Energy Systems Pedagogy with Thermoptim

The pedagogical method we recommend is based on a few major constants:

  • reduce the cognitive load of learners by limiting unnecessary theoretical developments as much as possible, which vary according to the scientific level of the learners

  • make them operational thanks to the simulator that allows them to study real problems and not caricatures of reality given too simplifying hypotheses

  • shift the content of teaching by reducing the equations and insisting on qualitative explanations of the physical phenomena that take place in the systems studied

  • sequence the sequence of concepts presented based on the RTM(E) model and the functional approach.

The training offer with Thermoptim has thus been completed and diversified and reaches a wide audience, nationally and internationally.

 

Three modes depending on the scientific level of the learners

 

It is well known that thermodynamics is a difficult subject to teach. The problem has been identified for a long time, and many efforts have been made to remedy it, but until recently there was still a lack of solutions, despite the efforts made by teachers and changes in curricula.

First of all, our main pedagogical objective was and still is to make our students able to study innovative energy systems, which involves:

  • sufficient mastery of the theoretical bases

  • in-depth knowledge of technological aspects (existing achievements, main constraints)

  • the ability to design and size innovative thermodynamic cycles.

To our surprise, our approach has proved to interest a much wider audience than that of our students at Les Mines, not only at university level, but also for the training of learners who do not have as much scientific background as our students, such as operators of propulsion systems and refrigeration and air conditioning installations of the French Navy or professionals in continuing education.

The result, after about 2010, was an effort to lighten the scientific content of teaching, with emphasis on understanding physical phenomena rather than studying the equations that describe them and that the latter learners never apply on their own in their professional practice.

In particular, it seemed preferable to us in this context to start the course by avoiding the notion of entropy difficult to understand by learners who do not have advanced knowledge of mathematics and physics. This led us to replace the entropic diagram (T,s) with the enthalpy-pressure (h, ln(P)) diagram.

At the same time, new tools have been developed during the preparation of our two MOOCs Thermodynamic Conversion of Heat, so that learners can work independently, the supervision being necessarily reduced in this context.

These are, on the one hand, self-assessment activities, and on the other hand, the guided explorations of models.

All these developments have led to an evolution of our initial pedagogical approach integrating on the one hand these new tools and on the other hand this concern to lighten as much as possible the scientific prerequisites. We are talking about a lightweight pedagogical presentation.

 

Our pedagogical approach can now be presented in three complementary modes. The corresponding resources are available in the Education section of the Thermoptim-Unit portal.

The first mode, the lightweight presentation, meets the needs of learners with minimal scientific background, and therefore does not involve entropy or exergy. The practical exercises use guided explorations of simple models. This is typically the course offered in our CTC MOOCs (in French) as well as in our Online course 2022 on Energy Systems.

The second mode, which can be described as progressive, is aimed at learners in bachelor's degree or professionals in activity, not particularly motivated by the theoretical aspects while being able to follow them if necessary. It begins with the lightweight presentation that is completed by introducing a cycle improvement approach based on the exergy balances and the comparison with the Carnot cycle in the entropic chart. The practical exercises use guided explorations of models as well as some Diapason sessions.

The third mode is intended for students in master or engineering school familiar with theoretical developments. It differs from the previous ones by three points:

  • First of all, these students are used to a "Cartesian" and disciplinary presentation of their teachings, and nothing prevents us from first introducing them to the whole theory before moving on to applications;

  • Then, as for them the use of entropy poses no problem, we can very quickly introduce entropic diagrams (T, s) and those of Mollier (h, s) as well as exergy balances ;

  • Finally, the use of Thermoptim can be done both in the form of exploration and model building.

The approach to improving cycles based on the exergy balances and the comparison with the Carnot cycle should also constitute in the third mode the guiding principle of analysis of the variants of the simple cycles. The practical exercises use either guided explorations, including those using Thermoptim's advanced features, or Diapason sessions where learners build their own models. 

 

Installing Eclipse on Mac

To launch Thermoptim on Mac, if you do not already have a Java development environment, you can use a tool available as freeware, called Eclipse. Developed in open source, Eclipse can be downloaded from the Internet at https://www.eclipse.org.

Eclipse allows you to write your classes in Java, compile them and test their integration directly into Thermoptim.

Installing Eclipse

To install the development environment, go to the Eclipse website, and follow the instructions.

Given the potential of Eclipse, which is a widely used environment, you will easily find sites explaining in detail how to install it for various operating systems.

When you start Eclipse, the page below offers you a whole series of possible actions. In the upper right part is a "Hide" button. Click on it to hide it.

start pageseclipsemac

Importing the Thermoptim project

An Eclipse workspace ("Workspace") allowing you to launch Thermoptim is available. It is called Thopt_Demo_Mac_Ecl_252_En and can be downloaded from the following address:

https://www.s4e2.com/download/soft/thopt/mac/Thopt_Demo_Mac_Ecl_252_En.zip

To import the project into Eclipse, do the following:

Select File/Import/General/Existing Projects into Workspace

Choose Select archive file and navigate through your files until you select the Thopt_Demo_Mac_En.zip archive.

The Eclipse screen should be analogous to this one, once the project tree is deployed.

MacEclipse screen.png

In the left part appears the contents of the archive, with different working directories and a number of working files. If you click on a file, it opens in the right panel.

The top bar has a list of menus. The ones that will interest us below are Project and Run.

Selecting Working Libraries

Eclipse should load the entire project, but it may be necessary to make some settings by hand.

This is especially the case to inform Java of the libraries needed to run the browser.

It is likely that the files .jar will be recognized, but it may be necessary to add the .zip by hand.

To do this, you must select the project by clicking on it on the left side of the screen, then go to Project/Properties and select Java Build Path and the Libraries tab. The list of automatically identified libraries is displayed. To add more, click in the window and then click add JARs and select all the files .zip to the root of the project, until you get the result of the figure.


javaBuilPathMac

Launching Thermoptim

To launch an application in Eclipse, you must choose the Java class that must be executed. The Thermoptim one is called pilot.Starter, which means Starter class of the pilot package.

Select Run/Run As.. A Java application, or click the green icon representing a right-facing arrow. A screen of the type below is displayed, with the list of existing classes with a main() method. Look in the list for the class Starter - pilot, if it is not selected by default as in the figure, then click on it to select it and click the "OK" button.

runConfigMac.png

You can also start by creating a launch configuration by going to Run/Run Configurations, and creating a new configuration with Thopt_Demo_Mac_Ecl_252_En project and Main class pilot.Starter. Be careful to respect lowercase and uppercase letters.Give a name to the launch configuration, and then click Apply.

 runconfigurationmac

Once these settings have been made, by clicking run, the windows of the diagram editor and the Thermoptim simulator should open.
 

Security Warning

The operating system may issue a security warning to warn you of the risks associated with running programs.

securitymac

In this case, validate the use of Eclipse.

Launching the Thermoptim Browser on Mac

To launch the Thermoptim browser on Mac, if you do not already have a Java development environment, you can use a tool available as freeware, called Eclipse. Developed in open source, Eclipse can be downloaded from the Internet at https://www.eclipse.org.

Eclipse allows you to write your classes in Java, compile them and test their integration directly into Thermoptim.

Installing Oracle's Java 1.8 Environment

In order to be launched, the Thermoptim browser needs a JAVA runtime environment containing special libraries called JavaFX.

For this software to run you must install on your system a runtime environment (the Java Runtime Environment or JRE) as well as, for Eclipse, a compilation environment (JDK). There are several, but the ones that contain JFX are those from Oracle up to version 1.8.

They can be downloaded and installed from this link, following the instructions given:

https://www.oracle.com/fr/java/technologies/javase/javase8-archive-downloads.html

Installing Eclipse

To install the development environment, go to the Eclipse website and follow the instructions.

Given the potential of Eclipse, which is a widely used environment, you will easily find sites explaining in detail how to install it for various operating systems.

When you start Eclipse, a page offers you a whole series of possible actions. In the upper right part is a "Hide" button. Click on it to hide it.

pagedemarrageeclipsemac

Importing the browser project

An Eclipse workspace allowing you to launch Thermoptim browser is available. It is called Nav_Thopt_Mac and can be downloaded from the following address:

https://www.s4e2.com/download/soft/thopt/mac/Nav_Thopt_Mac_En.zip

To import the project into Eclipse, do the following:

File/Import/General/Existing Projects into Workspace

Choose Select archive file and browse through your files until you select the Nav_Thopt_Mac_Fr.zip archive.

The Eclipse screen should be this one, once the project tree is deployed.

MacEclipse screen.png

In the left part appears the contents of the archive, with different working directories and a number of working files. If you click on a file, it opens in the right panel.

The top bar has a list of menus. The ones we'll be interested in below are Project and Run.

Selecting Working Libraries

Eclipse should load the entire project, but it may be necessary to make some settings by hand.

You must check that all the libraries needed to run the browser are declared.

It is likely that the files ending by .jar will be recognized, but it may be necessary to add by hand those ending by .zip.

To do this, select the project by clicking on it on the left side of the screen, then go to Project/Properties and select Java Build Path and the Libraries tab. The list of automatically identified libraries is displayed. To add more, click in the window and then on Add JARs and select all the files ending by .zip located at the root of the project, until you get the result of the figure.

javaBuilPathMac.png

Selection of the JDK and JRE

 By default, the JRE installed by Eclipse does not contain javaFX libraries. You must therefore declare to Eclipse to use Oracle's JRE 1.8.

To do this, go to Eclipse/Preferences, and then, in the Java/Installed JREs section, select this JRE and not the default one installed by Eclipse.


choixJRE_Mac.png

Launching the browser

 

To launch the browser, you must choose the Java class that must be executed. The browser one is called rg.espfx.EspFx, which stands for EspFx class of the rg.espfx package.

Select Run/Run As.. A Java application, or click the green icon representing a right-facing arrow. A screen of the type below is displayed, with the list of existing classes with a main() method. Look in the list for the class EspFx - rg.espfx, if it is not selected by default as in the figure, then click on it to select it and click the "OK" button.

runConfigMac.png

You can also start by creating a launch configuration by going to Run/Run Configurations, and creating a new configuration with Nav_Thopt_Mac as project and main class rg.espfx.EspFx. Be careful to respect lowercase and uppercase letters.Give a name to the launch configuration, and then click Apply.

runconfigurationmac

Once these settings are made, by clicking on Run/Run, the browser should open as well as the windows of the Thermoptim diagram editor and simulator, as shown in the figure below.

The menu at the top left of the browser screen allows you to select the guided exploration you want to study.


navThoptMac en

Security warning

The operating system may issue a security warning to warn you of the risks associated with running programs.

In this case, validate the use of Eclipse.

securityMac.png

 

Installing the Oracle JRE on Ubuntu

To run the Thermoptim browser, you need to install a JAVA runtime environment (JRE) containing special libraries called Java JFX.

Several JRE are available, but the one that contains JFX is Oracle's.

This note explains how to install it, in the latest Ubuntu LTS 22.04 release. It is largely inspired by this web page: https://www.wikihow.com/Install-Oracle-Java-on-Ubuntu-Linux.

Preparation

Start by checking if your Ubuntu Linux operating system is 32-bit or 64-bit. Open a terminal and run the command:

$ file /sbin/init

This will allow you to choose the type of file containing the JRE to download.

Then check which versions of Java are already installed, by the command:

$ java -version

If one already exists, you will to uninstall it.

If it's the OpenJDK/JRE, a command like this will allow you to do this:

$ sudo apt-get purge openjdk-*

Then create a directory to save the JRE files:

$ sudo mkdir /usr/local/java

JRE download

Download the Oracle JRE from this link choosing the 32-bit or 64-bit version that suits you:

https://www.java.com/download/linux_manual.jsp

As of this writing, the 64 bit file is called: jre-8u333-linux-x64.tar.gz

Copying and extracting the JRE

You can now copy this file to the /usr/local/java directory you created earlier and extract it.

To do this, go to your download directory and enter:

$ sudo cp jre-8u333-linux-x64.tar.gz /usr/local/java

Then go to the /usr/local/java directory and type:

$ sudo tar xvzf jre-8u333-linux-x64.tar.gz

Note the name of the directory where the files are extracted. Here: jre1.8.0_333.

JRE Statement

Declaring the JRE allows you to update environment variables so that the JRE can be recognized by the system.

Using a text editor you are familiar with, for example gedit, open the /etc/profile file:

$ sudo gedit /etc/profile

At the end of the file, add the following lines, replacing jre1.8.0_333 by the name of the extraction directory if different:

JRE_HOME=/usr/local/java/jre1.8.0_333

PATH=$PATH:$HOME/bin:$JRE_HOME/bin

export JRE_HOME

export PATH

Save the file and close it.

Inform the operating system:

$ sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/java/jre1.8.0_333/bin/java" 1

$ sudo update-alternatives --set java /usr/local/java/jre1.8.0_333/bin/java

When you restart Ubuntu, the environment variables will be updated permanently, but you can already launch the browser if you wish.

Browser launch

The browser can be launched from the main installation directory. There are two modes to choose from:

Directly, by right-clicking the NavThopt icon and choosing "Run as a program".

LanceurLinuxEn

Or, on the command line, by entering:

$ ./NavThopt

You can also launch Thermoptim alone by operating in a similar way, NavThopt being replaced by Thermoptim.

Thermoptim features

The Thermoptim software package provides a modeling environment integrating in a deeply interconnected way a diagram editor / synoptic screen, interactive charts, simulation functions and an optimization method based on the pinch method. Its objective is twofold: to facilitate and secure the modeling of energy conversion technologies.

Main simulator features

Thermoptim allows one to calculate the complete state of different fluids (temperature, pressure, mass volume, enthalpy, internal energy, entropy, exergy and quality), for ideal gases and condensable vapors. These fluids can undergo various transformations or processes:

  • compression and expansion, in open or closed systems. These can be adiabatic or polytropic, and are characterized by their isentropic or polytropic efficiency ;

  • combustion, also in a closed or open system, at set pressure, volume or temperature. Fuel can be introduced into the combustion chamber separately from the oxidizer, or premixed. The dissociation of the carbon dioxide can be taken into account ;

  • isenthalpic throttling ;

  • heat exchanges with other fluids: the software is able to calculate the UA product or the overall heat transfer coefficient across the surface of a heat exchanger for the following configurations: counter flow, parallel flow, cross flow or (p-n) type.

Fluid networks are represented by nodes (mixers, dividers and separators), which conserve enthalpy and mass flow-rate. The other elements (compressors, turbines, combustion chambers, heat exchangers) can be easily connected into these networks.

Fluid mixtures can be made. These are considered to be ideal gases. Specifically, Thermoptim allows one to process water vapor / gas mixtures and provides six types of processes to study them (heating, cooling, humidification, supply conditions, desiccation).

The software possesses a database of thermophysical properties of substances most commonly used in applied thermodynamics. The whole set of elements composing the system studied is grouped as a project which can be handled thanks to appropriate interfaces.

Advanced simulator features

In addition, Thermoptim incorporates very powerful advanced features for experienced users, which make it a very well suited tool for studying innovative systems with low environmental impact:

Thermoptim is thus a generic platform for modeling energy systems,capable of modeling a wide variety of systems, from the simplest to the most complex, equipped with powerful second Law analysis tools (exergy methods are increasingly considered to be among the best suited to carry out optimization studies, because they make it possible to take into account both the amounts of energy involved and their quality).

Thermoptim screenshot gallery

Here are some examples of Thermoptim's screens.

Synoptic of a regenerative reheat steam plant cycle

In this diagram, the boiler is represented in the upper part by four "exchange" processes.

At the HP turbine outlet, a divider separates the main steam flow into an extraction used to heat the water coming out of the open feedwater, while the rest of the flow is reheated and then expanded in the LP turbine.

At the bottom of the diagram, the water leaving the LP turbine is condensed, then compressed to the intermediate pressure and injected into the open feedwater where it is mixed with the extraction, which increases its temperature.

Water coming out of the open feedwater is then compressed to the maximum pressure of the cycle and directed to the economizer.

The small widget in the center of the screen summarizes the information on the energy balance of the cycle.
 

regenerative reheat steam plant cycle

Combustion process screen

Here is a combustion chamber screen configured to take into account a CO2 dissociation rate in fumes of 2%. The temperature of the fumes is set at 1065 °C and the corresponding lambda air factor is determined.

Combustion process screen

Optimization of a dual pressure combined cycle

Here is the synoptic of a dual pressure combined cycle being optimized by the pinch method. This method makes it possible to search for the configuration of the network of exchangers maximizing the electrical power produced. To do this, it draws the composite curves presented below.

At the beginning of the optimization process, the network of exchangers coupling the hot gas vein coming out of the gas turbine to the two steam circuits is not built, as in this figure. Only the "exchange" type processes of the steam circuits are defined, representing the two sets (economizer, vaporizer, superheater), and at least one gas cooling process (there are three here but it is not necessary).

Optimization of a combined cycle

When the optimization is completed, the network of exchangers is much more complex, as shown in the figure below. Some veins must be split in order to heat in parallel the steam circuits whose temperatures are close.

 

 Optimized combined cycle

 

Exergy composite curves of a dual pressure combined cycle

The red composite curve represents the cooling of the gas vein coming out of the gas turbine, and the blue the heating of water and steam in steam cycles.

The green curve is called Carnot Factor Difference Curve (CFDC). It corresponds to the difference between the two composites, and the black curve is called the Minimum Pinch Locus.

On this figure, the ordinates are expressed as Carnot factor θ = 1-T0/T, T0 being the temperature of the environment.

In this case, the irreversibilities of the system are exactly equal to the area underpinned by the green CFDC.

In this figure, the optimization method made it possible to minimize the pinch between the two curves: the green curve touches the black at the two pinch points.

Composite curves of a dual pressure combined cycle

 

Productive structures

This figure shows the correspondence between the diagram of a steam cycle and its productive structure.

Such a productive structure is interpreted as follows: the steam power plant is a machine which receives an external exergy input in the boiler, and by internal recycling, exergy is provided to the pump, which are the two production units in the left of the screen.

This exergy is partly converted into mechanical form in the turbine and partly dissipated in the condenser.

The net work is the fraction of mechanical power not recycled.

Correspondence between diagram and productive structure

Exergy balance sheets

This figure shows the exergy balance of a combined cycle automatically established by Thermoptim thanks to the productive structure of the project.

 Exergy balance sheets

Air treatment cycle

Here is the representation in the psychrometric chart of the air, of a summer air conditioning cycle. The outside air is first mixed with some of the indoor air that is recycled. The mixture is then cooled and condensed in a cold battery until its absolute humidity is equal to that corresponding to the supply conditions. The cooled air is then slightly warmed to lead to the desired comfort conditions.

 

Air treatment cycle

Example catalog

Example catalogs can be prepared to facilitate the loading of project and schema files.

This corresponds to Chapter 3 of the book Energy systems, 2nd Edition. On the image is selected the second guided exploration of Chapter 3.

Sample Catalog

Guided Explorations

The Thermoptim browser allows you to visualize guided explorations. Here is the tab presenting processes in the exploration dedicated to the discovery of Thermoptim.
 
Thermoptim browser
 
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