Reflections on Thermal Energy,
Reversible and Caloric Processes,
Exergy and Entransy – (Lecture II)
Institute of Engineering Thermophysics
Tsinghua University
Beijing, China, June 18, 2013
Prof. M. Kostic
Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITY
www.kostic.niu.edu
Slide 1
Some Challenges in Thermoscience Research
and Application Potentials
Energy Ecology Economy
Tsinghua University, XJTU, and HUST
China 2013: Beijing, Xi’an, Wuhan, June 14-28, 2013
Prof. M. Kostic
Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITY
www.kostic.niu.edu
Slide 2
Hello:
Thank you for the opportunity
to present a holistic, phenomenological
reasoning of some challenging issues
in Thermo-science.
Discussions are informal and not finalized yet.
Thus, respectful, open-minded arguments, and
brainstorming are desired for better
comprehension of tacit and often elusive
thermal phenomena.
•www.kostic.niu.edu
3
Slide 3
•Among distinguished invites were five
keynote speakers from China and seven
international keynote speakers: three from
the USA and one each from Japan, United
Kingdom, Singapore, and Spain; including
four Academicians and
•It has been my great pleasure and honor to
meet Prof. ZY Guo and other
distinguished colleagues,
•and even more so to visit
again and meet friends
six university Presidents/vice-presidents.
now!
Slide 4
•www.kostic.niu.edu
•www.kostic.niu.edu
Slide 5
•www.kostic.niu.edu
Slide 6
What is Energy ?
•More important than what it appears to be
•If one could expel all energy out of a physical system …
… then empty, nothing will be left …
•… so
ENERGY is EVERYTHING … E=mc2
Mass (m) and energy (E) are manifestation of each other and are equivalent;
they have a holistic meaning of “mass-energy”
•www.kostic.niu.edu
Slide 7
What is Energy ?
•“From the Sovereign Sun to the deluge of
photons out of the astounding compaction and
increase of power-density in computer chips …
Mass-Energy represents motion of a system structure, i.e., its representative particles at different
space and time scales, and ultimately motion of photons.
Where the Thermal Energy fits in?
•www.kostic.niu.edu
Slide 8
Energy Carriers &
“Underlying” Energy Carriers
Fundamental or “Underlying energy carriers” are the FOUR
fundamental forces/interactions (and related particles) in physics:
1.
2.
3.
4.
Strong nuclear
Weak nuclear
Electro-magnetic (EM), and
Gravitational
Underlying carriers for electro-chemical and thermo-mechanical
energy are photons (EM),
And “massive (‘convective’)” carriers may be electrons (or electron
shells) and bulk matter, including crystal shell (phonons)
•www.kostic.niu.edu
Slide 9
Heat Transfer Is Unique and Universal:
 Heat transfer is a spontaneous irreversible process where all
organized (structural) energies are disorganized or dissipated
as thermal energy with irreversible loss of energy potential
(from high to low temperature) and overall entropy increase.
Thus, heat transfer and thermal energy are
unique and universal manifestation of all
natural and artificial (man-made) processes,
… and thus … are vital for more efficient cooling and heating
in new and critical applications, including energy production
and utilization, environmental control and cleanup, and biomedical applications.
•© M. Kostic
•2009 January 10-12
Slide 10
2
…thus thermal & mechanical
energies are coupled
•www.kostic.niu.edu
Slide 11
Heat Is Transfer of Thermal Energy
…thus Q=Uin_transfer
• Philosophically, you cannot transfer something
that does not exist.
For example, you cannot transfer water unless you have
water. You cannot transfer energy (type) without having it
somewhere (stored) to transfer and store it somewhere else.
In the process (while transferring) you may
convert/reprocess (modify the "original structure") while
conserving the underlying substructure (true elementary
particles): existential conservationism.
• Some deny existence of ‘thermal energy.’
It is the same as denying existence of its (heat) transfer!
© M. Kostic
•041115
Slide 12
Interchangeability of heat and work?
• I have reservation about accuracy of "Heat and Work
Example" and “Thermal Energy” in:
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heat.html
• "This example of the interchangeability of heat and work
as agents for adding energy to a system can help to
dispel some misconceptions about heat.“
???
•www.kostic.niu.edu
Slide 13
Useful Energy: Work potential,
Exergy (and Entransy) concept(s)
Two systems in non-equilibrium have potential of extracting work (useful
energy). The maximum work potential is if they are reversibly brought to
mutual equilibrium while the work is extracted (thus re-arranging the nonequilibrium: entropy is conserved, thus over-all isentropic), otherwise part
or in-whole that work potential (i.e., non-equilibrium) will dissipate via heat
to thermal energy and generate entropy.
If one system is fixed (an infinite thermal reservoir) and taken as a
reference (like environment at To & Po), then that maximum work potential
depends on the other system state, i.e., it is independent of the process
path, thus, could be considerred the system property, called Exergy.
Note that there will be a need to reversibly exchange heat (and entropy) at
the reference temperature or reversibly regenerate heat internally, except
for isentropic processes.
•www.kostic.niu.edu
Slide 14
“Work Potential” NOT path dependent
(very important!)
Or any path
Also for any 1-2 states
(non-isentropic)
•www.kostic.niu.edu
Slide 15
All reversible processes are
“over-all isentropic” (entropy conserved)!
Exergy analysis to minimize and
optimize irreversibility
Entransy analysis to maximize
and optimize heat transfer
•www.kostic.niu.edu
Slide 16
Engineering Thermodynamics
7th Ed. By Moran et al, Wiley
But not ALWAYS true: Irreversible work will increase entropy thus resulting in
different state with the same internal energy as reversible work. It is, though, true if
ALL work is irreversibly converted to heat and stored as thermal energy, as in isohoric
processes (V=constant) with solids and liquids (as in the Jule’s experiments).
NOT true!
BUT so is E2-E1=Qin, if W=0
•www.kostic.niu.edu
Slide 17
Howard DeVoe, Thermodynamics and Chemistry (electronic)
textbook: www2.chem.umd.edu/thermobook/
on 11 April 2013
•www.kostic.niu.edu
Slide 18
Mechanical and Thermal
Energies
Are Distinguishable Within
Internal Energy!
DU12s= DU12v
U2s=U2v
U=Uth+Umech(elastic)
T2s=T2v (for Ideal Gas)
BUT!
2s≠2v
Ps>Pv; Ss<Sv
Vs<Vv,
Uth,s<Uth,v & Umech,s>Umech,v
Exs>Exv etc.
FORCE applied
or HEAT applied
•© M. Kostic
•2009 January 10-12
Slide 19
Thermal and Mechanical energies
© M. Kostic
1 kJ heating is NOT the SAME as 1 kJ compressing!
Thermal and Mechanical energies are distinguishable,
NOT the same Internal energy (as argued by some)!
•041115
Slide 20
•www.kostic.niu.edu
Slide 22
Note :
Q Irr  Q Gen   W Loss  T Ref S Gen ( any )
•www.kostic.niu.edu
Slide 23
IRREVERSIBILITY AND
REVERSIBLE HEAT TRANSFER:
The Quest and Nature
of Energy and Entropy
Prof. M. Kostic
Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITY
© M. Kostic <www.kostic.niu.edu>
041115
Focus and Goal:
Focuses on
philosophical and practical aspects
of energy and entropy,
with emphasis on
reversibility and irreversibility, and
goal to establish the concept of
“reversible heat transfer,”
regardless that heat transfer
is a typical irreversible process.
© M. Kostic <www.kostic.niu.edu>
041115
Objective:
… to emphasize known,
but not so well-recognized issues
about entropy, irreversibility and reversibility,
as well as to put certain physical and
philosophical concepts in perspective,
and initiate discussion and arguments about the
paper theme.
© M. Kostic <www.kostic.niu.edu>
041115
Heat Transfer:
Heat transfer like any other energy transfer,
may be achieved
from any-to-any temperature level,
and in limit be reversible,
if temperature of an intermediary cyclic
substance is adjusted as needed, using
isentropic compression and expansion
© M. Kostic <www.kostic.niu.edu>
041115
This is practically demonstrated…
This is practically demonstrated
in refrigeration and heat pump devices,
and enables further increase in energy
efficiency.
A dual power-and-heat-pump cycle is
introduced and analyzed here,
to provide for reversible heat transfer.
It may be considered as a reversible
heat-transfer transformer,
from-any-to-any temperature levels.
© M. Kostic <www.kostic.niu.edu>
041115
Limits and Practical Potentials:
The reversible heat transfer limits
are the most efficient
and demonstrate limiting potentials
for practical heat transfer processes.
© M. Kostic <www.kostic.niu.edu>
041115
REVERSIBILITY AND
IRREVERSIBILITY:
ENERGY TRANSFER AND DISORGANIZATION,
RATE AND TIME, AND ENTROPY GENERATION
Net-energy transfer is in one direction only, from
higher to lower potential (energy-forcing-potential), and
the process cannot be reversed.
Thus all real processes are irreversible in the direction
of decreasing energy-forcing-potential, like pressure and
temperature (forced displacement of mass-energy)
© M. Kostic <www.kostic.niu.edu>
2009 January 10-12
Local-Instant & Quasi-Equilibrium:
At instant (frozen) time, a locality around a point in space
may be considered as ‘instant-equilibrium’ (including
inertial forces) with instantaneous local-properties welldefined, regardless of non- uniformity.
Quasi-equilibrium is due to very small energy fluxes
due to very small gradients and/or very high
impedances, so that changes are infinitely slow, for all
practical purposes appearing as equilibrium with
virtually net-zero energy exchange.
© M. Kostic <www.kostic.niu.edu>
2009 January 10-12
REVERSIBILITY –Relativity of Time:
Therefore, the changes are ‘fully reversible,’ and along with
their rate of change and time, totally irrelevant (no
irreversible-permanent change; it could be put/reversed
back), as if nothing is effectively changing (no
permanent-effect to the surroundings or universe)
The time is irrelevant as if it does not exist, since it could
be reversed or forwarded at will and at no ‘cost’ (no
permanent change) and, thus, relativity of time.
Real time cannot be reversed,
it is a measure of permanent changes, like irreversibility, which
is in turn measured by entropy generation.
In this regard the time and entropy generation of the universe have
to be related.
© M. Kostic <www.kostic.niu.edu>
2009 January 10-12
Quasi-equilibrium Process :
in limit, energy transfer process with infinitesimal potential
difference (still from higher to infinitesimally lower potential, P).
Then, if infinitesimal change of potential difference direction is
reversed
P+dP → P-dP
with infinitesimally small external energy, since dP→0,
the process will be reversed too, which is characterized with
infinitesimal entropy generation,
and in limit, without energy degradation (no further energy
disorganization) and no entropy generation
thus achieving a limiting reversible process.
© M. Kostic <www.kostic.niu.edu>
2009 January 10-12
Entropy …
… entropy of a system for a given state is
the same, regardless whether it is reached
by reversible heat transfer or irreversible heat
or irreversible work transfer.
However, the source entropy will decrease
to a smaller extent over higher potential, thus
resulting in overall entropy generation for
the two interacting systems.
© M. Kostic <www.kostic.niu.edu>
041115
(a)
T
2S
W12= Q12
SG=DSS -DSR=0
Could be reversed
1R
2R
2S
1S
1S
SS
S
DSS
R
(b)
T
2S
W12= 0
Unrestricted
expansion
SG=DSS>0
Could NOT be
reversed
1S
2S
1S
S
S
Q12=0
DSS
© M. Kostic <www.kostic.niu.edu>
For eample:
 reversible expansion at
DSR
Q12>0
It is possible to obtain work
from the equal amount of
disorganized thermal energy
or heat, if such process is
reversible.
constant internal energy,
e.g. isothermal ideal-gas
expansion, (dW=dQ),
see Fig. 1a, and
 reversible adiabatic
expansion (dW=-dU).
 Work potential is lost during
unrestricted
expansion (Fig. 1b)
041115
Heat Transfer and
Irreversibility:
T
2R
(a)
1R
DT > 0
(b)
Multiple Heat
Reservoirs
with DT 0
2S
ENTROPY RANSFER
AND GENERATION
1R
2S
1S
2R
SG =DSS - DSR > 0
Irreversible
SG =DSS - DSR = 0
Could be reversed
1S
S
S
SG
DSR
DSR
DSS
DSS
(c)
Variable T
Reservoir
with DT 0
1R
2S
2R
SG =DSS - DSR = 0
Could be reversed
1S
S
DSR
DSS
© M. Kostic <www.kostic.niu.edu>
041115
Entropy …
We could consider a system internal thermal
energy and entropy, as being accumulated
from absolute zero level, by
disorganization of organized or higher level
energy potential with the corresponding
entropy generation.
Thus entropy as system property is
associated with its thermal energy.
© M. Kostic <www.kostic.niu.edu>
041115
Entropy Primer:
entropy could be transferred in reversible
processes along with heat transfer, and
additionally generated if any work potential
(including thermal energy’s) are disorganized
at the lower thermal potential during
irreversible processes.
Once a process completes, any generated
entropy due to irreversibility becomes
(permanent) system property and cannot be
reversed/destroyed by any process in nature
(thus, a permanent change).
© M. Kostic <www.kostic.niu.edu>
041115
Entropy Primer (2):
Thus, entropy transfer is
due to reversible heat transfer and could be
ether positive or negative,
while entropy generation is always
positive and always due to irreversibility.
© M. Kostic <www.kostic.niu.edu>
041115
T
1H
2H
TH
PC
TL
CPC
2L
1L
HPC
QL=TLDSL=THDSH= QH
T0
Reversible Heat Transfer
and Practical Potentials:
Dual Power-Heat Pump
cycle
SG=DSL-DSH>0
Irreversible
SG
DSH
(a)
S
DSL
T
1H
2H
TH
TL
Eq . (1)
Q H  TH  D S H
Eq . ( 2 )
Q L  TL  D S L  TL (D S H  D S 0 )
Eq . ( 3 )
SG=0
Power
Cycle
Reversible
Heat Transfer
T
C
(T H  T L ) D S H  (T L  T 0 ) D S 0
2L
2L′
1L
T
Heat Pump Cycle
C
COP PHP 
T0
WPC =WHPC
DSH
Saved Energy
QH

TL
TH
 5  500 %
S
DS0
(b)Kostic D<www.kostic.niu.edu>
DS′′L
S′L
© M.
QL
041115

T H  T0
T L  T0

350
1050

1050  300
350  300
Eq .( 5 )
Coefficients of Performance for Three
Typical Cases of Reversible Heat Transfer
TABLE I:
COEFFICIENTS OF PERFORMANCE FOR THREE TYPICAL CASES OF
REVERSIBLE HEAT TRANSFER
REVERSIBLE HEAT
TRANSFER TYPE
Heating from higher
temperature source:
Dual Power-Heat Pump
Cycle (introduced here)
COEFFICIENT OF PERFORMANCE
for TH> TL> T0> TR
QL
COP PHP 
Cooling:
Refrigeration or AirConditioning
COP R 
Heating from lower
temperature source:
Heat Pump
COP HP 
© M. Kostic <www.kostic.niu.edu>

QH
QR

W
QH
W
TL

T H  T0
TH
T L  T0
Eq. (4)
TR
Eq. (6)
T0  T R

TH
T H  T0
Eq. (7)
041115
the most efficient
reversible heat transfer
from system H
at higher temperature TH
to system L
at lower temperature TL
as presented on Fig. 3b
may be obtained
(as limiting case)
by using a
dual power-and-heat-pump
cycle (PHP),
which is governed
by the following conditions
(WPC = WHPC)
Conclusion

Energy is a fundamental concept indivisible from matter
and space, and energy exchanges or transfers are associated
with all processes (or changes), thus indivisible from time.

Energy is “the building block” and fundamental property of
matter and space, thus fundamental property of existence. For a
given matter (system) and space (volume) energy defines the
system equilibrium state, and vice versa.

For a given system state (structure and phase) addition of energy
will tend (spontaneously) to randomly distribute (disorganize)
over the system microstructure and space it occupies, called
internal thermal energy, increasing energy-potential
(temperature) and/or energy-displacement (entropy), and vice
versa.
© M. Kostic <www.kostic.niu.edu>
041115
Conclusion (2):

Energy and mass are conserved within interacting systems (all
of which may be considered as a combined isolated system not
interacting with others surrounding systems), and energy
transfer (in time) is irreversible (in one direction) from higher
to lower potential only, which then results in continuous
generation (increase) of energy-displacement, called entropy
generation, which is a fundamental measure of irreversibility,
or permanent changes, the latter also measured with the passing
time.

Reversible energy transfer is only possible as limiting case of
irreversible energy transfer at infinitesimally small energypotential differences, thus in quasiequilibrium processes, with
conservation of entropy. Since such changes are reversible, they
are not permanent (could be reversed without leaving any
relevant effect on the surroundings) and, along with time,
irrelevant (NOT permanent).
© M. Kostic <www.kostic.niu.edu>
041115
Conclusion (3):
 Entropy may be transferred from system to system by
reversible heat transfer and also generated due to
irreversibility of heat and work transfer.
 Heat transfer, like any other energy transfer, may be
achieved from any-to-any temperature level
(performed in real power and refrigeration cycles), and
in limit be reversible, if temperature of an
intermediary cyclic substance is adjusted as needed,
using isentropic compression and expansion. The
reversible heat transfer limits are the most efficient
and demonstrate limiting potentials for practical heat
transfer processes.
© M. Kostic <www.kostic.niu.edu>
041115
Conclusion (4):
 The “Dual Power-Heat Pump Cycle,” introduced here, may
be considered as a reversible heat-transfer transformer,
from-any-to-any temperature levels.
 The simple analysis of this dual, combined cycle (Eq. 4. and
Fig. 3b), to achieve reversible heat transfer only (from
higher to lower temperature system) and without any network produced or utilized,
 Presented emphasis (with analysis) of underlying physical
phenomena, including several hypothesis, is intended
contribution of this paper.
© M. Kostic <www.kostic.niu.edu>
041115
© M. Kostic <www.kostic.niu.edu>
041115
Compressed Liquid water
enthalpy corrections:
It is custom to approximate solid and liquid properties as being
function of temperature only, since they are virtually
incompressible:
Pdv compression work may be neglected.
For isothermal compression processes:
correction for liquid enthalpy approximation
“pumping” work, vdP
Analysis of water real properties shows that such a
correction is unnecessary for intermediate pressures
and temperatures, and it is even erroneous for higher
temperatures and pressures, and thus counterproductive
and misleading.
© M. Kostic <www.kostic.niu.edu>
041114
Compressed Liquid water
enthalpy corrections (2):
Solids and liquids are
virtually incompressible,
work, Pdv, could be neglected,
and properties will not be function of pressure but temperature only:
thus compression
u  u (T ) and
c p  c v  c (T )
•Even enthalpy …
h w / O ( P , T )  h f (T )  h sat (T )
However, enthalpy is unique,
since it is explicitly defined as a function of pressure:
h  u  P  v thus,
© M. Kostic <www.kostic.niu.edu>
h (T , P )  u (T )  P  v
041114
REAL fluid enthalpy CORRECTIONS
In all engineering references, and Thermodynamics textbooks [1, 2]:
dh  d ( u  P  v )  du
P

dv  v
 dP
 

corr . A
corr . B
 du  vdP  cdT  vdP
dv  0
corr . C
h corr ( P , T )  h f (T )  v f (T )  ( P  Psat ) or h corr ( P , T )  h f (T )  v f (T )  ( P  Psat )
    
    
correction
C
correction
C
However, REAL fluid enthalpy CORRECTIONS are not only due to change of
pressure (cor.C), but also to change of internal energy (cor.A) , and volume (cor.B):
corr . A  D u  u ( P , T )  u ( Psat , T )
corr . B  P D v 
 P  dv
corr .C  v D P 
 v  dP 
 Dh  Du 
 v  dP
v ( P , T )  v ( Psat , T )
© M. Kostic <www.kostic.niu.edu>
2
 h ( P , T )  h ( Psat , T )  ( corr . A )  ( corr .C )
 ( P  Psat )
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Isothermal vs. Isentropic
compression of sat. liquid water
For isentropic compression (q=0):
Du=q+wcomp= Pdv 0,
increase of internal energy
and temperature (for 12 oC,
from 260 oC to 272 oC,
see last row in Table I).
To maintain constant temperature in
isothermal compression,
there must be some cooling (q out),
thus internal energy decrease
(corr.A).
© M. Kostic <www.kostic.niu.edu>
041114
Recommended enthalpy correction in the literature
for isothermal compression
Recommended enthalpy correction in the literature is
more appropriate for the isentropic than for
isothermal processes, due to erroneous assumption
that internal energy is not, and enthalpy is,
dependent on pressure.
It is exactly opposite in Table I, see how the
corresponding values (u & h) change with pressure
at constant temperature of 260 oC.
© M. Kostic <www.kostic.niu.edu>
041114
Compressed Liquid water properties
and relevant enthalpy corrections
Corr.B small –may be neglected. BUT Corr.A & B are comparable and opposite sign.
So, take both or none, since it is more erroneous to take one (corr.C) only !
© M. Kostic <www.kostic.niu.edu>
041114
Compressed liquid
enthalpies
at different
temperatures
and pressures
more in error for higher
temperature and pressure
than the corresponding
saturated values
about the same
for the intermediate
temperatures
© M. Kostic <www.kostic.niu.edu>
041114
Conclusion
Recommendations in the literature for improvement of enthalpy
calculation of compressed liquids, by accounting for pressure
dependence, are not generally valid.
Those recommendations may be erroneous and thus
counterproductive and misleading, as is the case for
liquid water at higher temperatures and pressures.
For intermediate pressures and temperatures, the recommended
enthalpy corrections are unnecessary, since the errors are
about the same in magnitude (but opposite in sign) as
the corresponding saturated enthalpy values without any corrections.
The recommended enthalpy corrections are only useful
for smaller temperatures and pressures.
© M. Kostic <www.kostic.niu.edu>
041114
The Concept of "Entransy" May Be More
Important Than What It Appears at First
… but it has to be "properly" related to existing
concepts of Thermal energy (not precisely defined yet, see
elsewhere), Exergy and Entropy, as well as irreversibility
and reversibility.
Entransy concept and analysis have some unique
advantages over other approaches. There is a need to
define Entransy as a property (how it relates to other
thermodynamic properties) and as process energy flux
(how it relates to heat & work transfer and entropy transfer
& generation). We also could advance and synergize your
"Thermomass" concept with my work in that area.
www.kostic.niu.edu
Stretching the mind further …
Mass may be a special tensor-like quantity due to "over-allisotropic in all-directions" motion of elementary particles (that
make up its structure) and thus give rise to inertia if accelerated
in any direction, i.e., resisting change of motion in any and
all directions with equal components (the isotropic mass inertia).
There may be anisotropic masses, with bulk linear or rotational
motion, being the extreme cases. Note that fundamental
particles (without inertial mass, like photons and similar, but with
relativistic masses E/c^2) has to always move with ultimate
speed of light in vacuum, and such particles (some yet to
be discovered) might be moving (orbiting with twisting, stringlike vibration and rotation) within virtually infinitesimal spaces
and thus making-up other "massive" so-called elementary
particles
www.kostic.niu.edu
Deterministic vs. Probabilistic
All interactions in nature are physical and based on
simple cause-and-effect conservation laws, thus
deterministic and should be without any exceptional
phenomenon. Due to diversity and complexity of large
systems, we would never be able to observe
deterministic phenomena with full details but have to
use holistic and probabilistic approach for observation;
therefore, our observation methodology is holistic and
probabilistic, but phenomena have to be deterministic,
not miraculous nor probabilistic
www.kostic.niu.edu
Elementary Particles: Electron?
There is no proof that an electron, or any other elementary
particle, has or does not have a structure. The concept of
elementary particle is intrinsically problematic (just because we
cannot observe or reason a structure which exhibits certain
phenomena, does not mean it does not exist). Past and recent
history proved us to be wrong every time. Particularly
problematic is the current theory which requires elementary
particle annihilation/creation (“miraculous creationism”) while
using conservation laws. At the very least (in phenomenological
view) the elementary particles should be conserved and be the
building structure for other particles and systems. Note that
many concepts (in modern physics) are "virtual" entities that are
part of the mathematical theory, but are not directly observable.
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Boundary Forces …
There is no such thing as a unidirectional force or a force that
acts on only one body (no imaginary boundary vectorforces). Put it very simply: a forcing (force-flux cause-and-effect
phenomena) acts between an interface of pair of objects (forced
interaction: action-reaction, including process-inertial forces),
and not on a single object. The Newton Laws and the Laws of
Thermodynamics imply that all forces are massenergy interactions (forced displacements with momentum and
energy transfer and conservation) between different particulate
bodies due to non-equilibrium (available energy or work
potential, cause of forcing) towards the equilibrium.
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No Perfect Rigidity …
All matter must be somewhat elastic (can be
compressed or stretched). If bodies could be
perfectly rigid we'd have infinite forces acting with
infinite speeds for infinitesimal times (if you pushed
on one end of a perfectly rigid stick, the other end
would move instantaneously). System
components (bodies) that exert forces have to
be massive (2nd Newton Law) and with
accompanying reaction forces (3rd Newton
Law).
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Energy is bound by forced motion …
Energy is possessed (thus equilibrium property) by material
systems and redistributed (transferred) between and within
system(s), due to systems' non-equilibrium, via forceddisplacement interactions (process) towards the equilibrium
(equi-partition of energy over mass and space); thus energy is
conserved (the 1st Law) but degraded (the 2nd Law).
Effects are consequences of Causes except at Equilibrium they are
equal (reversible). The existence in space and transformations in
time are manifestations of perpetual mass-energy forced displacement
processes: with net-zero mass-energy transfer in equilibrium
(equilibrium process) and non-zero mass-energy transfer in nonequilibrium (active process) towards equilibrium. System components
(particles and bodies) that exert forces have to be massive (2nd
Newton Law) and with accompanying reaction forces (3rd Newton
Law).
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Force and Forcing …
Force or Forcing is a process of exchanging
useful-energy (forced displacement) with netzero exchange at forced equilibrium. The
Second Law provides conditions and limits for
process forcing (energy exchange direction
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Processes … Miracles
"Nothing occurs locally nor in the universe without
mass-energy exchange/conversion and irreversible
entropy production.
It is crystal-clear (to me) that all confusions related to the
far-reaching fundamental Laws of Thermodynamics, and
especially the Second Law (Abstract), are due to the lack
of their genuine and subtle comprehension."
The miracles are until they are comprehended and
understood.
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For further Info
you may contact Prof. Kostic at:
kostic@niu.edu
or on the Web:
www.kostic.niu.edu
Prof. M. Kostic
Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITY
© M. Kostic <www.kostic.niu.edu>
041115