Vapor compression basics

Eig. 7. Schematic flow diagram of a basic horizontal-tube vapor compression (VC) desalination plant, shown (a) with a mechanical, motor-driven compressor and (b) with a thermocompressor, using an ejector, where (------) represents vapor (—), brine and (-), product. 

Equipment diagram for refrigeration using a basic vapor compression cycle. 

Shen, L.S. "Essergy Analysis of Basic Vapor Compression Refrigeration Systems," M.S. Thesis, GA Tech, 1979. 

The basic t5q)es of evaporators are pot evaporators and circulation—either natural or forced—evaporators. Figure 11.20 shows a natural-circulation evaporator. To improve the economy of the process, vapor compression may be employed. Vapor-compression evaporators make the latent heat of condensation available at a higher temperature to use the energy potentials of vapors by compressing it and combining it with fresh steam input. 

The basic approach toward reducing corrosion and hydrogen bhstering in the various vapor-compression stages of catalytic cracking units should be aimed at decreasing the concentration of cyanide and disulfide ions in water condensate. Several methods for accomphshing this have been tried over the years. 

Figure 8.24. Simpler circuits of compression refrigeration (see also Example 8.17). (a) Basic circuit consisting of a compressor, condenser, expansion valve and evaporator (load), (b) Conditions of the basic circuit as they appear on a pressure-enthalpy diagram the primed points are on the vapor-liquid boundary curve, (c) Circuit with circulation of refrigerated brine to process loads, (d) Circuit with two-stage compression and intercooling.

To be useful, this type of simulator must calculate the thermodynamic properties of multicomponent mixtures in both liquid and vapor phases while predicting bubble and dew points or partial vaporizations or condensations. Using this basic information, the simulator must then make calculations for other processes, such as gas cooling by expansion, gas compression, multiple flashes condensations, and separations by absorption... 

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