Ministry of Education of the Republic of Azerbaijan Baku Engineering University Faculty: "Architecture and Construction". Department: "Architecture and Design". Course Title: Engineering communication systems of buildings

5 . II LAW OF THERMODYNAMICS

1. 
   ENTROPY
   

Divide any 1-2 process into elementary parts, elementary with temperature T. When 1 kg of gas is given a temperature of dq- in the process, it is called the heat brought to the ratio of dq / T, ds - is denoted by and here s - is called entropy (pic 1.12). From here elementary entropy change kC/(kqdər):


^ds  dq /T ⁽¹⁾
The entropy change in process 1-2 is defined as follows:


(2)

Pic 1.12
( dq  C_ dT  Pd ) Considering the expression in (2):
(3)
The equation of state of the gas P  RT  and p / T  R / v considering the replacement:

From the equations of state of the beginning 1 and end 2 points of the process Taking into account the substitution (4), the entropy change can be determined as follows:

Let's define entropy changes for basic elementary thermodynamic processes and describe them graphically in the T-s coordinate system. In the process of isochoria
v  const because v₂ / v₁ 1 and from expression (4):

get. T  s The isochoric process is described by a logarithmic curve (Pic 1.13).

Pic 1.13
In the izobar process of p  const because p₂ / p₁ 1 and from the expression:
(7)