ChE 135 Process Engineering Laboratory Formal Report
CLM
Determination of viscosity of sugar solution using falling ball method Christian Paul A. Camora 1, Jerome Christian M. Lumacad 1, Rainier E. Mendoza 1 1
University of the Philippines Diliman, Quezon City
Abstract. In this experiment, the viscosity of su gar solutions where determined via the falling ball method. Solutions of 0%, 10%, 20%, 30%, 40%, 50% and 60% sugar were prepared and then the viscosity of each solution was determined and was further compared. It can be concluded that viscosity increases in a nonlinear manner as concentration increases. Keywords: viscosity, viscosity, falling ball method, sugar solution
1 Introduction
µ= Viscosity is the fluid property that gives rise to the forces resisting the relative motion of the adjacent layers of the fluid. (Geankoplis, 1993) Because of this, it is an important parameter in the design of piping systems. There are various instruments that can be used in measuring the viscosity of a fluid (e.g. rheometer, rotational viscometer, cone-and-plate viscometers) (Secco, deBruyn, & Kostic, 2014) but the method used in the experiment is the falling ball method. This is one of the earliest and simplest methods to determine the viscosity of a fluid which only involves free fall of a sphere through the fluid. (Secco, deBruyn, & Kostic, 2014) Analysis of the data acquired in the experiment requires the application of Stokes’ Law given by Equation 1 where µ is the viscosity of the fluid, ρ s and ρf are are the densities of the sphere and fluid respectively, g is the acceleration due to gravity, d is the diameter of the sphere, and t is the time it takes for the sphere to travel the length l. (Measurement of Viscosity in a Vertical Falling Ball Viscometer, 2008)
( − ) 2 18
1
In the experiment, the effect of concentration of sugar on its viscosity is investigated. The relationship between concentration and viscosity will be established.
2 Materials and Methodology 2.1 Preparation of Sugar Solutions The stock solution (60% w/w sugar solution) was prepared by mixing 300 g of refined white sugar with 200 mL of water. It was stirred constantly over a hot plate until no more sugar sugar crystals were seen. The other solutions with concentrations of 10%, 20%, 30%, 40% and 50% by weight were each prepared by diluting a specified amount of stock solution with water. Mass and volume of the solutions (including pure water and a 60% w/w solution sample) were measured using an analytical balance and a graduated cylinder. Density was calculated then. Solutions were set aside as they reached room temperature.
ChE 135 – CLM – Determining Viscosity of Sugar Solutions
2.2 Determination of Viscosity Permanent marker was applied on glass beads. The mass of the glass beads was measured. The volume of a glass bead was calculated given its diameter of 4 mm. Two points were conveniently marked on the burette and the distance between them was recorded. For a number of trials, the time elapsed as a glass bead was dropped into the burette filled with sugar solution was recorded. This was done for all solutions.
Table 1. Density of Sugar Solutions
wt%
Density of Fluid (kg/m3)
0%
1000
10%
1059
20%
1118
30%
1177
40%
1236
50%
1295
60%
1354
Viscosity of sugar solutions were then calculated using the formula and the results were tabulated below.
Figure 1. Experimental Setup on Determination of Viscosity
Table 2. Summar of Results
3 Results and Discussion In this experiment, the viscosity of the different sugar solutions were determined using the formula:
( − ) 2 µ= 18
1
The total length travelled by the ball, is measured to be 0.51 meters while the diameter of the sphere, was measured to be around 4mm. Density of the sphere was also calculated and was equal to 2473.86 kg/m 3 while the density of the fluid varied with concentration and was calculated using the mixing rule. Both density of pure water (1000 kg/m 3) and pure sugar (1590kg/m3) were used to determine the densities tabulated below.
Average Time (s)
Terminal Velocity (m/s)
Viscosity (Pa-s)
0%
1.646667
0.309717
0.041496
10%
1.726667
0.295367
0.04177
20%
1.743333
0.292543
0.040415
30%
1.776667
0.287054
0.039395
40%
1.958333
0.260426
0.041448
50%
2.646667
0.192695
0.053347
60%
5.315
0.095955
0.101768
Sugar Solution (wt%)
Viscosity vs Concentration 0.12 0.1 ) s a 0.08 P ( y t i 0.06 s o c s i 0.04 V
0.02 Table 1. Densit of Su ar Solutions at different Concentrations 0 0%
20%
40%
Concentration (wt%)
60%
80%
ChE 135 – CLM – Determining Viscosity of Sugar Solutions
4 Conclusion and Recommendation It can be concluded that the settling time for the ball increases as the concentration of the sugar solution increases. This means that the sugar solution becomes more viscous as it gets more concentrated. Furthermore, based on the graph, it can then be concluded that the relationship between concentration and viscosity is nonlinear.
References Geankoplis, C. (1993). Transport Processes and Unit Operations. New Jersey: Prentice-Hall, Inc. Measurement of Viscosity in a Vertical Falling Ball Viscometer . (2008, October 27). Retrieved March 2, 2017, from American Laboratory: http://www.americanlaboratory.com/913-TechnicalArticles/778-Measurement-of-Viscosity-in-a-VerticalFalling-Ball-Viscometer/ Secco, R., deBruyn, J., & Kostic, M. (2014). Fluid Viscosity Measurement. In Measurement, Instrumentation, and Sensors Handbook (pp. 46-1-4631). CRC Press.
ChE 135 – CLM – Determining Viscosity of Sugar Solutions
Appendix: Sample calculations Add other appendices as needed
