Pressure drop chapter Subject

Refer to the earlier section in this chapter, because tubeside pressure drop and heat transfer are subject to the same conditions as other tubular exchangers. 

Fuel and air or nitrous oxide flow stabilities must be adequate for good precision. Intermediate balast tanks help to smooth out fluctuations caused by compressors.3 As mentioned in Chapter 2, section 5, nitrous oxide cools when it is subjected to a sharp pressure drop, which results in cooling of the cylinder head, and sometimes in instability. The effect is not as important if the nitrous oxide operating pressure... 

The solution of (7.3.3-1)-(7.3.3-2) is not straightforward. A detailed treatment of the subject is given in Chapter 12 on complex flow patterns. In many cases, a given type of velocity field can be imposed and the corresponding pressure field is calculated from a specific pressure drop equation. 

An alternative would be to use Figure 7-7 however, it does not go out to such a low CoVr value. The vendor would probably optimize this further for pressure drop and length by employing a multipoint sparger and spacers between the elements, both subjects beyond the scope of this chapter. 

In this chapter we get to know the second essential equation of surface science — the Kelvin5 equation. Like the Young-Laplace equation it is based on thermodynamic principles and does not refer to a special material or special conditions. The subject of the Kelvin equation is the vapor pressure of a liquid. Tables of vapor pressures for various liquids and different temperatures can be found in common textbooks or handbooks of physical chemistry. These vapor pressures are reported for vapors which are in thermodynamic equilibrium with liquids having planar surfaces. When the liquid surface is curved, the vapor pressure changes. The vapor pressure of a drop is higher than that of a flat, planar surface. In a bubble the vapor pressure is reduced. The Kelvin equation tells us how the vapor pressure depends on the curvature of the liquid. 

Equilibrium constants are also sometimes equal to system properties of interest, such as vapor pressures, solubilities, phase compositions, and so on. This is because quite often it can be arranged that all activity terms drop out (are equal to 1.0) except the one of interest, which can then be converted to a pressure or composition. In Chapter 14 we will see that wherever this is the case, we are dealing with a buffered reaction, and the subject is developed further there. 

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