Naphthyl fuel. The rocket fuel saga
Photos are clickable
The rocket flew on a completely new fuel - naphthyl, an environmentally friendly type of hydrocarbon fuel using polymer additives.
The use of naphthyl will allow a family of three-stage medium-class launch vehicles to launch more payload into all types of orbits than when using a chemical rocket engine based on an oxygen-kerosene pair.
Vostochny's full transition to naphthyl is planned for 2019.
A unique refueling complex that works with several types of fuel at once was developed and built in the Amur region by the Nizhny Tagil enterprise Uralkriomash. One of them is naphthyl - an environmentally friendly type of hydrocarbon fuel using polymer additives. Its use will allow a family of three-stage medium-class launch vehicles to launch a larger payload into all types of orbits than the previously used chemical rocket engine based on the oxygen-kerosene pair. The complete transition of Vostochny to naphthyl is planned for 2019.
The “Space Gas Station” from Uralkriomash significantly simplifies the system for refueling launch vehicles. With its appearance at the cosmodrome, there will be no need to prepare an individual launch complex for each launch. Now the organization of the process is universal.
Uralkriomash has been working on creating the infrastructure of the cosmodrome since 2012. As part of the Federal Space Program, for the first launch, which took place on April 28, 2016, the company’s specialists developed, produced, certified and delivered 20 tank cars model 15-558C-04 to the cosmodrome. They are designed for transportation and storage of liquid oxygen, nitrogen and argon. In addition, equipment for storing kerosene and naphthyl for all three stages of the launch vehicle was installed and launched at the facility. Uralkriomash employees also installed reinforcement blocks with electrical equipment, control points and pneumatic control. The equipment was tested for more than a year and in October 2017, it was recorded that it successfully passed all complex tests. And a month later - on November 28 - the launch of the Soyuz 2.1b launch vehicle, filled with naphthyl, took place.
Uralkriomash is a participant in all Russian space programs. Today, Tagil residents are working on the creation of the second stage of the Vostochny, which is designed for the Angara heavy launch vehicle. The company's specialists are developing project documentation naphthyl and oxygen filling systems for launch vehicle tanks. At the same time, work is underway to find mechanisms for supplying water to cool the “launch table”. Production of capacitive equipment and fittings has begun. The launch complex for Angara on Vostochny should be commissioned by 2021.
Let us remind you that today the third launch of the Soyuz-2.1a launch vehicle was carried out from the Vostochny Cosmodrome, which was successful.
"...And there is nothing new under the sun"(Ecclesiastes 1:9).
They have written, are writing, and will continue to write about fuels, rockets, and rocket engines.
One of the first works on liquid rocket engine fuels can be considered the book by V.P. Glushko "Liquid fuel for jet engines", published in 1936.
For me, the topic seemed interesting, related to my former specialty and studies at the university, especially since my youngest son “dragged” it: “Chief, let’s knead what the thread is and run it, and if you’re lazy, then we ourselves"Let's figure it out." Apparently they don't give me peace.
I really want to blow up my rocket engine properly.
We will “figure it out” together, under strict parental supervision. Hands, legs must be intact, especially strangers.
An important parameter is the oxidizer excess coefficient (denoted by the Greek “α” with the subscript “ok.”) and the mass ratio of the components Km.
Km=(dmok./dt)/(dmg../dt), i.e. the ratio of the mass flow rate of the oxidizer to the mass flow rate of the fuel. It is specific for each fuel. Ideally, it is a stoichiometric ratio of oxidizer and fuel, i.e. shows how many kg of oxidizer is needed to oxidize 1 kg of fuel. However, real values differ from ideal ones. The ratio of real Km to ideal is the oxidizer excess coefficient.
As a rule, α is approx.<=1. И вот почему. Зависимости Tk(αок.) и Iуд.(αок.) нелинейны и для многих топлив последняя имеет максимум при αок. не при стехиометрическом соотношении компонентов, т.е макс. значения Iуд. получаются при некотором снижении количества окислителя по отношению к стехиометрическому. Ещё немного терпения, т.к. не могу обойти понятие: . Это пригодится и в статье, и в повседневной жизни.
In short, enthalpy is energy. Two aspects of this article are important:
Thermodynamic enthalpy- the amount of energy spent on the formation of a substance from the initial chemical elements. For substances consisting of identical molecules (H 2, O 2, etc.), it is equal to zero.
Enthalpy of combustion- makes sense only if a chemical reaction occurs. In reference books you can find values of this quantity experimentally obtained under normal conditions. Most often, for combustibles this is complete oxidation in an oxygen environment, for oxidizers it is the oxidation of hydrogen with a given oxidizer. Moreover, the values can be both positive and negative depending on the type of reaction.
“The sum of the thermodynamic enthalpy and the enthalpy of combustion is called the total enthalpy of the substance. Actually, this value is used in the thermal calculation of liquid-propellant rocket engine chambers.”
Requirements for ZhRT:
-as a source of energy;
-as a substance that has to be used (at this level of technology development) for cooling the rocket engines and pumping pumps, sometimes for pressurizing tanks with RT, providing it with volume (stage rocket tanks), etc.;
-as to a substance outside the rocket engine, i.e. during storage, transportation, refueling, testing, environmental safety, etc.
This gradation is relatively arbitrary, but in principle it reflects the essence. I will name these requirements as follows: No. 1, No. 2, No. 3. Someone can add to the list in the comments.
These requirements are a classic example that “pull” the creators of RD in different directions:
# From the point of view of the LRE energy source (No. 1)
Those. you need to get max. Iud. I won’t bother everyone further, in general:
With other important parameters for No. 1, we are interested in R and T (with all indices).
It is necessary that: the molecular weight of combustion products was minimal, and the specific heat content was maximum.
# From the point of view of the launch vehicle designer (No. 2):
TCs must have maximum density, especially in the first stages of rockets, because they are the most voluminous and have the most powerful thrusters, with a high per second flow rate. Obviously, this is not consistent with requirement No. 1.
# From operational tasks important (No. 3):
Chemical stability of TC;
- ease of refueling, storage, transportation and manufacturing;
- environmental safety (in the entire “field” of application), namely toxicity, cost of production and transportation, etc. and safety during RD operation (explosion hazard).
For more details, see "The saga of rocket fuels - the other side of the coin."
I hope no one has fallen asleep yet? I feel like I'm talking to myself. Coming soon about alcohol, stay tuned!
Of course, this is just the tip of the iceberg. There are also additional requirements here, due to which one should look for CONSENSUSES and COMPROMISES. One of the components must have satisfactory (preferably excellent) coolant properties, because at this level of technology it is necessary to cool the combustor and the nozzle, as well as protect the critical section of the taxiway:
The photograph shows the nozzle of the XLR-99 liquid-propellant rocket engine: a characteristic feature of the design of American liquid-propellant rocket engines of the 50-60s is clearly visible - a tubular chamber:
It is also required (as a rule) to use one of the components as a working fluid for the turbocharger turbine:
For fuel components, “saturated vapor pressure is of great importance (roughly speaking, the pressure at which a liquid begins to boil at a given temperature). This parameter greatly influences the design of pumps and the weight of tanks.”/ S.S. Fakas/
An important factor is the aggressiveness of the TC towards the materials (CM) of the liquid propellant rocket engine and the tanks for their storage.
If fuel oils are very “harmful” (as some people are), then engineers have to spend money on a number of special measures to protect their structures from fuel.
Classification of liquid gas is most often based on saturated vapor pressure or, more simply put, boiling point at normal pressure.
High-boiling components of liquid fuel.
Such liquid rocket engines can be classified as multi-fuel.
A liquid-propellant rocket engine using three-component fuel (fluorine+hydrogen+lithium) was developed in.
Binary fuels consist of an oxidizer and a fuel.
Liquid propellant engine Bristol Siddeley BSSt.1 Stentor: two-component liquid propellant engine (H2O2 + kerosene)
Oxidizing agents
Oxygen
Chemical formula-O 2 (dioxygen, American designation Oxygen-OX).
Liquid propellant engines use liquid oxygen rather than gaseous oxygen - Liquid oxygen (LOX - briefly and everything is clear).
Molecular weight (for a molecule) is 32 g/mol. For lovers of precision: atomic mass (molar mass) = 15.99903;
Density=1.141 g/cm³
Boiling point=90.188K (−182.96°C)
From a chemical point of view, it is an ideal oxidizing agent. It was used in the FAA's first ballistic missiles and its American and Soviet counterparts. But its boiling point did not suit the military. The required operating temperature range is from –55°C to +55°C (long preparation time for launch, short time on combat duty).
Very low corrosiveness. Production has been mastered for a long time, the cost is low: less than $0.1 (in my opinion, several times cheaper than a liter of milk).
Flaws:
Cryogenic - cooling and constant refueling are required to compensate for losses before launch. It can also spoil other TCs (kerosene):
In the photo: protective device flaps of the kerosene refueling automatic docking station (ZU-2), 2 minutes before the end of the cyclogram when performing the CLOSE CHARGE operation did not close completely due to icing. At the same time, due to icing, the signal about the TUA leaving the launcher did not go through. The launch took place the next day.
The RB liquid oxygen filling unit was removed from the wheels and installed on the foundation.
It is difficult to use the CS and liquid rocket engine nozzle as a coolant.
"ANALYSIS OF THE EFFICIENCY OF USE OF OXYGEN AS A COOLER FOR A LIQUID ROCKET ENGINE CHAMBER" SAMOSHKIN V.M., VASYANINA P.YU., Siberian State Aerospace University named after Academician M.F. Reshetneva
Now everyone is studying the possibility of using supercooled oxygen or oxygen in a sludge-like state, in the form of a mixture of solid and liquid phases of this component. The view will be approximately the same as this beautiful ice slush in the bay to the right of Shamora:
Imagine: instead of H 2 O, imagine LCD (LOX).
Sugaring will increase the overall density of the oxidizer.
An example of cooling (supercooling) of the R-9A ballistic missile: for the first time, it was decided to use supercooled liquid oxygen as an oxidizer in a rocket, which made it possible to reduce the total time to prepare the rocket for launch and increase the degree of its combat readiness.
Note: For some reason, the famous writer Dmitry Konanykhin bent over (almost “chuckled”) Elon Musk for this same procedure.
Cm:
Ozone-O 3
Molecular mass=48 amu, molar mass=47.998 g/mol
The density of the liquid at -188 °C (85.2 K) is 1.59 (7) g/cm³
The density of solid ozone at −195.7 °C (77.4 K) is 1.73(2) g/cm³
Melting point −197.2(2) °C (75.9 K)
Engineers have long struggled with it, trying to use it as a high-energy and at the same time environmentally friendly oxidizer in rocket technology.
The total chemical energy released during the combustion reaction involving ozone is approximately one quarter greater than for simple oxygen (719 kcal/kg). Accordingly, Iud will be greater. Liquid ozone has a higher density than liquid oxygen (1.35 versus 1.14 g/cm³, respectively), and its boiling point is higher (−112 °C and −183 °C, respectively).
So far, an insurmountable obstacle is the chemical instability and explosiveness of liquid ozone with its decomposition into O and O2, in which a detonation wave appears moving at a speed of about 2 km/s and a destructive detonation pressure of more than 3 107 dyne/cm2 (3 MPa) develops, which makes the use of liquid ozone is impossible with the current level of technology, with the exception of the use of stable oxygen-ozone mixtures (up to 24% ozone). The advantage of such a mixture is also a higher specific impulse for hydrogen engines compared to ozone-hydrogen engines. Today, such highly efficient engines as RD-170, RD-180, RD-191, as well as accelerating vacuum engines, have reached Isp parameters close to the limit values, and to increase the efficiency there is only one option left, related to the transition to new types of fuel .
Nitric acid-HNO3
Condition - liquid at no.
Molar mass 63.012 g/mol (doesn't matter what I use or molecular mass - it doesn't change the point)
Density=1.513 g/cm³
T. melt.=-41.59 °C, T. boil.=82.6 °C
HNO3 has a high density, low cost, is produced in large quantities, is quite stable, including at high temperatures, and is fire and explosion-proof. Its main advantage over liquid oxygen is its high boiling point, and, therefore, the ability to be stored indefinitely without any thermal insulation. The nitric acid molecule HNO 3 is an almost ideal oxidizing agent. It contains a nitrogen atom and a “half” water molecule as “ballast”, and two and a half oxygen atoms can be used to oxidize the fuel. But that was not the case! Nitric acid is such an aggressive substance that it continuously reacts with itself—hydrogen atoms are split off from one molecule of acid and join neighboring ones, forming fragile but extremely chemically active aggregates. Even the most resistant grades of stainless steel are slowly destroyed by concentrated nitric acid (as a result, a thick greenish “jelly”, a mixture of metal salts, is formed at the bottom of the tank). To reduce the corrosiveness, various substances began to be added to nitric acid; just 0.5% hydrofluoric acid reduces the corrosion rate of stainless steel tenfold.
To increase the shock pulse, nitrogen dioxide (NO 2) is added to the acid. The addition of nitrogen dioxide to the acid binds the water entering the oxidizer, which reduces the corrosive activity of the acid, increases the density of the solution, reaching a maximum at 14% dissolved NO 2. The Americans used this concentration for their military missiles.
We have been looking for suitable containers for nitric acid for almost 20 years. It is very difficult to select construction materials for tanks, pipes, and combustion chambers of liquid propellant rocket engines.
The oxidizer option that was chosen in the USA is with 14% nitrogen dioxide. But our rocket scientists acted differently. It was necessary to catch up with the United States at any cost, so Soviet brand oxidizers - AK-20 and AK-27 - contained 20 and 27% tetroxide.
Interesting fact: In the first Soviet rocket fighter BI-1, nitric acid and kerosene were used for flight.
Tanks and pipes had to be made of Monel metal: an alloy of nickel and copper, it became a very popular structural material among rocket scientists. Soviet rubles were almost 95% made from this alloy.
Disadvantages: tolerable "muck". Corrosive active. The specific impulse is not high enough. Currently, it is almost never used in its pure form.
Nitrogen tetroxide-AT (N 2 O 4)
Molar mass=92.011 g/mol
Density=1.443 g/cm³
"Took up the baton" from nitric acid in military engines. It is self-flammable with hydrazine and UDMH. Low boiling point, but can be stored for a long time if special care is taken.
Disadvantages: the same nasty thing as HNO 3, but with its own quirks. May decompose into nitric oxide. Toxic. Low specific impulse. The oxidizing agent AK-NN was and is often used. It is a mixture of nitric acid and nitric tetroxide, sometimes called "red fuming nitric acid." The numbers indicate the percentage of N 2 O 4.
These oxidizers are mainly used in military rocket engines and spacecraft rocket engines due to their properties: durability and self-ignition. Typical fuels for AT are UDMH and hydrazine.
Fluorine-F 2
Atomic mass = 18.998403163 a. e.m. (g/mol)
Molar mass of F2, 37.997 g/mol
Melting point=53.53 K (−219.70 °C)
Boiling point = 85.03 K (−188.12 °C)
Density (for liquid phase), ρ=1.5127 g/cm³
Fluorine chemistry began to develop in the 1930s, especially quickly during the Second World War of 1939-45 and after it in connection with the needs of the nuclear industry and rocket technology. The name "Fluorine" (from the Greek phthoros - destruction, death), proposed by A. Ampere in 1810, is used only in Russian; in many countries the name is accepted "fluor". It is an excellent oxidizing agent from a chemical point of view. It oxidizes oxygen, water, and practically everything. Calculations show that the maximum theoretical Isp can be obtained on the F2-Be (beryllium) pair - about 6000 m/s!
Super? Bummer, not "super"...
You wouldn't wish such an oxidizer on your enemy.Extremely corrosive, toxic, prone to explosions upon contact with oxidizing materials. Cryogenic. Any combustion product also has almost the same “sins”: they are terribly corrosive and toxic.
Safety precautions. Fluorine is toxic, its maximum permissible concentration in the air is approximately 2·10-4 mg/l, and the maximum permissible concentration with exposure for no more than 1 hour is 1.5·10-3 mg/l.
The 8D21 liquid-propellant rocket engine using the fluorine + ammonia pair gave a specific impulse at the level of 4000 m/s.
For the pair F 2 +H 2 it turns out Isp = 4020 m/s!
Trouble: HF hydrogen fluoride in the exhaust.
Starting position after launching such an “energetic engine”?
A puddle of liquid metals and other chemical and organic objects dissolved in hydrofluoric acid!
H 2 +2F=2HF, at room temperature exists in the form of a dimer H 2 F 2.
Mixes with water in any ratio to form hydrofluoric acid. And its use in rocket engines of spacecraft is not realistic due to the deadly complexity of storage and the destructive effect of combustion products.
The same applies to other liquid halogens, for example, chlorine.
A hydrogen fluorine liquid-propellant rocket engine with a thrust of 25 tons to equip both stages of the rocket accelerator was supposed to be developed in V.P. Glushko based on a spent liquid-propellant rocket engine with a thrust of 10 tons using fluoroammonia (F 2 + NH 3) fuel.
Hydrogen peroxide-H 2 O 2 .
I mentioned it above in single-component fuels.
Walter HWK 109-507: advantages in the simplicity of the rocket engine design. A striking example of such a fuel is hydrogen peroxide.
Alles: the list of more or less real oxidizing agents is complete. I focus on HCl O 4. As independent oxidizing agents based on perchloric acid, the only ones of interest are: monohydrate (H 2 O + ClO 4) - a solid crystalline substance and dihydrate (2HO + HClO 4) - a dense viscous liquid. Perchloric acid (which, due to Isp, in itself is unpromising), is of interest as an additive to oxidizers, guaranteeing the reliability of self-ignition of the fuel.
Oxidizing agents can be classified as follows:
The final (most often used) list of oxidizers in conjunction with real combustibles:
Note: if you want to convert one specific impulse option to another, you can use a simple formula: 1 m/s = 9.81 s.
Unlike them, we have flammable ones.Flammable
Main characteristics of two-component liquid propellants at pк/pa=7/0.1 MPa
Based on their physical and chemical composition, they can be divided into several groups:
Hydrocarbon fuels.
Low molecular weight hydrocarbons.
Simple substances: atomic and molecular.
For this topic, so far only hydrogen (Hydrogenium) is of practical interest.
I will not consider Na, Mg, Al, Bi, He, Ar, N 2, Br 2, Si, Cl 2, I 2, etc. in this article.
Hydrazine fuels ("stinkers").
Wake up, sleepyheads - we have already reached alcohol (C2H5OH).
The search for the optimal fuel began with the development of liquid propellant rocket engines by enthusiasts. The first widely used fuel was alcohol (ethyl), used in the first
Soviet missiles R-1, R-2, R-5 ("legacy" of the V-2) and on the Vergeltungswaffe-2 itself.
More precisely, a solution of 75% ethyl alcohol (ethanol, ethyl alcohol, methyl carbinol, wine alcohol or alcohol, often colloquially simply “alcohol”) - monohydric alcohol with the formula C 2 H 5 OH (empirical formula C 2 H 6 O), another option: CH 3 -CH 2 -OH
This fuel two serious shortcomings, which obviously did not suit the military: low energy performance and.
Proponents of a healthy lifestyle (alcohol phobes) tried to solve the second problem with the help of furfuryl alcohol. It is a poisonous, mobile, transparent, sometimes yellowish (to dark brown) liquid that turns red over time when exposed to air. BARBARIANS!
Chem. formula: C 4 H 3 OCH 2 OH, Rat. formula:C 5 H 6 O 2. Disgusting slurry. Not suitable for drinking.
Hydrocarbon group.
Kerosene
Conditional formula C 7.2107 H 13.2936
A flammable mixture of liquid hydrocarbons (from C 8 to C 15) with a boiling point in the range of 150-250 ° C, transparent, colorless (or slightly yellowish), slightly oily to the touch
density - from 0.78 to 0.85 g/cm³ (at a temperature of 20°C);
viscosity - from 1.2 – 4.5 mm²/s (at a temperature of 20°C);
flash point - from 28°C to 72°C;
calorific value - 43 MJ/kg.
My opinion: it is pointless to write about the exact molar mass
Kerosene is a mixture of various hydrocarbons, which is why scary fractions appear (in the chemical formula) and a “smeared” boiling point. Convenient high-boiling fuel. It has been used for a long time and successfully all over the world in engines and aviation. This is what Soyuz aircraft still fly on. Low toxicity (I strongly do not recommend drinking), stable. Still, kerosene is dangerous and harmful to health (oral consumption).
The Ministry of Health is categorically against it!
Soldier's tales: good for getting rid of nasty ones.
However, it also requires careful handling during operation:
Significant advantages: relatively inexpensive, mastered in production. The kerosene-oxygen pair is ideal for the first stage. Its specific impulse on the ground is 3283 m/s, void 3475 m/s. Flaws. Relatively low density.
American rocket kerosene Rocket Propellant-1 or Refined Petroleum-1
Relatively was.
To increase density, leaders in space exploration developed syntin (USSR) and RJ-5 (USA).
.
Kerosene has a tendency to deposit tarry deposits in the lines and cooling path, which negatively affects cooling. This bad quality of his is emphasized.
Kerosene engines were most developed in the USSR.
A masterpiece of human intelligence and engineering, our “pearl” RD-170/171:
Now the term “hydrocarbon fuel” has become a more correct name for kerosene-based fuels, because from kerosene, which was burned in safe kerosene lamps by I. Lukasiewicz and J. Zech, the used UVG “went away” very much.
In fact, Roscosmos gives out misinformation:
After fuel components are pumped into its tanks - naphthyl (rocket fuel)), liquefied oxygen and hydrogen peroxide, the space transport system will weigh more than 300 tons (depending on the modification of the launch vehicle.
Low molecular weight hydrocarbons
Methane-CH4
Molar mass: 16.04 g/mol
Density gas (0 °C) 0.7168 kg/m³;
liquid (−164.6 °C) 415 kg/m³
Melting temperature=-182.49 °C
Bp = -161.58 °C
It is now considered by everyone as a promising and cheap fuel, as an alternative to kerosene and hydrogen.
Chief designer Vladimir Chvanov:
The specific impulse of an LNG engine is high, but this advantage is offset by the fact that methane fuel has a lower density, so the total energy advantage is insignificant. From a design point of view, methane is attractive. To free the engine cavities, you only need to go through an evaporation cycle - that is, the engine is more easily freed from product residues. Due to this, methane fuel is more acceptable from the point of view of creating a reusable engine and a reusable aircraft.
Inexpensive, common, stable, low-toxic. Compared to hydrogen, it has a higher boiling point, and the specific impulse paired with oxygen is higher than that of kerosene: about 3250-3300 m/s on earth. Not a bad cooler.
Flaws. Low density (half that of kerosene). In some combustion modes, it can decompose with the release of carbon in the solid phase, which can lead to a drop in momentum due to the two-phase flow and a sharp deterioration in the cooling mode in the chamber due to soot deposition on the walls of the combustion chamber. Recently, active research and development activities have been carried out in the field of its use (along with propane and natural gas), even in the direction of modifying existing gas. LRE (in particular, such work was carried out on).
Already in 2016, Roscosmos began developing a power plant using liquefied natural gas.
Or "Kinder Surpeis", as an example: American Raptor engine from Space X:
These fuels include propane and natural gas. Their main characteristics as combustibles are close (with the exception of higher density and higher boiling point) to hydrocarbons. And there are the same problems when using them.
-H 2 (Liquid: LH 2) stands out among flammables.
The molar mass of hydrogen is 2016 g/mol or approximately 2 g/mol.
Density (at no.)=0.0000899 (at 273 K (0 °C)) g/cm³
Melting point=14.01K (-259.14 °C);
Boiling point=20.28K (-252.87 °C);
The use of the LOX-LH 2 pair was proposed by Tsiolkovsky, but implemented by others:
From the point of view of thermodynamics, H 2 is an ideal working fluid for both the liquid propellant engine itself and the TNA turbine. An excellent coolant, both in liquid and gaseous states. The latter fact makes it possible not to be particularly afraid of the boiling of hydrogen in the cooling path and to use hydrogen gasified in this way to drive the pump.
This scheme is implemented in the Aerojet Rocketdyne RL-10 - simply a gorgeous (from an engineering point of view) engine:
Our analogue ( even better, because younger): RD-0146 (D, DM) - a gas-free liquid-propellant rocket engine developed by the Chemical Automatics Design Bureau in Voronezh.
Particularly effective with a nozzle made of Grauris material. But it doesn't fly yet
This TC provides a high specific impulse - when paired with oxygen, 3835 m/s.
This is the highest figure among those actually used. These factors determine the keen interest in this fuel. Environmentally friendly, at the “output” in contact with O 2: water (water vapor). Common, virtually unlimited supplies. Mastered in production. Non-toxic. However, there are a lot of fly in the ointment in this barrel of honey.
1. Extremely low density. Everyone has seen the huge hydrogen tanks of the Energia launch vehicle and the Space Shuttle. Due to the low density, it is applicable (as a rule) at the upper stages of the launch vehicle.
In addition, low density poses a difficult challenge for pumps: hydrogen pumps are multistage in order to provide the required mass flow without cavitating.
For the same reason it is necessary to install the so-called fuel booster pumping units (FPU) immediately behind the intake device in the tanks, in order to make life easier for the main fuel pump.
Hydrogen pumps also require a significantly higher rotation speed of the pump for optimal operation.
2. Low temperature. Cryogenic fuel. Before refueling, it is necessary to cool (and/or supercool) the tanks and the entire tract for many hours. LV tanks "Falocn 9FT" - a look from the inside:
More about "surprises":
"MATHEMATICAL MODELING OF HEAT AND MASS TRANSFER PROCESSES IN HYDROGEN SYSTEMS" N0R V.A. Gordeev V.P. Firsov, A.P. Gnevashev, E.I. Postoyuk
FSUE "GKNPTs im. M.V. Khrunichev, KB "Salyut"; "Moscow Aviation Institute (State Technical University)
The paper describes the main mathematical models of heat and mass transfer processes in the tank and hydrogen lines of the oxygen-hydrogen upper stage 12KRB. Anomalies in the supply of hydrogen to the liquid-propellant rocket engine were identified and their mathematical description was proposed. The models were tested during bench and flight tests, which made it possible to use them to predict the parameters of serial upper stages of various modifications and make the necessary technical decisions to improve pneumohydraulic systems.
The low boiling point makes it difficult to pump into tanks and store this fuel in tanks and storage facilities.
3. Liquid hydrogen has some properties of a gas:
Compressibility coefficient (pv/RT) at 273.15 K: 1.0006 (0.1013 MPa), 1.0124 (2.0266 MPa), 1.0644 (10.133 MPa), 1.134 (20.266 MPa), 1.277 (40.532 MPa);
Hydrogen can be in ortho and para states. Orthohydrogen (o-H2) has a parallel (same sign) orientation of nuclear spins. Para-hydrogen (p-H2)-antiparallel.
At normal and high temperatures, H2 (normal hydrogen, n-H2) is a mixture of 75% ortho and 25% para modifications, which can mutually convert into each other (ortho-para transformation). When o-H 2 is converted to p-H 2, heat is released (1418 J/mol).
All this imposes additional difficulties in the design of pipelines, liquid propellant engines, pumping pumps, operating schedules, and especially pumps.
4. Hydrogen gas spreads faster than other gases in space, passes through small pores, and at high temperatures penetrates steel and other materials relatively easily. H 2g has high thermal conductivity, equal to 0.1717 W/(m*K) at 273.15 K and 1013 hPa (7.3 relative to air).
Hydrogen in its normal state at low temperatures is inactive; without heating it reacts only with F 2 and in the light with Cl 2. Hydrogen reacts more actively with nonmetals than with metals. Reacts with oxygen almost irreversibly, forming water with the release of 285.75 MJ/mol of heat;
5. Hydrogen forms hydrides with alkali and alkaline earth metals, elements of groups III, IV, V and VI of the periodic system, as well as with intermetallic compounds. Hydrogen reduces the oxides and halides of many metals to metals, and unsaturated hydrocarbons to saturated ones (see).
Hydrogen gives up its electron very easily. In solution, it is detached in the form of a proton from many compounds, causing their acidic properties. In aqueous solutions, H+ forms a hydronium ion H 3 O with a water molecule. Being part of the molecules of various compounds, hydrogen tends to form a hydrogen bond with many electronegative elements (F, O, N, C, B, Cl, S, P).
6. Fire and explosion hazard. There is no need to pickle it: everyone knows the explosive mixture.
A mixture of hydrogen and air explodes from the slightest spark in any concentration - from 5 to 95 percent.
Is the Space Shuttle Main Engine (SSME) impressive?
Now estimate its cost!
Probably, having seen this and calculating the costs (the cost of putting 1 kg of payload into orbit), legislators and those who rule the budget of the United States and NASA in particular... decided “well, screw it.”
And I understand them - the Soyuz launch vehicle is both cheaper and safer, and the use of the RD-180/181 eliminates many of the problems of American launch vehicles and significantly saves taxpayers’ money in the richest country in the world.
The best rocket engine is one that you can make/buy that will have the thrust you want (not too much or too little) and be efficient enough (specific impulse, combustion chamber pressure) to cost will not become too heavy for you. /Philip Terekhov@lozga
Hydrogen engines are the most developed in the USA.
We are now positioned in 3rd-4th place in the “Hydrogen Club” (after Europe, Japan and China/India).
I will separately mention solid and metallic hydrogen.
Solid hydrogen crystallizes in a hexagonal lattice (a = 0.378 nm, c = 0.6167 nm), at the nodes of which there are H 2 molecules connected to each other by weak intermolecular forces; density 86.67 kg/m³; С° 4.618 J/(mol*K) at 13 K; dielectric. At pressures above 10,000 MPa, a phase transition is expected with the formation of a structure built from atoms and possessing metallic properties. The possibility of “metallic hydrogen” superconductivity has been theoretically predicted.
Solid hydrogen is the solid state of aggregation of hydrogen.
Melting point −259.2 °C (14.16 K).
Density 0.08667 g/cm³ (at −262 °C).
White snow-like mass, crystals of hexagonal system.
Scottish chemist J. Dewar was the first to obtain hydrogen in the solid state in 1899. To do this, he used a regenerative cooling machine based on the .
The trouble is with him. He constantly gets lost: . This is understandable: a cube of molecules is obtained: 6x6x6. Just “giant” volumes - just “refuel” the rocket right now. For some reason this reminded me. This nano-miracle has not been found for 7 years or more.
I’ll leave anameson, antimatter, and metastable helium behind the scenes for now.
...
Hydrazine fuels ("stinkers")
Hydrazine-N2H4
State at zero - colorless liquid
Molar mass=32.05 g/mol
Density=1.01 g/cm³
A very common fuel.
It keeps for a long time, and they “love it” for it. Widely used in spacecraft control systems and ICBMs/SLBMs, where durability is critical.
For those who are confused by Iud in the dimension N*s/kg, I answer: this designation is “loved” by the military.
Newton is a derived unit, based on which it is defined as a force that changes the speed of a body weighing 1 kg by 1 m/s in 1 second in the direction of the force. Thus, 1 N = 1 kg m/s 2.
Accordingly: 1 N*s/kg =1 kg m/s 2 *s/kg=m/s.
Mastered in production.
Disadvantages: toxic, smelly.
The toxicity of hydrazine to humans has not been determined. According to calculations by S. Krop, a dangerous concentration should be considered 0.4 mg/l. Ch. Comstock and co-workers believe that the maximum permissible concentration should not exceed 0.006 mg/l. According to more recent American data, this concentration at 8-hour exposure is reduced to 0.0013 mg/l. It is important to note that the threshold for the olfactory sensation of hydrazine in humans significantly exceeds the indicated numbers and is equal to 0.014-0.030 mg/l. Significant in this regard is the fact that the characteristic odor of a number of hydrazine derivatives is felt only in the first minutes of contact with them. Subsequently, due to the adaptation of the olfactory organs, this sensation disappears, and a person, without noticing it, can remain for a long time in a contaminated atmosphere containing toxic concentrations of the said substance.
Hydrazine vapors explode under adiabatic compression. It is prone to decomposition, which, however, allows it to be used as a monopropellant for low-thrust liquid rocket engines (LPRE). Due to the development of production, it is more common in the USA.
Unsymmetrical dimethylhydrazine (UDMH)-H 2 N-N(CH 3) 2
Chem. formula: C2H8N2, Rat. formula:(CH3)2NNH2
State at zero - liquid
Molar mass=60.1 g/mol
Density=0.79±0.01 g/cm³
Widely used on military engines due to its durability. When mastering ampullation technology, all problems practically disappeared (except for disposal and accidents with allowances).
Has higher impulse compared to hydrazine.
Density and specific impulse with basic oxidizers are lower than kerosene with the same oxidizers. Will spontaneously ignite with nitrogen oxidizers. Mastered in production in the USSR.
More common in the USSR.
And in the jet engine of a French fighter-bomber (good video, I recommend) UDMH is used as an activating additive to traditional fuel.
Regarding hydrazine fuels.
Specific thrust is equal to the ratio of thrust to weight fuel consumption; in this case it is measured in seconds (s = N s/N = kgf s/kgf). To convert weight specific thrust into mass thrust, it must be multiplied by the acceleration of gravity (approximately equal to 9.81 m/s²)
Left behind the scenes:
Aniline, methyl-, dimethyl- and trimethylamines and CH 3 NHNH 2 -Methylhydrazine (aka monomethylhydrazine or heptyl), etc.
They are not that common. The main advantage of flammable hydrazine group is its long shelf life when using high-boiling oxidizers. Working with them is very unpleasant - toxic flammable, aggressive oxidizing agents, toxic combustion products.
In industry jargon, these fuels are called “stinky” or “smelly.”
We can say with a high degree of confidence that if the launch vehicle has “smelly” engines, then “before marriage” it was a combat missile (ICBM, SLBM or missile defense system - which is already a rarity). Chemistry in the service of both the army and civilians.
The only exception, perhaps, is the Ariane launch vehicle - the creation of a cooperative: Aérospatiale, Matra Marconi Space, Alenia, Spazio, DASA, etc. It suffered a similar military fate in its “girlhood”.
Almost all of the military switched to solid propellant rocket engines, as they were more convenient to use. The niche for “smelly” fuels in astronautics has narrowed to use in spacecraft propulsion systems, where long-term storage is required without special material or energy costs.
Perhaps the overview can be briefly expressed graphically:
Rocket scientists are also actively working with methane. There are no particular operational difficulties: it allows you to raise the pressure in the chamber quite well (up to 40 M Pa) and get good performance.
() and other natural gases (LNG).
I will write about other areas for improving the performance of liquid-propellant rocket engines (metallization of fuels, use of He 2, acetam, etc.) later. If there is interest.
Using the effect of free radicals is a good prospect.
Detonation combustion is an opportunity for the long-awaited jump to Mars.
Afterword:
in general, all missile technical complexes (except for scientific and technological complexes), as well as attempts to make them at home, are very dangerous. I suggest you read carefully:. The mixture, which he was preparing on the stove in a saucepan, exploded as expected. As a result, the man received a huge number of burns and spent five days in the hospital.
All home (garage) manipulations with such chemical components are extremely dangerous and sometimes illegal. It is BETTER not to approach the places where they spill without a protective equipment and a gas mask:
Just like with spilled mercury: call the Ministry of Emergency Situations, they will quickly come and professionally pick up everything.
Thank you to everyone who was able to endure it all to the end.
Primary sources:
Kachur P. I., Glushko A. V. "Valentin Glushko. Designer of rocket engines and space systems", 2008.
G.G. Gahun "Design and design of liquid rocket engines", Moscow, "Mechanical Engineering", 1989.
Possibility of increasing the specific impulse of a liquid-propellant rocket engine
when adding helium to the combustion chamber S.A. Orlin MSTU named after. N.E. Bauman, Moscow
M.S. Shekhter. "Fuels and working fluids of rocket engines", Mechanical Engineering" 1976
Zavistovsky D.I. "Conversations about rocket engines."
Philip Terekhov @lozga (www.geektimes.ru).
"Types of fuels and their characteristics. Fuel is a flammable substance used to produce heat. Composition of the fuel. Combustible part - carbon C-hydrogen H-sulfur." - presentation by Oksana Kaseeva
Fakas S.S. "Fundamentals of liquid propellant engines. Working fluids"
Photos and video materials were used from the sites:
http://technomag.bmstu.ru
www.abm-website-assets.s3.amazonaws.com
www.free-inform.ru
www.rusarchives.ru
www.epizodsspace.airbase.ru
www.polkovnik2000.narod.ru
www.avia-simply.ru
www.arms-expo.ru
www.npoenergomash.ru
www.buran.ru
www.fsmedia.imgix.net
www.wikimedia.org
www.youtu.be
www.cdn.tvc.ru
www.commi.narod.ru
www.dezinfo.net
www.nasa.gov
www.novosti-n.org
www.prirodasibiri.ru
www.radikal.ru
www.spacenews.com
www.esa.int
www.bse.sci-lib.com
www.kosmos-x.net.ru
www.rocketpolk44.narod.ru
www.criotehnika.ru
www.transtank.rf
www.chistoprudov.livejournal.com/104041.html
www.cryogenmash.ru
www.eldeprocess.ru
www.chemistry-chemists.com
www.rusvesna.su
www.arms-expo.ru
www.armedman.ru
www.transtank.rf
www.ec.europa.eu
www.mil.ru
www.kbkha.ru
www.naukarus.com
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BLAGOVESHCHENSK, June 5 - RIA Novosti, Svetlana Mayorova. The problem of using heptyl in the space industry should be discussed openly, and the inclusion of an environmental component in the construction of the new Vostochny cosmodrome could be an important step in this direction, say environmentalists and scientists who shared with RIA Novosti their opinion on the use of toxic heptyl in rocket launches.
In April, Minister for Development of the Vostochny Cosmodrome Konstantin Chmarov, speaking to the press, mentioned the use of heptyl at the cosmodrome. At the same time, he noted that it will be used in the rocket’s upper stage. This statement caused protest sentiments among Amur residents. As reported, the region began collecting signatures against the use of highly toxic heptyl fuel at the Vostochny Cosmodrome.
An action against toxic fuel at Vostochny took place in BlagoveshchenskThe Vostochny Cosmodrome is planned to be built in the Amur region near the closed city of Uglegorsk. The first rocket launch from here is planned for 2015, the first manned launch for 2018.Pyotr Osipov, head of the Amur public environmental organization AmurSOES, shared with RIA Novosti the main concern of environmentalists when looking at the construction of the Vostochny cosmodrome.
“Why didn’t we raise this problem before? Because we were assured that there would be no heptyl. Not a word was said about the upper stage with this substance. The environmental component should be included in the basis for the construction of the Vostochny cosmodrome, and the use of the same upper stage with heptyl needs to be discussed openly,” the interlocutor noted.
As Lev Polyakov, deputy director of the Novosibirsk Scientific Research Institute of Biochemistry of the Siberian Branch of the Russian Academy of Medical Sciences, told RIA Novosti, the institute’s staff devoted a lot of time to studying the medical, social and environmental problems of using heptyl rockets. Scientists analyzed the cause-and-effect relationship of outbreaks of pathologies in the population living in areas where rocket stages fell, and conducted experiments on animals.
“Academician of the Russian Academy of Medical Sciences Lev Evgenievich Panin, who headed the scientific group that dealt with this issue, even gave a report on this topic at the Security Council. There is only one conclusion - heptyl has an effect even in the most minimal doses, even those that are considered maximum permissible,” said companion.
During public hearings held on June 17, 2010 in the closed city of Uglegorsk, it was stated that the new cosmodrome would use a new rocket fuel, naphthyl, instead of the toxic heptyl. Roscosmos, in response to an official request from RIA Novosti (signed by Deputy Head of Roscosmos Alexander Lopatin), confirmed the use of heptyl for launches at the Vostochny Cosmodrome.
Naphthyl, heptyl...let's go
According to Roscosmos, during the launch and flight of the Soyuz-2 launch vehicle itself, kerosene and liquid oxygen are used as rocket fuel components (RPF). But still, launches will not be possible without heptyl. The highly toxic fuel will be used in the Fregat upper stage.
“The first switching on of the Fregat RB engines is carried out already in outer space, at altitudes no lower than 180 kilometers. To operate in these conditions<…>cryogenic CRT (liquid oxygen and hydrogen) are of little use<…>. The Fregat RB is loaded with about 1.5 thousand kilograms of heptyl,” notes the official response from Roscosmos.
Roscosmos clarifies that at altitudes where multiple activations of the propulsion systems of the Republic of Belarus and spacecraft are necessary, the most effective are those that are stable over a wide temperature range, including heptyl.
The space agency emphasizes that heptyl is used by many space powers. Figures are given that the Fregat RB has already been used more than 35 times.
"The use of the Fregat RB at the Baikonur Cosmodrome has a positive conclusion from the state environmental assessment<…>No observations regarding violations of environmental safety during its operation were identified,” notes the deputy of Roscosmos.
“From the point of view of the fact that the upper stage will operate outside the atmosphere, it does not pose a danger, but heptyl still needs to be transported, the block needs to be refueled, and the remaining containers must be stored somewhere. The design of the Vostochny cosmodrome did not stipulate what measures to protect the population will be be undertaken in case of emergencies,” Osipov expressed concern.
A drop of heptyl...
According to scientists from the Novosibirsk Institute of Biochemistry of the Siberian Branch of the Russian Academy of Medical Sciences, a cause-and-effect relationship between heptyl and an increase in the incidence of the population living in areas adjacent to the fall areas has been proven. The research results were published in bulletins of the Siberian Branch of the Russian Academy of Medical Sciences in 2005-2006.
This is the publication “Impaired bilirubin metabolism and the development of hyperbilirubinemia in newborn rat pups under the influence of unsymmetrical dimethylhydrazine (heptyl)” and “Medical, social and environmental problems of the use of liquid fuel rockets (heptyl).”
The scientific secretary of the institute, Tatyana Goltsova, who also took part in this scientific work, told RIA Novosti that it is necessary to take into account where the upper stage will be refueled with heptyl and at the places where the stages fall.
“In Altai, in places where steps fell, there was a disturbance in bilirubin metabolism and the development of immunodeficiencies in the population. We needed to check the mechanism of action of heptyl on a living organism. It has been proven that these forms of pathology can be associated with the toxic effect of heptyl. Korolev was also categorically against its use.” , - said the interlocutor.
The pathology was identified in Altai and was expressed in the fact that the biliary function of the liver was impaired in children. Several hypotheses were then put forward.
However, none of them, except for “heptyl”, turned out to be tied to the time of the surge in pathologies. During that period, four SS-18 intercontinental ballistic missiles, for which heptyl is used as fuel, were detonated in Altai.
Suitcase moods
At a meeting of the Amur Regional Council on May 30, the problem of environmental safety of the Vostochny Cosmodrome was also raised by deputies. In particular, deputy Sergei Abramov, to the applause of a number of colleagues, insisted on conducting an independent environmental assessment and justifying the project.
“The cosmodrome at any cost? There is panic and suitcase sentiment in society. There is still no environmental assessment of the Vostochny cosmodrome. Why is the information presented in a distorted form or suppressed?” the deputy noted.
According to Roscosmos, cosmodromes are, in principle, not on the list of objects of the state environmental assessment. The list is determined by an article in the federal law of the same name dated November 23, 1995.
“It makes no mention of cosmodromes, as well as other capital construction projects that are not located in specially protected natural areas, the continental shelf or inland sea waters. Projects of capital construction projects<…>Vostochny cosmodrome will undergo state examination in accordance with the town planning code,” Lopatin said.
He noted that it is within this framework that an environmental impact assessment (EIA) will be carried out during the construction and operation of spaceport facilities.
The only components in the activities of the Vostochny Cosmodrome that must undergo environmental assessment will be the new products of the Republic of Kazakhstan in the space industry.
“Design materials for launch vehicles, upper stages and spacecraft planned for use at the Vostochny cosmodrome, which can be classified as new equipment and technologies, are also planned to be submitted for state environmental assessment at the federal level in 2014,” Lopatin assured.
The truth, partially told
In the summer of 2010, public hearings were held in Uglegorsk (by the way, a closed administrative-territorial entity) where the issue of assessing the environmental impact of the Vostochny Cosmodrome was discussed.
Then it was announced that the new cosmodrome would use the new Naftil rocket fuel, instead of the toxic heptyl. The emphasis was placed on this information, and not on the heptyl accelerator.
“It was said that this would be the most modern and environmentally friendly spaceport. If we had complete information, we could start a normal healthy dialogue, but now we feel deceived. Local authorities accuse people who raise this topic of being hysterical. This style of work?,” noted ecologist Osipov.
Roscosmos confirms that during public hearings in 2010, they discussed a promising middle-class launch vehicle with increased payload capacity, using low-toxic naphthyl (RG-1) as rocket fuel components.
“This fuel is not a mixture of “hydrogen, oxygen and kerosene”, but a hydrocarbon fuel with the smell of well-refined kerosene<…>Naphthyl (RG-1) has been produced and used as fuel during launches of Zenit-type launch vehicles since 1985,” Lopatin said in an official response.
The Space Agency notes that naphthyl differs from the T-1 kerosene currently used in the Soyuz type launch vehicle by a relatively lower content of aromatic compounds and a higher content of naphthenes. The physicochemical and toxic properties of kerosene T-1 and naphthyl (RG-1) are approximately the same.
Roscosmos notes that heptyl as a component of rocket fuel is used by all countries engaged in space activities. Scientists, including Panin, do not argue with this. “It can be argued that the use of heptyl in rocket and space technology is a worldwide problem,” Panin noted in his work.
Tatyana Goltsova also does not argue that the use of heptyl in the upper stage cannot be compared with the degree of its impact on the environment when used as the main fuel. The difference in the volume of use of this toxic substance is too great.
“If the Fregat upper stage is turned on in outer space, then all possible remains should burn out. In this case, we should be afraid of emergency situations,” noted the scientific secretary.
“There is a population here, albeit small, and it needs to be protected. It’s not enough to avoid emergency situations, you need to be prepared for them. Soyuz is a reliable rocket, but even it had unsuccessful launches,” the ecologist concluded.
Story. Facts
In August 2011, after the launch of the new Progress M-12M cargo ship, a malfunction of the propulsion system occurred, which led to its emergency shutdown. The fragments of the space truck, which did not burn in the dense layers of the atmosphere, fell in the Altai Mountains.
In September 2007, a Proton-M launch vehicle launched from Baikonur with a Japanese communications satellite fell into Kazakhstan, 50 kilometers southeast of the city of Dzheskazgan. The Proton tanks contained the highly toxic fuel heptyl.
And also for rockets. Global jet fuel production averages 5% of refined petroleum (about 2% in Europe and developing countries and 7% in North America). In peacetime, the military consumes approximately 10% of total jet fuel resources. The fuel mass makes up 30-60% of the aircraft's take-off weight, which greatly increases the importance of the fuel used. These fuels are single-component, i.e. mixing them is not allowed, with a very strictly specified and controlled technology for their production. Fuels must ensure complete safety; reliable engine starting in any conditions; stable combustion in a fast-moving air stream and at large excess air ratios (more than 2); complete combustion without smoke and soot; high speed and flight range of the aircraft. Jet fuels are obtained from petroleum fractions (C]0-C14 and higher), boiling in the range of 120-280, 60-280 (subsonic aviation) or 195-315 °C (for weighted jet fuel used on military aircraft at high supersonic speeds). Russian refineries produce jet fuels of the following grades: T-1, TS-1 and T-2 (subsonic aviation), RT (transitional fuel for subsonic and supersonic aviation when the aircraft speed is relative to 1190 km/h (the speed of sound in the air) and number Mach I is more than 1.5), T-6 and T-8B (for supersonic aviation with Mdo 3.5).
Specific requirements for the quality of jet fuels are dictated by the harsh operating conditions of the fuel system (filters, injectors, pumps etc.) engines of jet aircraft and powerful helicopters, for which engine failure (including during repeated starts in the air) can lead to major accidents with large casualties. Production of jet fuels with a lower calorific value (at the level of 43 MJ/kg), with a maximum content of mercaptan sulfur in the range of 0.001-0.003 May. %, with a low flash point and low saturated vapor pressure, with high thermal stability, with an almost complete absence of water (emulsion, dissolved, etc.), resinous compounds and mechanical impurities, requires the involvement of the most advanced hydrogenation processes in the production technology of these fuels (hydrodearomatization, hydrotreating, hydrocracking) for the production and purification of petroleum fractions, the use of anti-wear and antioxidant additives, etc.
The tendency of jet fuels to form carbon deposits is controlled by limiting the content of aromatic hydrocarbons (arenes) in them to no more than 10-22 May. %, as well as the height of the non-smoking flame, which should not exceed 20-25 mm.
The nature of the flame (its brightness) of jet fuels for supersonic aviation is assessed by the luminometric number (JI4). The higher J14, the lower the flame brightness. The completeness of fuel combustion depends on its chemical composition. Fuel enriched with aromatic hydrocarbons is prone to the formation of soot and deposits, as a result of which hot carbon microparticles appear in the gas flow of the flame, increasing the brightness of the flame. With increasing brightness, the radiation (radiation) of the flame increases, overheating the walls of the combustion chambers and reducing the service life of the engine. The luminometric number of jet fuel is determined by comparison with reference fuels, for which tetralin (tetrahydronaphthalene) with JI4 equal to 100 units is selected. (GOST 17750-72). The intensity (brightness) of the flame is measured with a luminometer. The best brands of jet fuel have LC = 60-75. Standards for jet fuel require high values of its density (at least 755-840 kg/m3), since with increasing fuel density, the aircraft's flight range increases for the same volume of fuel tanks.
In aircraft fuel tanks, fuel is cooled to minus 40-50 °C (at an altitude of 12-14 km or more), and in the fuel supply system, on the contrary, it is heated to 150-250 °C, while unsaturated hydrocarbons (alkenes), resins, Mercaptans begin to decompose with the formation of insoluble precipitates that clog filters, injectors and other fuel system devices. Therefore, jet fuels are subject to strict requirements for increased thermal stability under static and dynamic conditions (fuels for supersonic aircraft according to GOST 11802-88 and GOST 17751-79),
which is achieved by cleaning fuels and introducing additives. In table 2.9 provides the requirements for jet fuels TS-1 and RT in accordance with GOST 10227-98 and T-6 and T-8V in accordance with GOST 12308-89.
Jet fuels must be free of hydrogen sulfide, water-soluble acids and alkalis, naphthenic acid soaps, mechanical impurities and water, water-soluble alkaline connections; the fuel must withstand the copper plate test; the lower calorific value is standardized to be no less than 43.12 MJ/kg (TS-1 and RT) and no less than 42.9 MJ/kg (T-6 and T-8B), ash content no more than 0.003 May. %, as well as specific electrical conductivity (for safety purposes from static electricity), content of naphthalene hydrocarbons and additives. The height of the non-smoking flame is not less than 25 mm (TS-1 and RT) and not less than 20 mm (T-6 and T-8V). In Russia, the production and consumption of TC-1 fuel accounts for more than 70% of the balance of all jet fuels, although in developed countries the demand for deep hydrocracking jet fuels is increasing to ensure high thermal stability at temperatures above 150 ° C and minimal carbon formation of fuels such as T-6 and T -8V.
Prospects for increasing production of jet fuels. In the near future, it is unlikely that there will be a real alternative to jet fuels derived from oil. The rapid pace of continued aviation development requires a significant increase in jet fuel production. The first way to widely involve vacuum gas oils (heavy oil fractions) to produce high-quality jet fuel based on the processes of hydrocracking, catalytic cracking and deep hydrotreating of products is associated with high capital investments in refineries and rising fuel prices. The second way, more economical, is to legally expand the fractional composition of jet fuel by increasing the end boiling point and reducing the requirements for fuel quality (increasing the content of aromatic hydrocarbons and the temperature at which crystallization begins, etc.), but it requires optimization of some aircraft engine components. In table Figure 2.10 compares the requirements that are likely to be imposed on jet fuels in the United States in the future and the current standards for one of the most common jet fuels, JP-4.
The most common brands of jet fuel abroad (Jet Fuels, Jet Kero): Jet A-l, JP-1 and JP-4 in the USA, their French analogues TR-4 (from the 55-240 °C fraction, saturated steam pressure 13.7-20.7 kPa, crystallization onset temperature minus 60 °C) and TRO (from the 165-240 °C fraction, crystallization onset temperature minus 40 °C). In world markets (primarily in the countries of the European Union and NATO), the most common jet fuel is Jet A-1 according to the ASTM D1655-96c standard. The following additives are added to any brand of jet fuel: antioxidants (24 mg/l), metal deactivators (5.7 mg/l), antistatic additives (3 mg/l), anti-icing additives (0.10-0.15% ) etc.
An alternative fuel for aircraft (primarily for helicopters) is liquefied petroleum gases, which are in a liquid state at a pressure of 0.5-1.6 MPa (gas gasoline, natural gas liquids, propane-butane fraction). In 1987, a new ASKT (aviation condensed) fuel was tested for the modified Mi-8TG helicopter, consisting of 40% liquefied propane-butane fraction and 60% condensate fuel (motor fuel made from gas condensates). The resources of such fuel in the regions of the Far North and Western Siberia remain large, the cost of its production and the necessary modification of aircraft engines and helicopters themselves is low. In table 2.11 shows some ASCT indicators.
ASKT is an environmentally cleaner and less corrosive fuel; it does not contain sulfur compounds, resins, asphaltenes and other undesirable substances present in traditional jet fuels. ASKT has better starting properties, which is especially important for the operation of aircraft in northern regions. ASKT and TS-1 jet fuel are mixed (mutually dissolved) in any ratio.
Jet fuel production: about 7 million tons/year in Russia, 77 million tons/year in the USA and 110 million tons/year in the seven leading countries (USA, Japan, Germany, Italy, UK, Canada, France).
Rocket fuels are used only for liquid rocket engines (LPRE) with certain features of their use. Rocket fuels come in single-component and two-component types. Single-component rocket fuels contain both combustible elements and oxygen. Examples of such fuels: methyl nitrate CH30N02 (boiling point 64 °C); nitromethane CH3N02 (boiling point 101 °C). They burn without external oxygen supply and are used in cases where the oxygen supply is limited. A two-propellant rocket fuel is a hydrocarbon fuel (synthetic or natural) burned in the presence of a strong oxidizer (usually liquid oxygen). An example of a synthetic fuel is dimethylhydrazine (hydrazine, heptyl), or diamide H2N-NH2, boiling at 113°C. Natural fuels are either liquid hydrogen or hydrocarbons. Some commercial jet fuels, for example T-2 and T-6, as well as specially selected fractions of naphthenic oils (naphthyl) or synthesized naphthenic hydrocarbons can be used as hydrocarbon fuels.
Category: Gas and oil production technology