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> Turbo chargers are not heat recovery turbines they will not increase and engine thermal efficiency by any significant amount, diesels use turbo charging to in

> Turbo chargers are not heat recovery turbines they will not increase and engine thermal efficiency by any significant amount, diesels use turbo charging to increase power they are just as thermally efficient without them. This is 100% false, and trivially easy to google. But it also misses the point: turbochargers are heat engines: they convert heat to work. The fact that they use waste heat from exhaust means that they recover energy that is normally lost, which means it is a heat recovery engine. That work can be used any number of ways, but if it is used, you have increased the thermal efficiency of the engine. > The Freightliner still has a turbo charger like any diesel along with a recovery steam turbine, much of the effective heat recovery comes from capturing heat from the engine block itself not just hot exhaust gas. Those are both heat recovery engines. One is rankine cycle (the steam turbine), and the other is brayton cycle (the turbocharger). The only other difference is the source of heat. And again, to drive the point home: https://www.sciencedirect.com/science/article/pii/S1876610214014076/pdf?md5=81032aa431f1a3baea977a5b8820409a&pid=1-s2.0-S1876610214014076-main.pdf https://www.sciencedirect.com/science/article/pii/S187661021...

SigmundA 5y ago
If a turbocharger is configured to act as a heat recovery turbine it is significantly more complicated including again a generator. Therefore it can not be simpler than an electric motor, this should be obvious. This is referred to as turbo compounding not turbo charging [1]. Turbochargers allow more efficiency through engine downsizing and that they can be bypassed under light/cruising loads. That is you can have smaller engine that acts like a bigger engine under heavy loads but has the efficiency of a smaller engine at normal loads [2]. The turbo charger on the Frieghtliner is not part of the heat recovery system, it is compressing intake air in order to allow an increase of power by also injecting more fuel. If you attach a generator to the turbo to make it recover heat as output power it will no longer be able to use that work to compress intake air. Then it becomes a turbo-compounded engine. They use a steam turbine as it recovers more heat while adding almost no back pressure to the system. As shown to get a modest increase in thermal efficiency something much larger and more complicated must be used on a semi in addition to the turbocharger. Show me a fuel cell using a turbo charger to attain any significant heat recovery. Show me one that doesn't use a generator and is therefore simpler than an electric motor. You will not attain 60%+ thermal efficiency with a just a turbo charger and you know it. Fuel cells look to need a secondary combustion system in order drive the turbine properly due to them having no compression of their own so now you have a full gas turbine with generator on top of the fuel cell. 1. https://en.wikipedia.org/wiki/Turbo-compound_engine https://en.wikipedia.org/wiki/Turbo-compound_engine 2. http://large.stanford.edu/courses/2010/ph240/veltman1/ http://large.stanford.edu/courses/2010/ph240/veltman1/
- darksaints 5y ago
  I don't know where you keep getting this idea that I think a heat recovery turbine is simpler than a generator. All I said was that if you think a heat recovery turbine is too complex to be feasible, then you'll also think an electric motor is too complex to be feasible. Because neither are too complex to be feasible. And no, it is not complex at all. The turbine part stays the same as your garden variety turbocharger. Instead of directly attaching a compressor (which makes it a turbocharger), you directly attach a generator (which makes it a turbine-driven generator). In fact, you could even do both: power an intake air compressor as well as a generator. Literally anybody could build one in their back yard using parts ripped out of random cars at a junkyard. Without capturing any waste heat at all, Solid Oxide Fuel Cells are ~60% efficient. With a waste heat recovery turbine, you increase the efficiency. 75% efficiency is already feasible. https://www.sciencedirect.com/science/article/abs/pii/S0306261918310316?via%3Dihub https://www.sciencedirect.com/science/article/abs/pii/S03062... Yes, this solution is more complex than a normal fuel cell...in exactly the same way that a turbocharged engine is more complex than a naturally aspirated engine. That is to say not only is it entirely feasible, but it is a well developed easily adaptible solution that has been used for increasing efficiency for over a century now. Learn how to google...there are literally hundreds of papers detailing efficiency gains from using turbochargers on fuel cells. Hell, most turbocharger manufacturers are already making custom hybrid turbocharger/generator packages specifically designed for fuel cell use. https://www.garrettmotion.com/electric-hybrid/twostage-electric-compressor-for-fuel-cells/ https://www.garrettmotion.com/electric-hybrid/twostage-elect... https://www.mtu-solutions.com/eu/en/stories/technology/turbochargers-for-higher-engine-efficiency.html https://www.mtu-solutions.com/eu/en/stories/technology/turbo... https://cdn.borgwarner.com/docs/default-source/default-document-library/2014_whitepaper_charging-system-for-fuel-cell-applications_en.pdf?sfvrsn=b60acd3c_11 https://cdn.borgwarner.com/docs/default-source/default-docum... You thought it was infeasible because you were imagining a big ass steam engine, and when it was pointed out that turbochargers are an entirely commonplace form of heat recovery turbine, you backpeddled and tried to redefine words (b-b-b-but that's a Turbo Compounder!!!) to weasel your way out of it. Give it up. You're embarrassing yourself.
  - SigmundA 5y ago

SigmundA 5y ago

If a turbocharger is configured to act as a heat recovery turbine it is significantly more complicated including again a generator. Therefore it can not be simpler than an electric motor, this should be obvious. This is referred to as turbo compounding not turbo charging [1]. Turbochargers allow more efficiency through engine downsizing and that they can be bypassed under light/cruising loads. That is you can have smaller engine that acts like a bigger engine under heavy loads but has the efficiency of a smaller engine at normal loads [2]. The turbo charger on the Frieghtliner is not part of the heat recovery system, it is compressing intake air in order to allow an increase of power by also injecting more fuel. If you attach a generator to the turbo to make it recover heat as output power it will no longer be able to use that work to compress intake air. Then it becomes a turbo-compounded engine. They use a steam turbine as it recovers more heat while adding almost no back pressure to the system. As shown to get a modest increase in thermal efficiency something much larger and more complicated must be used on a semi in addition to the turbocharger. Show me a fuel cell using a turbo charger to attain any significant heat recovery. Show me one that doesn't use a generator and is therefore simpler than an electric motor. You will not attain 60%+ thermal efficiency with a just a turbo charger and you know it. Fuel cells look to need a secondary combustion system in order drive the turbine properly due to them having no compression of their own so now you have a full gas turbine with generator on top of the fuel cell. 1. https://en.wikipedia.org/wiki/Turbo-compound_engine https://en.wikipedia.org/wiki/Turbo-compound_engine 2. http://large.stanford.edu/courses/2010/ph240/veltman1/ http://large.stanford.edu/courses/2010/ph240/veltman1/

darksaints 5y ago
I don't know where you keep getting this idea that I think a heat recovery turbine is simpler than a generator. All I said was that if you think a heat recovery turbine is too complex to be feasible, then you'll also think an electric motor is too complex to be feasible. Because neither are too complex to be feasible. And no, it is not complex at all. The turbine part stays the same as your garden variety turbocharger. Instead of directly attaching a compressor (which makes it a turbocharger), you directly attach a generator (which makes it a turbine-driven generator). In fact, you could even do both: power an intake air compressor as well as a generator. Literally anybody could build one in their back yard using parts ripped out of random cars at a junkyard. Without capturing any waste heat at all, Solid Oxide Fuel Cells are ~60% efficient. With a waste heat recovery turbine, you increase the efficiency. 75% efficiency is already feasible. https://www.sciencedirect.com/science/article/abs/pii/S0306261918310316?via%3Dihub https://www.sciencedirect.com/science/article/abs/pii/S03062... Yes, this solution is more complex than a normal fuel cell...in exactly the same way that a turbocharged engine is more complex than a naturally aspirated engine. That is to say not only is it entirely feasible, but it is a well developed easily adaptible solution that has been used for increasing efficiency for over a century now. Learn how to google...there are literally hundreds of papers detailing efficiency gains from using turbochargers on fuel cells. Hell, most turbocharger manufacturers are already making custom hybrid turbocharger/generator packages specifically designed for fuel cell use. https://www.garrettmotion.com/electric-hybrid/twostage-electric-compressor-for-fuel-cells/ https://www.garrettmotion.com/electric-hybrid/twostage-elect... https://www.mtu-solutions.com/eu/en/stories/technology/turbochargers-for-higher-engine-efficiency.html https://www.mtu-solutions.com/eu/en/stories/technology/turbo... https://cdn.borgwarner.com/docs/default-source/default-document-library/2014_whitepaper_charging-system-for-fuel-cell-applications_en.pdf?sfvrsn=b60acd3c_11 https://cdn.borgwarner.com/docs/default-source/default-docum... You thought it was infeasible because you were imagining a big ass steam engine, and when it was pointed out that turbochargers are an entirely commonplace form of heat recovery turbine, you backpeddled and tried to redefine words (b-b-b-but that's a Turbo Compounder!!!) to weasel your way out of it. Give it up. You're embarrassing yourself.
- SigmundA 5y ago