Rating factors, heat pump

In the alternate interface a heat pump raises the temperature of near-waste heat from the PCU to the temperature at which nine-tenths of the HTE process heat is needed. The decrease in temperature at the heat exchanger that links the HTE plant with the nuclear plant reduces the tritium migration rate by about a factor of 100. In addition to mitigating tritium transport and creep of structures, structural material commodity cost is also reduced. 

Tubes with rough surfaces have much higher heat transfer coefficients than tubes with smooth surfaces. Therefore, tube surfaces are often intentionally roughened, corrugated, or filmed in order to enhance the convection heat iraiisier coefficient and thus the convection heat transfer rate (Fig. 8-28). Heat transfer in turbulent flow in a lube has been increased by as much as 400 percent by roughening the surface. Roughening the surface, of course, also increases the friction factor and thus the power requirement for the pump or the fan. 

For the proper selection and economical operation of size-reduction machinery, attention must be given to many details of procedure and of auxiliary equipment. A crusher, grinder, or cutter cannot be expected to perform satisfactorily unless (1) the feed is of suitable size and enters at a uniform rate (2) the product is removed as soon as possible after the particles are of the desired size (3) unbreakable material is kept out of the machine and (4) in the reduction of low-melting or heat-sensitive products, the heat generated in the mill is removed. Heaters and coolers, metal separators, pumps and blowers, and constant-rate feeders are therefore important adjuncts to the size-reduction unit. Factors to consider in specifying a size-reduction system, including energy efficiency and environmental issues, are discussed by Kukla and Hixon, ... 

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