Heat transfer with phase change

As the pressure in the pipe decreases in the direction of the flow, the saturation temperature of the liquid decreases, promoting an increase in vaporization. More bubbles are formed these interact to form a continuous 

Three main flow patterns exist at various points within the tube bubble, annular, and dispersed flow. In Section I, the importance of knowing the flow pattern and the difficulties involved in predicting the proper flow pattern for a given system were described for isothermal processes. Nonisother-mal systems may have the added complication that the same flow pattern does not exist over the entire tube length. The point of transition from one flow pattern to another must be known if the pressure drop, the holdups, and the interfacial area are to be predicted. In nonisothermal systems, the heat-transfer mechanism is dependent on the flow pattern. Further research on predicting flow patterns in isothermal systems needs to be undertaken 

SINGLE- PHASE FORCED CONVECTION SUBCOOLED BOILING BUBBLE FLOW ANNULAR FLOW WITH DROPLETS 

ANNULAR MIST FLOW TRANSITION REGION MIST FLOW 

SINGLE PHASE FORCED CON- VECTION SUB- COOLED BOILING BUBBLE COAGU- LATION SLUG FORMA- TION SLUG COAGU- LATION ANNULAR FLOW ANNULAR FLOW WITH DROPLETS 

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Kandlikar, S. G., 1989b, Development of a Flow Boiling Map for Subcooled and Saturated Flow Boiling of Different Fluids Inside Circular Tubes, Heat Transfer with Phase Change, ASME HTD Vol. 114, pp. 51-62, Winter Annual Meeting, San Francisco, CA. (4)... 

Heat transfer in two-phase flow can be studied most conveniently by adopting a two-part classification heat transfer without phase change, and heat transfer with phase change. In this section, the non-phase-change problems will be discussed the phase-change problem will be dealt with in Section III. 

It was shown that in heat transfer with phase change it is necessary to understand the phase-change phenomenon on the molecular level to model effectively the mass- and heat-transfer processes. An analytical expression for the rates of vaporization and condensation was developed. It was also shown that the assumption of a saturated vapor phase greatly simplified the calculation without a significant loss in accuracy for given examples. However, experimental verification of this simplified assumption is currently lacking. 

The analysis of tubular contactors for heat transfer with phase changes in fluid-fluid systems was shown to be heavily dependent on a proper understanding of two-phase hydrodynamics. It was shown that three basic flow patterns exist within a tube, each with a different heat-transfer mechanism. The formulation of the proper mass and energy models pinpointed three key... 

Figure 7 shows the process heat loop for transporting heat from the cold side of the PCU boiler to the hot side of the HTE boiler. This loop operates as a heat pump transferring heat from a cold source to a hot sink. Heat transfer with phase change is used at both the source and sink to achieve high heat fluxes and, hence, compact heat exchangers. An important question is the mechanical power consumption of the compressor and how it compares to the overall heat transfer rate. The compressor serves to... 

Geoffrey D SMcox, Ph.D. Professor of Chemical Engineering, Combustion, and Reactors, University of Utah Member, American Institute of Chemical Engineers, American Chemical Society, American Society for Engineering Education (Conduction, Convection, Heat Transfer with Phase Change, Section Coeditor)... 

Enthalpy balance for coolant heat transfer with phase change. 

The semiempirical approaches for the heat transfer coefficient can also be applied to more complex situations than those described earlier. Such cases include packed beds, agitated systems, non-Newtonian fluids, and heat transfer with phase change. 

Rolph WDIII, Bathe KJ (1982) An efficient algorithm for analysis of non-linear Heat transfer with phase change. Int J Numer Meth Eng 18 119-134... 

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