Ninguno
Páginas: 2 (455 palabras)
Publicado: 3 de septiembre de 2011
about pressure increases. Compressors, pumps, fans, blowers, and vacuum
pumps are all devices designed for this purpose. They are vital for the transport of fluids, for
fluidization of particulatesolids, for bringing fluids to the proper pressure for reaction or processing,
etc. We are concerned here not with the design of such devices, but with specification
of energy requirements forsteady-state compression causing an increase in fluid pressure.
Compressors
The compression of gases may be accomplished in equipment with rotating blades (like a
turbine operating in reverse) or incylinders with reciprocating pistons. Rotary equipment is
used for high-volume flow where the discharge pressure is not too high. For high pressures,
reciprocating compressors are required. The energyequations are independent of the type of
equipment; indeed, they are the same as for turbines or expanders, because here too potentialand
kinetic-energy changes are presumed negligible. Thus, Eqs.(7.13) through (7.15) apply to
adiabatic compression, a process represented by Fig. 7.5.
Compressor
2
1
Ws
.
Figure 7.5: Steady-state
compression process.
De donde,
7.3. Compression Processes273
Evaluation of C ig
P H as in part (a) with T2 = 365.8 K gives:
C ig
P H = 59.843 J mol−1 K−1
Whence, (H)S = −11,920 J mol−1
and Ws (isentropic) = (H)S = −11,920 J mol−1
This differs fromthe ideal-gas value by less than 2%.
7.3 COMPRESSION PROCESSES
Just as expansion processes result in pressure reductions in a flowing fluid, so compression
processes bring about pressure increases.Compressors, pumps, fans, blowers, and vacuum
pumps are all devices designed for this purpose. They are vital for the transport of fluids, for
fluidization of particulate solids, for bringing fluidsto the proper pressure for reaction or processing,
etc. We are concerned here not with the design of such devices, but with specification
of energy requirements for steady-state compression...
pumps are all devices designed for this purpose. They are vital for the transport of fluids, for
fluidization of particulatesolids, for bringing fluids to the proper pressure for reaction or processing,
etc. We are concerned here not with the design of such devices, but with specification
of energy requirements forsteady-state compression causing an increase in fluid pressure.
Compressors
The compression of gases may be accomplished in equipment with rotating blades (like a
turbine operating in reverse) or incylinders with reciprocating pistons. Rotary equipment is
used for high-volume flow where the discharge pressure is not too high. For high pressures,
reciprocating compressors are required. The energyequations are independent of the type of
equipment; indeed, they are the same as for turbines or expanders, because here too potentialand
kinetic-energy changes are presumed negligible. Thus, Eqs.(7.13) through (7.15) apply to
adiabatic compression, a process represented by Fig. 7.5.
Compressor
2
1
Ws
.
Figure 7.5: Steady-state
compression process.
De donde,
7.3. Compression Processes273
Evaluation of C ig
P H as in part (a) with T2 = 365.8 K gives:
C ig
P H = 59.843 J mol−1 K−1
Whence, (H)S = −11,920 J mol−1
and Ws (isentropic) = (H)S = −11,920 J mol−1
This differs fromthe ideal-gas value by less than 2%.
7.3 COMPRESSION PROCESSES
Just as expansion processes result in pressure reductions in a flowing fluid, so compression
processes bring about pressure increases.Compressors, pumps, fans, blowers, and vacuum
pumps are all devices designed for this purpose. They are vital for the transport of fluids, for
fluidization of particulate solids, for bringing fluidsto the proper pressure for reaction or processing,
etc. We are concerned here not with the design of such devices, but with specification
of energy requirements for steady-state compression...
Leer documento completo
Regístrate para leer el documento completo.