Junior Lab Abstracts

Fuel Cell Abstract The design of a 10kW fuel stack, operating at 120 V with efficiency over 40%, proves a useful exercise in convincing engineers of the future utility and productivity of this green energy source. In this experiment, real data from an existing, smaller fuel cell were collected to determine a non-theoretical characteristic curve for this design. Data found included the correlations between fuel flow, temperature, efficiency, and power. Increasing temperature resulted in an increased power by utilizing the experimentally calculated relationship dV/dt = 0.0317 ¹ 0.008 V/ °C. Hydrogen flow, a main cost factor of the design, was determined by finding the direct correlation between flow rates and current. The design, then, took into account the cost of materials, membrane size, temperature, and humidity to develop a realistic fuel stack that operates at 120 V and provides 10 kW of power. By maximizing power and efficiency, extrapolated from experimental data, a design was found which operates at 57.4% efficiency, almost 4 times the efficiency of a typical Carnot engine operating at the same temperatures [1].

This design, with its high efficiency and ability to operate at the standard voltage of most machinery, proves the utility and progress of this green technology.

Fluid Flow Abstract Experimentation on a lab scale pipeline system will determine the most important aspects for a renovation design for the Trans-Alaska Pipeline System. A set of laboratory experiments which examined the effects of fluid flow rate, length, fittings, and drag reducing agent on pressure drop were performed to begin this analysis. From these experiments, the laminar flow regime followed a linear relationship, whereas the turbulent regime yielded a relationship between pressure drop and volumetric flow rate to the power of 1.8. These fits were close, yielding a coefficient of determination of 0.9965 and 0.9996, respectively. The "hydraulically smooth" assumption used in the Blausius equation was verified. A calculation of the experimental roughness factor produced a value of 2.8 E-7, indicating negligible roughness. The efficiency of drag reducing agent at 20 ppm showed an exponential decrease with increased flow rate; the reduction of pressure drop varied between 70 and 60 percent. Further analysis demonstrated that diameter and flow rate are the most sensitive of these parameters. Increasing the diameter by 10% resulted in a 33% increase in pressure drop. The same increase in flow rate produced a 22% increase in pressure drop. New experiments were also designed to test the effect of changing temperature on flow and pressure, the effects of insulation, and the importance of viscosity.

These experiments demonstrate the importance of optimizing diameter and volumetric flow rate, and the design of experiments testing temperature, viscosity, and insulation will assist further optimization of the TAPS renovation.

Vapor Liquid Equilibrium Abstract The design of a flash system to purify a mixture of 3.8 wt% methanol, 5.7 wt % ethyl acetate and 90.5 wt% acetone to 97 wt % acetone is a simple task for a well-trained engineer. By gathering data to calculate the infinite dilution activity coefficients of the constituent binaries, the constants for an appropriate model can be calculated. The best model for this system is van Laar, which showed agreement with only 0.25% deviation between literature and experimental data.

The ethyl-acetate in acetone mixture was the focus of the experiment in which the infinite dilution activity coefficients for this binary were 1.562 and 1.106 for and respectively.

This information was used to model three isobaric flash systems and one isothermal system. All four achieved the process result of 97 wt% purity. The most effective in terms of cost and retrievability were the two tank isobaric and isothermal flash systems. Both processes retrieved between 1250-1350 L of acetone and cost less than $60 per L acetone produced. The final design chosen was the isothermal flash system, which runs at room temperature and just under 0.3 bar to produce 1320 L of acetone of 97.0 wt% purity.