Roman W. Morse and Kenneth A. Walz

Introduction Our goal was to design a method for measuring biodiesel viscosity that could be integrated into the laboratory curriculum for an intermediate level chemistry class. Many chemistry courses perform biodiesel synthesis experiments, but lack methods for measuring the properties of their fuel. Current methods for measuring viscosity are often too expensive to be used in a classroom.

Results

Experimental Methods

Discussion & Conclusions

Rationale

Next Steps - Plans for Future Work

Acknowledgements

Shell cup viscosity exponentially decays as temperature rises.

The biodiesel fuel used in this experiment was synthesized by students in the Madison College General Chemistry 2 course. This fuel was previously determined to meet all of the specifications for sale and use as B100 biodiesel blend stock (ASTM D6751). Both a heated sample of biodiesel (70℃) and a cooled sample (5-10 ℃) were used to run trials until the samples reached room temperature. A 4 ft. long polycarbonate tube was used for the cylinder and a small red mixing bead for the sphere. Two marks were made on the cylinder 1 meter apart from one another, leaving a reservoir at the bottom of the cylinder. The plastic cylinder was with one of the samples and began dropping the spheres through the fluid, recording both temperature and time for each trial.

This project was made possible by the Madison College Honors Program, under the leadership of Honors Program Director Julia Haseleu. Partial financial support for this project was provided by the Consortium for Education in Renewable Energy Technology and the National Science Foundation Advanced Technological Education Program (NSF ATE Grant Award # 1205015)

y  =  0.403x  +  4.780  R²  =  0.968  

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Fall  Time  (sec)  

Viscosity  (cP)  

Sphere  Fall  Time  vs  Shell  Cup  Viscosity  

y  =  14.083e-­‐0.027x  R²  =  0.99218  

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Viscosity

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Shell  Cup  Viscosity  vs  Temperature  

Viscosity can be measured two ways: recording the time it takes for the fluid to flow through an object, or recording the time it takes for an object to pass through the fluid. The first method is most often performed using a viscosity shell cup. The disadvantage of using the shell cup is the cost, around $250 each. The second method was employed in this experiment and a small sphere was passed through a biodiesel sample. Drag force is typically caused by air resistance but in the case of the sphere, the drag will be due to the viscosity of the fluid. This method could me less expensive and could be used by schools with limited budgets.

Viscosity is greatly dependent on the temperature of the fluid. Newton, Arrhenius and other notable scientists have attempted to model this phenomena through mathematics. The temperature-viscosity relationship has a direct impact on alternative fuels such as biodiesel because the fuel has to be used in a variety of climates. Which means the fuel must maintain integrity in the equatorial regions where the temperatures are around 30 ℃, and in regions closer to the poles where temperatures in the winter drop well below 0 ℃.

GOAL: To develop a low cost lab experiment for undergraduate chemistry students to explore the relationship between temperature and viscosity of biodiesel fuel.

The data from the experiment and a written laboratory procedure will be submitted for publishing by the end of the 2015. The write-up will also include an instructor supplement with information on the materials used, and how to calibrate their experiment should they use different materials.

y  =  9.4936e-­‐0.008x  R²  =  0.95846  

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Fall  Time  (sec)  

Temperature  (℃)  

Sphere  Fall  Time  vs  Temperature  

We were successful in relating the sphere fall time to viscosity. The relationship is linear with a proportionality constant. The equation takes the form:

Sphere fall time also exponentially decays as temperature rises.

y = mx + b x = shell cup viscosity (cP) y = sphere fall time (sec)

A Low Cost Procedure to Explore the Relationship Between Biodiesel Viscosity and Temperature

92% of the data falls within two standard deviation and 100% of the data falls within three standard deviations. Over 400 trials were performed. The data for the experiment resembles a normal distribution. This data illustrates the reliability of the falling sphere viscosity method for schools that seek to perform these experiments using low cost lab materials.