Product Development: Rescale existing turbomachine design vs full design process

When deciding on a new product line, manufacturers of turbomachines and their engineering teams must often decide whether to rescale a product that they already manufacture or to begin a full design process for a completely new machine. For example, a producer of 5 MW axial turbines wants to start manufacturing 10 MW turbines, does it make sense to create a brand new design from scratch or to simply scale up the 5 MW turbine they already produce to a similar 10 MW version? To answer this question, many considerations have to be taken into account, the general answer however is, that it is almost always a better idea to start a new design.

Improved Design Technology

Many manufacturers wrongly believe that by simply scaling their current product that they will save not only on design costs, but that they can leverage their existing manufacturing capabilities to stamp out a similar product. What is not factored in however is the progress of design technology and theory since their original machine was first conceptualized. The result from a simple scaling process will simply be a less optimized and efficient machine for any use as compared to a new configuration using the latest in design software. Increasing software sophistication and computing power are constantly pushing the boundaries of efficiency while minimizing operating costs. Simply put, your competitors will have designed a superior product compared to yours.

BladeProfiling-Turbomachinery-Design-Software

        AxSTREAM 3D Blade Design Software

Improved Materials

When was your current machine designed? Many older machines were created using materials that by today’s standards are simply not capable of operating at the extreme conditions  (mostly temperatures) required today to attain the energy efficiency requirements set up by ever increasing regulations. Depending on materials used, the optimal blading structure, bearings, etc. geometries would be significantly unique. If one were to simply scale up their current product, they would either be using old materials or have inefficiently designed machine components for a different material. In either case, their scaled machine will be inferior to a configuration that was conceptualized and optimized from scratch.

Scaling Factors

Another very significant aspect of machine resizing is that it is not a straight forward process; if you want to double your power generation in a turbine for example you are not going to be doubling the blade size or mean diameter, for example, even when considering the same boundary conditions (inlet pressure and temperature, as well as, outlet pressure, rotation speed, and so on). For each specific set of conditions, fluid, rotation speed, mass flow rate, etc. a unique flow occurs inside the different blades. Changing one parameter will lead to changes in the flow and therefore result in inefficiencies, as it is what happens in off-design conditions (the machine is not operating at its maximum performance). This is why flow similarity parameters become relevant.

Machine Purpose and Type

One of the obvious questions to ask is, what is the purpose of my new machine and how much larger (or smaller) will I need it to be? If the new machine is intended for use with a completely different fluid, a new design will be optimal as different fluids interact in unique ways with varied rotor and stator configurations.

The machine type that you are considering is also critical to the decision. Different turbomachines do not scale in similar fashion with increase in size. For instance, radial turbines are usually not as efficient as axial turbines when one starts to approach the 2 MW range. In this instance the ideal solution is for a complete redesign since a smaller scale version that the manufacturer may have had would not be configured to operate at higher power ranges efficiently.

 

Improving Turbine and Compressor Design Matching

Compressor-Turbine-MatchingOne of the most prominent steps of complete gas turbine design is turbine-compressor matching. There are three major components to a gas turbine: compressor, combustor, and turbine. Although all of the components are designed individually, each of the components needs to correspond within the same operating condition range since all are integrated into one cycle. Consequently, an optimal design of each component must fit the requirement of other component’s optimal parameters. Corresponding operating points for each component must be found at equilibrium with the engine, thus the overall performance of gas turbine can be reached within the defined range of parameters.

The idea behind component “matching” process is to find flow and work compatibility between corresponding components. Based on the mechanical constraints, gas generator speed and firing temperature of a gas turbine have limitations depending on: ambient temperature, accessory load and engine geometry. The match temperature chosen should be the ambient temperature which reach both upper limits at the same time.  Pressure ratio needed to allow a certain gas flow is also one of the most prominent parameters that has to be taken into consideration. Designers need to make sure that the gas flow through the power turbine from gas generator satisfy the pressure ratio needed for compressor power requirements. Gas generator can easily show an altered match temperature due to some conditions i.e: reduction in compressor efficiency (due to fouling, etc), change of thermodynamic properties of combustion product, gas fuel with lower or higher hearing value, etc. Match parameters of an engine could also be altered by changing the flow characteristics on the first turbine nozzle.Turbine-Compressor

Using characteristic map/curve as well as thermodynamic relationships of turbine and compressor, calculations can be performed to identify the permitted operating range. It must be taken into consideration that all calculated value must match the value from map data.

Trying to find the fastest solution for this step? SoftInWay’s turbine-compressor matching feature in AxSTREAM could help you cut engineering time and simplify the process. Combining performance maps of turbine and compressor, making it easier for the user to determine points of joints operations.

Take a look into AxSTREAM’s to learn more about this.

Reference:

https://www.grc.nasa.gov/www/k-12/airplane/ctmatch.html
http://cset.mnsu.edu/engagethermo/components_gasturbine.html
http://turbolab.tamu.edu/proc/turboproc/T29/t29pg247.pdf
http://scholarcommons.sc.edu/cgi/viewcontent.cgi?article=3255&context=etd
Turbine Compressor Matching Compatibility Mode Document

The Economic Optimization of Renewable Energy

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

 

Turbo pump design parameters for Liquid Propulsion

turbo3aLiquid propellant rocket is known as the most common traditional rocket design. Although the first design was launched back in 1926, liquid propellant rocket remains a popular technology which space exploration companies and institutions study for further improvement.

The implementation of this particular technology is based on a simple idea: fuel and oxidizer are fed through a combustion chamber where both liquids will met and burned to produce launching energy. In order to inject propellant to combustion chamber, a turbo-pump is used to create required pressure . The turbo-pump design and operating parameters contribute to the optimization of both turbo-pump and engine system performance. The pump needs to be designed to avoid cavitation while operates pushing the liquid to combustion chamber.

There are three different cycles which are often used in liquid propellant rocket: the staged combustion, expander and gas generator cycle. Configuration of the turbo-pump strongly relies on the cycle and engine requirements –thus the best design must be selected from options available for the particular cycle’s optimal parameters. For example for staged combustion cycle, where turbine flows is in series with thrust chamber, the application allows high power turbo-pumps; which means high expansion ratio nozzles can be used at low altitude for better performance. Whereas, for implementation of gas-generator cycle, turbine flows are linked in parallel to thrust chamber, consequently, gas generator cycle turbine does not have to work the injection process from exhaust to combustion chamber, thus simplified the design and allows lighter weight to be implemented.

Some parameters are interdependent when it comes to designing a turbo-pump, i.e: turbo-pump cycle efficiency, pump specific needs, pump efficiencies, NPSH, overall performance, etc. Often in practice, pump characteristics will determine the maximum shaft speed at which a unit can operate. Once it’s determined turbine type, arrangements, and else can be selected. Another thing that must be taken into consideration while designing a turbo-pump is how it affect the overall payloads.

Schematic of a pump-fed liquid rocket
Schematic of a pump-fed liquid rocket

Turbo-pump design affect payload in different ways:

  1. Component weight
  2. Inlet suction pressure. As suction pressure goes up, the tank and pressurization system weight increased and reduce the payload.
  3. Gas flowrate, since increase in flowrate decrease the allowable-stage burnout weight, which would decrease payload weight.

All those has to be taken into consideration while trying to select an optimal design of turbo-pump, since it crucially affects overall performance of the engine.

Want to learn more how to design a turbo-pump? Check out AxSTREAM as your design, analysis and optimization tool!

 

References:
Turbopumps for Liquid Rocket Engines
Design of Liquid-Propellant Rocket Engines
Principal of Operation – Liquid-propellant rocket
Staged combustion cycle
Gas-generator 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

What parallels exist between traditional Gas Turbines with SCO2 turbine of the future?

At the beginning of my studying of the peculiarities of supercritical CO2 (S-CO2) cycle I was wondering: why do scientists involved in this area state that highest temperature limit for the cycle is about 650-700 ˚C. In turn, the inlet temperature in the first stages of gas turbines handles the temperatures about 900 ˚C without cooling at similar pressure levels as for supercritical CO2 Turbines. As a result the following question rose in my mind – why the temperature magnitudes of 900 ˚C are not achievable in S-CO2 turbines?

As a next step, some investigations were performed with the aim to reveal the essence of such a temperature limit. Eventually the result was quite obvious but rather interesting. The density of S-CO2 is significantly higher than the density of combustion products at the same pressure and temperature magnitudes. This fact means that stresses at static vanes and rotating blades are significantly higher than in gas turbines vanes and blades at the same conditions. Therefore the maximum allowable temperature for S-CO2 turbine will be respectively less with the same high temperature material. However, you might say that there is another way to solve the problem with stresses, namely, increasing the chords of blades, leading edge thickness, trailing edge thickness, fillets etc. This approach would lead to such blades shape and turbine cascade configuration that their aerodynamic quality becomes very low so the gain in efficiency at cycle level will be leveled.

Interested in learning more about our research, and how using the AxSTREAM turbomachinery platform, we were able to study these phenomena?

Contact us for a chat!

Crowd Sourcing Innovation – What’s your vision?

Dear Friends,

I hope that you are having a great week. In case that you are not on our mailing list, I wanted to share some updates and discuss innovation.

Typically, every week we send marketing or information emails about our latest customers, case studies, upcoming webinars & seminars, etc.

However, after along product development meeting planning our next 3-9 month, I wanted to reach out to the world and ask: how can we help? What don’t you like about your current engineering process? How can you do what you do faster? What would it take to develop a truly more efficeint machine?

Simulation technology and computers have come a long way in the last 30+ years, and yet there are still many companies, and engineering departments stuck using old designs, and methods.

For those of you who have attended the 2005 Turbo Expo in Montreal, we first publically laid out the idea of “Collaborative Development” and “Crowd Sourcing Innovation”: Watch Video

We are working hard on getting ready the next generation of AxSTREAM Platform, and AxCYCLE, with features and level of integration, that the industry has never seen before.

If you have a few minutes, we would appreciate you answering a few questions, and providing some ideas / or some pains / frustrations you may currently have about your turbomachinery design/analysis process.
**** 10 people will be picked at random, to receive a free access to our online, self-paced, Turbomachinery Course of their choosing.

Please respond by filling out this questionnaire: Questionnaire

We greatly appreciate your help, and feedback.
Warmest Regards,
Valentine Moroz

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

Analyzing Thermal Power Generation Efficiency

Figure 1 - Thermal Power Plant Layout
Figure 1 – Thermal Power Plant Layout

Steam turbine power generating plants, also known as Thermal Power stations, are the most conventional type of electricity production today. Most of today’s electricity power is generated though this technology. Naturally, as implied by its name, a thermal power station uses steam power as its prime mover to convert energy in coal, or other fossil fuel, by heating water to steam and utilizing Rankine cycle principles to generate heat and electricity.

The basic theory of thermal power generation is pretty straight forward: in a simple thermodynamic cycle, saturated liquid water is heated to steam. The working fluid will then pass through a steam turbine, where its energy is converted to mechanical work to run the generator and produce the electricity. Then fluid will be condensed to be recycled back in the heater. Just as simple as that, electricity power is generated from the cycle based on Rankine cycle principle.

The utilization of thermal power station comes with the advantage of economical initial and generation cost, easy maintenance and simple cycle operation in practice. That being said, there are also couple major drawbacks associated to the technology, primarily, low overall efficiency –due to the nature of Rankine cycle’s characteristic of thermal efficiency and environmental issues.

There are many scientific reasoning behind thermal power generation’s low efficiency. It is important to know the reasons why to engage in a better technology. These are the primary reasons:

  • During the combustion of carbon, effective conversion more or less is found to be 90%, this happen primarily due to limitation of heat transfer where some heat are lost into the atmosphere. Coal also contains moisture that vaporizes and take the latent heat from combustions.
  • The thermodynamic step, working on Rankine cycle principle, is where 50% (or more) efficiency is consumed. When the steam is condensed for re-use, latent heat of condensation is lost in the cooling water, which decreases the energy input by a very significant magnitude. Losses can also happen in the blades and other components. The Rankine cycle efficiency is determined by the maximum temperature of steam that can be transferred through the turbine, which means the efficiency is also constrained by the temperature associated with the cycle. Two other main factors that affect the thermal efficiency of power plants are the pressure of steam entering the turbine and the pressure in the condenser. That being said, a cycle with supercritical pressure and high temperature usually results to a higher efficiency.
  • During a conversion of mechanical to electrical, some efficiency loss happens in the generator and transformer. A small percentage of energy generated will then be used for internal consumption.

Knowing the causes of low efficiency leads us to the next question: What are the steps to optimize our thermal power plant efficiency?

  • Since thermal efficiency depends on temperature and pressure, it can be improved by using high pressure and temperature steam, though obviously it will be limited based on the boundary conditions of the operating system. A lower pressure can also be set in the condenser.
  • Improvement could also be implemented by the application of reheating steam technology between turbine stages.
  • Waste heat recovery optimization, capture excess heat for reuse, and install insulation to reduce any losses.
  • Upgrading major systems/components of thermodynamic cycles and renewing materials to reduce natural losses in efficiency due to age.
  • Improve efficiency monitoring system to enable instant detection of losses as well as analyzing efficiency based on real data.

These are just some ways that could be utilized to optimize power generation efficiency, indeed each of the steps come with their own specific obstacles of implementation, but there are infinite ways that can be explored to advance the technology.

Learn more about maximizing your power plant productivity through our webinars and explore our tools to help with your efficiency optimization for power generation and component design!

Sources:
http://www.learnengineering.org/2013/01/thermal-power-plant-working.html

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