Advancing 3D-Printed Heat Exchangers in the DESOLINATION Project: A Milestone at LUT University

Advancing 3D-Printed Heat Exchangers in the DESOLINATION Project: A Milestone at LUT University

by | Oct 3, 2024 | Milestones, Results - Combination of CSP pland and forward osmosis desalination, Results - Pilot plant preparation

As part of the DESOLINATION project’s ongoing mission to decarbonize the desalination process, a major milestone has been achieved at LUT University: the experimental validation of a 3D-printed heat exchanger. This breakthrough demonstrates that additive manufacturing (also known as 3D printing) can significantly enhance the performance of heat exchangers used in supercritical carbon dioxide (sCO2) Brayton cycles, paving the way for more efficient energy systems.

Recently, the DESOLINATION project team reached a major milestone by successfully validating their experimental setup at LUT University. This validation process involved several key steps:

  1. Design: The team developed a blueprint for the 3D-printed heat exchanger, focusing on optimizing its shape and function.
  2. Simulation: Using tools like Computational Fluid Dynamics (CFD), the team simulated how the heat exchanger would perform under real-world conditions.
  3. Additive Manufacturing: The heat exchanger was printed using advanced 3D printing techniques, allowing for a more intricate and efficient design.
  4. Assembly: The printed parts were then assembled into a fully functional heat exchanger.
  5. Testing: The final step was to test the heat exchanger to ensure it could withstand the pressures and temperatures expected in the sCO2 Brayton cycle.

The successful completion of these steps demonstrates that 3D-printed heat exchangers can perform effectively in high-pressure, high-temperature environments. This breakthrough marks an important step toward integrating these advanced designs into real-world concentrating solar power (CSP) systems.

What is a Heat Exchanger?
What This Means for the Future of Sustainable Energy

The ability to use 3D-printed heat exchangers in sCO2 Brayton cycles has far-reaching implications for the DESOLINATION project and beyond. By improving the efficiency of energy conversion, these innovations will make it easier to generate clean electricity from renewable sources like solar power. This is particularly important for the project’s goal of decarbonizing desalination, which requires large amounts of energy to produce fresh water in arid regions.

The Role of Heat Exchangers in Desalination and Energy Generation

Heat exchangers are crucial in systems that convert heat into usable energy. In the DESOLINATION project, they are key components in the sCO2 Brayton cycle, a thermodynamic process that uses heat to generate electricity. When combined with concentrating solar power (CSP)—which concentrates solar energy to produce high levels of heat—these systems offer a more efficient way to produce power while reducing carbon emissions.

However, creating heat exchangers that can handle the extreme conditions required by sCO2 Brayton cycles (temperatures up to 600°C and pressures around 250 bars) presents significant challenges. That’s where additive manufacturing comes in.

Additive Manufacturing: A Game Changer for Heat Exchanger Design

Traditional manufacturing techniques often limit the design of heat exchangers, making it difficult to optimize them for maximum efficiency. Additive manufacturing, or 3D printing, solves this problem by allowing engineers to create more complex designs that would be impossible with conventional methods.

In the DESOLINATION project, the team used 3D printing to create highly specialized heat exchangers that are better suited to the high-pressure, high-temperature conditions of the sCO2 Brayton cycle. These new designs are expected to improve the overall efficiency of the system, making it more effective at converting solar energy into electricity.

As DESOLINATION moves forward, the continued development and testing of 3D-printed heat exchangers will play a crucial role in creating more sustainable, efficient energy systems. With each milestone, the project is getting closer to its vision of a world where desalination is powered by clean, renewable energy. By combining cutting-edge technologies like additive manufacturing and advanced thermodynamic processes, the DESOLINATION project is paving the way for a greener, more water-secure future.
Pushing the Limits of Heat Exchanger Design with CFD in the DESOLINATION Project

Pushing the Limits of Heat Exchanger Design with CFD in the DESOLINATION Project

by | Oct 3, 2024 | Milestones, Results - Combination of CSP pland and forward osmosis desalination, Results - Pilot plant preparation

The DESOLINATION project, funded by the European Union’s Horizon 2020 program, is making remarkable strides in its mission to decarbonize desalination. One of the most exciting developments comes from our work on optimizing heat exchangers for use in supercritical carbon dioxide (sCO2) Brayton cycles. These innovations could revolutionize how we generate power from renewable energy sources like solar power. Here’s a closer look at how Computational Fluid Dynamics (CFD) is playing a key role in this effort.
The Role of CFD: Optimizing Heat Exchanger Performance

Designing heat exchangers that can operate under these extreme conditions is no small feat. To ensure the best possible design, DESOLINATION is using Computational Fluid Dynamics (CFD)—a powerful computer tool that models how fluids flow and how heat is transferred in complex systems.

CFD allows the project team (particularly TEMISTh) to simulate the performance of the heat exchanger in a virtual environment. This includes analyzing key factors such as:

  • Thermal efficiency: How well the exchanger transfers heat from one fluid to another.
  • Pressure drop: The reduction in pressure that occurs as the fluid flows through the heat exchanger, which can impact overall system performance.
  • Thermomechanical constraints: The structural stresses the exchanger must withstand at high temperatures and pressures.

By using CFD, the team can find the optimal balance between thermal efficiency and pressure drop, ensuring the heat exchanger performs well while remaining durable.

What Are Heat Exchangers and Why Are They Important?

A heat exchanger is a device that transfers heat from one fluid (either a liquid or gas) to another. In energy systems, they are essential for converting heat into usable power. In the DESOLINATION project, the goal is to create highly efficient heat exchangers that can operate under extreme conditions—temperatures as high as 600°C and pressures up to 250 bars. These conditions are required for a supercritical carbon dioxide (sCO2) Brayton cycle, a process that uses heat to generate electricity more efficiently than traditional steam cycles.

Real-World Testing at King Saud University

After fine-tuning the design using CFD, the next step is real-world testing. The team plans to run these heat exchangers for 4,000 hours at a pilot plant in King Saud University. These tests will move the project closer to Technology Readiness Level (TRL) 7, meaning the technology will be ready for deployment in real-world systems.

The Role of CFD: Optimizing Heat Exchanger Performance

The preliminary results from these simulations are promising. The team believes that their designs could push the limits of what’s possible for heat exchangers in sCO2 Brayton cycles. If successful, these innovations will pave the way for more efficient concentrating solar power (CSP) plants, where solar energy is concentrated to generate high levels of heat, which can then be used to produce electricity.

CFD: More Than Just an Engineering Tool

Beyond its technical capabilities, CFD has also proven to be a powerful communication tool. The simulations it creates provide visually engaging representations of how heat and fluids move through the system, making it easier to explain the science behind the project to a broader audience.

By using CFD to design and optimize these cutting-edge heat exchangers, the DESOLINATION project is taking a huge step toward more sustainable and efficient energy systems, bringing us closer to a future where desalination can be powered by clean, renewable energy.

Innovative Thermodynamic Solutions: effective and efficient coupling of CSP and desalination technologies

Innovative Thermodynamic Solutions: effective and efficient coupling of CSP and desalination technologies

by | May 28, 2024 | Milestones, Results - Combination of CSP pland and forward osmosis desalination

Discover our groundbreaking work over the past year in advancing CO2 mixtures for thermodynamic cycles, pushing the boundaries of energy efficiency and sustainability.

The research team from the Energy Department at Politecnico di Milano (POLIMI), DESOLINATION project coordinator, has successfully simulated large-scale Concentrated Solar Power (CSP) plants using innovative CO2 mixtures, enhancing their efficiency and performance. Additionally, they introduced the CO2+SiCl4 mixture in literature for trans-critical cycles, showcasing its potential in improving cycle efficiency.

Our Journey in Thermodynamic Cycle Development

Over the past year, POLIMI has made significant strides in the development and simulation of thermodynamic cycles using CO2 mixtures. Here are some of the key milestones and achievements.

Introduction of CO2+SiCl4 Mixture Research

Introducing the CO2+SiCl4 mixture into the literature for transcritical cycles

With regard to the application of CO2 mixtures in thermodynamic cycles, the work was developed both on the simulation of the large-scale CSP plant with innovative CO2 mixtures, introducing the CO2+SiCl4 mixture into the literature for transcritical cycles, and adding details on the simulations and design of the DESOLINATION project’s demonstration plant, the 1.8 MWel cycle operating with the CO2+SO2 mixture.

Experimental investigation of the CO2+SiCl4 mixture as innovative working fluid for power cycles: Bubble points and liquid density measurementsv- Energy Journal
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In this perspective, complete off-design simulations have been carried out, including the behavior of the real heat exchangers that will be installed and including the management of the inventory of the cycle in off-design.

Learn more of the effect of supercritical CO2 Fluid Properties on Heat Exchanger Design…

Effects of Supercritical CO2 Fluid Properties on Heat Exchanger Design
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Simulation of the large scale CSP plant with CO2+SiCl4 mixture

POLIMI combined CSP with CO2-mixtures power cycles and forward osmosis desalination system, performing simulations in Dubai.

Using these innovative technologies, our CSP plant showed high solar-to-electric efficiencies (around 19% on yearly basis) and very low freshwater specific thermal consumption (about 10 kWhth/m3) when the PABG2000 is used as draw agent.

Characterization of the physical properties of the thermoresponsiveblock-copolymer PAGB2000 and numerical assessment of its potentialities in Forward Osmosis desalination
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Specifically, when comparing the CSP (concentrated solar power) +FO (forward osmosis) studied in DESOLINATION with the CSP+MED assuming the same solar plant and power cycles, the freshwater production is incremented by more than 50%.

When the solution of DESOLINATION is compared with a PV+RO plant, a reduction of reflective area of 28% is foreseen, if both freshwater and electricity are produced with the PV+RO plant.

Simulations of CSP combined with CO2 mixed power cycles and a forward osmosis desalination system in Dubai
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Finally, POLIMI also conducted an experimental campaign on the coalescer using a solution of water and PAGB2000, obtaining an expression of the separation efficiency, to be deployed in the simulations.

The research team from the Energy Department at Politecnico di Milano will shortly be publishing an article on the results of its Experimental study on coalescer efficiency for liquid-liquid separation.

Saty tuned!

Consults our literature to find out more

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Simulations of CSP combined with CO2 mixed power cycles and a forward osmosis desalination system in Dubai

Simulations of CSP combined with CO2 mixed power cycles and a forward osmosis desalination system in Dubai

by | Dec 27, 2023 | Milestones, Results - Combination of CSP pland and forward osmosis desalination

This year, our project coordinator, Politecnico di Milano (POLIMI) carried out simulations at its CSP (concentrated solar power) plant in Dubai to combine CSP with CO2-mixed electric cycles and a forward osmosis (FO) desalination system.

Using innovative technologies, POLIMI’s CSP plant has demonstrated high solar-electric efficiencies (around 19% on an annual basis) and very low specific thermal consumption of fresh water (around 90 kWhth/m3) when PABG2000 is used as the drawing agent. The synergy between electricity and freshwater production was effective.

In particular, if the CSP+FO solution studied in DESOLINATION is compared with the CSP+MED solution, assuming the same solar power plant and energy cycles, freshwater production is increased by over 40%.

The DESOLINATION project aims to develop an innovative desalination system combining direct osmosis and membrane distillation, using a draw-off solution. Forward osmosis means that seawater is extracted from the sea, the water is drawn through the membrane by the draw solution and the remaining minerals (brine) are rejected.

When the DESOLINATION solution is compared with a PV+RO plant, a 47% reduction in reflective surface is predicted, if the PV+RO plant produces both fresh water and electricity.

We have also carried out an experimental campaign on the coalescer* using a solution of water and PAGB2000, the aim being to obtain an expression for the separation efficiency, which will then be used in simulations.

*Coalescer: used to separate elements from an emulsion (i.e. liquid water and oil from compressed air using a coalescing effect)

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TEMISTh has launched the manufacture of DESOLINATION heat exchanger core!

TEMISTh has launched the manufacture of DESOLINATION heat exchanger core!

by | Nov 9, 2023 | Milestones, Results - Combination of CSP pland and forward osmosis desalination

The DESOLINATION project has reached an important milestone: after an initial design and simulation phase carried out by our project partner TEMISTh, the first heat exchanger model has now been printed!

Heat Exchangers can take different forms depending on many parameters: temperatures, pressures, chemical properties of the fluids, etc. But they are critical to the heat transfer within the CSP cycles to recover heat from the sun and make the turbine work.

In DESOLINATION, specific work will be on exchanging heat between the power cycle (air in the existing plant, CO2 in the innovative one) and the desalination draw solution (highly concentrated solution). New Printed Circuit Heat Exchangers (PCHEs) and Printed Fin Heat Exchangers (PFHEs) will thus be produced.

Following a simulation and design phase for supercritical CO2 and molten salt, our project partner TEMISTh has launched the manufacture of the Heat Exchanger core (system used to transfer heat between a source and a working fluid).

The aim of this first mock-up is to answer technical questions such as powder removal, assembly and design validation.

The next step is to test the mock-up on an sCO2 loop for validation.

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Effects of Supercritical CO2 Fluid Properties on Heat Exchanger Design

Effects of Supercritical CO2 Fluid Properties on Heat Exchanger Design

by | Oct 2, 2023 | Results - Combination of CSP pland and forward osmosis desalination

Supercritical CO2 (sCO2) in industrial applications is a promising solution for the reduction of equipment size and for the potential increasement of overall efficiency. The characteristics of CO2 near the critical point are advantageous for the heat transfer, with high specific heat capacity when compared to conventional liquid or gas coolants. Moreover, dopants can be mixed to CO2, in a blend, to further increase the heat transfer and elevate the critical point of the fluid. Under the framework of the Horizon 2020 DESOLINATION (DEmonstration of concentrated SOLar power coupled wIth advaNced desAlinaTion system in the gulf regION) project, a heat exchanger was designed using CO2 and blend as working fluids in an innovative power cycle bank of a concentrated solar power (CSP) plant coupled to a water desalination system. In this paper, the innovative heat exchanger is evaluated in terms of the geometry, focusing on heat transfer and turbulence, using computational fluid dynamic (CFD) simulations with SST k-ω turbulence model and real-gas models with REFPROP library for thermodynamic and transport properties. Within each fluid, the diameter of the channels varied from 1.8–2.2 mm and the results are compared to analytical models. The geometry with 1.8 showed a larger pressure drop, but also larger overall heat transfer coefficient. It is observed that both pressure drop and heat transfer decrease with the diameter. Blend as the hot fluid resulted in higher average temperature and heat transfer coefficient, but in lower pressure drop than pure CO2. Nusselt number correlations were compared, showing the decrease of its values with the diameter for pure CO2, while for the blend it was observed higher values for 2.0 mm of diameter, except for Fang and Xu correlation that showed the same trend as the CO2.

 

Keywords: supercritical CO2; heat exchanger; gas cooler; computational fluid dynamics
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Authors:

Afonso Lugo
Lappeenranta-Lahti University of Technology, Lappeenranta, Finland

Teemu Turunen-Saaresti

Lappeenranta-Lahti University of Technology, Lappeenranta, Finland
Jonna Tiainen
The Switch, Lappeenranta, Finland

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