Heat exchanger plates: ZBT researches graphite PPS as an alternative to PFAS

PFAS could soon be banned. Could graphite polyphenylene sufide be an alternative for heat exchanger plates? The ZBT is developing an extrusion process for this material.

Manufacturers of heat exchangers are currently facing a central issue: the preferred material for an important temperature range may soon no longer be available – however, a promising alternative material is still too complex and expensive to use. A ZBT research project is now addressing this challenge.

Plastic heat exchangers for the temperature range of 80°C to 130°C are currently made from fluorinated or partially fluorinated thermoplastics. These very durable materials belong to the group of PFAS (per- and polyfluoroalkyl substances). Chemical compounds of this group are also known as forever chemicals due to their extremely long durability. They are not biodegradable, accumulate in the environment, animals, and humans, and lead to health risks. Therefore, this group of chemicals could soon be banned in the EU.

Graphite-PPS: durable and highly conductive

A possible alternative: Graphite-PPS – graphite-filled polyphenylene sulphide. It is highly resistant to temperature and media and conducts both heat and electricity very well. However, this material is not suitable for film extrusion.

A research project with significant involvement from ZBT is currently developing an innovative process to enable the extrusion of Graphite-PPS sheets nonetheless. To achieve this, extensive studies on the extrusion of thermally and electrically conductive Graphite-PPS sheets using a wide-slot die will be carried out. Such a process would also be suitable for the production of bipolar plates for high-temperature PEM fuel cells. Therefore, the project will also optimise compound materials that are specifically tailored to the respective application.

Extrusion and embossing for heat exchangers and fuel cells

The process to be developed is intended to enable the extrusion of the sheets in the desired shape and size. Subsequently, the extruded sheets will undergo an embossing process, in which corresponding channel structures are introduced. For both applications, embossing tools need to be researched and developed to enable precise and efficient embossing of the sheets.

The project concludes with the development and research of new heat exchangers and HT-PEM fuel cells based on the developed Graphite-PPS sheets. For this purpose, the sheets will be qualified in terms of their performance and durability in the fuel cell as well as in the heat exchanger. Various tests and analyses will be carried out to evaluate the properties and suitability of the sheets for the respective applications.

An important aspect of the project is to optimise the thermal and electrical conductivity of the Graphite-PPS sheets. This is crucial for the efficiency and performance of the heat exchangers and fuel cells. By using graphite as a conductive material, the sheets can ensure effective heat transfer while also providing electrical conductivity for use in fuel cells.

Project title:
Graphite-PPS sheets for heat exchangers and high-temperature polymer electrolyte membrane fuel cells
Project acronym: GRETE
Funding measure:
Applied non-nuclear research funding in the 7th Energy Research Programme “Innovations for the Energy Transition” according to the announcement by the Federal Ministry for Economic Affairs and Energy of 18 June 2021
Duration: 1 January 2024 – 31 December 2026 (3 years)
Funding reference number: 03EN5041F

Image Collection

Project objective: Development of a system for the extrusion of graphite-PPS sheets with subsequent embossing

GRETE project: Together with partners, the ZBT is developing a process for the extrusion of graphite-PPS sheets using a wide-slot die for heat exchangers and fuel cells.

More Projects

12. September, 2024

Free simulation model for the calculation of hydrogen refuelling systems

Designing hydrogen refuelling systems for reliable and safe operation is a major challenge due to constantly changing requirements and rapid technological development. The HRS-Modell which has now been published, aims to help.

26. June, 2024

Project launch: DAC-2-E-Methane – storing green electricity surpluses in e-methane

Storing green electricity chemically instead of regulating it – this is possible with hydrogen and its derivatives. E-methane is a climate-neutral energy source if the carbon is captured from the air. A project that has now been launched is exploring the technical possibilities.

3. June, 2024

Project launch: Development of a multi-port cathode valve for fuel cell systems

Multi-port valves could reduce the number of valves in the cathode path of fuel cell systems, with advantages for mobile applications in particular. ZBT and Rheinmetall-Pierburg want to develop such a valve in order to reduce the use of materials and resources as well as costs in fuel cell production. ZBT is focussing on simulation, material tests and functional and endurance tests.