Engineering the Future: Cooling the Internal Combustion Engine

Join us in episode 15 as we shrink ourselves down to the size of ants and take a look at the intricacies of the internal combustion engine. How can we cool it down and why would we want to do that in the first place? Plus, we talk about Formula 1 and its future for sustainability!
Tejo Jehart

Full transcription of the interview


Jordan: Hello, curious minds! A very warm welcome to The Research Beat. With me, your host, Jordan Kruszynski. Today we’re going to be talking about engines. They’re all around us, but what goes into their design and what are they going to look like in the future? We’re gonna be going through this with Tejo Jehart, PhD candidate in Engineering Science from the University of Oxford.

Tejo, welcome to the show!

Tejo: Thank you very much, it’s a pleasure to be here. 

Jordan: So, Tejo, let’s go straight into it…


Can you give us an overview of your research? 


Tejo: Yeah, absolutely. Happily. As you mentioned, uh, I’m a PhD student in Engineering Science at the University of Oxford.

Um, and I work in Terminal Propulsion Systems research group. Now, what my group is specialize in is, as the name suggests, in terminal engines. Now there is a variety of different terminal engines, such as, jet engines, or sterling engines, ranking cycle engines. But  my team is mostly [00:01:00] focused on internal and combustion engines.

My research more specifically focuses on, um, heat transfer, heat transfer measurements and surface temperature measurements. All at very high. So we are talking about, uh, a microsecond changes in the wall heat flux. Now why, uh, we want to measure that? Well, we want to reduce the heat losses and the energy losses associated with it. We hope to understand that better in order to aid the development of computational tools that allow us to design better engines in the futures. So I would say that, in a nutshell, this is an overview of the research that I’m doing. 

Jordan: It’s very interesting.

So let’s just go through it step by step. 


Can you tell us what exactly is an internal combustion engine and where do we find them in everyday life? 


Tejo: Yeah. So, uh, I’m sure many of, uh, the [00:02:00] listeners will know what an internal combustion engine is. Simply speaking, it’s a device that converts the chemical energy stored in the fuel, fuel that can be gasier or liquid into the motion.

So it does that through combusting that fuel creating terminal energy and that terminal energy then rises pressure within the engine, within the combustion chamber, and we can utilize that pressure to create propulsion… 

Where we use them in practical application? There are numerous and countless applications. Of course, the most well known is probably application in our vehicles, in cars.

But of course we use them in many other applications as well. Uh, and particularly important is the heavy duty transport and the freight sector. So, talking about trucks, ships, but also aviation, [00:03:00] and even power generation. Sometimes we use internal combustion engines to create electricity… using natural gas or biogas. Or there obviously you see many other applications as well, such as small generators, that we use, you know, at ferries for example. So they’re really, really conscious of applications where we use them!

Jordan: So the internal combustion engine is really powering the entire modern transport system.

Tejo: Yeah, we could say that. Of course the electrification and electric proportion is now becoming important as well. Uh, but still a significant proportion of the transport sector is powered by an internal commercial engine. Exactly. 

Jordan: As well as you just mentioned, the very important act of mowing the lawn. 

Tejo: Yeah, that’s definitely an important if we want to [00:04:00] keep our lawns nice and nice and green. 

Jordan: So you just touched on electrification there, which we’re going to get into later… 


But first, why is it so important to reduce heat losses in these engines? 


Tejo: Yeah, that’s a very good question. So, um, a typical internal combustion engine will only manage to convert about a third of energy stored in the fuel into a useful work.

So, of course we would want to increase that. Now the other two thirds are heat losses. About the third of the energy is heat loss through the exhaust system. Now that is just a characteristic of terminal engines and there’s not that much that we can do there… however, one third of energy is lost through the walls of the combustion chamber. So, combustion chamber is basically a volume where we create combustion and where we extract useful work [00:05:00] and any heat losses there will directly impact our efficiency. And of course, we want to improve the efficiency. So, we want to reduce this heat losses as much as we can!

Now the theoretical studies, uh, performed before say that even if we do manage to reduce this while, uh, heat flux deficiency potential, but are quite limited… But we still have an ambition to try to reduce wall heat losses because of the number of downstream effects. So by reducing the wall heat losses, we can reduce the size of the cooling system.

So you’ll be aware that every car that we have on the road  has a cooling system. They have a radiator… they have a grill… and that’s how we cool that access heat cuz otherwise the engines would over. Now that comes with a weight penalty that comes with a [00:06:00] cost penalty. And that also comes with an aerodynamic penalty.

So if we manage to reduce the wall heat losses, hen we can reduce the size of the cooling system – that can reduce the weight of the vehicle. And weight has a very important effect on the energy required to move the car around. We can reduce aerodynamic, again, very important!

A way to improve the efficiency of cars. And perhaps critically as well, we can benefit from reduction of emissions from the engines. So not just carbon dioxide emissions, but also emissions of other polys in particularly in particular during the coldstar phases. So, yeah, it’s very important to try to reduce the heat losses out of these engines…

Jordan: So there’s a really nice mixture of ambitions there reducing emissions generally, which is important. There’s the kind of engineering challenge of just constantly improving the way that things are designed and then the desire to make vehicles and engines more efficient, able to move more effectively with less energy input and less loss of energy through waste. So, Tejo…


Tell us, what kind of methods are you looking at to reduce heat loss? 


Tejo: Yeah, so there are a number of methods that industry has been using in the past and is trying to implement in the future as well. So the first, you know, a method that we can apply right away is to try to reduce surface to volume ratio…

So for a desired power output, we need a certain volume of the engine, a certain volume, total volume of all combustion chambers, uh, combined. Um, but if we can manage to improve the surface to volume ratio, in other words,[00:08:00] keeping the same volume, but decreasing the surface area of the surrounding walls, well, that’s the first step we can use to try to reduce the heat losses!

So that’s something that, you know, manufacturers have already been trying to achieve. Of course, all within technical limits… 

We have some other methods that have been used before. One of them is the sodium field works. So, um, in order to control the ingress and egress of gases, um, such as air and exhaust gases in the internal combustion engine, we need to control that with engine walls.

And typically those walls would be solid metal walls, which is not the best again, in terms of controlling and keeping the heat within the combustion chamber. So, sodium field walls have been implemented, especially in high performance applications. That means that [00:09:00] part of the volume is void and that also, uh, that basically helps to create an insulation.

Um, we can try to reduce the gas temperatures. The high gas temperature is what is driving the heat loss in the first place. So if we can try to reduce that, then we can, you know, reduce the heat losses as well.

And there are methods that have been implemented such as reusing part of the exhaust gases in the combustion chamber as this helps to decrease the cylinder temperatures. Uh, the lean air fuels mixures, so, in other words, meaning having an access of air, so more air than we need, uh, turns out to help reduce the cylinder temperatures as well. But of course there’s a limit to how lean we can go as a combustion instability, uh, than up here. 

Um, but more recently, a lot of focus has been on developing special [00:10:00] in insulating materials. So as I’ve mentioned, traditionally we’ve been using metal for combustion chambers. So that would be a aluminum or some steel and metals obviously conduct heat very well, uh, but we want to reduce the heat losses. Uh, so initial research in that has started back in the, I would say 1980s, initially for military purposes, uh, where a thick ceramic coats were used And, it did allow reduction of the heat losses to a certain extent, but it had a number of, uh, other issues, namely, Um, the, the fresh charge of air was getting preheated, which then prevented us from using very high compression ratio, for example, and high compression ratios is one of the means how we can increase the efficiency. So there was a trade off and the benefit of using the codes wasn’t substantial enough. [00:11:00] But more recently we’ve been focusing on very, very thin, uh, in insulating materials , that have not only low, uh, terminal conductivity, but also low terminal capacity. And what we try to achieve with that is we try to achieve the temperature swing on the surface of this. So, basically we want the temperature to rapidly swing from, you know, low temperature, close to the atmospheric air temperature, at a beginning of the cycle, at the beginning of the process, and then rapidly race to a temperature of 800 degrees Celsius or even more within even spend a few microseconds.

In other words, we want to keep the temperature of the walls as close to the temperature of the working gas in engine. Because in theory, that should allow, uh, us to reduce the heat losses without any negative, uh, effects of [00:12:00] preheating intake care and needing to reduce compression ratio and so on and so forth.

So that’s , the most recent development, in terms of trying to reduce the heat losses. So, the so-called, temperature shrink coatings. 

Jordan: It is really fascinating to hear how many different techniques there are for making potential improvements and that this device, this mechanism, the internal combustion engine, which has humble origins, has gone on being improved, is had research plowed into it again and again over, many decades.

And really interesting to see something that just doesn’t stop being improved in the research world. 

Tejo: Yeah, absolutely. Yeah. And you know, the characteristic of the internal combustion engine is that we often have to play with trade-offs. So we want to find an optimal trade-off where, you know, we can achieve the highest possible efficiencies within the budget limits and technical limits.

Jordan: So modern engine [00:13:00] development involves quite a lot of computer modeling. 


Could you explain to us how your work connects to the modeling and why it’s so important within your field? 


Tejo: Yeah. First maybe explain why modeling is so important. Developing, modern, sophisticated internal combustion engine without computation modeling is simply not possible anymore.

And the reason being that we have extremely strict emission regulations, but also a very high efficiency. So effectively we want to trace almost molecule by molecule, um, as to what is happening within the, uh, internal combustion engine. And because of the trade offs that I mentioned, there’s a lot of things that we need to consider!

So how we guide the airflow, how we mix it with fuel, how we creat the motion of, the charge inside the cylinder, etc. And simply doing that with experimental tests [00:14:00] would be too expensive, too long, and probably we wouldn’t achieve adequate results. So computational modeling is really, really important.

The important aspect of research is to accurately create these computational models. So these are basically mathematical tools and they need to be experimentally validated with basic experiments. And this is where my work hopes to help. So, part of the computation modeling is also to predict the heat losses.

Heat losses directly affect the cellular temperatures, the emperatures directly affect efficiency and emissions generation. Uh, so we want to understand accurately what heat losses we will have and moving further forward into the future, we want to understand how this term of swing coatings will behave.

In other words, what temperature swings will be achieving in [00:15:00] different operating conditions. Uh, so if we can, uh, accurately measure the surface temperature on them, will that and directly help feed information for tuning effectively computational models for heat transfer…

Jordan: And yours is not the only discipline where computer modeling is becoming more and more important as the complexity of ideas and potential applications increases.

Like you said, it’s not possible to apply all the resources needed to actually, in some cases just afford, to make a practical experiment. So you need to use the modeling to see if we do this, how is it likely to work?

Tejo: Exactly. So we always start with, you know, initial, uh, computational modeling. So, initially very simple mathematical models to create a basic design, then that upgrades to a sophisticated three 3D models  of engines to again try to trace almost molecule by molecule. Um, and then when we have that concept, [00:16:00] established, then typically we would create an experimental setup, which would be a smaller version of the real engine. So a single cylinder version of the engine, due to final development on that, before creating a full size engine and just proof its concept.

Jordan: So in burning issues, we really want to hear about the academic matters that are important to you and… Tejo, 


I think first you’re going to tell us a little bit about efforts involved in academic work? 


Tejo: Yeah, academic work and you know, a work of a PhD student is definitely difficult. Uh, some of the challenges that I find particularly difficult are finding a novelty, especially in the field that, you know, has been, um, extensively researched in the past, you know, almost a hundred years we could say. Um, so finding a novelty is definitely difficult. [00:17:00] Um, and in particular when we are talking about experimental work, there’s a significant amount of effort needed to prepare experiments. to plan them, to prepare them, to run them at, you know, a level that gives us the accuracy that we need.

So, um, a significant amount of time is needed for often very limited research output. You know, often we do experiments only to find out that we can repeat experiments. You know, we don’t have valuable conclusions after that. So, I would say that can be quite, uh, mentally challenging the lack of clear research outputs often.

Um, so I would say that is a difficulty of research or in particular of a PhD research where we are even more limited with the time to deliver the output cuz that is what will allow us to graduate at the end of the day. 

For the [00:18:00] researchers and professors, of course, there are other challenges as well. Often, they need to combine a lot of work so that often do not just reserve, but also, need to teach, need to lecture, need to prepare tutorials, need to mark tutorials. They obviously need to do research as well, and for that, often they need to apply for funding. Um, so, funding applications are usually quite extensive, because not rarely we talk about millions, right?

So those millions have to be spent wisely. That means that the application processes for this funding opportunities are usually very lengthy and difficult to get. So yeah, definitely for researchers there’s a lot to handle. And in particularly in our field, uh, the field of internal combustion engines funding available have been quite significantly reduced in the recent years. So it’s becoming harder,[00:19:00] to obtain funding because, of course, a lot of efforts are put into electrification, which is extremely, extremely costly… so, those are definitely some of the challenges that I would say are, are burning…

Jordan: So on the point of finding novelty:


How much pressure does this really put on academics? Are you always seeking to find novelty at any cost effectively? 


Tejo: Yeah. Majority of the research output needs to be novel or significantly better than before, or provide some improvement. So sometimes researchers would prepare a technique that is a slight improvement of the previous technique. But if you know it turns out to be an improvement, then that will be a novel research output. 

Some work can be done only to verify the work of others. See if you can obtain the same. And if [00:20:00] you obtain contradicting results, you know, trying to understand why the results are contradicting… Um, so I would say, mostly we have these two types trying to verify the work of others but often definitely provides some novelty to the field.

Jordan: On the points of funding, you mentioned to me previously always having to be on the hunt for new funding opportunities. 


Can you tell us a little bit about that and the kind of pressure that academics like you face in trying to always find that next opportunity? 


Tejo: Yeah, I mean there’s definitely a pressure, uh, funding is needed in order to run a research laboratory.

Funding is where, you know the salaries are sometimes covered from funding is what provides for the equipment necessary for research, and whether that’s, you know, licensed equipment for computational software or hardware and experimental material.[00:21:00] In addition to that, researchers, you know, want to have PhD students in their teams, and often these PhD students need to be funded as well in order to cover the tuition phase and, and also provide for the living, for them attendance. So in order to secure funding for that, again, researchers need to try to obtain that funding. And like I said, that funding, you know, is out there, but it’s, it is quite difficult to, to obtain. So yeah, it’s definitely, uh, a pressure on, on researchers and professors to get funding and get funding on time… Sure.

Jordan: So, Teo, in this discussion, we’ve touched a little bit upon electrification.

And we’re really going to go into this subject now and into a few other things through the lens of Formula One, actually. So we’ve had a look at a few articles from the BBC and from The Guardian, and these [00:22:00] articles are all about Formula One’s plans for 2026.

Formula One. Would you mind telling our audience about what’s going on here?


Tejo: Yeah. Formula One, as, you know, the most sophisticated, almost the most sophisticated, engineering we can think of, with high publicity, will go to a hundred percent sustainable fuels by 2026. And they already have 10% biofuel plans at the moment. So what does that mean?

Well, that means that we use similar technology to what we use currently. So using an internal combustion engine in a hybrid application together with a electric powertrain. So we use a combination of the internal combustion engine and of the electric motor. But instead of using fossil fuels as an energy source, the Formula One is planning to use sustainable fuels. What [00:23:00] that means is that fuels are either created by bioprocessing, such as processing of waste or capturing the solar energy with, for example, biomaterials, or producing those fuels synthetically, which effectively means that we use electricity.

For example, access renewable electricity when there is a surplus of, uh, wind power and use that electricity to create a synthetic fuel. So these fuels are very similar to fossil fuels, but they’re artificial in their origin, and their, um, their compounds are more predictable. Because when we are talking about fossil fuel like petrol, it consists of a range of different fuel molecules, whereas synthetic fuel we can quite closely target which molecules we want to [00:24:00] have and that can help us make better engines as well. So, yeah, formula One is trying to, um, we’ll go to a hundred percent sustainable fuels by 2026, and that basically means that any carbon dioxide that is emitted by the engine is the one that has been previously captured from the atmosphere – there will be a sort of net zero, um, carbon output from this power trains. 

Jordan: So there won’t be any additional carbon coming out of the engine and its processes and… 


Where is electric electrification tied to synthetic fuels? 


Well, we have a quotation here from Ross Brown, F1 managing Director of Motorsports, which makes it clear.

The great appeal is when we find the solution, you can use it in your road car without making any changes to the engine. We will have close to 2 billion internal combustion engines on the planet, and whatever electric solution we find, whatever hydrogen solution we find, there’s still going to be 2 billion cars. There are parts of the world where those cars won’t [00:25:00] change to electric”. 

So electrification is coming, but the point here is that until it’s implemented fully, the synthetic fuels that Formula One is developing, can actually be used in standard road cars to alleviate the problem of carbon output…

Tejo: Absolutely. Yeah. So, you know, the typical life expectancy of cars use on the road is extended, right? So it’s not uncommon now to see cars on the road from, you know, the early two thousands. Um, and of course, you know, these cars might be running on, uh, for long the steel, cuz often when we dispose them here, they often go to other, uh, countries in development and they’re used there for another 20 years or so.

So internal combustion engines will be around, um, you know, from, uh, engines from previous generations, but also from, from nowadays and, you know, uh, from future years as well. Um, and they can B carbon neutral providing the fuel for them is [00:26:00] carbon neutral. So if we manage to create a synthetic fuel that scale, that are a direct drop-in replacement for current petrol and diesel, then we can significantly reduce emissions from those older vehicles.

But then we also have applications where electrification simply will not work, for example, applications such as ships, maritime transport – electrification, there simply will not be possible, not at least in the foreseeable future, because the weight and the size and the cost of the batteries needed to propel a vessel from China to US, would pretty much take all the space that is currently available for freight…

But of course, we want to decarbonize those sectors as well. So, internal combustion engine, powered  by synthetic renewable fuel, has definitely high potential to help the similar with aviation, for [00:27:00] example. The battery-powered flights, long distance flights, will not be possible, not at least in foreseeable future with, you know, the physics that we know at the moment…

Um, so yeah, all these sectors will definitely be some form of combustion in the future. And the important thing is to try to give them the renewable fuel that they can operate on. 

Jordan: briefly just tell us a little bit about the substances involved in this, because I think many people will have heard of hydrogen as something that’s going to be very important in the future for synthetic fuels, but there’s also ammonia as well.

Tejo: Yeah, so hydrogen and ammonia are currently, you know, the two carriers that are most hyped about and for a good reason. Um, hydrogen is the simplest synthetic fuel that you can obtain. So you can directly use electricity from let’s say surplus [00:28:00] renewable wind generation to create hydrogen out of water.

Now, don’t be afraid that water will… we won’t get lost that water. So we won’t be using any water but … so hydrogen is the implest synthetic fuel that we can do and, therefore, also the most efficient synthetic fuel that we can do.

And it can be used in many  different applications. It can be used in industrial processes where high temperature is needed, such as steel production, concrete production. It can be used in heating, electrification of heating, is possible to a certain extent, but definitely comes with, you know, a significant increase in generation capacity needed in order to heat all the homes with electricity…

Uh, so hydrogen will be definitely helping there. Uh, but like you [00:29:00] mentioned, it can be used as a fuel in internal combustion engines as well. 

Ammonia is… we like to call it a hydrogen carrier. So, ammonia, consists of nitrogen and hydrogen. And hydrogen is the substance that we use as a fuel that we combust and that propels, then our internal combustion engines.

And why ammonia is attractive is because if we pressurize it a little bit or cool it down a little bit, it is in liquid form. And that is very important because liquid fuel carries a lot more energy in a particular volume than the gases fuel, such as hydrogen. So that is, uh, particularly important in applications such as, you know, vessels like we mentioned before. They need a lot of energy in relatively compact space. So that’s where ammonia has its potential. Basically carrying fuel in a liquid [00:30:00] form. And on top of that ammonia, the supply chain of ammonia is really well established… because we use ammonia in many chemical processes, such as production of fertilizers, etc.

So this is why hydrogen and pneumonia are of particular interest as future fuels.

Jordan: So Teo, tying everything together… 


What’s your hope for the future of your research? 


Tejo: Good question. If I touch firstly on my personal research, as I mentioned,  hope to be able to measure the very fast temperature swings on the surface of the coatings that we plan to use in internal commotion engines and being able to measure that would directly help improve the computational models that we use to develop engines. 

So that’s a hope for my personal research, I would say. For research in my field, my hope would be of course to improve the efficiency of [00:31:00] combustion engines further, and reduce the emissions that they generate, so that they can help us propel the means of transport, uh, in the future where electrification will struggle. So, where electrification struggle is, as we mentioned, you know, heavy duty transport, shipping, flying, but also automotive applications! Especially in low cost cars – we will really struggle to create low-cost electric cars. So that is where I hope that my research… might be able to help in the future as well.

Jordan: So really critical work seeking to reduce emissions and make the whole transport system more effective and cleaner, not just for people but for the whole world. 

Finally, Teo,


How can our listeners reach you if they’d like to learn more about what you do?


Tejo: Yeah, I think the best way to reach me would be through my LinkedIn profile.

So, if you search under my name, Tejo Jehart, then you should be able to find me. And yeah, I would be more than happy to connect and, uh, to get in touch with you!

Jordan: Wonderful. Well, Tejo, thank you so much for joining us today and sharing your expertise and understanding with us!

Tejo: It’s been a pleasure! Than you so much for invitation and yeah, really nice talking to you. 

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