排序方式: 共有3条查询结果,搜索用时 15 毫秒
1
1.
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. 相似文献
2.
A single on/off valve is used to carry out the position control of the asymmetrical hydraulic cylinder. The influence of the
nominal flow rate on the positional accuracy of piston is investigated and the proximate formula for calculating the nominal
flow rate of on/off valve is introduced. The system structure proposed in this paper could avoid cavitation and hyper pressure
in two chambers to some extent. The simulation results indicated that the control method in this paper could satisfy the expected
control requirements. 相似文献
3.
The energy balance, air internal energy, enthalpy and exergy transfers of high pressure switching expansion reduction (SER)
are comparatively analyzed in this paper to give a better understanding about the exergy analysis and its difference between
energy conversion analyses for the pneumatics. In SER, the exergy transfer efficiency is much lower than the enthalpy efficiency.
The enthalpy efficiency is primarily related to the initial pressure of supply tanks, and the exergy efficiency is primarily
related to the pressure reduction ratios. Heat transfers increase the internal energy, enthalpy and exergy of air; the influence
on exergy is relatively small. The total enthalpy in SER decreases as the air temperature decreases in the expansion process
of the air. And exergy loss is primarily related to the irreversible process of isenthalpic throttling but not energy conversion.
Based on the analyses, to improve the exergy efficiency of the pneumatics, the pressure reduction without power output should
be avoided. 相似文献
1