Water Vapour Jet
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err.. I don't mind any commments... help point me in the right direction if Im not already am.. plus makes me ask more questions. :)
However, I still stand by my statement. This is because even with a fine mist of water vapour, there is still that volume that could have been occupied by the air/fuel mixture thus reducing volumetric efficiency... I mean.. you can even notice an increase in power just by polishing your intake manifold insides, which only causes a small increase in flow.
As far as driving around on a hot sunny day and cool nights, well.. the key here is Mass air flow. On both days you will suck in the same volume of air.. but wait... volume is not equal mass.. that would be volume x density. So on a hot sunny day, you suck in the same amt of volume of air but density is low so overall mass flow is reduced. So you say that when you spray a fine mist of water, mass is the same while intake temperatures are reduced.. well that's exactly what happens.. but with water saturation, combustion temperatures drop and so does power..
However, I still stand by my statement. This is because even with a fine mist of water vapour, there is still that volume that could have been occupied by the air/fuel mixture thus reducing volumetric efficiency... I mean.. you can even notice an increase in power just by polishing your intake manifold insides, which only causes a small increase in flow.
As far as driving around on a hot sunny day and cool nights, well.. the key here is Mass air flow. On both days you will suck in the same volume of air.. but wait... volume is not equal mass.. that would be volume x density. So on a hot sunny day, you suck in the same amt of volume of air but density is low so overall mass flow is reduced. So you say that when you spray a fine mist of water, mass is the same while intake temperatures are reduced.. well that's exactly what happens.. but with water saturation, combustion temperatures drop and so does power..
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hahaha.. this is getting interesting! :D okok.. lets see.. high temp air= high energy within each air molecule= more distance between each air molecule = low air density...therefore high air temp=low air density and low air temp= high air density..
so when high air temp is reduced by cool fine water spray the air molecule will loose its energy and 'clump' together. The closer they 'clump' together the more oxigen molecules u'll get in the same volume..
Also if the water is being sprayed fine enough it'll have a very large surface area to absorb large amt of heat from its surrounding and hence transforming its current state(liquid) to a gaseous state which will
not affect the amount of inlet volume..
Another thing is that temperature will not affect the volumetric efficiency.. engine capacity, construction of ports, type of throttle body, type of air metering device and type of air filter will affect volumetric efficiency.
One more thing is a cooler intake charge will not reduce the combustion temp since the cooler the intake charge the more oxigen and fuel u can pack into an engine, the more violent the explosion of the charge will be hence increasing the combustion temp..
cheers ;)
so when high air temp is reduced by cool fine water spray the air molecule will loose its energy and 'clump' together. The closer they 'clump' together the more oxigen molecules u'll get in the same volume..
Also if the water is being sprayed fine enough it'll have a very large surface area to absorb large amt of heat from its surrounding and hence transforming its current state(liquid) to a gaseous state which will
not affect the amount of inlet volume..
Another thing is that temperature will not affect the volumetric efficiency.. engine capacity, construction of ports, type of throttle body, type of air metering device and type of air filter will affect volumetric efficiency.
One more thing is a cooler intake charge will not reduce the combustion temp since the cooler the intake charge the more oxigen and fuel u can pack into an engine, the more violent the explosion of the charge will be hence increasing the combustion temp..
cheers ;)
Hmm/... The VE I guess it seems you are right.. I need to read up on that. IT seems that I ddn't understand the theory fully but anyways.. I still say that a mist of water will slightly reduce performance.. at best there will be no effect.
I did not say with cooler intake charge... I said "with water saturation"
Anyway.. let's break it down.. why do we get an increase in HP when temperature is low? because when temperature is lower air density increases. And with higher air density, mass flow will be increased. Okay.. that's settled.
In a closed system. The mass flow rate at point A must equal the the mass flow rate at point B...
So the total mass entering the combustion chamber must equal the mass of air as read at the MAF plus the mass of the mist of water plus the mass of fuel.
It doesn't matter what the water does because mass of air at pt A must equal mass of air at pt B.
So... Fuel and the mass of air is the same but there is water in the chamber
Some of the energy that could otherwise be used to propel the cylinder downward has been used to convert water into steam and steam into superheated steam.....
Thus this explains why I believe that there will be a reduction in performance due to aquamist type devices... :blink:
I did not say with cooler intake charge... I said "with water saturation"
Anyway.. let's break it down.. why do we get an increase in HP when temperature is low? because when temperature is lower air density increases. And with higher air density, mass flow will be increased. Okay.. that's settled.
In a closed system. The mass flow rate at point A must equal the the mass flow rate at point B...
So the total mass entering the combustion chamber must equal the mass of air as read at the MAF plus the mass of the mist of water plus the mass of fuel.
It doesn't matter what the water does because mass of air at pt A must equal mass of air at pt B.
So... Fuel and the mass of air is the same but there is water in the chamber
Some of the energy that could otherwise be used to propel the cylinder downward has been used to convert water into steam and steam into superheated steam.....
Thus this explains why I believe that there will be a reduction in performance due to aquamist type devices... :blink:
actually...water injection systems have been around for a very very long time and have proven to be useful n does assist in avoiding detonation....allowing force-fed cars to run higher boost safely...
it is true that more air and fuel into a engine results in more power, but a turbocharger that compresses air, also heats it up. Higher air temperatures lead to thinner air resulting in a non-consistent stoechiometric ratio which can lead to a lean mixture and then detonation, which can be damaging to our engines..
in turbo'd engines, the air and fuel mixture that enters the cylinder can explode prematurely due to the an engine's extreme environment...causing damage.
To avoid damaging the engine by detonation or pre-ignition phenomena, water is injected, along with fuel into the combustion chambers in order to provide a water/air/fuel mixture which not only burns more efficiently and avoids detonation or pre-ignition but also provides additional inlet air cooling which results in much denser air.
density of air is not the same as the volume of air......
Just my 2 cents... correct me if i am wrong.
cheers!! :)
it is true that more air and fuel into a engine results in more power, but a turbocharger that compresses air, also heats it up. Higher air temperatures lead to thinner air resulting in a non-consistent stoechiometric ratio which can lead to a lean mixture and then detonation, which can be damaging to our engines..
in turbo'd engines, the air and fuel mixture that enters the cylinder can explode prematurely due to the an engine's extreme environment...causing damage.
To avoid damaging the engine by detonation or pre-ignition phenomena, water is injected, along with fuel into the combustion chambers in order to provide a water/air/fuel mixture which not only burns more efficiently and avoids detonation or pre-ignition but also provides additional inlet air cooling which results in much denser air.
density of air is not the same as the volume of air......
Just my 2 cents... correct me if i am wrong.
cheers!! :)
I've read from some website that with turbo engines, the usual practice to prevent detonation is to use a richer than necessary air/fuel mixture, which can actually result in slower combustion. Water injection allows the air/fuel mixture to be of the optimum ratio because the cooling part is done by the water, and not fuel. Thus, a/f ratio is not overly rich to slow down combustion yet the water mist is cooling it enough to prevent detonation.
And not to forget that it's much cheaper to cool using water than petrol!
And not to forget that it's much cheaper to cool using water than petrol!
water is H2O, where O represents oxygen. when water dries or gets heated up it changes form into air frm liquid. It only changes form. the oxygen (O) is still there to support combustion. when we talk about air, it is the oxygen content that we are concerned with. therefore, theorethically, this mist thing does improve power or better combustion or wateva u wanna call it.
sad thing is, the increase would be so small u wouldnt even feel it. better save ur time n money on other things. if stuff like that actually works it would come straight off the factory..
rollo:
the fuel only gets heated up when it goes into the combustion chamber. fuel is still cool in ur petrol tank.
Does all this make sense??
true that the fuel gets heated up when it enters the hot combustion chamber. getting heated up would mean that it absorbs heat from the surrounding area like the air it has mixed with. my thinking is that if the fuel was initially cooler to begin with, it would absorb more heat from the intake air it atomises or vapourises in, cooling down the air further, making it denser.
i began thinking about this when i found out from some city taxi drivers that there would be some power loss felt when running on natural gas as compared to petrol. one factor is that as natural gas did not require atomisation or vapourisation, it does not absorb heat from the air it mixes with. in contrast, petrol needs to be atomised or vapourised when it mixes with air and it would absorb heat from that air.
just my thoughts...
fair enough u have a point. however there is no point cooling the air when its already in the combustion chamber as the amount of oxygen would remain the same. lets not forget why we want cooler air in the first place.
also, cooling the fuel would require energy, and lost of power would occur there. we know how much power we lose from air conditioners alone. lets not imagine how much we lose cooling liquid/petrol.
also, cooling the fuel would require energy, and lost of power would occur there. we know how much power we lose from air conditioners alone. lets not imagine how much we lose cooling liquid/petrol.
i remember 1 fellow who did this in his 2nd gen civic. he ran the fuel line between the fuel pump & the carb float bowl along the aircon tube hose which transports the aircon gas from the cooling coil evaporator back to the compressor & wrapped them closely together. the aircon gas in this hose was cold enough to help cool the fuel. he said the effect is that the engine feels more alive. so i guess the cool fuel would have helped cool the air it mixed with as the air-fuel mixture travels from the carb down through the intake manifold & finally into the combustion chambers, and also the cooled fuel would be denser & more energy content per unit volume.
with multipoint fuel injection nowadays, the fuel injector nozzle is placed close to the inlet of the combustion chamber & so in effect, the fuel is virtually sprayed straight into the combustion chamber as the inlet valve opens and may not have time to further cool the air already in the combustion chamber before the ignition starts. so with multipoint fuel injection, cooling the fuel may not have much effect at all.
i suddenly remembered reading somewhere that when (not too excessive) water droplets turn into steam in the combustion chamber of an internal combustion engine, the expansion of steam would help push down the piston in the power stroke, just like in those old reciprocating steam engines used in the old steam locomotives. it may not help increase power but it may help reduce fuel consumption as less fuel is required to push the same piston down.
my 2¢
Use a metal intake pipe, run the aircond cooling coil around it. Then insulate the whole thing.. you get a condenser-like intake hose. No one has done it before as to my knowledge.. might be too wild, the idea.
Still, the main point is to get cooler air from outside, not cooling it down in the intake system.
Still, the main point is to get cooler air from outside, not cooling it down in the intake system.
Actually what we need to aid combustion is just O2. H20 remains H20 even when combusted. The hydrogen ions/atoms and the oxygen atoms won't be separated with this process.
Still again.. IMHO the only way to increase power with water injection is with tuning. If tuning is kept stock, there should be no difference in power. In fact, some have shown that it actually drops slightly.
Yeah, they do sell fuel coolers --QuoteBegin-rollo |
| @Dec 28 2004, 19:51 i suddenly remembered reading somewhere that when (not too excessive) water droplets turn into steam in the combustion chamber of an internal combustion engine, the expansion of steam would help push down the piston in the power stroke, just like in those old reciprocating steam engines used in the old steam locomotives. it may not help increase power but it may help reduce fuel consumption as less fuel is required to push the same piston down. my 2¢[/quote] Yeah, but energy is from the fuel that was supposed to be used to move the cylinder has been used to expand the water vapour. |
i've seen such a cooler being offered for sale by a US company & it looks a smaller version of an oil cooler. that company also mentioned that this heat exchange device can be used to cool the ATF. however, i can't remember the brand name or that company name. |
|
Yeah, but energy is from the fuel that was supposed to be used to move the cylinder has been used to expand the water vapour. [/quote] i've also read some where that in the absence of any water droplets as in a normal conventional combustion process, the air-fuel mixture burns, creating heat & also the carbon dioxide & other stuff which expands to push down the piston. when there are also water droplets present before the combustion, the air-fuel mixture also burns & also creating heat, carbon dioxide & other stuff like before but now the water droplets gets turned into steam by the heat and this steam also expands in the cylinder, giving a helping hand. |
Maybe natural gas has a lower energy rating and the systems using natural gasses are less efficient? Natural gas combustion doesn't have as much development as our conventional systems. [/b][/quote] according to paragraph 4.9 of this gasoline faq at http://www.faqs.org/faqs/autos/gasoline-faq/part1/ , the energy content per unit mass for natural gas is higher than that of petrol/gasoline. admittedly, i was made to understand that the engines in our ngv taxis r still optimally tuned to run on petrol but not so on natural gas bcos these engines were factory tuned on petrol before the taxis were fitted with natural gas/petrol dual fuel systems. by right, an engine optimally tuned for natural gas would take advantage of natural gas RON of more than 100 (120, i think) which would mean higher compression ratios & more aggressive ignition timing advance curves. but if so, such an engine would run poorly on RON97 petrol. my 2 cents. |
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