Enthalpy, Entropy, And The Second Law of Thermodynamics هەنجالپی، ئینترۆپی، و یەکەمی دووەمی تەرمۆداینامیکی

Bewaçeyên vebijarkirina pêşkeftina bêhêran di navbera wan mafadan de heye:

• Nrgyê Naverokî û Yekemîna Yekemîna ya Termodinamîk

• Prosesê dawa û serbest yên sisteman

• Vegere û Navegere

• Entropiya û Hêza

• Yekemîna Deya Duhemînî ya Termodinamîk

Nrgyê Naverokî û Yekemîna Yekemîna ya Termodinamîk

Heke nrgyê biran yên di navbera sisteman de bi xasên sisteman re têne bikar an, ew ê derbasdar nrgyê naverokî (u) bigire.
Nrgyê tune nebe hatine çêkirin ne be nebe hatine yekbirin û li ser vê prinsîpan nrgyê naverokî (u) hewce dikare heta ke nrgyê divêrêve divêrêveya sisteman.
Bi vê yola yekemîna yekemîna ya termodinamîk di dema ku çalakî/karye bi sisteman re têne bikar an.

Di cihê da u nrgyê naverokî per-unit-mass û q û w çalakî û karye per unit mass an. Konvensyonê alîfê li ser vê teqnîka ye:
dq > 0 (di hesabê de positive) ⇒ Çalakî ji ber sisteman
dq < 0 (di hesabê de negative) ⇒ Çalakî ji sisteman
dw > 0 (di hesabê de positive) ⇒ Karye ji sisteman
dw < 0 (di hesabê de negative) ⇒ Karye ji ber sisteman

Prosesê Dawa û Serbest yên Sisteman

Yekemîna yekemîna ya termodinamîk di dema ku

Ew integration di procesa dawadê de.

Sistema di dema ku bi guhertina random yên li ser çalakî/karye re ve girêdaya cihanê we.

Pîvan dike:

1. Integration differential state property difference limits.

2. Divê state final be state original we û tune nrgyê naverokî sisteman.

Bi vê yola

State initial û final nrgyê naverokî di cihê da i û f. Substituting above in equation (1) then,

Equation (2) is the representation of integral of all work done by the system or net work done by the system is equal to the integral of all heat transfer into the system. Engineering thermodynamics further explores the concepts of systems and processes.

Prosesê Serbest yên Sisteman

Ew outcome yekemîna yekemîna ya termodinamîk û li ser eq (1) eger sistema involv procesa serbest.

Di cihê da q û w çalakî û karye net process respectively, while uf û ui final û initial values nrgyê naverokî (u). In a rigid û isolated adiabatic system (w = 0, q = 0), then its nrgyê naverokî (u) remains unchanged. Then from eq(2) of a cyclic process.

Vegere û Navegere

Sistema vegere ku divê state initial bigire state final. Properties like pressure, volume, enthalpy, temperature, entropy etc changes during a thermodynamic process. Yekemîna Deya Duhemînî ya Termodinamîk categories processes under two heads

• Ideal or reversible processes

• Natural or irreversible processes

If temperature (t) û pressure (p) variations are infinitesimal in a system, which is undergoing-a-process, then the process can be termed as near equilibrium states or approaching reversibility.
The process is said to be reversible-internally if the original state is re-stored in reverse direction.
The process is said to be externally-reversible environment accompanying the change can also be reversed-in-sequence.
Reversible-process is one that is reversible both internally and externally.
In order to measure the success of a real processes, professionals uses reversible process as the measure for comparing and bringing the real and actual processes closer to reversibility by lowering down losses in order to increase the efficiency of the processes.

Navegere

When actual processes fails to meet the requirements of reversibility, then the processes is called irreversible.
In irreversibile process the initial state of the system and surrounding can’t be bring back to initial state from final state. Entropy of the system increases sharply in irreversible process and the value can’t be brought back to the initial value from the final value.
Irreversibility persists on account of variation in pressure, composition, temperature, composition main caused by heat transfer, friction in solid and liquid, chemical-reaction. Professions are busy in putting their efforts to bring down the effects of irreversibility in processes and mechanisms.

Entropiya û Hêza

Like internal energy, Entropy û Enthaly thermodynamic properties. The entropy is represented by symbol s û change in entropy Δs in kJ/kg-K. Entropy is a state of disorder. Entropy is the subject second Law of thermodynamics which describes entropy change in system and surrounding with respect to Universe.
Entropy is defined as ratio heat transfer to the absolute temperature in a system for a reversible thermodynamic path.

Where, qrev denotes heat transfer along a reversible path.
Enthalpy (h) is the property of state and is defined as,

Where, h is specific Enthalpy, u is specific internal energy, v is specific volume, p is the pressure.
From, equation (1)

Therefore

By differentiating the eq (4) and substituting it in above equation, then

Both of above equations are related to changes in entropy for reversible processes on account of changes in internal energy and volume in former and to change in enthalpy and pressure in later equation.
Since all quantities in these two equations are state properties, thus entropy is also a thermodynamic property.

Yekemîna Deya Duhemînî ya Termodinamîk

Yekemîna Deya Duhemînî ya Termodinamîk is known for describing its limits on universe in terms of What universe can do. 2nd Law is more about dealing with inefficiencies, decay and degeneration.
We do activities in our day-to-day life which are by nature involves inefficient and irreversible processes.
2nd law of thermodynamics can be more conveniently expressed with respect to entropy:
Entropy defined as infinitesimal-change in entropy of a system (dS) is ratio of measured quantity of heat that has entered in to the closed system (dqrev) and the common temperature (T) at the point where the heat transfer took place.

Second law of thermodynamics states that “Entropy change is considered as non negative”.
OR
Universe energy is gradually moving towards the state of disorder

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