Discussion – Alien Signal or Radio Noise: Leveraging Turbomachinery

[:en]The Internet practically exploded early yesterday morning with talk of an extraterrestrial discovery after a signal was detected by a Russian telescope. The star in question, HD 164595 located a vast 95 light years away, sent out a strong radio spike that was picked up and sparked a boom of excitement. According to an article published by National Geographic, however, this signal may not be what it was first interpreted as.

Astronomers have pointed their radio telescopes towards the stars for over half a century, hoping to catch a glimmer of life beyond this planet. Short of a futuristic rocket ship, these telescopes seem to be the best bet for catching a peak of something out of this world. That is a main causStarse as to why this discovery is so tantalizing to both scientists and the rest of us earthlings. However, after further investigation, neither the Allen Telescope Array, commanded by the SETI (the Search for Extra-Terrestrial Intelligence) Institute, nor the Green Bank Telescope, used by the Breakthrough Listen project, turned up additional signals or observations.

Another issue that has risen according to this article is that the signal did not repeat and could have been caused by something else. A source on Earth, such as a faulty power supply, military transmission, or arcing electrical fence for example. Another possible explanation could be that gravity from another object in space amplified a weaker signal. That being said, it would appear that HD 164595 is similar in many ways to our sun. It is composed of the same ingredients, is approximately the same age and has at least one planet in its orbit. This would suggest that theoretically, it would be plausible for life to exist within this system.

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Turbocharger Design and Industry Usage Discussion

An opportunity to discuss turbocharger usage and design with Softinway engineer Ursula Shannon in a question and answer format:

What are some of the major current turbocharger design challenges?

When it comes to turbocharger design, there are two challenges that engineers generally face. “Turbo lag” and turbo boost power at varying engine RPMs. “Turbo lag” is the time that it takes for the engine to produce enough exhaust to start the turbocharger “working”. This can vary greatly depending on engine size, turbocharger geometry, exhaust output etc. Ideally, engineers want to reduce this “Turbo lag” by as much as possible in any given situation, as during that time, the exhaust is “wasted” in a sense. Finding the most efficient configuration with all of the parameters in mind can be a very challenging scenario from a design perspective.

The turbo boost design challenge is one of efficiency at variable exhaust outputs. A smaller charger for example will start to boost at lower engine speeds while a larger one will start to boost at engine speeds. The trade off however is that a smaller turbo will start to create what is known as back pressure at higher speeds, and this results in a loss of potential power. A larger turbocharger, will be able to create more overall boost at higher speeds, however the “Turbo Lag” is more pronounced as more engine exhaust is required. Minimizing these trade offs is another key challenge in turbocharger design.

Finally, the process of turbocharger design process itself is complex, and requires highly specialized software such as our own here in Softinway (AxSTREAM).

Turbocharger blog 3

AxSTREAM Turbocharger Design Software ( Flowpath Design and Optimization )

turbocharger blog 2

AxSTREAM Turbocharger Design Software (Compressor 1D Design and Analysis)

What are some design changes do you see coming to turbochargers in the future?

As I mentioned some of the challenges engineers face in turbocharger design, currently many technologies and methods are being developed to alleviate some of the issues faced.

Two stage turbochargers are good example of trying to offer a solution to the boost powers at varying engine outputs, using a smaller turbocharger that operates at low RPMs and a larger turbocharger that operates at higher RPMs.

Electronic energy storage setups are currently being developed and used in European race cars which uses the output side of the turbocharger as a sort of generator which stores energy in a battery from turbocharger operations and acts as a boost during a turbocharger’s lag period.

Continue reading “Turbocharger Design and Industry Usage Discussion”

The Economic Optimization of Renewable Energy

[:en]Global warming has been a very popular topic these days. With up-trend of clean technology and realization that strict climate policy should be implemented, demand of renewable energy sky-rocketed as conservative plants popularity falls. Number of coal power plants have significantly dropped since its peak era, being known as the largest pollutant contributor as it produces nitrogen oxide and carbon dioxide, the technology is valued less due to its impact on nature. Renewable energy comes from many sources: hydropower, wind power, geothermal energy, bio energy and many more. The ability to replenish and having no limit in usage and applications make renewable energy implementations seems attractive. Aside from that, they also produce low emission, sounds like a win-win solution for everyone. Theoretically, with the usage of renewable energy, human-kind should be able to meet their energy need with minimal environmental damage. With growth rate ranging from 10% to 60% annually, renewable energy are getting cheaper through the technology improvements as well as market competition. In the end, the main goal is still to generate profit, though these days taking impact on nature into the equation is just as important. Since the technology is relatively new, capital cost still considerable higher compared to some cases with more traditional (–and naturally harmful) implementations. So the question is: how to maximize the economic potential of a renewable energy power generation plant?

The Economic Optimization of Renewable Energy

Living up to the maximum potential of any power generation plant starts in the design process. Few examples for solar power plant: designers should take into consideration type and quality of panels, it’s important to see the economic-efficiency tradeoff before jumping into investment; looking into the power conversion is also one of the most important steps, one should take into consideration that it would be worthless to produce more energy than the capacity that are able to be transferred and put to use, though too low energy generation would mean less gross income.

Another example, for a geothermal power plant, many studies have shown that boundary conditions on each components play a big role in determining the plant’s capacity and efficiency. High efficiency is definitely desired to optimize the potential of a power plant and minimized the energy loss. Though, should also be compared to the economic sacrifice; regardless of how good the technology is, if it doesn’t make any economic profit, it would not make sense for one to invest in such technology. Low capital cost but high operating expenses would hurt the economic feasibility in the long run, whereas high capital cost and low operating expense could still be risky since that would mean a higher lump sum of investment upfront, which might or may not breakeven nor profitable depending on the fluctuation of energy market.

Modern technology allows investors and the engineering team to make this prediction based on models developed by the experts. SoftInWay just recently launched our economic module, check out AxCYCLE to optimize your power plant!

Reference:

[1] Optimal design of geothermal power plants 

[2] Strategies in tower solar power plant optimization[:cn]Global warming has been a very popular topic these days. With up-trend of clean technology and realization that strict climate policy should be implemented, demand of renewable energy sky-rocketed as conservative plants popularity falls. Number of coal power plants have significantly dropped since its peak era, being known as the largest pollutant contributor as it produces nitrogen oxide and carbon dioxide, the technology is valued less due to its impact on nature. Renewable energy comes from many sources: hydropower, wind power, geothermal energy, bio energy and many more. The ability to replenish and having no limit in usage and applications make renewable energy implementations seems attractive. Aside from that, they also produce low emission, sounds like a win-win solution for everyone. Theoretically, with the usage of renewable energy, human-kind should be able to meet their energy need with minimal environmental damage. With growth rate ranging from 10% to 60% annually, renewable energy are getting cheaper through the technology improvements as well as market competition. In the end, the main goal is still to generate profit, though these days taking impact on nature into the equation is just as important. Since the technology is relatively new, capital cost still considerable higher compared to some cases with more traditional (–and naturally harmful) implementations. So the question is: how to maximize the economic potential of a renewable energy power generation plant?

The Economic Optimization of Renewable Energy

Living up to the maximum potential of any power generation plant starts in the design process. Few examples for solar power plant: designers should take into consideration type and quality of panels, it’s important to see the economic-efficiency tradeoff before jumping into investment; looking into the power conversion is also one of the most important steps, one should take into consideration that it would be worthless to produce more energy than the capacity that are able to be transferred and put to use, though too low energy generation would mean less gross income.

Another example, for a geothermal power plant, many studies have shown that boundary conditions on each components play a big role in determining the plant’s capacity and efficiency. High efficiency is definitely desired to optimize the potential of a power plant and minimized the energy loss. Though, should also be compared to the economic sacrifice; regardless of how good the technology is, if it doesn’t make any economic profit, it would not make sense for one to invest in such technology. Low capital cost but high operating expenses would hurt the economic feasibility in the long run, whereas high capital cost and low operating expense could still be risky since that would mean a higher lump sum of investment upfront, which might or may not breakeven nor profitable depending on the fluctuation of energy market.

Modern technology allows investors and the engineering team to make this prediction based on models developed by the experts. SoftInWay just recently launched our economic module, check out AxCYCLE to optimize your power plant!

Reference:

[1] Optimal design of geothermal power plants 

[2] Strategies in tower solar power plant optimization[:]

Variable Speed Compressor for HVAC and Refrigeration.

Even though energy consumption for HVAC and refrigeration system is considerably smaller than most technology applications, energy savings is still desired for many reasons: cleaner technology, saving cost, fuel economy and many more. Improvements in insulation, compressor efficiency and optimization of the cycle can be implemented to achieve better performance. Installation of variable speed drives is one way to optimize the potential of HVAC system.

Refrigeration

Although has been implemented to various HVAC components, variable-speed drive is considerably still one of the “newer” advancements in the compressor industry. These devices are able to precisely control the motor speed and trim/balance systems. Variable speed control compressor gives end-users the comfort of matching the speed to what is needed at the time; giving precise temperature control with less cycling and longer run times. With longer run times, the technology also helps to remove moisture and relative humidity during the summer; or on the other hand during the winter by increasing the speed of compressor, system are able to deliver hotter air.

Compared to fixed compressor, where there are only two options for end-users to set: maximum capacity or completely off; variable speed drives gives the end-user an ability to adjust power output to compressor. The technology also comes with the benefit of less energy wasted from off and on cycle, precise load matching and low amp gradual compressor motor startup; therefore, improving the efficiency on certain conditions.

Compressor

Coupling variable speed drives to centrifugal compressor alter the behavior of the component. Although, not always requiring smaller energy (i.e at or near full load) compared to fixed speed compressor, installation of VSD could really benefit the users in terms of power consumption (i.e at part lift), to optimize even further implementation of both compressor types would benefit both conditions.

Want to learn more? Design your most efficient compressor using AxSTREAM

Reference:

Variable Speed Air Compressor

Reduction In Power Consumption Of Household Refrigerators By Using Variable Speed Compressors

The Impact of Variable-Speed Drives on HVAC Components

Heat pump and refrigeration cycle

 

Re-inventing the wheel (or perhaps our education system)?

I hope everyone is having a great week. I wanted to write about our education system, as it relates to Turbomachinery, and perhaps some challenges that educators / students face, and some ideas for how things can be improved.

As computation technologies have evolved over the last 30-40 years, it seems that a large number of education institutions are still behind.

Part of my job at SoftInWay, is to make sure that local  & global Universities involved in Turbomachinery have the most advanced software tools, so that the students graduating from undergraduate, as well as Masters and PhD level programs, have some kind of relevant skills to develop / optimize Turbomachinery, as well as know how to use relevant software tools.

From talking to Academia from different countries, it seems that professors (perhaps due to bureaucracy of their positions) are often faced with several challenges / decisions:

1. No budget for software tools thus forced to use free tools

2. Desire to create their own software, to eventually spin off and start a company

3. Lack of deep technical program, thus only picking macro topics as they relate to turbomachinery as general thermodynamics, etc. (which is important also).

What’s the problem with all of these approaches: When students graduate, and want to go into the field of Turbomachinery, a large portion of these students think that “Turbomachinery Design” can be done with CFD.

Looking at the last 5-10 years of CFD as it relates to Turbomachinery, people have been in several “camps”, with the most known names (such as products from Ansys, or CD Adapco (now owned by Siemens), Numeca, and some free open source CFD codes.  Additionally, there has been a plethora of free or academic codes written by 100s of wide-eyed graduates students in hoping of making the next big software company.

Why does this cripple the education system, industry and the general concept of innovation? First of all, in all of these packages, you are going on the assumption that you already have a geometry of the turbomachinery and generally know what the machine looks like. Granted, some advertise that by “partnering” with other vendors they can do 1D or inverse design, when looking at these options closely, they are still very weak.   At the same time, there are lessor known CFD packages (from example our Turbomachinery specific CFD module AxCFD that we offer) that while hasn’t been aggressively marketed, comes at 30% of the cost, and has not only faster computation speed, but is fully integrated in a complete turbomachinery design platform. While this is a great option for students, very few know about it, and we are always stuck with a thought “people need to understand the complete process of design, not just CFD, so let’s focus on teaching that, and sharing that message”.

In addition to working with Universities, another part of my job at SoftInWay is hiring, so what have i learned from looking at 1000s of resumes from masters and PhD students?

If you start to dig deeply, about what candidates have learned about turbomachinery design, how well do they understand, for example, compressor aerodynamics, or gas turbine cooling, quite often the answers come up short. This creates a steep learning curve, not just for our company, but also for major manufacturers and service providers.

We believe, that instead of the next generation of students, trying to re-invent the wheel, and spend their 2,3,4,5,6 years of education  on equations and writing code, for a problem that has been solved, they should use a holistic approach, to advance, Power Generation, Transportation, Propulsion and Advance the clean energy space.

We have created a range of free resources for students in an online university format (learn.softinway.com) and encourage everyone to dig deeply, and together we can create a greener world, for the future generations.

Additionally, our turbomachinery development platform AxSTREAM (r), is the only platform in the world which is wholly integrated and developed in-house, including thermodynamic cycle design, 1D,2D,3D turbomachinery design, analysis and optimization, rotor dynamics and bearing design, stress analysis, advanced optimization and visualization, etc.

** Feel free to fact check this by looking at your current software simulation tools, and see how many modules or features or “tools” are borrowed from other companies.  How can one ever learn and understand how things work and talk to each other, if knowledge is not developed, but rather borrowed.

If  you are a student, or a professor at a college or university, and are interested in improving your turbomachinery program, and giving your students the extra skills (fundamentals and software), to really develop innovations, please write me a message !

Message Me

Upcoming Webinar: Power Plant Cost Estimation

[:en]

Cost Estimation and Economic Analysis for Power Plants

Thursday, January 21st | 10:00 – 11:00 AM EST

The Kendall Cogeneration Station in Cambridge, MA

Registration is open for our first webinar of 2016.

The processes of power plant design, enlargement, and redesign must consider certain factors, such as technological scheme, basic cycle parameters, equipment configuration, and fuel type. These factors have long reached beyond the scope of the technical and physical, and must consider economic criteria. Economic indicators are fundamental when selecting a specific solution. Therefore, even at the initial stages of a project, engineering problems should be considered in parallel with the assessment of economic efficiency. In addition, a power plant is a very complex entity, and introductory capital costs cannot be the only economic criteria considered. The economic indexes over the entire lifecycle of the plant must be accounted for.

The modern world has seen extensive investment in the field of cost estimation. The approximate estimation of cost and economic efficiency of a power plant, however, is a complicated and time-consuming process. It demands a high level of knowledge and information.

In order to simplify this process, and make it available for the engineering community, SoftInWay, a leading turbomachinery solutions provider, developed the new AxCYCLE Module for Economic Analysis. This webinar will demonstrate the module and discuss its extensive capabilities and applications.

We look forward to a great webinar and your challenging questions. Please register ahead of time and if you have any specific questions, let us know during the registration so that we can try to incorporate the answers into our presentation.

[su_button url=”http://www2.softinway.com/powerplanteconomics” target=”blank” background=”#ef322d” color=”#f6f1f1″ center=”yes” radius=”round” icon=”icon: arrow-right” title=”Register”]Register[/su_button]

 [:cn]

Cost Estimation and Economic Analysis for Power Plants

Thursday, January 21st | 10:00 – 11:00 AM EST

The Kendall Cogeneration Station in Cambridge, MA

Registration is open for our first webinar of 2016.

The processes of power plant design, enlargement, and redesign must consider certain factors, such as technological scheme, basic cycle parameters, equipment configuration, and fuel type. These factors have long reached beyond the scope of the technical and physical, and must consider economic criteria. Economic indicators are fundamental when selecting a specific solution. Therefore, even at the initial stages of a project, engineering problems should be considered in parallel with the assessment of economic efficiency. In addition, a power plant is a very complex entity, and introductory capital costs cannot be the only economic criteria considered. The economic indexes over the entire lifecycle of the plant must be accounted for.

The modern world has seen extensive investment in the field of cost estimation. The approximate estimation of cost and economic efficiency of a power plant, however, is a complicated and time-consuming process. It demands a high level of knowledge and information.

In order to simplify this process, and make it available for the engineering community, SoftInWay, a leading turbomachinery solutions provider, developed the new AxCYCLE Module for Economic Analysis. This webinar will demonstrate the module and discuss its extensive capabilities and applications.

We look forward to a great webinar and your challenging questions. Please register ahead of time and if you have any specific questions, let us know during the registration so that we can try to incorporate the answers into our presentation.

[su_button url=”http://www2.softinway.com/powerplanteconomics” target=”blank” background=”#ef322d” color=”#f6f1f1″ center=”yes” radius=”round” icon=”icon: arrow-right” title=”Register”]Register[/su_button]

 [:]

Explaining the Binary Power Cycle

Geothermal energy is known to be a reliable and sustainable energy source. As the world gives more attention to the state of the environment, people lean towards using more energy sources which have little to no impact on nature. Where it is true that currently no other energy source can outperform fossil fuel due to its energy concentration, geothermal energy is a good prospect as a temporary substitute until a better form of energy supply is found.

There are two types of geothermal power sources; one is known as the steam plant and the other is the Binary cycle. Binary cycles have the conceptual objectives of: high efficiency — minimizing losses; low cost to optimize component design; and critical choice of working fluid. This particular type of cycle allows cooler geothermal supply to be used, which has a huge benefit since lower temperature resources are much more common in nature.

blog - binary power1blog - binary power2

 

 

 

 

 

 

The way a binary cycle works can be explained using the diagram shown above. Since the temperature of geothermal source is not high enough to produce steam, hot water is fed into a heat exchanger. From there, secondary liquid with lower boiling water than water i.e. isobutane, absorbs the heat generated. As the steam of secondary liquid moves the turbine, electricity will then be produced. This whole process repeats in a cycle since the secondary fluid will then condense back to its liquid state and being used for the same process.

From the process described above, it can be seen that binary cycle is a self-contained cycle — ‘nothing’ goes to waste. This fact leads to the potential of having low producing cost energy source from binary power cycle. That being said, due to the lower temperature, the conversion efficiency of the geothermal heat is also considerably low. Consequently, Carnot efficiency of such process is lower than most power cycles. Large amount of heat is required to operate a binary cycle, leading to a better and larger equipment. Not only that since a bigger amount of heat energy has to be let out to the environment during the cycle, a sufficient cooling system must be installed. Although the production cost is found to be lower, the investment cost for installation would be very expensive. Then, the main question to this particular technology implementation would be how to improve the quality of production and economic feasibility?

First, one of the main aspect of binary power cycle is to overcome water imperfection as a main fluid. Consequently choosing optimal working fluid is a very essential step. Characteristic of optimal working fluids would include a high critical temperature and maximum pressure, lower triple-point temperature, sufficient condenser pressure, high vaporization enthalpy, and other properties.

Second, it was studied on multiple different events that well-optimized ORCs perform better than Kalina cycles. The type of components chosen in the cycle also affect the cycle performance quite substantially, i.e plate heat exchanger was found to perform better in an ORC cycle in the geothermal binary application compared to shell-and-tube. Addition of recuperator or turbine bleeding also have the potency to improve the overall performance of a binary cycle plant. It is important to model multiple thermodynamic cycle to make sure that the chosen one is the most optimized based on the boundary conditions. While designing ranges of thermodynamic cycles, it is common that the cycle is modeled based on ideal assumptions. For binary cycle in geothermal application, plant efficiency would be the most important parameter. In order to achieve a desired plant efficiency, both cycle efficiency and plant effectiveness should be maximized.

Additionally, pinch-point-temperature between condenser and heat exchanger is a substantial aspect to pay attention to, even the smallest change of in temperature is considered a significant change. Thus, including this parameter is a very important aspect.

This particular cycle has many potentials which haven’t been explored. Enhance the advantages of your binary power cycle using our thermodynamic tool, AxCYCLE.

Ref:
https://en.wikipedia.org/wiki/Binary_cycle
http://www.technologystudent.com/energy1/geo3.htm
http://www.researchgate.net/publication/229148932_Optimized_geothermal_binary_power_cycles

Will gas turbines be the next generation of automotive propulsion?

Almost every car produced nowadays is propelled by a Reciprocating Internal Combustion Engine (RICE). Fueled by gasoline or diesel, these engines have pistons inside the cylinders which move up and down, compressing and expanding the mixture. They are connected to a crankshaft that converts the movements into a rotational motion to turn the wheels that move the car.

Big engine makers are constantly researching and developing to make engines lighter, more powerful, more fuel efficient, and more environmentally friendly. But isn’t there a better way to power the automobile Industry?

After WWII, the gas turbine (GT) engine (turbojet) was a trend for aircraft propulsion. A few companies did some research and explored the idea of using a GT to power a car. The GTs mentioned here are evidently not turbojets, but turboshafts where almost any power is used from exhaust. Instead there is a power turbine activated by the combustion gases that would be connected to a gearbox and consequently to the wheels.

Figure 1 - GM Firebird II
Figure 1 – GM Firebird II

The first company to ever build a GT car was Rover in 1950 with the JET 1. A few years later GM also built a number of futuristic prototypes called the Firebirds.

While some companies came up with GT cars, it was Chrysler that invested the most in this concept, spending a lot of time and money doing R&D for almost 20 years (from 1950 to 1970).

Figure 2 - Chrysler Gas Turbine, 1962
Figure 2 – Chrysler Gas Turbine, 1962

For the first time ever in 1963, more than just a prototype came out and fifty-five cars were built and given to people to try as a daily mode of transport. Although reviews were generally good, the project did not go any further.

Figure 3 - A 831 Gas Turbine
Figure 3 – A 831 Gas Turbine

The car used the A-831 GT, a dual spool, and free shaft engine with an output of 130 horse power, weighing 410 lbs. It comprised a single stage centrifugal compressor rotating at a maximum of 44,600 rpm (CR=4:1), the air, after leaving the compressor, would go through 2 regenerators working as heat exchangers using hot gases from the exhaust to increase temperature before the combustion to reduce fuel consumption. From the combustion chamber, the gases travelled by a single stage axial turbine that activated the compressor and the accessories and posteriorly through a variable geometry power turbine nozzle, to control the amount of gas that would go through, before the free single stage axial power turbine that was connected to a Torqueflit, 3 speed automatic transmission.

Chrysler ended up destroying all but nine of the cars.  Today they are in museums or in Jay Leno’s garage.

Why didn’t a car with a well-reviewed engine and a futuristic concept stick? Why are GTs present in so many industries but not in Automotive? They’re faster, simpler, have a better power-to-weight ratio and require less maintenance.

While they have advantages, however, they also have some disadvantages. Some of the Chrysler car users mentioned a lack of engine brake, lack of support when maintenance was needed and noise. This could easily be solved, and Chrysler did fix some of this issues. What ultimately killed the project was the low throttle response in comparison to RICE and fuel consumption. GTs are very fuel efficient for high speeds with constant throttle, but cars operate at relativity low speeds with a big vary of throttle. This has a big impact in the GT fuel efficiency. Although the company tried to resolve this issue, the 1970’s oil crisis made the scenario even worse.

Figure 4 - Jaguar C-X75 GT
Figure 4 – Jaguar C-X75 GT

It’s possible that soon electric hybrid vehicles will mean the GT finally becomes a viable power source for cars. Whether braking or accelerating, the micro gas turbine runs at a relatively constant rpm and generates electricity to be stored in batteries. Those batteries are connected to electric motors (4 in the Jaguar C-X75 case, one on each wheel) that run the car. Two known prototypes are the Jaguar C-X75 using two 70kW micro turbines produced by Bladon Jets, and the Capstone CMT 380 using a single 30 kW micro gas turbine

What Turbomachinery does to Avert Climate Change (Part 2 of 2)

[:en]Last week I described two ways which the turbomachinery industry addresses climate change. This week, I explain two more:

  1. Waste Heat Recovery

Even though processes are becoming more and more efficient they are still mostly wasteful (Figure 1).

Figure 5 Typical energy distribution in a system
Figure 1 Typical energy distribution in a system

The excess energy from processes is eventually released into the environment but bringing down the temperature of the exhaust allows multiple things; direct reduction of the global warming potential as well as possibility to utilize this heat to boil a working fluid before running it through a turbine where it can generate some power without requiring burning additional fuel. A well-known example of such a system is the traditional gas-steam cycle that allows turning a 45% efficient gas turbine cycle into a 60% system by utilizing the gas turbine exhaust heat to boil some water in a secondary loop before passing the resulting steam through a different turbine. In the same manner waste heat recovery can be applied with different fluids (including the trending refrigerants like R134a & R245fa, steam and the state-of-the-art supercritical CO2 as shown on Figure 2) and a multitude of applications; internal combustion engines, steel production plants, marine transports, etc.

Figure 6 Example of a simple, recuperated Brayton, supercritical CO2 cycle that uses the exhaust flow of a gas turbine to heat its working fluid
Figure 2 Example of a simple, recuperated Brayton, supercritical CO2 cycle that uses the exhaust flow of a gas turbine to heat its working fluid
  1. Selection of the best working fluid

Whether it’s deciding to design the main energy conversion cycle or its waste heat recovery system one of the critical parameters to pay close attention to is the working fluid selection; good selection of the fluid will often lead to make a compromise between cost/availability, thermodynamic performance (see Figure 3) and environmental friendliness. One must make sure that the performances of the designed cycle with the chosen fluid are high enough and the fluid cheap enough to make the concept financially viable without sacrificing pollution considerations which can prove devastating in case of leaks.

Figure 7 Example of a fluid performance comparison at different temperatures
Figure 3 Example of a fluid performance comparison at different temperatures

The working fluid selection is also performed so that in addition to the environmental footprint being reduced the physical footprint is minimized as well; this is done through the selection of high density fluids (helium, SCO, etc.) which allows for a reduction in component size and therefore cost (as portrayed on Figure 4), – indirectly it also allows for less material being produced which also “saves trees”.

Figure 8 Example of difference in power density between supercritical carbon dioxide (left) and steam (right) for a 10 MW power turbine
Figure 4 Example of difference in power density between supercritical carbon dioxide (left) and steam (right) for a 10 MW power turbine
[:cn]Last week I described two ways which the turbomachinery industry addresses climate change. This week, I explain two more:

  1. Waste Heat Recovery

Even though processes are becoming more and more efficient they are still mostly wasteful (Figure 1).

Figure 5 Typical energy distribution in a system
Figure 1 Typical energy distribution in a system

The excess energy from processes is eventually released into the environment but bringing down the temperature of the exhaust allows multiple things; direct reduction of the global warming potential as well as possibility to utilize this heat to boil a working fluid before running it through a turbine where it can generate some power without requiring burning additional fuel. A well-known example of such a system is the traditional gas-steam cycle that allows turning a 45% efficient gas turbine cycle into a 60% system by utilizing the gas turbine exhaust heat to boil some water in a secondary loop before passing the resulting steam through a different turbine. In the same manner waste heat recovery can be applied with different fluids (including the trending refrigerants like R134a & R245fa, steam and the state-of-the-art supercritical CO2 as shown on Figure 2) and a multitude of applications; internal combustion engines, steel production plants, marine transports, etc.

Figure 6 Example of a simple, recuperated Brayton, supercritical CO2 cycle that uses the exhaust flow of a gas turbine to heat its working fluid
Figure 2 Example of a simple, recuperated Brayton, supercritical CO2 cycle that uses the exhaust flow of a gas turbine to heat its working fluid
  1. Selection of the best working fluid

Whether it’s deciding to design the main energy conversion cycle or its waste heat recovery system one of the critical parameters to pay close attention to is the working fluid selection; good selection of the fluid will often lead to make a compromise between cost/availability, thermodynamic performance (see Figure 3) and environmental friendliness. One must make sure that the performances of the designed cycle with the chosen fluid are high enough and the fluid cheap enough to make the concept financially viable without sacrificing pollution considerations which can prove devastating in case of leaks.

Figure 7 Example of a fluid performance comparison at different temperatures
Figure 3 Example of a fluid performance comparison at different temperatures

The working fluid selection is also performed so that in addition to the environmental footprint being reduced the physical footprint is minimized as well; this is done through the selection of high density fluids (helium, SCO, etc.) which allows for a reduction in component size and therefore cost (as portrayed on Figure 4), – indirectly it also allows for less material being produced which also “saves trees”.

Figure 8 Example of difference in power density between supercritical carbon dioxide (left) and steam (right) for a 10 MW power turbine
Figure 4 Example of difference in power density between supercritical carbon dioxide (left) and steam (right) for a 10 MW power turbine
[:]

What Turbomachinery does to Avert Climate Change (Part 1 of 2)

[:en]Most people complain about climate change, but few take measures to address it. In this article we will see some ways turbomachinery-oriented companies contribute to the well-being of the planet.

  1. Selection and optimization of energy conversion technology (recuperation, proper selection of expander configuration, etc.)

Not all technologies are created equal; where you would use a steam turbine is not necessarily where you would want a gas turbine or an organic Rankine cycle (ORC) instead. Each one of them has its pros and its cons; ORC exist because they do not require as much energy as what is needed for steam cycles, gas turbines have a great power density and an outstanding start-up time (several minutes instead of hours) which makes them great candidates for punctual, unexpected peaks in power demand, etc.

Figure 1 Simple Rankine cycle schematics
Figure 1 Simple Rankine cycle schematics

Now, take the case of a gas, steam or ORC; they all include, in their most basic configuration, a compressing element (compressor or pump), an expander (usually a turbine), a cooling/condensing component and a heating component (boiler, combustion chamber, HRSG, etc.) as one can see on Figure 1 and each of these have an associated efficiency.

This means that their careful design and thorough optimization should be performed in order to maximize the overall performance of the full system. Whether it’s used for power generation or propulsion the result is the same; more power generated for the same amount of heat input (usually the combustion of fuel). However, before starting the full design of the different components the entire system needs to be optimized as well; correct positioning of extractions/inductions, appropriate cooling parameters, use of recuperation/regeneration (see Figure 6), and so on.

Figure 2 Recuperated Rankine cycle
Figure 2 Recuperated Rankine cycle

 

Only when the cycle boundary conditions (and therefore its configuration) are fixed the full design of the components can be performed although some preliminary studies should be undertaken to determine the feasibility of these designs and get an estimation of the components performances. Another goal of such feasibility studies is to determine such things as the estimated dimensions of the components, the configuration of the expander (axial, radial, axi-radial, counter-rotating, etc.) Finally some compromises always need to be done between efficiency improvement and cost of manufacturing, operation and maintenance.

 

 

 

  1. Operation at optimal conditions (design point for overall cycle and each component)
Figure 3 Comparison of efficiency and power rating for axial and radial configurations of turbines
Figure 3 Comparison of efficiency and power rating for axial and radial configurations of turbines

Each energy conversion system whether it is for power generation, propulsion or any other application is designed for a set of operating conditions called a design point. This is where the system will typically be optimum for and where it will be running most of its “on” time. This is why ensuring that the design point (or design points) is accurately defined is critical since operation outside of these defined conditions will lead to additional losses that translate into a lesser power production for the same cost of input energy. Performance prediction of systems at off-design conditions is an essential part of any design task which allows restricting system operation to conditions of high components efficiency. If the pump/compressor is operated at a different mass flow rate its pressure ratio will be different and so will be the efficiency and therefore the amount of power generated by the expander, see Figure 4.

Figure 4 Performance map of a centrifugal compressor showing its efficiency as a function of the mass flow rate for different rotation speeds
Figure 4 Performance map of a centrifugal compressor showing its efficiency as a function of the mass flow rate for different rotation speeds

In our next post, we will continue the discussion of the turbomachinery industry as it relates to climate change. Stay tuned![:cn]Most people complain about climate change, but few take measures to address it. In this article we will see some ways turbomachinery-oriented companies contribute to the well-being of the planet.

  1. Selection and optimization of energy conversion technology (recuperation, proper selection of expander configuration, etc.)

Not all technologies are created equal; where you would use a steam turbine is not necessarily where you would want a gas turbine or an organic Rankine cycle (ORC) instead. Each one of them has its pros and its cons; ORC exist because they do not require as much energy as what is needed for steam cycles, gas turbines have a great power density and an outstanding start-up time (several minutes instead of hours) which makes them great candidates for punctual, unexpected peaks in power demand, etc.

Figure 1 Simple Rankine cycle schematics
Figure 1 Simple Rankine cycle schematics

Now, take the case of a gas, steam or ORC; they all include, in their most basic configuration, a compressing element (compressor or pump), an expander (usually a turbine), a cooling/condensing component and a heating component (boiler, combustion chamber, HRSG, etc.) as one can see on Figure 1 and each of these have an associated efficiency.

This means that their careful design and thorough optimization should be performed in order to maximize the overall performance of the full system. Whether it’s used for power generation or propulsion the result is the same; more power generated for the same amount of heat input (usually the combustion of fuel). However, before starting the full design of the different components the entire system needs to be optimized as well; correct positioning of extractions/inductions, appropriate cooling parameters, use of recuperation/regeneration (see Figure 6), and so on.

Figure 2 Recuperated Rankine cycle
Figure 2 Recuperated Rankine cycle

 

Only when the cycle boundary conditions (and therefore its configuration) are fixed the full design of the components can be performed although some preliminary studies should be undertaken to determine the feasibility of these designs and get an estimation of the components performances. Another goal of such feasibility studies is to determine such things as the estimated dimensions of the components, the configuration of the expander (axial, radial, axi-radial, counter-rotating, etc.) Finally some compromises always need to be done between efficiency improvement and cost of manufacturing, operation and maintenance.

 

 

 

  1. Operation at optimal conditions (design point for overall cycle and each component)
Figure 3 Comparison of efficiency and power rating for axial and radial configurations of turbines
Figure 3 Comparison of efficiency and power rating for axial and radial configurations of turbines

Each energy conversion system whether it is for power generation, propulsion or any other application is designed for a set of operating conditions called a design point. This is where the system will typically be optimum for and where it will be running most of its “on” time. This is why ensuring that the design point (or design points) is accurately defined is critical since operation outside of these defined conditions will lead to additional losses that translate into a lesser power production for the same cost of input energy. Performance prediction of systems at off-design conditions is an essential part of any design task which allows restricting system operation to conditions of high components efficiency. If the pump/compressor is operated at a different mass flow rate its pressure ratio will be different and so will be the efficiency and therefore the amount of power generated by the expander, see Figure 4.

Figure 4 Performance map of a centrifugal compressor showing its efficiency as a function of the mass flow rate for different rotation speeds
Figure 4 Performance map of a centrifugal compressor showing its efficiency as a function of the mass flow rate for different rotation speeds

In our next post, we will continue the discussion of the turbomachinery industry as it relates to climate change. Stay tuned![:]