#182      20 min 03 sec
Greener revs: Squeezing more efficiency out of gasoline engines

Control engineer Associate Professor Chris Manzie makes the case that there's a lot of life left in the internal combustion engine, and that petrol engine technology will continue to evolve alongside its hybrid and electric counterparts. With host Dr. Shane Huntington.

"The goal of many groups around the world at the moment is essentially looking into what you might call an omnivorous engine, where you can feed any sort of fuel in and it will learn how to make best use of it." -- Assoc Prof Chris Manzie





           



Assoc. Prof. Chris Manzie
Associate Professor Chris Manzie

Associate Professor Chris Manzie has worked in the Department of Mechanical Engineering at the University of Melbourne since 2003. His research is principally associated with developing and applying control and optimisation tools to energy systems in order to improve performance in various metrics such as economy and emissions. A large focus of his research to date has been in the automotive field, arguably the world’s largest consumer-focused industry.

He has published over 80 peer reviewed papers in international journals and conferences, and received recognitions including an 2011-14 Australian Research Council Future Fellowship to work in alternative fuels and advanced vehicle technologies, a 2009 Young Tall Poppy Award for Outstanding Achievements in the Area of Science, Teaching Excellence Awards and several conference paper awards. He has received over seven million dollars in competitive grant funding since 2004 and has collaborated with a number of industry partners including Ford, Pacifica, ANCA, ANCA Motion, DSTO, BAE Systems, Department of Transport and Virtual Sailing Pty Ltd.

Publications

Credits

Host: Dr Shane Huntington
Producers: Kelvin Param, Eric van Bemmel
Audio Engineer: Gavin Nebauer
Episode Research: Dr Dyani Lewis
Voiceover: Nerissa Hannink

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VOICEOVER 

 


Welcome to Up Close, the research talk show from the University of Melbourne, Australia. 

SHANE HUNTINGTON 
I’m Shane Huntington. Thanks for joining us. Whether the focus is on reducing emissions levels or the cost of production, for designers of automobile engines, efficiency remains a crucial concern and motivation in their work. In today’s car market, the efficiency of a vehicle is one of the most important factors in its success and consumer expectation continues to drive innovation in this area. But after so many years of optimisation, how much more can we get from car engines? Today on Up Close, we speak to a control systems engineer about this very problem. Chris Manzie is an Associate Professor from the Department of Mechanical Engineering in the Melbourne School of Engineering, the University of Melbourne. Chris’s work looks at how existing automobile engines can be controlled to achieve ever greater efficiency improvements. Welcome to Up Close, Chris.

CHRIS MANZIE 
Thanks, Shane. 

SHANE HUNTINGTON
Now, why are engines not 100 per cent efficient? Where is the energy actually going that we’re losing?

CHRIS MANZIE
So engines have to overcome pumping losses, moving a piston up and down requires you to move gases around in producing useful work and that means that we don’t use all of the fuel for propulsion of the vehicle. Other losses, probably the major one in an internal combustion engine, is really heat loss. We actually create useful work by burning the fuel and when we burn the fuel we tend to produce quite a bit of heat and that really just gets thrown out the exhaust pipe in a lot of cases. There’s also instances of friction in engine whenever we have rotating parts. We need to use some of our chemical energy to overcome the mechanical losses caused by friction.

SHANE HUNTINGTON
I’d like to you explain the term work, because when you use that particular word, you were using it in a different way to what most people would use when they go into their paid job each day.

CHRIS MANZIE
Yes. So in terms of work or mechanical work, what we’re looking at is expending energy to create something useful, like moving a boulder from the bottom of a hill to a top of a hill. It requires energy to be expended or work to be done to create that movement.SHANE HUNTINGTONThe automobile’s been around for quite a while now. What sort of increases in efficiency have there been since the first days of the automobile?

CHRIS MANZIE
Well, interestingly enough, the first automobiles were electric vehicles. Back in the 1890s, the first production vehicles ran off electric engines. They had reasonably high efficiency; they didn’t burn fuel. Of course, fuel’s notoriously been very cheap over the years, so efficiency wasn’t a major selling point for manufacturers through a lot of the history of the automobile and it’s only I guess since the 1970s that we’ve looked at trying to get more and more out of this resource. We’ve sort of seen over the last 30 years improvements in peak efficiency throughout the engines that are on sale.

SHANE HUNTINGTON
When we consider these engines themselves and their design, what sort of things have changed or are they essentially the same device?

CHRIS MANZIE
They’re essentially the same device. We can do two things with fuel. We ignite it using a spark plug and that creates a small explosion that’s used to produce useful work, moving a piston up and down. That’s what’s known as a spark ignition engine, usually fuelled with something like gasoline or petrol. The other option is we have a diesel engine, which is a compression ignition engine and there we basically just compress the fuel air mixture in the cylinder until it self-ignites. They’re the two types of engines that we can have and those fundamental principles have been used for decades. Of course, what we’re looking at doing more recently is controlling more aspects of the engine, so we now see things like very fine control over the amount of injected fuel, so we have electronic fuel injection. We have things like variable valve actuation so we can change the cams on an engine or cam timing. We can also turbo-charge engines. I guess what we’re tending to see in a general trend based around these fundamental engine designs is more and more actuation capability all trying to either squeeze more efficiency or more power out of these basic designs.

SHANE HUNTINGTON
When we look at some of the vehicles coming out today, one of the common terms we hear used is hybrid. How does a hybrid vehicle differ from the traditional gasoline or petrol run vehicles?

CHRIS MANZIE
So a hybrid actually has an internal combustion engine in it, normally spark ignition or a gasoline engine, but it also has this extra capability of a small electric motor or potentially quite large electric motor that can also be used for propulsion. Why this improves the efficiency or fuel economy of vehicles is the electric motor can actually be run as a small generator when the vehicle is slowing down. So instead of using frictional brakes where we essentially dissipate the energy of the vehicle through heat, what we’re looking at doing is dissipating the energy of the vehicle by producing electricity and that electricity can in turn be used later on to propel the vehicle. In a sense, we reduce the heat losses and improve the overall vehicle efficiency.

SHANE HUNTINGTON
Now, we’ve seen over recent decades major changes in aircraft design and the way in which the aerodynamics of an aeroplane actually work and increases in efficiency as a result. In terms of cars and especially in terms of cars driven by normal people, not race car drivers, what is actually going on there? Is efficiency being changed by the new parameters that cars are being built to or are they moving too slow for that to have an effect?

CHRIS MANZIE
The car industry is actually an interesting one in that it’s not solely efficiency that determines whether people buy a vehicle. It’s a very personal choice and therefore there are constraints in designing the shape of a vehicle. People are more influenced by how the vehicle looks rather than how it drives. To give you an example, there’s potentially further reductions in aerodynamic drag as aerodynamics are looked at more and more by vehicle manufacturers. The limit is probably not a physics based one but more a consumer acceptance.

SHANE HUNTINGTON
These days there are a number of fuel alternatives that people can use in their vehicles. To rattle off a few, there’s ethanol, there’s a range of different octane levels for unleaded petrols or gasolines, there’s LPG, there’s diesels. Where is the sweet spot for efficiency between these various fuels?

CHRIS MANZIE
For reasons of efficiency alone in terms of getting useful work out of a given volume of fuel, the actual fuel itself doesn’t necessarily play a very big part in that decision. Engine calibrators or engine control designers will tend to design the engine control unit or engine computer to maximise the efficiency of a given fuel. If a car’s designed to run on a certain type of fuel, it’ll tend to do pretty well running on that specific fuel.

SHANE HUNTINGTON
Chris, for a given fuel - pick any one you like and there’s a number - what properties affect the performance of that fuel?

CHRIS MANZIE
There’s a few things. There’s its chemical composition, so how much chemical energy is actually in the fuel and really then how well it’s going to burn. So fuel like hydrogen burns very easily, but in general is not a very dense fuel so we actually need to pump in quite a lot into the cylinder to get useful work out of it.

SHANE HUNTINGTON
When we take a fuel and we fill up our tank with that particular fuel, are there properties of the fuel that sort of are inconsistent that cause problems with the performance of the vehicle?

CHRIS MANZIE
Traditionally, when we’ve looked at gasoline and the composition of gasoline or petrol, it’s pretty tightly regulated so the gas stations sell basically a known composition of fuel. As we move towards more alternative type fuels, so biofuels, ethanol blends, LPG and CNG, the composition can actually change quite a bit and what this can affect is the flammability properties of the fuel as well as the amount of energy that’s in a given volume of the fuel. Traditional engine controllers, which may have been developed around knowing what the fuel is, are therefore not necessarily going to perform as well as they could for an unknown fuel composition.

SHANE HUNTINGTON
As a control systems engineer, how would you go about dealing with this particular problem for an engine?

CHRIS MANZIE
The goal of many groups around the world at the moment is essentially looking into what you might call an omnivorous engine, where you can feed any sort of fuel in and it will learn how to make best use of it. From a control systems perspective, what we’re looking at is having controllers that actually adapt based on some feedback from the vehicle or the engine, adapt the control signals that are being sent. So we may look at adjusting the amount of fuel that’s going into the cylinder. We may look at adjusting the spark timing or the valve timing and doing this in a way that tries to optimise the vehicle’s performance.

SHANE HUNTINGTON
How fast do you expect these sorts of changes will be made? I mean, are we talking about millilitres of fuel going in and adaptations being made on that level?

CHRIS MANZIE
It depends. If we’re looking at fuel composition only, that’ll generally be quite a slow change in terms of what’s being actually fed into the engine. So you may be driving on 100 per cent gasoline and you decide to fill your tank - if it’s 10 per cent of fuel left in the tank - you will it with 50 per cent ethanol based fuel. What actually goes into your engine is not going to be 50 per cent ethanol. It’ll be some lower concentration of ethanol and depending on what evaporates out of the tank first, that’ll dictate how quickly the actual composition does change. In general, for a fuel composition of fairly slow time varying process and therefore the controllers don’t necessarily need to adapt on that time scale of milliseconds.

SHANE HUNTINGTON
I’m assuming you don’t do this on the open road with a vehicle. How do you go about measuring these efficiency levels?

CHRIS MANZIE
In the lab environment, what we’ll tend to do is measure the amount of fuel that’s gone into the engine and then measure the useful work using an engine dynamometer or a chassis dynamometer to measure how much power’s being produced by the engine or the vehicle. In that controlled environment it’s much easier to do. Out on the open road, generally you can’t get a specific or an instantaneous measurement of efficiency as you’re driving around the city. With production sensing capability it’s quite a difficult thing to do. Potentially you can do things like perturb your inputs to an engine and look at whether the amount of fuel you’re putting in for a given amount of power out goes up or down. In that way you can seek to optimise operation without explicitly measuring what that efficiency number is.

SHANE HUNTINGTON
This is Up Close, coming to you from the University of Melbourne, Australia. I’m Shane Huntington and in this episode we’re talking about squeezing ever more efficiencies out of car engines with engineer Associate Professor Chris Manzie. Chris, when you talk about optimisation, this is one of the key goals in having control of these parameters. What things would you change or would you want to control if you had that control in a vehicle in real time?

CHRIS MANZIE
So the things that we look at controlling, things like spark advance, how or at what time the fuel air mixture is ignited. We might change the air fuel ratio of the mixture, the composition of the gas in the chamber. We can change the valve timing, changing the mixing characteristics of the fuel in the air. Depending on the engine, if it’s a turbo-charged engine we may be looking at turbo-charger speeds and that type of things or looking at changing essentially how much fuel and air comes into the engine and the type of combustion that’s going on.

SHANE HUNTINGTON
Chris, are we approaching the limit to how much we can squeeze out of these engines with current fuels? Can you put a number on what that efficiency level will be?

CHRIS MANZIE
There are research engines at the moment that are getting for combustion of fuels up around the 40 to mid-40 per cent and certainly with diesel engines those type of 40 per cent efficiencies have been achieved. As we move towards sort of downsized and turbo-charged engines, we’re starting to see those types of numbers in production, as well. It’s probably not going to go much past there. If we start getting up into the high 40 per cent efficiencies, you need to start looking at fuel cell vehicles to maintain that type of level.

SHANE HUNTINGTON
So far, Chris, we’ve been talking about the efficiency of these vehicles, but what about the emissions levels of these vehicles? How well are these two things correlated or are we trading off one to get the other in every circumstance?

CHRIS MANZIE
There is some trade-off. For example, when we use a catalytic converter, that puts a restriction on the air fuel ratios that we can have in the cylinder if we want that catalytic converter to operate at its maximum conversion efficiencies. In that context, we’re running at an air fuel ratio for a gasoline engine of around 14.6 to one and as you start to deviate from that number, your nitrous oxide emission levels will go up or your hydrocarbons or your carbon dioxides. The need to have good catalytic converter efficiency puts an additional constraint on the engine control, which might otherwise be able to operate slightly more efficiently. They are at some level a bit of a trade-off, but it’s one that I think as a society we’re prepared to accept.

SHANE HUNTINGTON
How exactly does a catalytic converter actually work in a car?

CHRIS MANZIEWhat a catalytic converter does is it really looks at taking the emissions that we don’t want to see out of the exhaust and acts as a catalyst, as the name suggests, for chemical reactions that will have by-products that are much friendlier. So carbon dioxide and water in the ideal case. 

SHANE HUNTINGTON
Your work must somehow feed back into the sort of engine design work that is done out in the industry. Should we expect to see some of these improvements coming through as a result of this research?

CHRIS MANZIE
Well we work quite closely with Ford Australia on a number of programs, but in general, what we’re tending to see with engine controllers in production is more of a shift towards model based control design and that’s really being led by the academic research that’s being conducted here and other places around the world.

SHANE HUNTINGTON
Now, we haven’t talked about the driver yet, but I have to assume that there is an impact that they’re having on the efficiency of the car depending on how they actually drive it. Is it true and what can you do about that?

CHRIS MANZIE
Yeah, it’s absolutely true. With an engine, its efficiency forms a type of surface. So if we look at the operating range of an engine over a speed pressure surface, you have an efficiency peak which will be characterised by sort of mid-range manifold pressures and engine speeds. If you start to move away from that preferable operating point, your efficiency will drop significantly down. So you may go from a 40 per cent efficiency down to 15 per cent if you’re operating in a really bad region for engine efficiency. So that might be wide open throttle and low speed type operation. What that means is that if you’re able to drive and keep the engine operating close to its peak efficiency, you’ll be able to get significantly better fuel economy from the vehicle. So that tends to be characterised by less sudden acceleration, so you avoid those wide open throttle situations and I guess that’s why we’re seeing gear box selection and continuously variable transmission - CVTs - as having such a big impact on the real world fuel economy that’s achievable.

SHANE HUNTINGTON
Chris, in my vehicle - I have an automatic vehicle and it has a tacho in it so I can tell how many revs per minute the engine is doing but it doesn’t have anything that gives me indication of the efficiency depending on how I’m driving. Is that the sort of thing we should be seeing in cars so that we can modify our behaviour?

CHRIS MANZIE
Yeah and actually some of the newer vehicles - the Nissan Leaf, for example, although it’s a battery powered vehicle, has a little computer display on the dashboard that if you drive more efficiently you’ll actually start to see a little tree grow and leaves appear on the tree as a more useful feedback for the average driver than necessarily a tacho or some other feedback. There is work, particularly in the HMI or human machine interface fields to work out how best to convey the information about driving behaviour.

SHANE HUNTINGTON
When we look at the designs coming out in the next five to 10 years, how far do you think these things will do? I mean, will our cars essentially be telling us how to drive and giving sort of haptic feedback that prevent us from driving poor? Is that where you think these things will go?

CHRIS MANZIE
So I think in terms of the power train, we’re likely to see a much greater proliferation of electrified vehicles. So these will vary from small hybrid vehicles through to full parallel hybrids and even some electric vehicles. In terms of the actual cars themselves and how they behave, I think there is certainly going to be a greater deal of not quite autonomous driving but maybe the car talks to the driver in a much more constructive way to adjust the driving patterns. So we can start to see things like adaptive cruise control, which is primarily used at the moment for safety reasons, maintaining a constant distance to the car in front and actually slowing the vehicle down to a stop. We may start to see that being used to gain efficiency in how the car is being driven. I guess there’s also a large push towards the use of ITS in vehicles, so intelligent transportation systems. More sensing capability and more communication capability in vehicles. Cars starting to talk to each other and let the driver or occupants know about upcoming road conditions and that information can also be used to improve safety and improve efficiency in how the vehicles are travelling.

SHANE HUNTINGTON
Associate Professor Chris Manzie from the Department of Mechanical Engineering in the Melbourne School of Engineering, the University of Melbourne, thank you for being our guest on Up Close today and giving us an understanding of control systems engineering for car engine efficiency.

CHRIS MANZIE
Thanks, Shane.

SHANE HUNTINGTON
Relevant links, a full transcript and more info on this episode can be found at our website at upclose.unimelb.edu.au. Up Close is a production of the University of Melbourne, Australia. This episode was recorded on 9 February 2012. Our producers for this episode were Kelvin Param and Eric van Bemmel, audio engineering by Gavin Nebauer, background research by Dyani Lewis. Up Close is created by Eric can Bemmel and Kelvin Param. I am Shane Huntington. Until next time, goodbye.

VOICEOVER
You’ve been listening to Up Close. We’re also on Twitter and Facebook. For more info, visit upclose.unimelb.edu.au. Copyright 2012 The University of Melbourne.


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