SpinOffs

   

In Thermodynamics: “What Goes Around-Comes Around” is a Good Thing

by Francis A. Di Bella, P.E. on Jun 28, 2019 10:07:50 AM

When discussing the efficiency of transforming one form of energy to another, circularity is the way to go. Anyone who has spent even a little time studying engineering thermodynamics knows that the continuous transformation of energy from a heat energy source to produce mechanical or electrical power must contend with components that operate in a cycle. The key word here being “continuous”. The combustion of any carbon-hydrogen bond material (i.e., fossil fuels), or the liberation of heat energy from any number of materials when placed in a piston-cylinder, would not be very useful if the piston is not returned to its initial “precombustion” position. It is literally the difference between the one-time launching of an object from the cylinder or the continuous production of rotary shaft power; power that can be used to propel a vehicle forward or turn an electric generator. It is the cyclic operation of the fluid in the thermodynamic cycle that enables heat engines and refrigeration cycles to provide continuous power, or cooling, that is needed for the safety, security, comfort and all the other “hierarchy of needs” that was so well formulated by the renowned humanist psychologist, Dr. Abraham Maslow.

The Ultimate Fluid Model: Non-Equilibrium Modeling

by Mark R. Anderson on May 24, 2019 10:42:37 AM

In this blog series, I covered a lot of thermo-fluid options in engineering analysis, from the simplest perfect gas (When Perfect is Good Enough – Perfect Gas Models) and ideal liquid, (Fluid Modeling: Liquified ) to much more complex approaches (Going Through a Phase – Modeling Phase Change with Cubics) and (Getting Real – Advanced Real Gas Models). In this blog, I’ll cover the ultimate in thermo-fluid modeling: non-equilibrium modeling. It's rare and expensive, sort of like the Schorschbrau’s Schorschbock 57, a beer that sells for $275/bottle.

Going Through a Phase – Modeling Phase Change with Cubics

by Mark R. Anderson on Apr 26, 2019 9:32:08 AM

When fluids undergo a phase change (see Phase Change - Make Mine a Double), it typically has a very significant effect of the flow behavior and energy level of the system.  Some examples of this are: cavitation in a pump, condensing near the exit of a steam turbine, even the everyday phenomenon of the weather is basically a never-ending phase change process of water, and its interaction with air. 

What do Undergraduates, a Chimney, Renewable Energy and an Open Pit Mine Have in Common?

by Francis A. Di Bella, P.E. on Apr 19, 2019 10:14:00 AM

It sounds like an opening to a joke, but I wanted to share some creative thinking sparked during a field trip to a local gas turbine cogeneration plant with some undergraduate students I teach. The students were learning about basic thermodynamics, and visiting a power plant was a good way to give them perspective of what a kW is, and how much hardware and floor space is needed to generate 21,000 of them. I scheduled the trip for when the Gas Turbine system was “down for routine maintenance”, so the students could really crawl in and around the “beast” and be able to hear the explanations of the tour guide. 

Topics: thermodynamics

What's Better than Perfect? Semi-Perfect Gas Models

by Mark R. Anderson on Mar 8, 2019 10:30:00 AM

In a previous blog, Fluid Phenomena Primer: Energy Versus Temperature, Specific HeatI explained the behavior for gas phase fluids and how the temperature is affected at high energy levels.  In another blog, When Perfect is Good Enough - Perfect Gas Models, we looked at the simple perfect gas model.  In this blog, we’ll explore the next step up in the hierarchy of gas thermodynamic modeling: semi-perfect gas.

Phase Change - Make Mine a Double!

by Mark R. Anderson on Feb 22, 2019 10:40:06 AM

As I’ve always said, there’s as much thermodynamics in a glass of beer, as there is in a power plant. Don't believe me? Read on. Phase change is common phenomena that we see all the time.  We’re most familiar with H2O, of course, in its various forms: ice, water, and steam. This is partly because it’s a very common substance (on Earth anyway) but also because it’s one of the rare fluid types that readily changes phase at temperatures and pressures humans can typically dwell in. 

 

Back to Beer...

When Perfect is Good Enough - Perfect Gas Models

by Mark R. Anderson on Feb 15, 2019 10:22:00 AM

What is a perfect gas?

A perfect gas is one that has a linear variation in energy with respect to temperature and a linear variation in pressure with respect to temperature at constant volume. The perfect gas model is the simplest of all models for gas phase fluids. For a perfect gas, we need only two unique properties of the substance to determine the relationships between pressure, density, energy, and temperature. 

 

Fluid Phenomena Primer: Energy Versus Temperature, Specific Heat

by Mark R. Anderson on Feb 8, 2019 10:10:29 AM

As one might expect, the temperature of a substance typically increases as energy is added to it. This is the case with most substances in all phases. The exception is when a substance crosses to a different phase, which usually involves no temperature change. The energy difference between these phases is called the “energy of formation”.  

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