Heat exchanger general theory

Statement of the problem. In the theory of heat exchange between liquid metals (Pr C 1), the fluid field is usually considered on the basis of the ideal fluid model [48], since the hydrodynamic boundary layer lies deep inside the thermal boundary layer. In this case, generally speaking, the Peclet number need not be sufficiently large for the thermal boundary layer approximation to be applicable. 

The mathematical solution to equation 6.10 is also available for the more general case of finite volume or limited bath conditions, where equilibrium at the particle-solution interface is assumed at all times and the macro-concentration of ions A in the external solution is time-dependent. An analogous situation arises in the theory of heat transfer where the mathematical solution also serves the case of ion exchange ... 

The coefficient of turbulent viscosity vr is the most important among them. A number of scientific efforts were spent for estimating it with respect to the whole wide spectrum of problems of fluid mechanics and heat and mass exchange. Thousands of lengthy papers have been devoted to the problem of turbulence . However, we still have no any sufficiently grounded and generally accepted theory. Turbulence still remains to be the most serious challenge to theoretical physics. 

General Considerations. The importance of fouling phenomena stems from the fact that the fouling deposits increase thermal resistance to heat flow. According to the basic theory, the heat transfer rate in the exchanger depends on the sum of thermal resistances between the two fluids, Eq. 17.5. Fouling on one or both fluid sides adds the thermal resistance R, to the overall thermal resistance and, in turn, reduces the heat transfer rate (Eq. 17.4). Simultaneously, hydraulic resistance increases because of a decrease in the free flow area. Consequently, the pressure drops and the pumping powers increase (Eq. 17.63). 

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