5 ms·

Why are there no improvements in traditional petrol engines? They basically convert 60% into heat. Like use the heat to run a steam engine?

by perf1 4y ago

iiv 4y ago
There have been huge improvements since the first petrol engine, and huge improvements in the last 20 years as well. Petrol engines are some of the most studied and meticulously engineered things ever created.
yreg 4y ago
There has been a myriad of improvements in traditional petrol engines?
- wizofaus 4y ago
  Yet our cars still can't fly, and still emit greenhouse gases...
  - yreg 4y ago
    Are you waiting for a petrol engine that doesn't emit gases? I don't understand your comment.
    - wizofaus 4y ago
      Why not? We've been promised carbon capture forever...
  - djmips 4y ago
    We do have flying cars.
    - wizofaus 4y ago
      Can you name a single person you know of with one?
      - djmips 4y ago
        It's amazing what we do have. Just the computers alone are more than anyone could have ever imagined. But as for flying cars, they do exist, but we just don't need them.
      - yreg 4y ago
        I know a person who built one (actually more than one). Issue is that I don't think it's a good idea. https://www.youtube.com/watch?v=jf3I0ORN3ac https://www.youtube.com/watch?v=jf3I0ORN3ac
      - abenga 4y ago
        Isn't this called a helicopter? Aside from the noise, etc. issues with them, what would be the difference between a flying car and a helicopter? The need for a pilot's license to fly one?
        wizofaus 4y ago
        Price and ease of street parking come to mind!
shakezula 4y ago
What do you mean? The amount of improvements in standard ICE engines are mind-blowing. The fuel efficiency and power they manage these days is insane. You’re quoting that 60% figure and neglecting that most of the losses from that are thermodynamic and mechanical losses at transfer points that can’t really be overcome. At some point you have to lose some heat along the way.
monkpit 4y ago
We’ve been improving them for like 150 years, and they’re still getting better. For example, Mazda’s Skyactiv to increase compression ratios.
doug_life 4y ago
Turbochargers do exactly that. They take waste gas/heat to turn a pump and provide more oxygen for combustion. Also look into the F1 ERS systems that recover waste energy.
kwertyoowiyop 4y ago
Drive a car from the 1980s for a little while, then come back and we can discuss how much better engines are today. Lots!
skykooler 4y ago
One big limitation is the Carnot efficiency - for any heat engine (which internal combustion engines are) there's a maximum upper bound on the efficiency, which for gasoline and diesel is around 37%. Beyond that point you can't extract any more energy out of the waste heat without removing energy from somewhere else in the system.
formerly_proven 4y ago
Petrol engines can physically only achieve around 55-60 % efficiency, so getting up to ~35-40 % vehicle efficiency is actually really good. Large scale Diesel engines get really, really close (within a few points) of the hypothetical frictionless-no-heat-radiation-no-flow-losses efficiency possible with their parameters.
phkahler 4y ago
There is a fundamental limit to ICE efficiency dictated by the laws of thermodynamics. You can push that theoretical limit up, but it is dependent on having a higher compression ratio. Diesel engines use higher compression ratios for ignition, but they are dirty (in comparison). Higher compression ratios tend to result in more NOx emissions too, so for the regular car makers there is a direct trade between efficiency/emissions/reliability. But even if you aim for highest efficiency at all cost, you'll never get close to 100 percent, as the theoretical max never goes there (or does it at infinite compression ratio?).
VLM 4y ago
The term to google for is cogeneration. Sometimes all people need is the correct search term. The problem with cogeneration is its usually incredibly heavy and there aren't many uses for very low temperature process heat in most real-world applications. Another problem with cogeneration is you might get a small percentage boost by connecting a backup generator to the HVAC system but the capex can be VERY high if done safely and reliably, and system complexity seems to scale at an exponential rate. It seems a no-brainer to dump the radiator heat from a backup generator into an office building thereby burn less natgas to heat the building; however you factor in that you have to frost-proof it all and its going to be hundreds of gallons of anti-freeze in those pipes which is expensive and all pipes leak eventually with has ecological issues, and you can't have exhaust leaks into the building and over half the time you need cooling not heating anyway and the HVAC cannot be made smaller because you still need to heat even when the gen is off and the HVAC system will be less reliable because it'll be more complicated and the backup gen will be less reliable because its more complicated, perhaps making the backup gen less reliable than wall power. So shrug shoulders and dump the gen heat using an air cooled radiator, even in the winter.
skunkworker 4y ago
There is, especially in Racing. In Formula 1 some engines have reached 52% thermal efficiency [1], but the amount of hardware required in order to capture the excess heat (see MGU-H)[2], makes this costly and difficult to improve upon, and currently with the new F1 engine regulations they are dropping some complex systems so the barrier to entry is less expensive. [1] https://www.racefans.net/2021/11/11/how-f1-can-push-the-worlds-most-efficient-engine-even-further/ https://www.racefans.net/2021/11/11/how-f1-can-push-the-worl... [2] https://www.quora.com/What-are-MGU-H-and-MGU-K-in-an-F1-car-How-does-it-work https://www.quora.com/What-are-MGU-H-and-MGU-K-in-an-F1-car-...

Why are there no improvements in traditional petrol engines? They basically convert 60% into heat. Like use the heat to run a steam engine?

by perf1 4y ago

Why are there no improvements in traditional petrol engines? They basically convert 60% into heat. Like use the heat to run a steam engine?

iiv 4y ago

There have been huge improvements since the first petrol engine, and huge improvements in the last 20 years as well. Petrol engines are some of the most studied and meticulously engineered things ever created.

yreg 4y ago

There has been a myriad of improvements in traditional petrol engines?

wizofaus 4y ago
Yet our cars still can't fly, and still emit greenhouse gases...
- yreg 4y ago
  Are you waiting for a petrol engine that doesn't emit gases? I don't understand your comment.
  - wizofaus 4y ago
    Why not? We've been promised carbon capture forever...
- djmips 4y ago
  We do have flying cars.
  - wizofaus 4y ago
    Can you name a single person you know of with one?
    - djmips 4y ago
      It's amazing what we do have. Just the computers alone are more than anyone could have ever imagined. But as for flying cars, they do exist, but we just don't need them.
    - yreg 4y ago
      I know a person who built one (actually more than one). Issue is that I don't think it's a good idea. https://www.youtube.com/watch?v=jf3I0ORN3ac https://www.youtube.com/watch?v=jf3I0ORN3ac
    - abenga 4y ago
      Isn't this called a helicopter? Aside from the noise, etc. issues with them, what would be the difference between a flying car and a helicopter? The need for a pilot's license to fly one?
      - wizofaus 4y ago
        Price and ease of street parking come to mind!

shakezula 4y ago

What do you mean? The amount of improvements in standard ICE engines are mind-blowing. The fuel efficiency and power they manage these days is insane. You’re quoting that 60% figure and neglecting that most of the losses from that are thermodynamic and mechanical losses at transfer points that can’t really be overcome. At some point you have to lose some heat along the way.

monkpit 4y ago

We’ve been improving them for like 150 years, and they’re still getting better. For example, Mazda’s Skyactiv to increase compression ratios.

doug_life 4y ago

Turbochargers do exactly that. They take waste gas/heat to turn a pump and provide more oxygen for combustion. Also look into the F1 ERS systems that recover waste energy.

kwertyoowiyop 4y ago

Drive a car from the 1980s for a little while, then come back and we can discuss how much better engines are today. Lots!

skykooler 4y ago

One big limitation is the Carnot efficiency - for any heat engine (which internal combustion engines are) there's a maximum upper bound on the efficiency, which for gasoline and diesel is around 37%. Beyond that point you can't extract any more energy out of the waste heat without removing energy from somewhere else in the system.

formerly_proven 4y ago

Petrol engines can physically only achieve around 55-60 % efficiency, so getting up to ~35-40 % vehicle efficiency is actually really good. Large scale Diesel engines get really, really close (within a few points) of the hypothetical frictionless-no-heat-radiation-no-flow-losses efficiency possible with their parameters.

phkahler 4y ago

There is a fundamental limit to ICE efficiency dictated by the laws of thermodynamics. You can push that theoretical limit up, but it is dependent on having a higher compression ratio. Diesel engines use higher compression ratios for ignition, but they are dirty (in comparison). Higher compression ratios tend to result in more NOx emissions too, so for the regular car makers there is a direct trade between efficiency/emissions/reliability. But even if you aim for highest efficiency at all cost, you'll never get close to 100 percent, as the theoretical max never goes there (or does it at infinite compression ratio?).

VLM 4y ago

The term to google for is cogeneration. Sometimes all people need is the correct search term. The problem with cogeneration is its usually incredibly heavy and there aren't many uses for very low temperature process heat in most real-world applications. Another problem with cogeneration is you might get a small percentage boost by connecting a backup generator to the HVAC system but the capex can be VERY high if done safely and reliably, and system complexity seems to scale at an exponential rate. It seems a no-brainer to dump the radiator heat from a backup generator into an office building thereby burn less natgas to heat the building; however you factor in that you have to frost-proof it all and its going to be hundreds of gallons of anti-freeze in those pipes which is expensive and all pipes leak eventually with has ecological issues, and you can't have exhaust leaks into the building and over half the time you need cooling not heating anyway and the HVAC cannot be made smaller because you still need to heat even when the gen is off and the HVAC system will be less reliable because it'll be more complicated and the backup gen will be less reliable because its more complicated, perhaps making the backup gen less reliable than wall power. So shrug shoulders and dump the gen heat using an air cooled radiator, even in the winter.

skunkworker 4y ago

There is, especially in Racing. In Formula 1 some engines have reached 52% thermal efficiency [1], but the amount of hardware required in order to capture the excess heat (see MGU-H)[2], makes this costly and difficult to improve upon, and currently with the new F1 engine regulations they are dropping some complex systems so the barrier to entry is less expensive. [1] https://www.racefans.net/2021/11/11/how-f1-can-push-the-worlds-most-efficient-engine-even-further/ https://www.racefans.net/2021/11/11/how-f1-can-push-the-worl... [2] https://www.quora.com/What-are-MGU-H-and-MGU-K-in-an-F1-car-How-does-it-work https://www.quora.com/What-are-MGU-H-and-MGU-K-in-an-F1-car-...