Effervescent Energy Drink for Underseat Bicycle Hydration System

1. Effervescent Energy Drink for Underseat Bicycle Hydration System School of Chemical, Biological, and Environmental Engineering Bryant Mandrawa (mandrawb@onid.orst.edu) Sponsor: Frank Bretl - VelEau, Corvallis, OR Issue Cyclists have demanding hydration requirements. The challenge of hydration is currently solved by cage mounted water bottles and hydration backpacks. But bottles can be hard to use, sometimes larger volumes are needed for longer rides, and many cyclists do not like to wear a pack. VelEau has developed a new system that solve these issues. Effervescing sport drink tablets are becoming a popular hydration additive, and VelEau wants to understand how these products will affect their hydration system performance. How it works? The cap of the bottle is designed with a valve that allows the air to go in but not out to prevent negative pressure inside the bottle. The cap is also designed to prevent water and air leakage. Putting the effervescent tablet inside the bottle will cause chemical reaction which creates pressure build-up inside the bottle which will generate a driving force to push the water out once the bite valve is opened. Method A mathematical model is to be developed and verified so the behavior of effervescent tablets, including the pressure build-up inside the bottle and output flow rate of water could be determined. Objective Performance of the VelEau hydration system is being studied with different types of effervescent tablets. Chemical Reaction: 3 NaHCO3(aq) + H3C6H5O7 (aq) → 3 H2O(l)+ CO2 (g)+ 3 Na3C6H5O7 (aq) Area-dependent Kinetics: Generation of CO2: Figure 3. Volumetric flow rate vs. volume prediction for NuuN effervescent tablet with 19 °C of water. Time-dependent Pressure Prediction: Figure 2. Height vs. volume graph for VelEau hydration bottle. It fits the sixth order of polynomial graph quite well. Volumetric Flow Rate Prediction: Figure 1. Pressure vs. time graph for NuuN effervescent tablet using 2 different volumes (1.0 L and 0.50 L) at 19 °C. The results were similar to the model of pressure build-up for both cases. Variable Description k = rate of disappearance of tablet [m4/s] γ= production rate of CO2 per unit area [mol/m2-s] A0 = initial surface area of tablet [m2] t = time [s] nCO2= number of moles of CO2 [mol] Hw= height of water inside the bottle [m] Constants H = Henry’s constant for CO2 [m3-Pa/mol] R = Ideal gas constant [J/mol-K] Acknowledgements Frank Bretl for sponsorship frank@veleau.com Dr. Philip Harding for guidance philip.harding@oregonstate.edu Andy Brickman for hardware support Sue Butlers, women’s pro winner of the Mud Slinger race on May 2nd, 2010 in Oregon who relies on a VelEau system for race-day hydration. (http://photos.oregonvelo.com)