Compressibilities of Liquids

Many transient flows of liquids may be analyzed by using the full time-dependent equations of motion for incompressible flow. However, there are some phenomena that are controlled by the small compressibility of liquids. These phenomena are generally called hydraulic transients. 

The basic steam cycle for a steam turbine installation is called a Rankine cycle (named after Scottish engineer and physicist William John Macquorn Rankine). This cycle consists of a compression of liquid water, heating and evaporation in the heat source (a steam boiler or nuclear reactor), expansion of the... 

To describe the flow in a horizontal heated capillary we use the mass, momentum and energy balance equations. At moderate velocity, the effects due to compressibility of liquid and vapor, as well as energy dissipation in gaseous and liquid phases are negligible. Assuming that thermal conductivity and viscosity of the vapor and the liquid are independent of temperature and pressure, we arrive at the following system of equations ... 

All fluids are compressible to some extent but the compressibility of liquids is so low that they can be treated as being incompressible. Gases... 

Here, (instead of the more cumbersome notation 0T1) is used for the coefficient of isothermal compressibility of liquid 1. The presence of the second liquid gives rise... 

Piezometer Method. To measure the compressibility of liquids near 1 atm we have developed a piezometer system (87). 

TABLE 3 Thermal Expansion Coefficients and Isothermal Compressibility of Liquids and Solids... 

Ignition Caused by Compression of Liquids. Liquids can be ignited by sudden compression. This can happen when there is water hammer caused by the pressure surge from quick-acting valves and from the compression in liquid pumps. Sudden compression can occur with liquids, for example if a tank car is bumped rapidly and the liquid goes to one end very quickly, possibly trapping some vapor bubbles that compress and create local hot spots that can cause ignition. 

B. Pressure and Volume. Two of the other important system variables which are usually at our disposal experimentally are volume and pressure. In the study of reactions between gases it is possible to keep either the pressure or the volume of the system fixed. The simplest procedure is to maintain a gas system in a vessel at fixed volume. For reactions in liquid and solid systems, the pressure is most conveniently controlled, volume control being either unimportant or unattainable owing to the small coefficient of compressibility of liquids. ... 

The compressibility of liquids was first demonstrated experimentally by Canton,5 who showed, for example, that water and mercury occupied different volumes according as they were cooled from a higher temperature to a lower in an open or in a sealed thermometer in the open tube the liquid was exposed to the atmospheric pressure and occupied a smaller volume. Canton found that the relative change in volume of water was 0-000046 per atm. at 10°, and he found (correctly) that the compressibility of water decreases with rise in temperature, whereas later workers found that of other liquids increases. Spirit of... 

The compressibilities of liquids were measured by 0rsted,i using a piezometer (Greek to press, pdxQov, a measure the name is due to Perkins, 1820). 

The number of formulae representing the effect of temperature on latent heat, and empirical formulae for latent heats, is large, and latent heat is a quantity which is peculiarly adaptable to representation by empirical formulae, some of which agree with experiment for one group of liquids and fail for others. In the following, 4 and 4/ are the total and internal ( l.VIIIL) latent heats in g.cal. per g., L =M1 and Qg the densities in g./ml. of liquid and vapour, vt, Vg the specific volumes of liquid and vapour in ml. /g., p the vapour pressure, T the abs. temp., Tb the b.p. abs., Tc the critical temperattire, pc the critical pressure, Vc the critical volume, Qc the critical density, d —TjTc r=TdT, c or Cp is the specific heat, M=mol. wt., a=coefiicient of expansion of liquid, =compressibility of liquid, k, K, ki, k2, Aq, B, m, , /q, s are constants. 

Measurement of Compressibilities of Liquids, pages 57-61. 2. Values of Compressibilities of Liquids, pages 61-62. 3. Velocity of Sound in Liquids, pages 62-66. 4. Compressibility Formulae, pages 66-68. 5. Compressibilities of Solutions, pages 68-70. E—viscosity of uquids. 

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