Negative Adiabatic Lapse Rate of Water: Result of Negative Compressibility | Chapter 06 | Advances and Trends in Physical Science Research Vol. 1
When the pressure of fluid changes
without heat addition, the temperature of the fluid changes; the rate at which
the temperature changes with pressure is called the adiabatic lapse rate.
According to thermodynamic equations, the adiabatic lapse rate is positive if
the thermal expansion coefficient is positive and negative if this coefficient
is negative. The adiabatic lapse rate of water is the rate at which its
temperature changes with pressure at constant entropy S, and salinity. Experiments show, however, that the adiabatic
lapse rate is also positive for substances with negative thermal expansion,
although for water it is negative when it has negative thermal expansion. The
present paper develops a theory showing that the adiabatic lapse rate must always
be positive, but is negative for water because it has negative compressibility
in that temperature-pressure region. Numerous substances with negative
compressibility have already been identified. The result shows that the
traditional thermodynamic equations cannot be used to describe the adiabatic
compression of substances because they are derived from the equation which
describes heat exchange. The traditional equations predict that substances with
negative thermal expansion absorb heat under compression, while numerous
experiments show that they express heat. Result also shows that water absorbs
heat when it has negative thermal expansion. As many substances with negative
compressibility have recently been found, this explanation appears to be
plausible. Therefore, the study suggests precise experiments in this
low-pressure region. Taking the salinity of water into account does not change
the results of the theory.
Biography of author(s)
Igor Stepanov
Institute
of Science and Innovative Technologies, Liepaja University, Liela 14, Liepaja,
Latvia, LV-3401, Latvia.
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