Compensation of pressure enthalpy effects on temperature fields for throttling of high-pressure real gas

  • Yuxi Luo (罗语溪)
  • Jiuxing Liang (梁九兴)
  • Xuanyin Wang (王宣银)
  • Zhipeng Xu (徐志鹏)
Article
  • 29 Downloads

Abstract

For the pressure enthalpy of high pressure pneumatics, the computational fluid dynamics (CFD) simulation based on ideal gas assumption fails to obtain the real temperature information. Therefore, we propose a method to compensate the pressure enthalpy of throttling for CFD simulation based on ideal gas assumption. Firstly, the pressure enthalpy is calculated for the pressure range of 0.101 to 30 MPa and the temperature range of 190 to 298 K based on Soave-Redlich-Kwong (S-R-K) equation. Then, a polynomial fitting equation is applied to practical application in the above mentioned range. The basic idea of the compensation method is to convert the pressure enthalpy difference between inlet air and nodes into the compensation temperature. In the above temperature and pressure range, the compensated temperature is close to the real one, and the relative temperature drop error is below 10%. This error is mainly caused by the velocity difference of the orifice between the real and ideal gas models. Finally, this compensation method performs an icing analysis for practical high pressure slide pilot valve.

Key words

real gas effect pressure enthalpy temperature field throttling computational fluid dynamics (CFD) Soave-Redlich-Kwong (S-R-K) equation 

Nomenclature

Aeff

Equivalent cross-sectional area of orifice, m2

cp

Isobaric specific heat

E

Air energy, J

F

External body force

g

Gravitational body force

h

Enthalpy of a unit mass of air, J/kg

hp

Pressure enthalpy, J/kg

ht

Temperature enthalpy, J/kg

J

Diffusion flux

keff

Effective conductivity

p

Absolute air pressure, Pa

qm

Air mass flow rate, kg/s

R

Gas constant, J/(g·K)

Sh

Heat of chemical reaction, and any other volumetric heat sources defined, kJ

Sm

Mass added to the continuous phase from the dispersed second phase, kg

t

Time, s

T

Temperature, K

u

Velocity vector, m/s

Z

Compressibility factor

λ

Specific heat ratio

ρ

Density of air, kg/m3

τ̿

Stress tensor

ν

Specific volume

0

Reference state

c

Compensated temperature

H

High pressure

id

Ideal gas assumption

k

Calculation times

L

Low pressure

n

Parameter of nodes

p

Isobaric process

CLC number

TK 121 

Document code

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Copyright information

© Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  • Yuxi Luo (罗语溪)
    • 1
  • Jiuxing Liang (梁九兴)
    • 1
  • Xuanyin Wang (王宣银)
    • 2
  • Zhipeng Xu (徐志鹏)
    • 3
  1. 1.School of EngineeringSun Yat-sen UniversityGuangzhouChina
  2. 2.State Key Laboratory of Fluid Power Transmission and ControlZhejiang UniversityHangzhouChina
  3. 3.College of Metrology and Measurement EngineeringChina Jiliang UniversityHangzhouChina

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