Plynový/parový vstrekovací mechanizmus - gas/steam injection

Zdá sa že ma už niekto predbehol s nápadom zlepšeného rozprašovania za použitia nadkritickej kvapaliny/pary. Na jednej stránke popisujú napríklad trysku s vysokou turbulenciou a kavitáciou. The link here. Ak plynom vhodne spôsobíme kavitáciu v kvapaline, môžeme dosiahnuť dobré rozprašovanie. Autori uvádzajú dôvody prečo nadkritickou tekutinou dosiahnu lepšie rozprášenie.

It sems like somebody got the improved spraying characteristic idea with supercritical fluid. Link above. They show also nozzle with high turbulence and cavitation. Cavitation in fluid helps with spraying by rapidly disintegrating fluid flow.

Cavitation and bubble dynamics -

- uvádza veľa teórie a praktické testy kavitácie a vplyvu bubliniek. Zaujímavý poznatok je že voda s 20% vzduchu v mikrobublinkách má rýchlosť zvuku len 20m/s ! Takže pri transporte kvapaliny je plyn prekážkou, ale vo fáze rozprašovania sa dá tento jav využiť. Propán v nadkritickom stave má schopnosť rýchlo difundovať do vody, pri zmene v toku dôjde k peneniu.

Prieskum rôznych zakončení trysky a ich vplyv na výsledný rozstrek + obrázky. link tu.
Zaujímavé zistenie je že korunkové zakončenie výtoku uľahčuje kavitáciu v pretekajúcej tekutine. Link tu.

Ešte jedna možnosť je použiť rozprašovaciu ihlu roztáčanú prietokom plynu.

OK, spomenul som si na to ako este vylepšiť zumotor. Myslím, že MPI vstrekovač je riešený ako vzduchový rozprašovač benzínu, tlak vzduchu a tlak benzínu. Podstatné, že má podobne ako striekacia pištoľ prívod plynu zdola aj zhora. Niečo podobné by som použil na zumotor. Aha, takto, plyn by mohol byť propán, a kvapalina nasýtený roztok NH4NO3, ale tlak propánu si ešte musím overiť, možno by nestačil.
Cieľom je chrániť steny piestu a valca a vôbec pred priamym stykom so vstrekovanou kvapalinou ako aj jej rozkladnými produktami. Ostatne tie rozkladné produkty pri styku s plynom tu spomenutým spôsobujú horenie a vývin tepla. Keďže ideme na čo najväčší výkon - náš cieľ, niekedy môže byť výhodnejšie mať ako spalný produkt CO namiesto CO2. Navyše by malo byť propánu viac ako stechiometrický pomer aj preto, lebo tam máme ešte nejaký zvyšný nespálený vzduch.

A to najlepšie na záver? Pomer palivo/okysličovadlo je ľahko a pevne nastaviteľný, vyskúšateľný vo voľnej prírode. V podstate je to raketový motor. Druhá vynikajúca vec je nastaviteľná doba horenia. Rozmýšľate tuho ako na to? Jednoducho, nastavením parametrov rozprašovania sa dá nastaviť veľkosť kvapiek a/alebo aj ich penetrácia a tým jeden zo základných parametrov horenia. Vyšším tlakom plynu dosiahneme lepšie rozprášenie a aj lepšiu distribúciu kvapiek.

Nemôžem sa dočkať vyskúšať to v praxi.

English version: Allright, I came with an idea how to improve the zumotor concept. I think that MPI injector for example is designed as a combined petrol spraying device with a petrol input and an air input. The important thing here is to have two air inputs in the top and bottom part of the injector, just like any paint spray-gun. I would like to use something like that on the zumotor. Now to explain its use: The gas could be propane and the fluid high-temperature saturated ammonium nitrate solution. Propane is easily available, but I have to re-check the useable pressure. It can be stored in liquified form, and gasified and heated directly in some upper part of the injector system with engine temperature. Remember, that we only need it to work with fully-heated motor.

We want to protect the walls of the cylinder and lining from the decomposition products of the ammoniun nitrate, since it is highly reactive. Well, that is good, since we have lots of hydrocarbon gas to burn it with (that is the purpose of the outer gas inlet, like in a spraygun). We want to use more gas (mixture ratio) than needed to burn with the nitrate for three reasons: to get some more heat, since there is lot of water vapour, there is some residual oxygen, plus for pressure, we like lighter molecules better so having CO molecules instead of CO2 molecules offers some advantage, and at this time we only care about maximum power we can possibly get from the system (CO may be also useful later, it can be burned with other residues on a catalyst before a second turbo maybe?).

The best thing of it all? The fuel/oxidiser ratio is easily fixed by tuning the injector, and you can try it out outside of the engine for burning performance. It has become - in fact - a rocket engine. The other outstanding property of this design are the burning properties, which can be set on the fly by changing the oxidiser droplets size and distribution, penetration. In ordinary gas powered sprayers this is done by changing the gas pressure.

I can't wait to finally try it sometimes. Yes, I will be insured by that time.

EDIT: propane properties - Autoignition temperature : 470 °C, oh how I love thee.
at 65°C - 25bar, 85°C - 37bar pressure. That could almost suffice.

• Critical temperature : 96.6 °C
• Critical pressure : 42.5 bar

General supercritical fluid properties: ability to diffuse through solids like a gas and dissolve materials like a liquid, heat of evaporation is zero. This well helps combustion properties, I just don't yet have a definite answer to the heating to such high temperatures reliably.

Cieľ je taký aby sme skladovali skvapalnený plyn pod nízkym tlakom, ľahko s ním manipulovali a presne dávkovali do splyňovača kde vznikne prehriata para s vysokým tlakom (trochu amatérske a navyše zase potrebujeme dávkovacie/vstrekovacie čerpadlo). Tlak v spaľovacom priestore je už okolo 30barov. Iná možnosť je mať kontinuálny splyňovač kde už bude pripravený plyn s vysokým tlakom a my budeme ovládať plynový ventil (neznáma hustota prehriatej pary??). Ani jedna možnosť sa mi nepozdáva.

Waiit... let's think about it again please? So, we have a liquid on input and we need an inline fuel injector pump? The car already has one! I could as well try putting LPG to the pump an try it with a regular injector! This way we would keep the inline injector for the whole ride, and the engine would be eating the lpg/propane all the time. Only the injector would be two-part. First, the valve that would open at some pressure, then the heated gasifier which leads to a spray-type nozzle. Good thing is as any painter knows that by not supplying the paint (oxidiser in our case) you suck the remainter of the fluid from the nozzle and clean it. This would be nice.

So, the material to be used for tubing, storing, heating, injection pump and injector itself has to be a very exotic one, don't you think? Exotic it is, but not very unusual too. Titanium alloy. Get a hint from this PDF listing a lot of novel alloys that might provide good pricing with extra properties.

And now a webpage of the century, electric energy generators which work by simply sucking warm and cold seawater. Welcome to the OTEC - but this is allowed by use of modified Rankine thermal cycle, the Uehara-Rankine cycle. Why is this so important? It allows energy recovery from heat surces with only 10 deg. difference! That is the waste heat unusable for anything else. The main difference between this project and many others is that this one works as a demo and 1MWe ship-borne facility is nearing its completion in India. To tell the truth, I was impressed that India plans to deploy one THOUSAND these facilities at 50MW each! The by-product of this system is distilled water - surely a very valuable commodity, since the only investment during use is maintenance and protection. Believe it or not, but UAE (emirates) are interested in a ship like that, but which only produces drinkable water, not electricity. The budget was ~250milion dollars for version with electric output. REPORT HERE.