| Propellant Heats of Formation, Hydrogen Atoms, Oxygen Atoms & Densities | ||||
| Propellant | Heat of Formation ( J / kmol ) | Hydrogen | Oxygen | Density ( kg / m^3 ) |
| Water | -285,830,000 |
2 |
1 |
997.000 |
| Water at 373 K | -280,183,000 |
2 |
1 |
958.400 |
| Water at 394 K | -278,600,000 |
2 |
1 |
944.000 |
| Water at 452 K | -274,240,000 |
2 |
1 |
903.000 |
| Water at 531 K | -268,310,000 |
2 |
1 |
848.000 |
| Water at 624 K | -261,290,000 |
2 |
1 |
784.000 |
| Steam at 373 K | -239,300,000 |
2 |
1 |
0.588 |
| Steam at 394 K | -238,595,000 |
2 |
1 |
0.557 |
| Steam at 452 K | -236,647,000 |
2 |
1 |
0.485 |
| Steam at 531 K | -233,995,000 |
2 |
1 |
0.413 |
| Steam at 624 K | -230,872,000 |
2 |
1 |
0.351 |
| Hydrogen | -8,123,000 |
2 |
0 |
70.800 |
Propellant density is the density of the propellant, commonly expressed in kilograms per cubic meter. The greater the propellant density, the greater the amount of propellant that can be stored in a given tank and the greater the mass of propellant than can be pumped for a given pump. Propellant density generally increases with increasing molecular weight of the propellant molecules. Propellant density also generally increases with increasing molecular weight of the component atoms of the propellant molecules.
Propellants with a high density are often used when high thrust is desired, for instance, when operating at low altitude. Propellant density is used to calculate propellant volume ratio, which is in turn used to calculate the tank mass.
propellant volume ratio = propellant mass ratio / propellant density
tank mass = tank pressure * 3.0 / effective tensile * ( fuel volume ratio + oxidizer volume ratio + propellant volume ratio )
This is used in tripropellant rocket, pumped rocket and rocket cost.
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