It is well known, that any liquids are evaporated. Evaporation is a process when molecules of liquid having enough kinetic energy can escape from liquid surface. The vapor exists always above the liquid. If we have open vessel the evaporation process is continued uninterruptedly until vessel contains the liquid. During evaporation, the liquid is under atmospheric pressure and vapor pressure is pressure equaled partial pressure of vapor in gas mixture above liquid. The liquid boils at temperature, when vapor pressure will be equaled to atmospheric pressure.
If the vessel is closed, the evaporation process is proceeded up to so called “equilibrium” or when number of molecules that escape from liquid surface will be equaled number of molecules that are returned into the liquid. In other words, we have deal with so called equilibrium of “liquid-vapor” system.
Pressure and temperature of this system are connected to each other and define by conditions of equilibrium. Pressure and temperature in liquid phase are equaled to pressure and temperature in gaseous one. The pressure of these equilibrium systems is called the saturation vapor pressure.
Together with it, there are some physical properties that are different for liquid and saturated vapor.
- specific heat capacity;
- thermal conductivity.
Oxygen is not an exception to the rule. In submarine’s LOX tanks, the oxygen is in two phases — saturated liquid and saturated vapor.
This chapter contains reference information that is necessary for selection and calculation of oxygen cryogenic systems applied in submarines. The chapter contains empirical formulas and polynomials and graphs for determining values of different physical properties of saturated liquid (LOX) and gaseous oxygen (GOX).
It should be verified every correlation before it will be applied. We recommend to perform the verification using some basic points (two at least). What points we keep in mind?
The first point is the boiling point (BP). The saturated temperature and pressure in this point are well known (p=1.01325 bar; T=90.15K).
The second point is the critical point (CP). The critical temperature and pressure are well known (Pcr=50.43 bar; Tcr=154.58K) as well.
The third point that can be used is the Triple point (TP) (Pt=0.148 kPa; Tt=54.35K).
The reference technical data for different physical properties of oxygen are known for two first points as rule. As for third point there is problem. Instead of Triple point can be used any point (with guarantee data) in intervals between BP and CP or between CP and TP.
It should be noted especially the thesis
EXPERIMENTAL STUDIES OF LIQUEFACTION AND DENSIFICATION OF LIQUID OXYGEN
performed by Jonathan Koert Partridge
for the degree of Master of Science in Mechanical Engineering in the Department of Mechanical, Materials, and Aerospace Engineering in the College of Engineering and Computer Science at the University of Central Florida Orlando, Florida.
Table of Content
|1.1||OXYGEN BASIC PHYSICAL PROPERTIES||7|
|1.2||OXYGEN SATURATED VAPOR PRESSURE||15|
|1.3||OXYGEN VAPOR AND LIQUID DENSITY||26|
|1.4||OXYGEN VAPOR AND LIQUID HEAT CAPACITY||36|
|1.5||OXYGEN ENTHALPY OF VAPORIZATION||42|
|1.6||THERMAL CONDUCTIVITY OF SATURATED VAPOR AND 51 LIQUID OXYGEN||51|
|1.7||VISCOSITY OF SATURATED VAPOR AND LIQUID OXYGEN||59|
|1.8||LIQUID OXYGEN SURFACE TENSION||66|
|1.9||CALCULATION OF OXYGEN LOSSES TO REDUCE THE LOX 69 TANK PRESSURE||69|
- Title – LIQUID OXYGEN SYSTEM FOR AIP SUBMARINES. CHAPTER 1. LIQUID OXYGEN REFERENCE INFORMATION
- Classification – UNCLASSIFIED Author – Bakst A.
- Issue Data – 2014‐08
- Updated – 2016‐04
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- Cover – 2 slides;
- Tables – 5;
- Figures – 32 (pictures, graphs);
- References – 7;
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