Normally producer gas is cooled to normal temp and fed to engine fully replacing diesel as fuel. It is done after cleaning and washing then removal of water. As gas is produced at 677 degree celcius, after cleaning through cyclone and ceramic filters it particulate loading is 1.0 mg/Nm3. My gas is available at 600 degrees. Can i directly feed it to utilise its sensible heat and avoid derating of diesel engine ??.
you can use it, but you should to note that each engine is made for a specific fuel
I will make necessary changes in compression ratio and ignition timings. But real issue is how to design intake valve so that mixture hits the wall not producer gas itself. Can it still work in aluminium engines??. If yes what should be parameters to get more than 50% thermal efficiency ??. Can i increase volumetric thermal energy more than from diesel fuel to overate engine and get more thermal efficient ??
Upendra Singh
Is it a problem to cool down your gas? Without cooling volumetric efficiency of the engine may drop significantly. Obviously it depends on gas flow rate. Can you specify any other details about the engine (dual fuel or spark ignition, supercharging, intercooler present or not etc.). It would be easier to say something helpful for you.
No. Idea is to use sensible heat of gas. It is an SI engine. Gas and air mixture is to be compressed 10 degree before autoignition of gas mixture that is 527 degrees. It makes compression ratio of 4. This gives thermal efficiency of 31%. Cooling has been increased by using liquid coolant. But problem is how to keep max specfic heat ratio.greater to make efficiency higher. We can 15% gain in efficiency by using sensible heat too if volumetric efficiency is not affected much.
The warmer gas the lower a ratio of specific heats, so thermodynamic efficiency drops. I do not see how do you want to increase efficiency in this way, especially that you assume compression ratio of 4. In this case theoretical efficniency of Otto cycle equals only ~42.5%.
Your engine will handle above mentioned conditions (temperature of mixture). It is a similar situation to using uncooled EGR. It works in many SI engines. On the other hand you should not expect too higher efficiency using too warm mixture.
OK. Then we will use cooler gas as my aim is to get electrical efficiency of 45% ~ thermal efficiency of 50%. As auto ignition temp is determined by lowest ignition component that is ethane we can heat gaseous mixture to 517 degrees( ethane AIT 527). By using intial mixture temp of 320K we can get thermal temp ratio of 790/320 = 2.46875. If we assume cp/cv to 1.27 then this gives compression ratio of 20 for chemical efficiency of 90%. This gives thermal efficiency of 50% and electrical efficiency of 45%. Can we acheive that ??.
I do not think so. The problem is more complex. For example, in real engine the higher compression ratio the lower mechanical efficiency, so overall efficiency will have a maximum at a value of compression ratio of approximately 14. Another thing is that it is hard to have stable autoignition for various loads of engine. IMHO it will be better to go to an engine with forced (spark) ignition, instead of HCCI (what you have suggested above). I don not know how large is your engine, but you should assume final value of efficiency not higher than 40% in best case.
Yes to compress at higher pressure we need more energy but this energy is compensated by high thermal efficiency we acheive. Can you please simulate conditions that at what max compression ratio we get the maximum power ??. My intention is too increase compression ratio as max as possible as my fuel has higher ignition temo. I am running engine to drive compressor which has stable load except on start and stop condition. The engine has to run min 12 hrs per day. In fact i wish it to run on 24x7 basis except quarterly maintenance schedule. I keep gaseous mixture 10 degree below AIT and use plugs for ignition. This will help me acheive better control on engine timings.
@ Upendra Singh It would not be simple to calculate analitycally the most convenient compression ratio for your engine. I mentioned the estimated value of 14, but it is not known, for example, what is a knock resistance of your gas. Besides this many important things are related directly to design of a used engine. To have a relatively precise answer you will need to perform a complex 3D simulation for your case. Another way is to select the compression ratio experimentally, starting from a moderate value taken from a similar engine fueled by a gas similar to yours.
Can we simulate engine in ENSYS software??. I dont know how to calculate knock resistance of gas.
I think you mean ANSYS. If so, I don't think it is suitable for your purposes. You can use for example GT Power, AVL Boost or Ricardo Wave. In such solvers you can define your own fuel.
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