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 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.
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.
The last few decades have brought with them a dramatic increase in the development and use of turbochargers in automobiles, trains, boats, ships, and aircrafts. There are several reasons for this growth, including rising demand for fuel efficiency, stricter regulations on emissions, and advancements in turbomachinery design. Turbochargers are appearing more and more and are replacing superchargers.
Turbochargers are not the only turbomachinery technology growing in popularity in the marine, automobile, and railroad industries. Organic Rankine Cycles are being applied to take advantage of the exhaust gas energy and boost engine power output. ORCs, a system for Waste Heat Recovery, improve the overall efficiency of the vehicle, train, or boat, and reduce specific emissions.
As the size of the engines we consider increases, there is more heat available to recuperate, and more potential WHR systems to use. For instance, we can consider different combinations of these systems with both non-turbocharged and turbocharged engines. We are able to design and compare engine boost system combinations, with and without a turbocharger, with and without a blowdown turbine, and with and without a WHR system, at the cycle and turbine design levels.
In our upcoming webinar, we will do just that. We will design different combinations for larger ICEs and compare the results. This webinar will also cover introductions to these systems and application examples for supplementary power production systems in the automotive and marine industries.
We hope you can attend! Register by following the link below.
It is very interesting to take a look at how gas turbine technology has made its way into aircraft propulsion and improved over time. When the idea of a turbojet was introduced by Frank Whittle and others in the 1920s, no one could have guessed that it would change the future of air propulsion. The Committee on Gas Turbines from the National Academy of Sciences reported (1940): “In its present state … the gas turbine engine could hardly be considered a feasible application to airplanes mainly because of the difficulty in complying with stringent weight requirements imposed by aeronautics” . This puts into perspective the immense advancement that gas turbine development has made to be an integrated part of aircraft propulsion today.
A quick look at the engine characteristics reveals the great advancement in design and manufacturing of jet engines from the early turbojets to the most advanced turbofans today. For instance, General Electric’s J31, with an overall pressure ratio of 3.8:1 and maximum thrust of 1,650 lbf, was one of the first manufactured jet engines in the United States . Nowadays, Rolls-Royce Trent 1000 has achieved a maximum thrust of 78,000 lbf with an overall pressure ratio of more than 50:1 . Without a doubt, gas turbine technology has made a huge impact on aircraft propulsion and there will be more to come in future.
Whether it’s to drive you to work, power up your electronic devices, fly you to your holiday destination (extraterrestrial or not), or even set up the perfect lighting for this Valentine’s Day, your daily life requires power production. Although renewable energies are gaining popularity, many people remain unprepared to make the complete switch to these innovative power sources (except Iceland). Making the things we have more “energy efficient” or “green” has become an attractive marketing tool for many of businesses.
It’s Throwback Thursday which means we have another one of our favorite past webinars! This week’s is called Developing Reliable, High Performance, Advanced 3D Blades. It was the first of three in a special Steam Turbine Series
This week’s TBT webinar, Design of Impulse and Reaction Turbines Webinar #2: Applications for Supercritical CO2 Cycle, discusses important considerations for using high-density working fluids with small turbine sizes. Structural constraints and performance are considered and the full design process is demonstrated.
This webinar covers:
Supercritical CO2 cycle overview
Estimation of impulse and reaction turbine application rationality in modern supercritical CO2 cycles taking into consideration structural requirements and performance goals
Comparison of CO2 and steam turbines (impulse and reaction) for the same boundary conditions
Detailed flow path design with AxSTREAM
Who should watch:
Mechanical and aerospace engineers working on conceptual turbine design
Operation/Overhaul/Engineering managers seeking to increase energy efficiency
Everyone interested in how SoftInWay Inc., and AxSTREAM can help them with creating more efficient Turbomachinery
You can find the recording here, in our video center. Not registered for our center? Not a problem, just register and you’ll be emailed access info for all of our free learning materials.
Turbochargers, nowadays, are becoming increasingly common in the internal combustion engines of automobiles in order to improve fuel economy and meet government emission regulations. A turbocharger must provide a designed increase in pressure under load condition (design point) while generating enough power at the low end (loss mass flow region). Internal combustion engine working characteristics, however, prevent a centrifugal compressor from generating enough boost at the low end when radial turbine rotational speed is low. Continue reading “Free Webinar: Maximizing Turbocharger Boost with Advanced Design Features”→
Mini and Micro gas turbines are becoming increasingly relevant among today’s research of power production technologies. These turbines are smaller, lighter, less-polluting, and less expensive than traditional power generation units. Gas turbines have high-grade waste heat, low maintenance costs, and low vibration levels. The micro versions of these turbines play a key role in micro combined heat and power (CHP) and micro power generation. Continue reading “Mini and Micro Gas Turbines”→