SpinOffs

   

To The Question of sCO2 Compressor Upstream Conditions Selection

by Oleg Zubalev, CAE Software Design Engineer on Sep 10, 2021 10:00:00 AM

The compressor is generally one of the most sensitive components of an sCO2 cycle. This makes it a challenge to design a robust compressor while keeping the thermodynamic cycle close to optimal.

Super Critical CO2 Compressor Design

by Mark R. Anderson, CTO of Concepts NREC on Aug 14, 2020 11:00:00 AM

Super critical carbon dioxide power (sCO2) cycles are attracting a lot of interest these days all over the world. Many initiatives using various levels of private and public funding are in progress in several countries right now. Preliminary testing on small scale units have shown that such systems are technically viable. The next round of larger scale testing under way now will determine if the concepts are financially viable as well.

Entropy Happens… Deal with It!

by Francis A. Di Bella, P.E. on Jul 19, 2019 9:09:00 AM

If there’s one thing good about sitting in snarled traffic in Boston, it’s that you get to see some very original bumper stickers. The most recent bumper sticker I saw was probably the strangest one, no doubt created by some engineering professor who doesn’t see that the glass is half full, but that it has a safety factor of 2! Nevertheless, the bumper sticker stated the obvious when one thinks about it: ENTROPY HAPPENS! And then, to emphasize the point, the artist has the letters slowly “evaporating,” demonstrating graphically that entropy proceeds from order to chaos.

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.

Abstracts From Papers Presented at Turbo Expo 2019

by Barbara Shea on Jun 21, 2019 9:22:14 AM

Wow, Concepts NREC had a lot going on at this year's ASME Turbo Expo 2019 in Phoenix, AZ! We held our North American CAE User Group Meeting, spoke to over 200 people at our booth, chaired several sessions and presented two papers. In case you were not able to go, here are the abstracts from the two papers:

Turbomachinery equipment is generally segmented based on whether it extracts energy (e.g., turbines) or adds energy (e.g., pumps and compressors). The addition of energy is usually used to compress or move a fluid. When the fluid is a gas, the turbomachinery equipment is typically referred to as a fan, blower or compressor. This blog will explore the differences between these three devices and where they are used.  

Performance Corrections for Compressor Maps

by Mark R. Anderson on Apr 9, 2019 9:56:09 AM

Turbomachinery performance is almost always analyzed and tested with a fixed inflow condition. In other words, the assumption is that the inflow fluid temperature and pressure is defined and unchanging over the map of machine performance. Since varying conditions often exist in practice, the performance maps are sometimes normalized, as shown in the figure below. The pressure ratio of a compressor is plotted versus a corrected mass flow range and rotational speed. 

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.

Temperature envelopes in the turbomachinery industry are constantly increasing as the state of the art evolves in pursuit of better performance. This means engineers need to design compressors with higher and higher exit temperatures, and turbines and nozzles with continuously increasing inlet temperatures. This rise in temperature greatly impacts the selection criteria for materials used. 

Specific Speed Demystified

by Mark R. Anderson on Jan 11, 2019 9:40:00 AM

In my blog Flow Coefficient and Work Coefficient, I outlined the basic concept behind the flow and work coefficient. These nondimensional parameters are widely used to characterize axial and radial turbomachinery. Another widely used parameter for radial design is “specific speed”. For something with such a finite name, specific speed is perhaps the most mysterious and non-intuitive parameter in all of turbomachinery. In this blog, I'll lay the ground work for understanding specific speed.

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