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.

Fluid Modeling: Liquified

by Mark R. Anderson on May 10, 2019 10:30:23 AM

Continuing on the topic from my previous blog, Getting Real – Advanced Real Gas Models, the counterpart to the perfect gas model for liquids is the “ideal liquid” model.  The ideal liquid model is very simple and is defined as:

 

            Density = constant

            Specific heat = constant

            Sonic velocity = constant

            Viscosity = constant…. or a simple temperature function

 

Getting Real – Advanced Real Gas Models

by Mark R. Anderson on May 3, 2019 10:28:59 AM

The Refprop program

The calculations in the National Institute of Standards and Technology (NIST) Refprop program are generally considered the most accurate thermo-fluid models available.  The routines are widely used in many applications. 

 

The models

Several different models are embedded in the Refprop formulation. The most important are the  Benedict-Webb-Rubin equations of state for the pressure-temperature-density relationship. 

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. 

Simple Stall - Video Blog - Part 2

by Mark R. Anderson on Apr 12, 2019 9:33:58 AM

Our CTO, Mark Anderson, takes a fundamental look at simple stall and its impact on turbochargers stability and range. This is the second video in this 2-part series. Be sure to watch Part 1 first!

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. 

Simple Stall - Video Blog - Part 1

by Mark R. Anderson on Apr 5, 2019 10:03:00 AM

Our CTO, Mark Anderson, takes a fundamental look at simple stall and its impact on turbochargers stability and range. This is the first video in this 2-part series. 

Water & Turbomachinery - Two Great Things, That Go Great Together

by Andrew Provo on Mar 22, 2019 10:17:34 AM

I work with water a lot here at Concepts NREC. Water is frequently the fluid that flows through various types of rotating equipment we design to either release or store energy. Mankind’s fascination with manipulating the movement of water goes way back; read Mark Anderson’s blog on  Early Water Handling to see just how far back it goes. Today, more advanced turbomachinery is used for both hydroelectric and hydrokinetic applications. 

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.

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