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

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

Working Fluid in Organic Rankine Cycles

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ORC Fluid

The choice of the working fluid for any given application is a key issue and should be done based on specific applications to achieve maximal efficiency. For working fluids in ORC, a green energy alternative, there are some requirements to keep in mind:

•Thermodynamic performance
Low pump consumption and high critical point

•Positive or isentropic saturation vapor curve
Avoid wetness in flow path, i.e. avoid damages of flow path elements

•High vapor density
Decrease sizes of equipment (expander and condenser)

•Acceptable pressures
High pressures usually lead to higher investment cost and increasing complexity

•High stability temperature
Prevent from chemical deterioration and decomposition at high temperatures

•Low environmental impact and safety level
•Good availability and low cost Continue reading “Working Fluid in Organic Rankine Cycles”

About This Blog + Other Exciting Announcements!

websitehomepoage
Softinway New Website

Welcome! We’re glad you stopped by.

It’s a new year and a new SoftInWay.

Well, almost.

We’re still the same, but if you’ve been here before, either on our main website or this very blog, you may have noticed some vast changes. We’ve updated our website and added some great features for our clients, software users, and readers (yes, you too!). Features like a live chat support tool, a user forum, easy access to our User Center, and training courses and schedules all from our home page.

We thought this would be a great way to communicate better, create conversation and listen to you. Continue reading “About This Blog + Other Exciting Announcements!”

Calculating Sections in Steam Turbines

9 Section Axial Steam Turbine
9 Section Axial Steam Turbine

What’s a better way to begin our brand new turbomachinery blog then by addressing a common design question about something we are very familiar with – steam turbines?

Many times the question, “How many calculation sections do you recommend for the (insert any number here)-stage steam turbine?” travels through our tech support emails and we always answer our clients with what we think is best practice. Continue reading “Calculating Sections in Steam Turbines”

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