop as well as the Reynolds number and entrance length is smaller. As the mass flow rate is increased to 200 kg/min and 300 kg/min there is an increase in the velocity which is 0.6124 and 0.9291 respectively, pressure drop Reynolds number and entrance length. This results supports the theory that velocity is proportional to pressure drop whereby when the velocity is increased the pressure drop increases as well. This phenomenon occurs when any fluid that moves in a pipe; there is a collision between molecules because of the random movements of molecules which results in the decrease in the kinetic energy. This loss of kinetic energy is converted into some other form of energy. As we know from continuity equation; A1 x V1 = A2 x V2 that, if the cross section of flow is not changing then velocity of fluid has to be same. Due to this reason, pressure energy is converted into kinetic energy to keep the velocity same. Hence we observe drop in pressure. When you increase the velocity of fluid, the collision between molecules increases resulting into greater loss of kinetic energy, in turn, a greater pressure drop would occur. Velocity is also known theoretically to be proportionate with the Reynolds number whereby proven using the equation;
Equation 11:
62
The following formula also proves that the viscosity of the fluid is proportionate to the Reynolds number where if the viscosity increases the Reynolds number would as well increase and vice versa. The objective of this experiment is to determine the entrance length of polymer addition in fluids which is where Xanthan Gum and Polyacrylamide was added using the various concentrations as mentioned above.
From the results of Xanthan Gum additions, we can see a common pattern in the change of the entrance length. The change in the entrance length may not be significant however the results show a significant trend. From the theory studied, there are several reasons this occurs. Firstly, by increasing the concentration of Xanthan Gum from 0.01 to 0.1, the viscosity of the fluid is as well increased as we can observe from the viscosity difference that resulted from the results of the rheometer experiment. This shows Xanthan Gum polymer gives an effect on the viscosity as proven in the theory states that it increases the viscosity by adding a small amount close to 1 %. Therefore by adding the viscosity to the fluid the velocity would also increase as the drag reduces. This occurs because the friction among the molecules is reduced hence creating a larger pressure drop as stated above. Hence, this also increases the Reynolds number as can be seen from the results above where it decreases with increased viscosity. This whole phenomenon gives an effect to the entrance length by applying the theory and formula in general for Newtonian flow;
Equation 10: XD/D = 4.4Re1/6 (for turbulent flow)
From the results of the entrance length for Xanthan Gum at 100 kg/min mass flow rate we can see the difference where from the concentration of 0.01 %, we get an entrance length close to as the results of water. This indicates the slight increase in its viscosity which has given effect to the entrance length. As the concentration is increased to 0.025, 0.05, 0.075 and 0.1 we monitor the difference of the entrance length to reduce even more significantly from 1.8 to 1.0 meters. The similar situation occurs at 200 kg/min and 300 kg/min flow rate for Xanthan Gum polymers as well.
For the concentration of 0.075 %, we observe the results to be out of range. This might have happened due to some errors.
Among the errors that would have occurred are the possibility of air bubbles in the fluid which caused the reading to fluctuate as air bubbles can be compressed.
Another error that might have occurred is the possibility that the concentration mixture could have been wrongly done or the reading misinterpreted which is both human errors. Therefore as we can conclude by using the equation for entrance length above, as the Reynolds number is decreased the entrance length would as well be reduced hence the transition from laminar to turbulent would be faster allowing the overall development length to reduce. The similar effects are observed with the mass flow rate of 200 kg/min where with thickness of 0.01 to 0.1 % the entrance length is reduced by 0.9 meters and 300 kg/min, the entrance length is reduced by 1.0 meters. The pattern observed from here comparing all the three flow rates is that at higher flow rates the effect becomes more minimal.
As for the results on the entrance length of Polyacrylamide polymer, similar effects occur as the results of Xanthan Gum except that due to its higher viscosity which is 0.002244(0.01%), 0.003016(0.025%), 0.004462(0.05%), 0.00609 (0.075%) and 0.007563(0.1%) compared to Xanthan Gum of viscosities 0.001785(0.01%), 0.002418(0.025%), 0.003964(0.05%), 0.005193(0.075%) and 0.006963(0.1%), the velocity is increased from by 0.0005 m/s (100kg/min), 0.001 (200 kg/min) and 0.01 (300 kg/min) compared to Xanthan Gum of 0.0002 (100 kg/min), 0.0004 (200 kg/min) and 0.0004 (300 kg/min) hence causing a much higher pressure drop as proven in the results section in the previous subtopic. Therefore, this results in a shorter entrance length.
Therefore by comparing both the polymers we can say that polyacrylamide would provide better effects compared to the use of Xanthan Gum. Furthermore, along conducting the experiment Polyacrylamide is also proven to have a longer run duration compared to Xanthan Gum because Xanthan Gum is synthesized from cabbage, which is an organic material whereby it has the tendency to biologically degrade which in turn decreases its viscosity therefore it spoils and its viscosity effect decreases. Whereby, polyacrylamide which is formed chemically from acrylamide subunits has very late decay time. However both has its benefits and uses in different fields as stated in theory therefore both polymers provide benefits to the development length of fluids.
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CHAPTER 5
CONCLUSION AND RECOMMENDATION
5.1 Conclusion
Literature review has highlighted the importance of the different fluid properties of polymer flows and shown the importance of the work of numerous researchers in this field. However, there was not much published work on the study of turbulent entrance length in pipe flow. Several researchers have developed empirical equations to characterize the entrance length of turbulent Newtonian flow however, little has been done to characterize the entrance length of turbulent Non-Newtonian flow, and therefore the conclusion of this study is expected to provide future researchers with an experimental solution for characterizing the entrance length of turbulent Non- Newtonian flow. Before initiating our experiment we also have identified the steps required in order to run the study, which could prove vital for the experiments to be conducted then. In our methodology we have discussed the steps in getting familiar with the flow loop and the additional apparatus required. Therefore, our experiments could be conducted with complete understanding of the phenomena occurring in the flow as well as the ability to analyze the result. From the results obtained, we could identify the difference of polymer addition in comparison to plain tap water. Our experiment results indicated a difference in the entrance length with Xanthan Gum and Polyacrylamide polymers addition. The entrance length was taken to be the point where the pressure difference becomes constant or a very slight difference. This is the point where the fluid has developed whereby from laminar to turbulent and is proven from the theory of the textbook and reference. [23] Besides that from the study we can also conclude that the addition of polymer provides significant difference in the entrance length whereby as the concentration of polymer is higher the entrance length reduces. This concept has been proven experimentally and tallies with the literature where a higher viscosity results in an increase of velocity because of drag reduction where the friction among molecules id reduced giving a higher pressure drop so as a higher Reynolds Number. Hence, the transition from laminar to
turbulence is increased. [19]. In conclusion, this experimental study was a success as the results proved above that polymer does effect the entrance length of fluid therefore in other words, higher viscosity reduces the entrance length of the fluid.
5.2 Future Work
For the future work of this study, it has been identified that there is room for improvement where necessary improvements and modifications could be made in order to increase the quality as well as the productivity of the research. Among the few measures that could be taken are:
Use a wider variety of polymer of different properties where the results would be more accurate to the theory when compared whereby a wider set of results could be studied.
Use higher concentration variance to get better results where the changes are more visible.
To implement more accurate measuring devices whereby the data collected would be more precise and accurate. Besides that a standard polymer mixing method should also be implemented to reduce losses during mixing and accurate measurement of materials.
Implement a cheaper and suitable polymer which required a very small amount to increase the viscosity greatly as well as also having a longer degradation time where its viscosity remains constant for a longer period.
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APPENDICES
Appendix 1 1. Image of Polymer Flow Loop Test Rig
2. Images of procedures of experiment
2.1 Flow loop tank for storing water and mixing polymers
2.2 Control panel of flow loop used to control flow rate and power on/off
70
Appendix 2 2.3 Valve along pipeline to measure pressure drop
2.4 Pressure transducer to measure pressure drop along test tube
2.5 Data results of flow experiment on computer