Comfortable with Uncomfortable

Today in fluid mechanics class we had a guest speaker, Dr. Placek's daughter, a Georgia-Pacific production manager. She was a graduate of the Auburn University chemical engineering program. This was an especially interesting lecture because I am also an employee of Georgia-Pacific. Also, she helped motivate the students to continue to work hard on understanding processes. As an engineer on the job site, it is important to be able to be comfortable with uncomfortable situations.

Automotive Chemical Engineering Problem

I have a 93' camaro Z28. Initially, I have 2 U.S. gallons of extremely high octane fuel (essentially pure octane) in the fuel tank. I burn 0.75 U.S. gallons of the fuel in the 275 hp motor. High octane fuel has an average specific gravity equal to 0.740. According to the U.S. EPA high octane fuel has an energy content equal to 35MJ/L. If the car produces 11,000 ft·lb_f of torque, what is the cars efficiency of turning the energy of combustion into useable torque measured at the wheel? Assume the combustion reaction proceeds to completion because almost all of the undesired products will be converted to desired products by the catalytic converter. It is a reasonable approximation to average the enthalpys of the 300 °F gases exiting the dual 3 in. diameter exhaust pipes.

a.) What is the initial and final internal energies of the octane in the fuel tank?
b.) Write the balanced chemical equation for the motor
c.) What is the mass of the combined exhaust gases?
d.) How much energy leaves the system in the form of heat? 
e.) What is the thermal efficiency of the motor?

Bunsen Burner

Example of an ignited Bunsen burner.

Today, in my microbiology lab we used Bunsen burners to heat sterilize needles which allowed us to transfer bacteria from culture to culture. I became mindful of the velocity profile that was being displayed by the flame of the Bunsen burner. The burner is attached to a natural gas (primarily methane) line in the laboratory. When the methane is lit it displays the three dimensional, conic velocity profile of the methane flow that is coming out of the natural gas line. The highest velocity corresponds to the part of the flame that has the tallest height which is found in the center.

Twist In Time

Today, at the end of my thermodynamics class, we took a video quiz on the below video. We are beginning our study on the concept of entropy and the reversibility and irreversibility of thermodynamic processes. There were two questions on the quiz: 1.) is this process reversible? 2.) explain, using terminology from your fluid mechanics course, the behavior of the fluid and why that supports your answer to question 1. This process is irreversible. There are several factors that combine to make this process irreversible. First, the shear force is introducing friction to the fluid. There is also a factor of irreversibility introduced when the fluid begins mixing. This experiment is designed to minimize the factors that cause irreversibility and appear to be reversible. The laminar flow reduces the mixing factor (turbulent flow would mix the fluids more vigorously). One piece of evidence that proves the experiment to be irreversible is the slight change in geometry of the colored drops of fluid when the container was returned to its initial state.

Water Faucet Valves

Today, as I was turning on the water in the sink I became mindful of the mechanics behind the water flowing from the faucet. There are multiple types of valves that are utilized in the plumbing of a water faucet. Examples include, butterfly valves, ball valves, wedge gate valves and check valves. To be able to competently work in industry, it is critical for a chemical engineer to have an understanding of the mechanics of a valve. When you turn the handle on the faucet you are operating a valve that is used as a throttling device which allows you to control the flow coming out of the faucet.

Example of wedge-gate valve.

Example of a ball valve.