- Isenthalpic process
An isenthalpic process is one that proceeds without any change in
enthalpy , "H"; or specific enthalpy, "h". [ cite book | last = Atkins | first = Peter
authorlink = Peter Atkins
coauthors = Julio de Paula
title = Atkin's Physical Chemistry
publisher = Oxford University Press
date = 2006
location = Oxford
pages = 64
isbn = 9780198700722 ]In a steady-state, steady-flow process, significant changes in pressure and temperature can occur to the fluid and yet the process will be isenthalpic if there is no transfer of heat to or from the surroundings, no work done on or by the surroundings, and no change in the kinetic energy of the fluid.G.J. Van Wylen and R.E. Sonntag, "Fundamentals of Classical Thermodynamics", Section 5.13 (3rd edition)] (If a steady-state, steady-flow process is analysed using a
control volume everything outside the control volume is considered to be the surroundings. [G.J. Van Wylen and R.E. Sonntag, "Fundamentals of Classical Thermodynamics", Section 2.1 (3rd edition)] )The throttling process is a good example of an isenthalpic process. Consider the lifting of a relief valve or safety valve on a pressure vessel. The specific enthalpy of the fluid inside the pressure vessel is the same as the specific enthalpy of the fluid as it escapes from the valve. With a knowledge of the specific enthalpy of the fluid, and the pressure outside the pressure vessel, it is possible to determine the temperature and speed of the escaping fluid.
In an isenthalpic process:
* "h"1 = "h"2
* "dh" = 0Isenthalpic processes on an
ideal gas follow isotherms since "dh" = "C""p"0("T"2 − "T"1)See also
*
Isentropic process
*Adiabatic process References
G.J. Van Wylen and R.E. Sonntag (1985), "Fundamentals of Classical Thermodynamics", John Wiley & Sons, Inc., New York ISBN 0-471-82933-1
Notes
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