Insights and intelligence.

Case studies. Thought leadership. White papers. Technical updates. Find the latest insight from Reaction Engines here – including examples of how our technology is making a difference in the commercial sector, and intelligence on where our ground-breaking work can take us in the future.

Preparing for lift-off.

How responsive launch will be critical to defence in space.

Thought Leadership

The need to rapidly respond to events and threats within the space domain has become more evident with the recent geopolitical situation highlighting the importance of access to information to build resilience. This paper explains what responsive launch entails, what it could look like, and highlights the case for a UK capability towards responsive launch.

Further, better, faster, longer.

Why improved thermal management of batteries is critical to the EV business case.

Whitepaper

The future of cars is electric. The UK Government will ban the sale of internal combustion engine (ICE) vehicles in 2030, making it one of fourteen countries that have announced ICE restrictions.

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Thought leadership.

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Technical updates.

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White papers.

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Case studies.

Faster, further, longer
Removing heat would see a step change in EV battery technology

The future of cars is electric. The UK Government will ban the sales of internal combustion engine (ICE) vehicles in 2030, making it one of fourteen countries that have announced ICE restrictions.

Faster, further, longer
Removing heat would see a step change in EV battery technology

The future of cars is electric. The UK Government will ban the sales of internal combustion engine (ICE) vehicles in 2030, making it one of fourteen countries that have announced ICE restrictions. Most automotive manufacturers have pivoted to electric vehicles (EVs), with Audi expecting to be completely electric by the 2030s. According to BloombergNEF, half of global passenger-vehicle sales in 2035 will be electric.

A thriving space economy is coming.
It will need a reliable space transport network.​

As part of the #SpaceInfrastructure2040 series with the TWI and Lloyds Register, our CEO Mark Thomas discusses how space can offer a solution to Earth’s energy and resource challenges.

A thriving space economy is coming.
It will need a reliable space transport network.​

As part of the #SpaceInfrastructure2040 series with the TWI and Lloyds Register, our CEO Mark Thomas discusses how space can offer a solution to Earth’s energy and resource challenges.
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Thought leadership.

Cooling rocket plume exhaust gases with Nammo Westcott

Nammo Westcott, commissioned by the European Space Agency, is currently constructing and will operate the UK National Space Propulsion Test Facility at Westcott Venture Park, Buckinghamshire, UK.

Cooling rocket plume exhaust gases with Nammo Westcott

Nammo Westcott, commissioned by the European Space Agency, is currently constructing and will operate the UK National Space Propulsion Test Facility at Westcott Venture Park, Buckinghamshire, UK. The National Space Propulsion Test Facility will provide world-leading facilities within the UK that will enable rocket engines up to 1.5kN to be tested in high-altitude (near vacuum) conditions, cementing Westcott as the centre of excellence for space propulsion within the UK.

Waste heat energy recovery with Brunel University

Brunel University had been reviewing current methodologies for waste heat recovery in industrial processes, specifically heat recovery opportunities for energy optimisation in the steel/iron, food and ceramic industries.

Waste heat energy recovery with
Brunel University

Brunel University had been reviewing current methodologies for waste heat recovery in industrial processes, specifically heat recovery opportunities for energy optimisation in the steel/iron, food and ceramic industries. Industrial waste heat is energy that is generated through industrial processes which is lost and released into the environment. With Reaction Engines’ expertise in heat exchange technology, Brunel engaged the Applied Technologies team with a view to identifying and developing a more viable solution for the capture and re-use of high grade (high temperature) waste heat.
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Technical updates.

Reaction Engines completes further validation of SABRE technology

We are pleased to announce that we have completed the testing of two vital sub-systems of SABRE; the HX3 heat exchanger and the advanced hydrogen preburner.

Reaction Engines completes further
validation of SABRE technology

We are pleased to announce that we have completed the testing of two vital sub-systems of SABRE; the HX3 heat exchanger and the advanced hydrogen preburner. These sub-systems supply heat energy and air to the air-breathing core of the engine. Alongside our partners at Airborne Engineering and S&C Thermofluids, we have been able to conduct agile and robust testing campaigns in challenging circumstances. These experiments have yielded high levels of insight and expertise and are the latest in a wider series designed to validate SABRE technology.

White papers.

Further, better, faster, longer.​

Why improved thermal management of batteries is critical to the EV business case.​

Please enter your details below to download the document:

Faster, further, longer

Removing heat would see a step change in EV battery technology

The future of cars is electric. The UK Government will ban the sales of internal combustion engine (ICE) vehicles in 2030, making it one of fourteen countries that have announced ICE restrictions. Most automotive manufacturers have pivoted to electric vehicles (EVs), with Audi expecting to be completely electric by the 2030s. According to BloombergNEF, half of global passenger-vehicle sales in 2035 will be electric.
This rise in EVs has been driven, in no small part, by constant, incremental improvements in EV battery technology. Better battery performance allowed EVs to travel farther and charge quicker, making them more tempting to the average driver. But potential converts still worry about range anxiety, long waits at charge points, and expensive battery replacements every few years. Growth will likely continue steadily, but a step change in battery technology could provide the catalyst we need to allay concerns and deliver a giant leap in sales.

Too hot to handle?

Batteries have improved gradually through ever better designs. But all face an ongoing challenge that has not yet been properly addressed – heat management. If this could be addressed, we could see a step change in performance and lifetime.

Currently the battery packs that power most EVs are made up of Li ion cells – some use thousands of small cells, some use hundreds of larger ones. These come in one of three formats – cylindrical, prismatic or pouch cells. Each has benefits and drawbacks, but all create complex patterns of heat transfer, and all suffer due to too much heat in the wrong places.

EV battery packs have the best thermal stability and lifetime if – when the vehicle is being driven – they maintain a temperature between 15 to 35°C, with a maximum across cell temperature difference of 5°C. To make things more complicated, they should be charged at temperatures of around 50°C to minimise dendrite formation.

Li ion batteries generate large amounts of heat in use, especially during rapid charging and accelerating. And this heat is very unevenly distributed, meaning some cells, or parts of cells, degrade much quicker than others. A single cell’s immature deterioration can considerably reduce performance and efficiency of the whole battery pack.

The safety of the vehicle is also a serious consideration. Li-ion batteries are particularly susceptible to thermal runaway events – a repeating cycle in which excessive heat causes more heat until operation ceases or an explosion occurs. This is due to their propensity to self-heat once the electrolyte inside reaches a certain temperature.

Current battery cooling does not solve the problem

For the above reasons, EV battery packs employ battery thermal management systems (BTMS). A BTMS must provide the necessary heat transfer for optimal charging and discharging, in the confined space available in the battery pack, and be manufactured economically. This is no small ask.

There are two main types of BTMS: active and passive. Active systems depend on forced circulation of a coolant such as water or air. Passive systems use methods like heat pipes or hydrogels to remove heat from the pack. The complexity of these systems adds significantly to the cost of the battery pack – in the region of 10-20%.

Alongside cost, one of the biggest problems with current BTMS options is that they create thermal gradients. For example, a cold plate beneath the cells cools the bottom much faster than the top. Meanwhile, a liquid cooling loop will remove heat more effectively from cells at the start of the loop but by the end it can’t absorb any more heat.

Temperature gradients cause adverse voltage distributions and differential ageing between the cells. In other words, the cell does not age uniformly, an ageing gradient occurs inside the cell, reducing the efficiency and lifespan of the batteries. Strong thermal gradients can also lead to deformations in cylindrical cells.

If we could develop a cost-effective way to deliver isothermal heat management – ie maintaining a consistent and even temperature throughout the cells and the system – we could deliver a big change to battery performance.

A revolution in battery cooling technology

At Reaction Engines, we’re pretty good at thermal management. Our expertise has been developed through years of work on our revolutionary hypersonic air breathing rocket engines, which can cool passing air from 1,000oC to -150oC in 1/20th of a second.

Taking this expertise, we looked at how heat can be better managed within EV batteries.

The trick was to use the system itself to manage heat evenly. So, when one spot rises in temperature, we wanted to take that heat and dump it in a cooler place first. That is an efficient immediate solution, as the heat has less far to travel. Cooling heat pipes still take heat out of the whole system, but in the meantime, all the cells within it stay perfectly regulated. All components stay cooler, which ensures any degradation is slow and even.

A perfect heat management system might use materials with complex structures to manage this in a highly sophisticated way, and this was our first thought. But we needed a solution that was affordable to the average EV battery manufacturer. So, we went back to the drawing board – same idea, but with the starting point of making it affordable. We relooked at the concept and considered how we could create something cost-effective that still did the job.

After a few iterations with different materials and designs, we created a simple foil that could be attached to any battery cell. This creates a thermal ground plane which transfers heat evenly across the surface, then takes it out of the system, so you’re not left with hotspots.

The nature of the foil design means that the benefits are realised not just on a specific one-cell basis, but across the whole system. They equalize thermal gradients across the whole battery pack. So it all degrades at the same time, in the same way. Plus, unlike rigid cooling systems, which can suffer from the thermal resistance of air bubbles in the interface between cooling and the cells, our solution is malleable and conformable, so it adheres to the cells – even pouch cells which expand and compress during use.

The benefits of isothermal EV batteries

Improved cooling and isothermal performance means batteries last longer because parts are exposed to less heat and therefore degrade more slowly. And because all parts degrade uniformly, batteries don’t need to be replaced when only certain parts are degraded. The whole battery lasts for the whole of its useful life. This could easily add an extra two years to the battery’s lifetime.

There are other benefits too. Pushing a car to its limits of charging (eg using ultra-rapid chargers) or discharging (eg accelerating) creates heat. This creates risk of thermal runaway if just a single part crosses a certain temperature threshold, so BTMS’s limit performance to keep batteries at safe temperatures. But this control system is based on poor knowledge of heat within the cell, so must set cautious safety limits based on the potential hottest point, limiting efficiency.

Isothermal heat management would eliminate these dangerous hotspots and create an even, easily measurable temperature across the cell. That would give BTMS control systems much greater scope to enable faster charging and better vehicle performance, without the risk of overheating, unlocking the full potential of the battery.

Finally, we can reduce weight. Because they’re so lightweight, BTMS developed using our foils can be up to 35% lighter, making vehicles more ‘fuel’ efficient.

Altogether, this adds up to a step change in battery performance. We expect that deploying these foils would deliver a 20-30% improvement in battery performance.

How Reaction Engines can help battery manufacturers

At Reaction Engines, we are heat management experts. We believe our thermal management expertise to be a decade ahead of anyone else. But we are not large-scale manufacturers. We are therefore looking to partner with innovative battery companies or vehicle OEMs. We are looking for partners interested in licensing our design, or who we can work with to design new battery systems which build in isothermal heat management from the ground up.

We have a patented recyclable foil design, and patented techniques for fitting or retrofitting it to a range of EV fuel cells to ensure they adhere in ways that deliver near-perfect isothermal cooling. The secret is in how you deploy them into a complex battery design. But once you have them in, they are easy to scale and do not add to end-of-life costs.

The commercial opportunity for EV batteries

What does all this mean for the bottom line?

Taken together, the heat management innovation discussed in this article, will allow us to help battery manufacturers offer a 1.5 step change in performance, charge speed, and battery lifetime. This could benefit all battery manufacturers, but for a bold new player in particular – who is open to new approaches – this could be a significant opportunity to leapfrog the competition.

For the vehicle OEM they are selling to, this would mean they have better performing, longer lasting, cheaper vehicles, giving them a better proposition, which they can back with longer warranties – would you buy a car guaranteed for eight years of battery life, if there was a similar model that guaranteed ten?

Ultimately, this would be good for the manufacturers, good for the consumer, and good for a world where competition for battery materials is hotting up, and pressure on environmentally friendly battery disposal is rising.

Space Infrastructure

The Final Frontier

A thriving space economy is coming.
It will need a reliable space transport network.

As part of the #SpaceInfrastructure2040 series with the TWI and Lloyds Register, our CEO Mark Thomas discusses how space can offer a solution to Earth’s energy and resource challenges.

Mark Thomas – Chief Executive Officer, Reaction Engines Ltd.

If we are to continue thriving as a connected, energy-hungry planet, we will eventually need to look beyond our own atmosphere.

Space – if we can access it economically – offers a tantalising solution to global energy and resource challenges, and a raft of opportunities in manufacturing, communications, and tourism. Money is pouring in, with vocal cheerleaders in the likes of Elon Musk, Jeff Bezos and Larry Page. The global space economy is estimated to be £400 billion by 2030, and will be far bigger by 2040.

The possibilities are as fantastic as they are transformational. Space-based solar panels could offer ‘always-on’ power, overcoming the intermittency and land requirements of terrestrial renewables. These would be fixed to satellites with a clear line of sight of the sun, generate electricity, and beam it in microwaves to ground receivers. The UK Space Agency has commissioned a study of its feasibility by 2050 and a number of concepts, including CASSIOPeiA in the UK, are in development.

Asteroids full of raw materials could in theory be mined to meet growing demand for infrastructure. Though early attempts have failed, and profitable missions are probably a way off, asteroid mining could well be a nascent industry within 20 years, as dwindling earthly resources and rising environmental costs make the rewards of off-planet mining greater.

Space could also be a destination for manufacturing. It’s low gravity, low temperatures, near vacuum, and abundant solar power, offer useful conditions for some advanced materials production. The moon could become a base for manufacturing space infrastructure for more distant missions, including asteroid mining. Research is already looking at using lunar dust to create oxygen for rocket fuel and metal powders for 3D printing.

Space tourism is likely to evolve into a mature industry by 2040. And the dream of colonising planets – long the realm of science fiction – is starting to feel within reach.

We need a mature transport infrastructure to serve the space industry

If we are to realise these opportunities, and others, we will need ways to make accessing space routine. Just as with earth-bound industries, we need to be able to take machinery, parts, and people, to and from our factories, mines, and tourist attractions.

This means affordable rockets, widely available launch facilities, and economies of scale. A truly mature space industry would see routine rocket launches on a daily basis.

Making this viable will come down to cost. Whilst rocket launches have come down from around $150 million to $25 million, these are still big price tags. They also come with a failure risk of around 5%, adding to overall costs and making routine human space flight unacceptably risky.

A future space infrastructure will need rockets capable of launching for under $1million in today’s money, and with a safety record comparable to aviation, whilst also being environmentally sustainable.

For a long time this has felt like science fiction, but it’s starting to feel very real.

Opening up the space economy – affordable, reliable, space transport

To underpin this future, Reaction Engines’ is researching and developing a revolutionary new propulsion technology that could enable far more affordable rockets. Our Synergetic Air-Breathing Rocket Engine (SABRE) can propel an aircraft to five times the speed of sound in the atmosphere, and 25 times in space.

Our unique innovation is ‘air breathing propulsion’ (see ‘How the SABRE engine works’). This is a fundamental redesign of rocket engines, enabling a far more efficient propulsion system, which in turns allows more versatile rocket designs. This increases launch rates, whilst dramatically lowering manufacturing and operational costs of future launch vehicles.

Reaction Engines propulsion technology is undergoing R&D and testing, with key technologies successfully demonstrated.

Investors are bought in, from private individuals enthused about the space opportunity, to industries such as Boeing and Rolls-Royce who see benefits to their own R&D, to our government who wants the UK to be a leader in space.

We hope that by 2040 our technology will be at the heart of a new space transport industry, with air breathing engines offering a complimentary capability and extremely attractive alternative to rockets (as well as on hypersonic planes travelling twice the speed of Concorde). In the meantime, our revolutionary heat management technology is finding other applications in optimising automotive engines, improving electric vehicles, and generating power from waste heat.

A future space economy will see countries establish space ports as transit hubs, much as air- and seaports serve their respective industries. These will provide a base for spacecraft to travel back and forth between satellites, space stations, and eventually the moon, mars, and the asteroid belt. They will link space and ground infrastructure, ferrying in replacement parts and taking space ores and advanced materials to factories and resellers. Like shipping, rail, and air before it, space transport will one day evolve from the realms of the imagination, to a routine and highly efficient logistics operation.

How the SABRE engine works

In a rocket engine, fuel is mixed with an oxidiser, and combusts to generate propulsion. But carrying this oxidiser on board adds a lot of weight. SABRE generates its own oxidiser from the air around it, thanks to a feat of precision engineering.

During flight, air is sucked into the engine. Rapidly slowing air from hypersonic speeds to a standstill creates high compression, heating it to over 1,000oC.

SABRE’s precooler – a system of thousands of tubes that allow coolant to be injected and removed for extremely efficient cooling – rapidly cools the air to ambient temperatures or down to -150oC in 1/20th of a second.

This has two critical effects. The heat extracted from the air powers a compressor via a turbine. The low temperature air feeds into this compressor, creating oxidiser. This is combusted with hydrogen to create propulsion.

This highly efficient system can be built into a lightweight aircraft or spacecraft design. Outside the atmosphere, it switches to a highly efficient rocket mode, which uses stored liquid oxygen in far smaller quantities.

All this is made possible by the design of the precooler, which incorporates thousands of millimetre size tubes, made from hair-width materials, to deliver revolutionary heat management and fully proven to Mach 5 (1,000oC) temperatures. Reaction Engines worked closely with experts from TWI to understand how to join these together to optimise efficiency and ensure no leakage under extremely harsh temperatures and pressures.

Rocket cooled:

Intercooler for rocket plume technology

How we made a difference

Nammo Westcott, commissioned by the European Space Agency, is currently constructing and will operate the UK National Space Propulsion Test Facility at Westcott Venture Park, Buckinghamshire, UK. The National Space Propulsion Test Facility will provide world-leading facilities within the UK that will enable rocket engines up to 1.5kN to be tested in high-altitude (near vacuum) conditions, cementing Westcott as the centre of excellence for space propulsion within the UK. A key enabler of the facility is the rocket plume intercooler (heat exchanger) which will cool the rocket exhaust gases from temperatures of in excess of 2,000°C to less than 50°C.

Nammo Westcott is a major supplier of chemical propulsion systems to key spacecraft manufacturers. Its rocket engines and thrusters serve commercial, defence and science markets. Nammo is involved in the development, production and test activities in rocket engines test services, chemical propulsion subsystems, monopropellant attitude control system thrusters and hypergolic bipropellant apogee engines.

The challenge

Nammo required a heat exchanger / intercooler that would be able to withstand the extreme temperatures generated from the firing of the rockets and to remove that heat from the generated exhaust plume to allow the vacuum pumps to reliably operate and maintain the simulated high altitude conditions. Quenching gas temperatures in excess of 2,000°C was a unique challenge and required a partner with expertise in providing first-class thermal management solutions. Nammo approached numerous companies all over the world but none, other than Reaction Engines, could provide a solution on the scale that they required.

The rocket plume intercooler core

The rocket plume intercooler
outer vacuum vessel (shell)

Creating value

Nammo Westcott is a major supplier of chemical propulsion systems to key spacecraft manufacturers. Its rocket engines and thrusters serve commercial, defence and science markets. Nammo is involved in the development, production and test activities in rocket engines test services, chemical propulsion subsystems, monopropellant attitude control system thrusters and hypergolic bipropellant apogee engines.

Technical specification

Vessel Diameter: 1.7m
Total Height: 1.8m
Total Length: 4.5m (inc. diffuser adapter)
2.0m (ex. diffuser adapter)
Heat exchanger core size: 1m x 1m x 1m
Dry Masses:
Core:
Main Vessel:
Diffuser adapter:
Total (dry) mass:
Wet mass:

810kg
1180kg
435kg
2425kg
+100kg
Inlet temperature (’shell side’): ~2,300°C
Outlet temperature (’shell side’): < 50°C
Heat Rejection: 1.5 to 2.0 MW
(depending on rocket under test)

Heat capture:

Effective waste heat recovery system

Background

Brunel University had been reviewing current methodologies for waste heat recovery in industrial processes, specifically heat recovery opportunities for energy optimisation in the steel/iron, food and ceramic industries. Industrial waste heat is energy that is generated through industrial processes which is lost and released into the environment. With Reaction Engines’ expertise in heat exchange technology, Brunel engaged the Applied Technologies team with a view to identifying and developing a more viable solution for the capture and re-use of high grade (high temperature) waste heat.

About Brunel University

Brunel University’s research focuses on areas in which it can integrate academic rigour with the needs of governments, industry and the not-for-profit sector, delivering creative solutions to global challenges and bringing economic, social and cultural benefit.

Brunel’s Research Institutes and Research Centres pioneer world-leading research inspired by an ambition to address society’s most pressing challenges.

The challenge

The main challenge for the university was to identify a partner who could provide a solution which could handle very high temperatures and high pressures required. Reaction Engines was a logical choice owing to our ground breaking thermal management technology developed under the SABRE program. SABRE’s heat exchanger, or “precooler” as it is officially known, was validated in 2019 at temperatures representative of Mach 5 and has the ability to quench gas temperatures in excess of 1000°C down to ambient within a very small volume.

Supercritical CO2

Using supercritical CO2 as the working fluid in power cycles instead of steam increases the efficiency of the overall heat recovery and allows for a significantly smaller footprint. Utilising waste heat reduces the carbon intensity of processes by reducing the energy consumption and hence lowering operating costs.

In a sCO2 cycle the working fluid remains in the same supercritical state throughout the process. The turbines for sCO2 are significantly smaller than steam turbines because of the high density of the working fluid, this holds true for most of the components and also there is no need for the massive condensers associated with steam plants. It was estimated that sCO2turbines could be as little as 10% of the size of a steam equivalent. Furthermore, sCO2 can operate over a wide range of temperatures with higher efficiencies than steam.

Creating value

Having identified supercritical CO2 as a working fluid to demonstrate, Brunel required a primary heat exchanger to capture the heat with a specification exceeding the state of the art. The heat exchanger required a very low shell side (flue gas) pressure drop, yet able to withstand working pressures up to 130 bar, and temperatures up to 650°C.

Using proprietary modelling software, the Applied Technologies team designed and developed a heat exchanger to deliver the required performance well within the pressure drop requirements – as well as the capability to deliver additional heat recovery for a future proofed system. The installed system captures the waste heat from an exhaust duct, and converts it to useful electrical energy (via a turbine) for export to the electrical grid. The complete primary heat exchanger was designed to ASME BPVC and was fully CE marked (Cat. IV PED).

Reaction Engines completes further
validation of SABRE technology

We are pleased to announce that we have completed the testing of two vital sub-systems of SABRE; the HX3 heat exchanger and the advanced hydrogen preburner. These sub-systems supply heat energy and air to the air-breathing core of the engine. Alongside our partners at Airborne Engineering and S&C Thermofluids, we have been able to conduct agile and robust testing campaigns in challenging circumstances. These experiments have yielded high levels of insight and expertise and are the latest in a wider series designed to validate SABRE technology.

Background

The advanced hydrogen preburner is a lean-burning hydrogen combustor. In SABRE it provides heat energy to the engine cycle at take-off and early flight. The HX3 is a microtube heat exchanger that connects to the preburner and exchanges heat between combustion gas and helium.

The advanced hydrogen preburner and HX3 together provide the heat source to the core engine to enable flight from sea level.  As the aircraft accelerates, the heat energy converted in the engine intake and extracted through the precooler gradually takes over the energy provided by the preburner extracted through the HX3 heat exchanger.

Test Campaigns

The objectives of both campaigns were to manufacture full size test rigs to validate performance modelling and de-risk high temperature operation in advance of further integration. The preburner test campaign further aimed to show that our novel fuel injection system would function at full scale, that we are able to control the heat output precisely and provide even temperature to the HX3.

SABRE cycle

The HX3 campaign was commissioned with Airborne Engineering at their test facility in Buckinghamshire. Airborne has been a close collaboration partner of Reaction Engines for many years over a number of rocket engine, combustion and heat exchanger test campaigns with complex instrumentation and control challenges. Airborne designed and built the custom hot gas source for the HX3 tests, which was capable of providing partially combusted air with variable massflow and temperatures controlled from 428℃ to well in excess of 928℃. The test rig also required closed-loop feedback control of the mass flow of hydrogen and air for combustion, the mass flow of helium coolant and the pressure of the hot coolant exhausted from the heat exchanger.

James Macfarlane, Managing Director of Airborne Engineering, had this to say regarding the test campaign:

“This programme continued the close working relationship that we have with Reaction Engines. Together we have successfully delivered another cutting-edge test campaign to further the evolution of SABRE technology. Despite the complex nature of the testing requirements, and the high accuracy required for the hot-gas uniformity and flow control, we are pleased to have developed a custom solution for them that was not only efficient to test but worked first time.”

The preburner test campaign was conducted in collaboration with S&C Thermofluid at Kemble Airfield in Gloucestershire. Their air delivery system using Gnome gas turbines was able to provide the temperature pressure and mass flows required to test the preburner at full conditions needed for a SABRE engine. In addition S&C already had a hydrogen delivery rig available that was suitable for this campaign.  The partnership has worked really well and despite the challenges facing everyone, the test campaign itself was completed in under a month.

Results

The HX3 achieved a top temperature 1126℃, making it our hottest test to date, even higher than the precooler’s validation at speeds representative of Mach 5 in 2019. Performance exceeded model predictions with slightly more heat exchange and less pressure loss than expected. Similarly, the preburner exceeded expectations and actually provided a larger performance envelope. The preburner campaign involved testing a lot of new technology at the same time and significant redesigns were expected, however only relatively minor issues ensued.

Shaun Driscoll, Programmes Director at Reaction Engines had this to say about the test campaigns:

“These test campaigns have been a huge success and we are very pleased with the results. With excellent teamwork and the help of our close partners we have been able to verify model predictions on real hardware, gain useful insight into performance and limitations and move onto the next phase of the development of our technology.”

The fact that both campaigns not only proved but exceeded model predictions is testament to Reaction Engines’ modelling capabilities. Ultimately all objectives were achieved and a huge amount of expertise has been gained that will benefit our wider technology programmes and will underpin the innovation and advances already made being across a variety of commercial sectors.

HX3 nozzle
HX3 nozzle
HX3 test article
HX3 test article
Preburner control room at Kemble Airfield
Preburner control room at Kemble Airfield
Preburner test article
Preburner test article
Custom hot-gas source for HX3 designed by Airborne Engineering Ltd.
Custom hot-gas source for HX3 designed by Airborne Engineering Ltd.
Custom hot-gas source for HX3 designed by Airborne Engineering Ltd.
Custom hot-gas source for HX3 designed by Airborne Engineering Ltd.

Further, better, faster, longer.​

Why improved thermal management of batteries is critical to the EV business case.​

The future of cars is electric. The UK Government will ban the sale of internal combustion engine (ICE) vehicles in 2030, making it one of fourteen countries that have announced ICE restrictions.

Introduction

Why thermal management could transform the EV market.

With thanks to the following contributors:

Josh Denne – Head of SME Programmes, Advanced Propulsion Centre, UK
Professor Greg Offer – Professor in Electrochemical Engineering, Imperial College London
Simon Dunnett – Electrification and Energy Efficiency Solution Manager, Horiba Mira
Dr Yura Sevcenco – Technology Development Manager, Reaction Engines

Most automotive manufacturers have pivoted to electric vehicles (EVs), with Audi expecting to be completely electric by the 2030s. According to BloombergNEF, half of global passenger-vehicle sales in 2035 will be electric.

It’s unsurprising, therefore, that the global EV batteries market is expected to grow from $19.78 billion in 2020 to $22.99 billion in 20211. For battery manufacturers, the opportunity is clear but getting ahead of the competition depends on seeking out technological innovations that deliver a step change in EV performance, that translates into genuine customer benefit.

“‘Range anxiety’, long charging times, and long-term battery performance are among the main barriers to uptake [of EVs].” According to 2020 research for the UK Department of Transport2,

One of the biggest opportunities across all these parameters is thermal management. Better thermal management of batteries would offer longer times between charges, faster charges, longer vehicle lifetime and more efficient driving – addressing key concerns of consumers

It is also vital for futureproofing. Existing heat management will not be enough for the power and energy dense batteries of the future, which are being designed to enable longer journeys and faster charge times.

Our recent roadmap highlighted cross-industry consensus that thermal management was an area that needs a major improvement.

Josh Denne, Head of SME Programmes at the UK’s Advanced Propulsion Centre.
Professor Greg Offer of Imperial College London adds “by designing cells to remove thermal bottlenecks and allowing the heat to be properly moved out of the battery, the system can operate more efficiently.” His own work suggests addressing heat spots could achieve a 10-15% range increase, 200% longer lifetime through reduced degradation, and 15-20% cost reductions.
Total cost of ownership could be reduced by 60-70%. This would be a truly disruptive advance. If widely adopted it should significantly accelerate electrification in EVs. We really are hoping innovation in thermal management will trigger a revolution in the battery industry.
Professor Greg Offer, Professor in Electrochemical Engineering, Imperial College London.

Too hot to handle: why heat is such a problem for batteries.

The battery packs that power most EVs currently are made up of Li ion cells; some use thousands of small cells, some use hundreds of larger ones. These come in one of three formats: cylindrical, prismatic or pouch cells. Each has benefits and drawbacks but all create complex patterns of heat transfer, and all suffer due to too much heat in the wrong places.

EV battery packs have the best thermal stability and lifetime if, when the vehicle is being driven, they maintain a temperature between 15 to 35°C, but they should be charged at temperatures of around 50°C to minimise dendrite formation. They also work best when they are of a uniform temperature, with a maximum cell temperature difference across the cell of 5°C.

Li ion batteries generate large amounts of heat in use, especially during rapid charging and accelerating. This heat is very unevenly distributed meaning some cells, or parts of cells, degrade much quicker than others. A single cell’s immature deterioration can considerably reduce performance and efficiency of the whole battery pack.

Cells really dislike having one end hot and one end cold – it has a big negative impact on efficiency and degradation. When you have 500kg of cells, you need to get all that heat out quickly. And as cells become more powerful, they become more densely packed and create more heat, so thermal management is high on the priority list for battery and EV manufacturers.
Simon Dunnett, HORIBA MIRA
Professor Greg Offer of Imperial College London adds “by designing cells to remove thermal bottlenecks and allowing the heat to be properly moved out of the battery, the system can operate more efficiently.” His own work suggests addressing heat spots could achieve a 10-15% range increase, 200% longer lifetime through reduced degradation, and 15-20% cost reductions.

The current limits of battery cooling technology.

For the above reasons, EV battery packs employ battery thermal management systems (BTMS). A BTMS must provide the necessary heat transfer for optimal charging and discharging in the confined space available in the battery pack, and be manufactured economically. This is no small ask.

There are two main types of BTMS: active and passive. Active systems depend on forced circulation of a coolant such as water or air. Passive systems use methods like heat pipes or hydrogels to remove heat from the pack. The complexity of these systems adds significantly to the cost of the battery pack – in the region of 10-20%.

Alongside cost, one of the biggest problems with current BTMS options is that they create thermal gradients. For example, a cold plate beneath the cells cools the bottom much faster than the top. Meanwhile, a liquid cooling loop will remove heat more effectively from cells at the start of the loop but by the end it cannot absorb any more heat.

Temperature gradients cause adverse voltage distributions and differential ageing between the cells. In other words, the cell does not age uniformly. An ageing gradient occurs inside the cell, reducing the efficiency and lifespan of the batteries. Strong thermal gradients can also lead to deformations in cylindrical cells.

These issues compromise power efficiency when driving and when charging which, in turn, means slower charging and faster degradation, and therefore ever shorter periods between charges.
If a cost-effective way to deliver isothermal heat management could be developed, i.e. maintaining a consistent and even temperature throughout the cells and the system, a big chance could be delivered to battery performance.

“New recyclable multi-function materials together with active cooling strategies to cope with high-power applications are needed. Keeping batteries at their optimal temperature will require new materials and methods to more efficiently heat batteries and effectively manage and dissipate heat.” According to the Electrical Energy Storage Roadmap 20203.

“We’ve been on the journey of optimisation with ICEs for a hundred years,” says Josh Denne. “We’re only just starting for EVs. Thermal management is where some of the big short term gains are to be had”.

The benefits of isothermal EV batteries.

Improved cooling and isothermal performance means batteries degrade more slowly. Due to uniform degradation of parts, battery packs don’t need to be replaced when only certain cells are degraded. This could easily add an an extra two years to the battery pack’s life time.

An even more significant benefit in making EVs attractive to the consumer is faster charging. Pushing a car to its limits of charging (e.g. using ultra-rapid chargers) creates heat. This creates the risk of thermal runaway if a single part crosses a temperature threshold, so BTMS’s limit performance to keep batteries at safe temperatures. This control system is based on poor knowledge of heat within the cell, so cautious safety limits are set based on the hottest point which limits efficiency.

Isothermal heat management would create even, easily measurable temperature across the cell. That would give BTMS control systems greater scope to allow faster charging without risk of overheating.

It really is rocket science – our revolution in battery cooling technology.

At Reaction Engines, our next-generation thermal management expertise has been developed and adapted from our ground-breaking space technology programme. Having developed heat exchange technology able to quench airflow temperatures of over 1000 ̊C to ambient in a fraction of a second, we are experts in the field of thermal management. We believe our technology and expertise to be at least a decade ahead of anyone else.

Taking this expertise, we looked at how heat can be better managed within EV batteries.

“The trick was to use the system itself to manage heat evenly,” explains Dr Yura Sevcenco, Technology Development Manager at Reaction Engines.

So, when one spot rises in temperature, we take that heat and dump it in a cooler place first. That is an efficient immediate solution, as the heat has less far to travel. Cooling heat pipes still take heat out of the whole system but, in the meantime, all the cells within it stay perfectly regulated. All the components stay cooler and at the same temperature, which ensures any degradation is slow and even.

“A perfect heat management system might use materials with complex structures to manage this in a highly sophisticated way, and this was our first thought. But we needed a solution that was affordable to the average EV battery manufacturer. So, we went back to the drawing board – same idea, but with the starting point of making it affordable. We relooked at the concept and considered how we could create something cost-effective that still did the job,” explains Dr Yura Sevcenco. After a few iterations with different materials and designs, we created a simple foil that could be attached to any battery cell. This creates a thermal ground plane which transfers heat evenly across the surface, then takes it out of the system, so you’re not left with hotspots.

The nature of the foil design means that the benefits are realised not just on a specific one-cell basis but across the whole system. They equalise thermal gradients across the whole battery pack so it all degrades at the same time, in the same way.
Plus, our solution is malleable and conformable, unlike rigid cooling systems which can suffer from the thermal resistance of air bubbles in the interface between cooling and the cells. This means our solution adheres to the cells, even pouch cells which expand and compress during use.

Finally, we can reduce weight. BTMS developed using our foils can be up to 35% lighter because they’re so lightweight, making vehicles more ‘fuel’ efficient.

Altogether, this adds up to a step change in battery performance. We expect that deploying these foils would deliver a 20-30% improvement in battery performance.

However, we are not large-scale manufacturers. We are therefore looking to partner with innovative battery companies or vehicle OEMs. We are looking for partners interested in licensing our design, or who we can work with to design new battery systems which build in isothermal heat management from the ground up.

The bottom line: the business benefits of better batteries.

Heat management innovations, effectively deployed, would allow battery manufacturers to realise a 1.5 step change in performance, charge speed, and battery lifetime. This could benefit all types of battery manufacturers, and the whole supply chain.

For the first movers, it could bring a chance to secure significant market share as vehicle OEMs clamour for the best batteries.

For the vehicle OEMs, it would mean they have better performing, longer lasting, cheaper EVs. This gives them a better customer proposition, which they can confidently back with longer warranties.

This would be good for the manufacturers, good for the customers, and good for a world where competition for battery materials is hotting up.

Battery and EV manufacturers need to actively pursue innovative approaches to thermal management with the goal of creating isothermal batteries, including engagement with researchers and innovators in this field.

“There is colossal room for improvement,” concludes the Advanced Propulsion Centre’s Josh Denne.

Battery cooling is a critical strategic requirement for EV companies and will only become more critical. Not just for cars but for buses, trucks and many other types of road vehicles. If we want better time frames for EV adoption, we need better thermal management, and neat, affordable solutions that meet the challenging package and weight constraints that vehicle designers aspire to achieve.
Josh Denne, Head of SME Programmes, Advanced Propulsion Centre, UK