Subcooled/compressed liquids

A vapor-compression refrigeration system is conventional except that a countercurrent exchanger is installed to subcool the liquid from the condenser by heat exchange with the v stream from the evaporator. The minimum temperature difference for heat transfer is 10(°F). Amm is the refrigerant, evaporating at 22(°F) and condensing at 80(°F). The heat load on the evapo is 2,000(Btu)(s) . If the compressor efficiency is 75 percent, what is the power requirement ... 

L axial length of nozzle liquid must be subcooled (compressed) water... 

Subcooled or compressed liquids exist at temperatures below the saturation or boiling temperature for a given pressure. In general, subcooled liquids exhibit little change in properties resulting from pressure changes and properties are driven primarily by temperature. 

Figure 24.24a shows the corresponding simple compression cycle, but with subcooled condensate. The cycle is basically the same as before, except that the liquid leaving the condenser is now subcooled rather than being saturated. 

Mist flow, one component In a one-component system with finely dispersed drops in the mist flow, the mass transfer between phases over a large interfacial area has to be considered. For the compression wave the frozen state can be assumed to be subcooled liquid, superheated vapor conditions generated by the wave are fairly stable, and the expressions for the two-component system are valid (Henry, 1971) ... 

So, when r s > list (low subcooling, flashing before the choke print), use the compressible solution, Eq. (26-95) with T sp = Is- Otherwise (for high subcooling, no flashing before the choke point), use the liquid orifice equation, Eq. (26-94k... 

Liquids are usually moved by pumps, generally rotating equipment. The same equations apply to adiabatic pumps as to adiabatic compressors. Thus, Eqs. (7.13) through (7.15) and Eq. (7.17) are valid. However, application of Eq. (7.14) for the calculation of Wj = AH requires values of the enthalpy of compressed (subcooled) liquids, and these are seldom available. The fundamental property relation, Eq. (6.8), provides an alternative. For an isentropic process,... 

Reversible, adiabatic (isentropic) pumping of the saturated liquid to the pressure of the boiler, producing compressed (subcooled) liquid. The vertical line (whose length is exaggerated in Fig. 8.3) is very short, because die temperature rise associated with compression of a liquid is small. 

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