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O’ZBEKISTON RESPUBLIKASI OLIY TA’LIM VAZIRLIGI
TOSHKENT KIMYO TEXNOLOGIYA INSTITUTI
SHAHRISABZ FILIALI
OZIQ-OVQAT MAHSULOTLARI TEXNOLOGIYASI va
SANOAT UZUMCHILIGI fakulteti
Texnologik jarayonlarni va ishlab chiqarishni avtomatlashtirish va boshqaruv
yo’nalishi 6-20 guruh talabasi Azamatov Inomjonning
Asosiy texnologik jarayonlar va qurilmalar fanidan

MUSTAQIL ISHI

Mavzu: 7 BOSIMNING ISSIQLIK QUVVATLIGIGA TA'SIRI,BOSIMNING ISSIQLIK KUCHGA TA'SIRI , BOSIMNING ISSIQLIK KUCHGA TA'SIRI ,ENERGIYA BALANSLARI ASOSLARI, ENTALPİYA-KONSENTRASİYA DIAGRAMMALARI.

BAJARDI: Azamatov . I .

TEKSHIRDI: Elamanov . A .

SHAHRISABZ-2021-2022

3.7 THE EFFECT OF PRESSURE ON HEAT CAPACITY 85

3.7 THE EFFECT OF PRESSURE ON HEAT CAPACITY

The data on heat capacities given in the handbooks, and in Appendix C, are usually for the ideal gas state. Equation 3.13a should be written as:
C^°_p ¼aþbTþcT² þdT³ (3.19)
where the superscript ° refers to the ideal gas state.
The ideal gas values can be used for the real gases at low pressures. At high pressures the effect of pressure on the specific heat may be appreciable.
Edmister (1948) published a generalized plot showing the isothermal pressure correction for real gases as a function of the reduced pressure and temperature. His chart, converted to SI units, is shown as Figure 3.2. Edmister’s chart was based on hydrocarbons, but can be used for other materials to give an indication of the likely error if the ideal gas specific heat values are used without corrections.
The method is illustrated in Example 3.4.

EXAMPLE 3.4

The ideal state heat capacity of ethylene is given by the equation:
C^°_p ¼3:95þ15:610²T8:310⁵T² þ17:610⁹T³ J=molK
Estimate the value at 10 bar and 300 K.
Solution
Ethylene:

critical pressure	50.5 bar
critical temperature	283 K

C^°_p ¼3:95þ15:610² 3008:310⁵ 300² þ17:610⁹ 300³

¼43:76J=molK
P_r ¼ ¼0:20

T_r ¼ ¼1:06
From Figure 3.2:
C_p C^°_p 5J=molK