cool_t Posted July 11, 2009 Author Posted July 11, 2009 I've hurd that cold air is better for combustion Yes...Well if we think about heat vrs. cold....I would rather have my jet cold then hot. In all forms of fuel combustion motors the colder the better...less friction...
Moa Posted July 11, 2009 Posted July 11, 2009 Yes...Well if we think about heat vrs. cold....I would rather have my jet cold then hot. In all forms of fuel combustion motors the colder the better...less friction... Too cold and lubricant viscosity is too high (not slippery enough). There is an optimum temperature range which you must be always consider, in piston-powered aircraft at least. A descent at low engine power can easily cool the engine too much and cause problems with fuel freezing and insufficient lubrication. During a long descent engine power must occasionally be increased to prevent problems, particularly if the decent is to land since if you abort and need full throttle then fuel icing could seriously ruin your day (or life!). 1
cool_t Posted July 11, 2009 Author Posted July 11, 2009 Too cold and lubricant viscosity is too high (not slippery enough). There is an optimum temperature range which you must be always consider, in piston-powered aircraft at least. A descent at low engine power can easily cool the engine too much and cause problems with fuel freezing and insufficient lubrication. During a long descent engine power must occasionally be increased to prevent problems, particularly if the decent is to land since if you abort and need full throttle then fuel icing could seriously ruin your day (or life!). Sure....But the "Colder" Something is the closer it is to "Zero" friction...hence less wear and tear, heat, friction and physical stress. The internal combustion engine is how old? There heavy, they have many moving parts, fuel consumption limits any form of transportation....If they were smart they would start making HYDROGEN engines for all forms of transportation; and you can re-use the expended remains "Water" and then extract the Hydrogen from the water, over and over and over again. But for SOME un-godly reason there is this thing called the "Global-Economy" and they wont put forth effort 2 use logic and get things on the roll.
EinsteinEP Posted July 12, 2009 Posted July 12, 2009 Cheers, all. Sorry to rain on the parade in this thread, but combustion engines perform better when ingesting cold air because of density differences, not specifically the air temperature When you consider the chamber temperature of a combustion engine goes anywhere from a few hundred degC to a few thousand, a difference of even 30 degC in the intake air is in the noise. However, colder air is usually denser air which means there's more O2 per gulp which allows more combustion. Superchargers work off of this principle (take a big gulp of air, squish it down it a higher pressure/density before stuffing it in the combustion chamber), but even supercharged engines get a performance boost from denser intake air. Props and turbines love dense air too because they get more push for each swing of the blade. "Cold shock" when yanking back the throttles on a high performance engine refers to the uneven expansion and contraction of the metal pieces of the engine, not fuel lines freezing. Cold shock will greatly reduce the life of an engine, and while catastrophic failure due to cold shock is theoretically possible, I've never heard of it. And yes, while the internal combustion engine concept is over a hundred years old, it is the cheapest, easiest, most reliable, and most powerful form of vehicle power we have. I'm all for hydrogen/fuel cell/fusion/fission/ion-powered engines, as long as I can get it for around $350/mo. and still have reasonable insurance payments! Have fun! Shoot to Kill. Play to Have Fun.
Moa Posted July 12, 2009 Posted July 12, 2009 Cheers, all. Sorry to rain on the parade in this thread, but combustion engines perform better when ingesting cold air because of density differences, not specifically the air temperature When you consider the chamber temperature of a combustion engine goes anywhere from a few hundred degC to a few thousand, a difference of even 30 degC in the intake air is in the noise. However, colder air is usually denser air which means there's more O2 per gulp which allows more combustion. Superchargers work off of this principle (take a big gulp of air, squish it down it a higher pressure/density before stuffing it in the combustion chamber), but even supercharged engines get a performance boost from denser intake air. Props and turbines love dense air too because they get more push for each swing of the blade. "Cold shock" when yanking back the throttles on a high performance engine refers to the uneven expansion and contraction of the metal pieces of the engine, not fuel lines freezing. Cold shock will greatly reduce the life of an engine, and while catastrophic failure due to cold shock is theoretically possible, I've never heard of it. And yes, while the internal combustion engine concept is over a hundred years old, it is the cheapest, easiest, most reliable, and most powerful form of vehicle power we have. I'm all for hydrogen/fuel cell/fusion/fission/ion-powered engines, as long as I can get it for around $350/mo. and still have reasonable insurance payments! Have fun! Sure cold is good if you are only considering the combustion part. You also get throttle valve sticking when descending through cold, can cause engine failure. Curtains for you. Therefore you need to keep the engine reasonably warm. No point having super efficient cool engine if there are ice problems in fuel lines (low throttle setting) and unable to adjust throttle when needed (throttle freezing). Carnot cycle combustion engines are ubiquitous but not that efficient. Rotary engines are better (although they have other disadvantages). Hydrogen power is a problem (either as fuel-cell or combustion source) because the electrolysis to produce it requires electrical power (eg. from gas turbine or nuclear power station). Hydrogen is more like an energy storage option rather than energy source itself. Hydrogen itself is very bad for existing engines (destroying rubber seals etc) so engines using it for combustion are more expensive. Hydrogen will not solve the worlds energy demands.
cool_t Posted July 13, 2009 Author Posted July 13, 2009 Cheers, all. Sorry to rain on the parade in this thread, but combustion engines perform better when ingesting cold air because of density differences, not specifically the air temperature When you consider the chamber temperature of a combustion engine goes anywhere from a few hundred degC to a few thousand, a difference of even 30 degC in the intake air is in the noise. However, colder air is usually denser air which means there's more O2 per gulp which allows more combustion. Superchargers work off of this principle (take a big gulp of air, squish it down it a higher pressure/density before stuffing it in the combustion chamber), but even supercharged engines get a performance boost from denser intake air. Props and turbines love dense air too because they get more push for each swing of the blade. "Cold shock" when yanking back the throttles on a high performance engine refers to the uneven expansion and contraction of the metal pieces of the engine, not fuel lines freezing. Cold shock will greatly reduce the life of an engine, and while catastrophic failure due to cold shock is theoretically possible, I've never heard of it. And yes, while the internal combustion engine concept is over a hundred years old, it is the cheapest, easiest, most reliable, and most powerful form of vehicle power we have. I'm all for hydrogen/fuel cell/fusion/fission/ion-powered engines, as long as I can get it for around $350/mo. and still have reasonable insurance payments! Have fun! Sure...Sweet.....Money is the issue always....But still in all obtaining Higher speeds in less dense, colder air, with less friction should allow you air craft higher mach numbers faster than in LOMAC
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