Model of Thermal Powerplant With Thermoelectric Condenser

As part of my IB MYP Personal Project, I created a model of a thermal power plant. The aim was to demonstrate the use of thermoelectricity in condensers to conserve thermal energy lost when the steam is condensed back to water, before being circulated back to the boiler.

Thermoelectricity is the direct conversion of heat difference into electrical energy via the Seebeck effect; although current thermoelectric generators are quite inefficient, when used in the condensers in power plants, they have been show to conserve ca. 3% of the energy generated. However, this figure might increase in the near future. If implemented on a global scale, thermoelectricity generate enough electricity to support several households (up to 90 million).

This thermal power plant has three main stages: boiler, turbine (with the DC generator) and (modified thermoelectric) generator.

I was able to generate 4-6V each with the turbine and thermoelectric generators, sufficient to light 3-4 LEDs. The project can be significantly modified to suit one's needs, or to make it more efficient. Possible modifications are included at each step.

Below the components for each stage are depicted.

Supplies

Boiler

Pressure Cooker
Gas Stove (or Induction Cooktop)

Turbine

Order Online, or
Make your own

Condenser

2 Aluminium Water Blocks 120x40 mm

3 Peltier Modules (ideally, TEC1-12715)

Immersible Water Pump

Battery (9V)

2 Beakers, or Containers

Water (Cooled to 5-15° C)

General

Transparent Plastic PVC Piping

Soldering Wires

Tools

Soldering Iron and Solder
M-Seal (or any other waterproof sealant
Tape (ideally, transparent)
Thermal Paste
Scissors

Step 1: Set-up the Turbine

I pre-ordered my steam turbine from:

https://www.amazon.in/gp/product/B08392RZ7N/ref=pp...

For those outside India, you can order yours at:

https://www.amazon.com/Eisco-PH0497A-Water-Turbine...

This turbine came with an LED; as a result I had to remove the bottom casing with a screwdriver, disconnect the wires from the LED, and connect them to a Voltmeter. This way, I could measure the exact voltage produced by the turbine. Take care to cover any exposed with some plastic coating to prevent short circuits between the wires of the turbine; you can also fix the junctions away from each other if necessary.

Then, test the turbine by blowing into the inlet. I could generate up to 1.5V this way; with steam, more voltage will be generated, so a relatively low voltage is not an issue at this stage.

You can also create your own steam turbine, by following the instructions here:

However, there are some differences between the two models. In the video, the steam is let to escape, but this model requires the steam to be collected into the condenser. To pass the steam through to the condenser, you will have to seal both ends of the turbine, and collect the steam in a narrow pipe at the outlet.

Step 2: Setup the Boiler

The boiler can be of your choice. I chose a pressure cooker on a gas stove, as it can produce large amounts of steam very quickly. You can also place the pressure cooker on an induction cook-top. It is not advisable to use an immersion heater on the market, as these are designed to heat water more slowly.

Step 3: Create the Condenser

This is the heart of the model. First, decide which aluminum water block will be for steam and which for the cold water. It is ideal to mark the water blocks in some way to indicate this (in the image, the blue water block is for the cold side). Then, check which side of the Peltier modules is the cold side/hot side; in my case, the labelled side was cold. Thus, the Peltier modules will be sandwiched between the two water blocks, with the cold Peltier module side facing the 'cold water block', and the hot side will face the 'hot water block'.

Arrange the Peltier modules side-by-side (same side up), and apply a pea-sized drop of thermal paste at the center of each module. Then, align and place the respective water block on the Peltier modules; place the water block horizontally on the modules, so that the thermal paste at the center is spread evenly across the module. (Thermal paste optimizes heat transfer) Make sure no module is poking out in any way, and that they are arranged parallelly. Wait for around 5 minutes, and then flip the modules and water block carefully, ensuring that they remain attached and do not shift position. Apply thermal paste on the other side, and place the other water block, while taking all the aforementioned precautions; additionally, if all the outlets of a water block face in one direction, e.g. in the above image, the two water blocks can be placed facing in opposite directions. (This will make the later pipe connections easier; however, it depends on the setup you choose.) Tape the modules and water blocks in place.

Tip: It is likely that you'll be dealing with a tangle of wires attached to the Peltier modules. As a result, it is a good idea connect the Peltier modules in series, like the cells of a battery, with the negative terminal of one module connected to the positive module of the next, and then wrap them with a rubber band, before performing this step.

Step 4: The Piping

All the piping connections were done with the transparent PVC pipes. Above is a schematic with all the piping connections (double lines represent piping). I shall also describe the connections in text. Connect the pipe to the outlet, by either wrapping the pipe around the outlet or putting it into the outlet, and then sealing the opening of the outlet. Make sure the pipe does not cause any blockages, e.g. come into contact with the turbine blades.

Connect the pressure cooker (or boiler) to the inlet of the turbine. For the pressure cooker, one can remove the whistle, and connect to metal outlet to the pipe. Then connect the outlet of the turbine to one of the inlets of the hot water block. (shown in images) Connect the other one (the outlet) with a pipe to an empty container. (shown in images) Connect one of the inlets of the cold water block to the water pump, which should be immersed in a beaker (or container) of cold water. Connect the outlet of the cold water block back to the container.

The water pump should be connected to a 9V battery, outside the beaker (make sure the connection with battery is well outside the beaker; otherwise, a short circuit will occur). Optional: To control the water pump more effectively, you can use a switch.

Seal the pipe connections with a waterproof sealant (surround the opening with the sealant and then let it dry for at least 10-20 min). This will ensure that the steam does not escape before passing through the turbine, and powers the turbine with the greatest possible force. Also, if steam seems to be escaping from the turbine, seal the turbine by surrounding the casing with the sealant. (second-last image)

Precaution: Make sure that the sealant does not block or clog the pipes.

Tip: Sometimes, the pipe might not fit neatly around the outlets or inlets (e.g. the outlet of the water pump.) In this case, cut a short section (2-3 cm) of a pipe with a smaller diameter, wrap this smaller pipe around the outlet, and then wrap the larger pipe around the smaller pipe. (last image)

Step 5: Test the Models

So, you have finally finished all the pipe and wire connections. Connect the terminals of the turbine to those of the voltmeter and turn the water pump on. Now, simply turn on your boiler (i.e. turn on the gas stove or induction cooktop to heat the pressure cooker). Within a few minutes, the turbine should start spinning quite quickly, and you should get a voltage reading. (I got a reading of approximately 4.5V). Next you can connect the voltmeter to the terminals of the Peltier modules (if you have connected them in series, then connect the voltmeter to the outermost terminals). You should get a reading of around 4V. If you want, connect a 2-3 LEDs to the turbine or Peltier module.

Precaution: If you want to touch or move any component of the model while steam is passing, be careful, as the components might be quite hot. Use a glove to touch the aluminium water blocks, turbine or boiler. Also make sure that the water pump is running and circulating cold water whenever the boiler is on and up to 10 minutes after it is turned off. Otherwise, the Peltier modules might overheat and get damaged.

Step 6: Conclusion

As part of the project, I also decided to investigate the potential consequences of introducing thermoelectric condensers in thermal power plants.

Thermal powerplants are only 30% efficient. Using current technology, thermoelectricity can increase the efficiency of thermal powerplants by roughly 3.3% (the example was for a 2000 MW thermal powerplant with bismuth telluride as the thermoelectric material). Although this figure is low, assuming the same level of efficiency for all powerplants when thermoelectricity is used globally across several powerplants, a lot of energy can be saved. In 2018, 26, 589 TWh of electrical energy was produced. Out of this, 38% of this, i.e. 10103 TWh comes from coal powerplants alone. 3.3% of this is 316 TWh, enough for up to 90 million households per year (using average global electricity usage as 3,500 kWh per person per year). By increasing the efficiency of thermal powerplants, we can also make them more sustainable. Thus, implementing thermoelectricity in powerplants can make a significant impact.

Step 7: Feedback

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