Design Considerations for Turbo Expander Supersonic Turbines with Liquid to Gas-Liquid Flow Transition

by Oleg Dubitsky, Corporate Fellow, Director of Corporate Technology on Sep 25, 2020 11:00:00 AM

A small turbine (for ORC, air liquification processes) , operating with low volumetric flows at inlet and significant pressure ratio in a single stage configuration (to reduce costs) is often associated with flow of media with transition from liquid to gas-liquid state, with operating levels of Mach numbers above 1.8 at nozzle exit, that assumes convergent-divergent nozzle geometry, and may require partial admission.

Using an Economizer in Centrifugal Compressor Chiller Cycles

by Daniel V. Hinch, Corporate VP Sales and Marketing, Concepts NREC on Sep 18, 2020 11:00:00 AM

In the chiller industry, the evolution of centrifugal compressor chiller cycles has led to an interesting and powerful cycle and related compressor configuration which involves reinjection of refrigerant between stages. Such systems are thermodynamically identified broadly as cascade cycle options and have the common objective of improving the Coefficient of Performance (COP) of the standard refrigeration cycle.

Optimization using Dakota in Concepts NREC’s TurboOPT II

by Rachel Moore, Senior Software Engineer on Sep 11, 2020 11:00:00 AM

Automated optimization is becoming more and more common place in the turbomachinery industry today.  What was once exclusively the domain of academics and high-end researchers, has become much more widespread today.  The rise of optimization is directly related to ever increasing computer power available and the advent of new software tools to set it up.  Virtually every category of turbomachinery has adopted it, at least to some degree.  One can find many examples of advanced optimization in the open literature but more practical applications can add value to your product line in a very reasonable time and effort.  

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.

Turbomachinery Design for Medical Devices Including Compressors, Fans, Blowers, and Pumps

by Daniel V. Hinch, Corporate VP Sales and Marketing, Concepts NREC on Aug 7, 2020 11:00:00 AM

Turbomachinery is used in a very wide variety of industries and applications.   While applications like aerospace ‘jet engines’ or powerplant steam turbines are the applications that come to mind for a lot of people, turbomachinery is integrated with or buried in a huge range of other equipment, and often transparent to the user.   I give a talk to local middle school sciences classes on what turbomachinery is, and give a quiz at the end of the talk where I ask them to list every piece of turbomachinery in their home. The students have surprised me with their understanding and reasoning ability, and I now have a list of 20 to 30 examples of turbomachinery running in their homes.

Flow Analysis of Multi-Staged Axial and Radial Turbomachinery

by Mark R. Anderson, CTO of Concepts NREC on Feb 6, 2020 12:58:56 PM

When designing a turbomachine, the best analytical approach is not necessarily the most accurate method possible, but the one that will generate the best candidate design in the time and budget available.  It makes little sense to do analytical work down to a 1/10% accuracy,  while ignoring candidate designs that might yield improvements 20 times that amount if they were considered in the first place.  Mastering the art of modern engineering requires an intuitive sense for the cost and accuracy of a given analytical method, and knowing when to move between them. 

This blog article is a follow up for the earlier blog “Coupled Optimization of Preliminary Design Geometry of Low Flow  Steam Turbine with Curtis Stage Layout and Rankine Cycle Parameters”, which considers more complicated case  of coupled optimization of regenerative Rankine cycle and 2 stage turbine geometry with change from partial to full admission flow.

Designing turbines for low flow Rankine Cycle for steam is challenging due to their small size, manufacturing restrictions, clearances and cost constraints. Such turbines operate at significant pressure ratios that require use of partial admission and are likely to operate in choked supersonic flow mode due to reduced stage count (controlled by cost).

In many instances, the design of new turbofan engine is an iterative process of optimizing engine cycle parameters (i.e. thermodynamics) and executing  preliminary design geometry of engine components (i.e. aero design, constrained with structural, manufacturing, fitting in engine layout, size, weight  & other requirements) for the best performing  realizable  solution.  Consideration of the preliminary design of the engine in the totality of these requirements seems to be an interesting topic to address.


 Coupling cycle calculations with detailed preliminary design of turbomachinery components for getting optimized turbofan engine is the topic of this article. Detailed preliminary design means generating geometry and getting flow data and performance for each component of the multistage geometry of the engine, sufficient in the scope to move design process to 2D and 3D considerations.

Super Critical Carbon Dioxide Turbomachinery Design

by Mark R. Anderson on Nov 8, 2019 1:49:58 PM

Why supercritical CO2?


Super critical carbon dioxide (sCO2) is one of the hottest topics in the turbomachinery world right now.  From my own experience, I remember when the subject occupied a few sleepy sessions at the ASME Turbo Expo several years back.  Today, its possible to spend the entire week at the conference and never leave a well-attended session dedicated specifically to sCO2

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