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| Turbocharger power input (consumption) |
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| JPortici:
--- Quote from: firewalker on March 25, 2020, 05:02:47 pm ---Is the amount of power a turbocharger need the main reason for not having electrically driven turbines? Alexander. --- End quote --- a conventional exhaust driven turbocharger in full power turns at 100k+ RPM and at the same time is way hotter than 150 °C :) that will add some complexity |
| tautech:
--- Quote from: Circlotron on March 26, 2020, 01:09:20 am ---I imagine that if intake pressure was much higher than exhaust pressure you would get blow-through during valve overlap. --- End quote --- Exactly this is the great advantage with turbo'ed diesels. The proper cylinder scavenging promotes cleaner and better burns. Some good general reading on turbochargers are books by Hugh MacInnes from way back in the 80's. |
| langwadt:
--- Quote from: tautech on March 27, 2020, 08:18:56 am --- --- Quote from: Circlotron on March 26, 2020, 01:09:20 am ---I imagine that if intake pressure was much higher than exhaust pressure you would get blow-through during valve overlap. --- End quote --- Exactly this is the great advantage with turbo'ed diesels. The proper cylinder scavenging promotes cleaner and better burns. --- End quote --- if efficiency was the only object maybe but exhaust gas recirculation to reduces the amount oxygen to reduce the amount of NOx. and since diesels always run with excess oxygen in the exhaust a three-way catalyst won't work to reduce NOx so you need things like Adblue |
| tautech:
--- Quote from: langwadt on March 27, 2020, 09:05:37 am --- --- Quote from: tautech on March 27, 2020, 08:18:56 am --- --- Quote from: Circlotron on March 26, 2020, 01:09:20 am ---I imagine that if intake pressure was much higher than exhaust pressure you would get blow-through during valve overlap. --- End quote --- Exactly this is the great advantage with turbo'ed diesels. The proper cylinder scavenging promotes cleaner and better burns. --- End quote --- if efficiency was the only object maybe but exhaust gas recirculation to reduces the amount oxygen to reduce the amount of NOx. and since diesels always run with excess oxygen in the exhaust a three-way catalyst won't work to reduce NOx so you need things like Adblue --- End quote --- EGR is something completely different where a portion of exhaust gasses are diverted into the intake manifold. It uses a separate piped connection and valving to accomplish it. EGR is quite different to engine valve overlap where boost pressure can momentarily pass from intake to exhaust when the valve timing overlaps and in doing so scavenges the combustion chamber of any remaining exhaust gasses. |
| langwadt:
--- Quote from: tautech on March 27, 2020, 09:14:39 am --- --- Quote from: langwadt on March 27, 2020, 09:05:37 am --- --- Quote from: tautech on March 27, 2020, 08:18:56 am --- --- Quote from: Circlotron on March 26, 2020, 01:09:20 am ---I imagine that if intake pressure was much higher than exhaust pressure you would get blow-through during valve overlap. --- End quote --- Exactly this is the great advantage with turbo'ed diesels. The proper cylinder scavenging promotes cleaner and better burns. --- End quote --- if efficiency was the only object maybe but exhaust gas recirculation to reduces the amount oxygen to reduce the amount of NOx. and since diesels always run with excess oxygen in the exhaust a three-way catalyst won't work to reduce NOx so you need things like Adblue --- End quote --- EGR is something completely different where a portion of exhaust gasses are diverted into the intake manifold. It uses a separate piped connection and valving to accomplish it. EGR is quite different to engine valve overlap where boost pressure can momentarily pass from intake to exhaust when the valve timing overlaps and in doing so scavenges the combustion chamber of any remaining exhaust gasses. --- End quote --- yes EGR is the exact opposite. So why would it be and advantage to scavenge any remaining exhaust gasses only to add it back via the intake to meet emissions demand |
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