We have just released the newest version of AxCYCLE, our software tool for thermodynamic cycle design and analysis. AxCYCLE 4.0 has some brand new features that will inevitably aid you in designing optimal Gas, Steam, Combined, Turbocharger, Supercritical CO2, Organic Rankine, and Waste Heat Recovery Cycles.
Take a look at the latest updates and additions:
Turbine Efficiency Calculation
In previous versions of AxCYCLE, efficiency was an input parameter that needed to be changed manually for each off-design condition. The Calculated Efficiency option will automatically recalculate the efficiency for off-design conditions.
Several new components were added to the AxCYCLE library for more sophisticated and customizable cycles.
Bearing: Used to simulate mechanical energy losses in bearings. The estimated mechanical losses are assigned as a power value and are accounted for in the total energy balance
Gearbox: Used to simulate the mechanical energy transfer between two shafts considering mechanical energy losses in the gearbox. These losses are measured using a gearbox efficiency value.
End Seal: Used to simulate seal leakage. The value of the leakage depends on the difference between the upstream and downstream pressure.
Steam Cycle Builder
AxCYCLE’s new wizard for the creation of basic steam cycles. It can be used for steam cycles with regenerative heating, optional moisture separators, and re-heaters. The Builder creates a cycle diagram with the correct fixed conditions and initial values, meaning the generated cycle is ready for calculation! It does all of the work for you!
Learn more about AxSTREAM and AxCYCLE on our website, or email us at firstname.lastname@example.org to find out exactly how we can help with your next turbomachinery project.
Gas turbines are continuing their trend in becoming more efficient with each generation. However, the rate at which their efficiency increases is not significant enough to match more and more constraining environmental goals and regulations. New technologies like combined cycles therefore need to be used to increase cycle-specific power (more power produced without burning additional fuel).
The first generation of combined cycles featured a bottoming steam cycle that uses the heat from the gas turbine exhausts to boil off water in order to power a turbine and generate power. This traditional approach has been around since about 1970 and nowadays allows obtaining an additional 20% in cycle thermal efficiency (40% in simple gas turbine cycle configuration vs. 60% as a combined gas-steam cycle).
While this traditional approach is definitely effective, it does have some drawbacks; the equipment usually takes a significant amount of 3D space, there is always the risk of corrosion and substantial structural damage when working with 2-phase fluids, and so on. This, therefore, allows for different technologies to emerge, like supercritical CO2 cycles.
A supercritical fluid is a fluid that is used above its critical pressure and temperature and therefore behaves as neither a liquid nor a gas but as a different state (high density vs gas, absence of surface tensions, etc.). As a working fluid, supercritical CO2 has numerous advantages over some other fluids, including a high safety usage, non-flammability/toxicity, high density, inexpensiveness and absence of 2-phase fluid.
Moreover, steam turbines are usually difficultly scalable to small capacities which mean that they are mostly used in a bottoming cycle configuration for high power gas turbines. On the other hand supercritical CO2 (Rankine) cycles can be used for smaller machines as well as the bigger units while featuring an efficiency comparable to the one of a typical Rankine cycle and estimated lower installation, operation and maintenance costs.
The paper I presented at the ASME Power & Energy 2015 compares different configurations of SCO2 bottoming cycles for an arbitrary case for different boundary conditions before applying the selected cycle to a wide range of existing gas turbine units. This allowed determining how much additional power could be generated without needing to burn additional fuel and the results were far from insignificant! For the machines studied the potential for power increase ranges from 15% to 40% of the gas turbine unit power. Want to know how much more power you can get with your existing machines? Contact us to get a quote for a feasibility study before designing the waste heat recovery system yourself or with our help.
The sun is starting to shine and the weather is warming up. The schools are closed, the beaches are open, and everyone is itching to get to their vacation. But summer will be over before we know it! Don’t wait too long to begin planning for the final months of 2015. Take a look at our fall and winter courses that are now open for registration. Early sign-ups qualify for discounted prices! Here’s what’s available for the rest of the year:
Also don’t forget about our monthly webinars! Keep an eye out for email invitations to our live presentations and demonstrations of the industry’s latest trends and developments. You can find all of our recorded webinars in our learning portal – SoftInWay Turbomachinery University. Your free registration gives you access to all recordings!
In a few weeks, SoftInWay will be on its way to Montreal, Canada for ASME’s Turbo Expo! We are looking forward to a busy and exciting conference.
What we’re most excited for:
1. Montreal AfterWork: Professional Networking Event
This event is being held for professionals involved in Energy, Technology, Finance, and Startups to meet and network in a casual and enjoyable environment. All Turbo Expo attendees and local Montreal professionals are welcome to come by, have a drink, and chat about the latest developments in their field!
Date/Time: 6:30-9:00pm | Tuesday, June 16, 2015 Location: Santos Tapas Bar | 191 Rue St Paul W, Montreal, QC, H2Y1Z5 Canada Attire: Business Casual Registration: www.zurichafterwork.com/rsvp/
Demystifying “Pushbutton” Approaches for CFD & FEA Design, Analysis, Redesign, & Optimization of Turbomachines
Although there is not just one way to design a turbomachine there sure is one way not to do it; blindly.
A misconception that I commonly see when teaching engineers about fundamentals of turbomachines, as well as when leading design workshops, is that some engineers (mostly the younger generations) envision themselves plugging numbers, pushing buttons and getting results immediately without any real brain power behind their actions.
Nowadays, software packages are an integral part of an engineer’s toolkit, but in the same way that a mechanic would not (or should not) use a screwdriver as a hammer, each software has its own applications and ways to use it.
The history of turbochargers in Formula 1 is pretty fascinating. Turbochargers were initially introduced in 1905, applied to large diesel engines in the 1920’s and found their way into commercial automobiles in 1938. However, it took a few more decades for the turbochargers to be used in Formula 1 car racing.
When Renault decided to enter the sport in 1977, they started their engines based on the novel turbocharger concept. As one would expect, their first design suffered from constant reliability problems through all the races it competed in. As Renault focused their development entirely on the engine, the car’s aerodynamics worsened; it suffered a huge turbolag under acceleration, and when the boost finally triggered the tires were not able to handle it . “So the engine broke and made everyone one laugh”, Jean-Pierre Jabouille, the driver, admitted in an interview. At the time, everyone was looking at the turbo engines as something that no one would ever hear about again.
Our next webinar is on Thursday, April 30th! Are you an engineer involved in the Aerospace Industry and its latest development, a manager interested in improving the performance of your aircraft engines, or a student interested in the future of aerospace and the current climate of the industry? You should attend! During the webinar we will be taking a close look at the most recent trends and developments of compressors in aircraft engines with a focus on the key factors for the successful development of aircraft engines.
Key factors for successful development of aircraft engines include technological viability, performance, and re-usability. As one of the industry’s most high-technology products, aircraft engines require innovation in manufacturing and especially in design. They also face the need for continuous development in its technical capabilities in terms of achieving not only higher efficiencies and reliability but also safety and environmental legislations.
On March 18th and 19th I attended a Gas Turbine conference in Beijing, China, where I had been invited as a Chairman and speaker. It was a great learning experience, with many interesting presentations involving energy and modern turbomachinery. I wanted to summarize some topics and ideas which I found particularly interesting.
Supply: Projections for China through 2020 show increases in the Liquefied Natural Gas supply. This LNG will most likely stem from the new agreement between China and Russia. At the same time, still today within China, there is not enough pipe line capacity to efficiently transport it. These two factors make the price very high. In order for Gas Turbine technology to really become economically viable, there needs to be a decrease in the price of fuel, perhaps cheaper locally manufactured machines, and tax & other incentives. Today for most, it is simply a lot more expensive than traditional fossil fuel technology which accounts for more than 60% of all energy being generated today.
It is common knowledge that CFD analyses are more of a “see you tomorrow” affair than an “I’ll grab a coffee and I’ll be back”.
Although the fairly recent developments in electronics allow for more computing power while being more affordable, it can still take a significant amount of time to run a good CFD case.
One of the main advantages of running CFD is that there is no need to have an actual, manufactured prototype in order to run an experiment. Prototypes have been known to be mainly restricted to companies/individuals that had manufacturing capabilities and quite a lot of money on their hands. However, with recent advancements like 3D printing, this prototyping is not only possible but is also relatively fast (and getting faster everyday with new techniques being developed).
It comes to a point where it is worth evaluating, qualitatively, each method, however different they actually are.
Although CFD is an extremely common practice in modern day engineering and is immensely useful, it tends to sometimes completely replace actual prototyping and this can create some issues… Indeed, CFD is neither an exact science nor it is always “cheap” (some complex problems can easily cost several thousand dollars in computing costs) but either way it sure has its perks. These two arguments are unfortunately largely part of a general misconception of CFD that decision makers and the younger generation of engineers are often victims of. When managers are given the choice between purchasing a software that can supposedly simulate any physical problem (CFD case) and a machine that can physically build components (manufacturing case) the upfront cost strongly leads these decision makers to adopt the first option.
However, CFD does not always suffice. Results of CFD analyses are influenced by numerical and modeling errors, unknown boundary conditions or geometry and more. Refining your mesh is becoming easier and ultimately leads to reduced numerical errors while, at the same time, increasing your calculation time. Modeling errors can come from misuse or inaccuracy of certain models when trying to simulate real, complex physics like turbulence. And so on to the point that different codes and even different engineers can find some minor discrepancies in the final results of the same case.
This means that less experienced engineers tend to over-trust their results, thinking of CFD as the universal answer to every physical problem. To place (smartly) more confidence in CFD results the codes should be calibrated and corrected based on experimental results that do require prototyping at some point unless a product is wrongly put on the market without proper physical testing – which can happen, unfortunately. Comparing both an original and an optimized geometry in CFD is perfectly possible and realistic but as for any solver a baseline should be created. One cannot simply say he has improved the efficiency of a machine by 2% if the original machine was not analyzed beforehand.
Calibration of the CFD models is based on available data from experiments and this data is often very limited compared to the results that CFD can provide. While a physical test would provide values like power as well as some pressures and temperatures in most cases, CFD analyses can go way beyond this by providing parameters distributions, flow recirculation areas, representation of the boundary layer appearing on the surfaces, etc. that allow getting a good understanding of what is happening to the flow within the machine, which is something that definitely cannot be appreciated in most experimental runs. Beside the mentioned disadvantages that 3D printing has, an important one that is shared with CFD is that the time needed to build a geometry strongly depends on its size. However, CFD can deal with the repetition of an element in a row fairly accurately while the entire wheel has to be manufactured to be analyzed. This sort of restrains rapid prototyping to smaller machines, at the moment.
For these reasons and despite all these “warnings”, CFD remains and will remain an essential engineering tool that provides a good comparison of cases rather than a truly accurate representation of the reality we live in. As a conclusion, CFD still continues to evolve with the recent technological developments and should be supplemented with experimental testing instead of substituting it.