Numerical Study on Fuel Preheating at Cold Start Phase in an Ethanol Flex Fuel Engine

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Ying Wang ◽  
Zhensheng Liu

The low vapor pressure of ethanol and the high latent heat of vaporization at low temperatures cause the difficulties of cold start in a flex fuel vehicle when it is fueled with pure ethanol. Preheating fuel is one of the effective methods to solve the above cold start problem. Thus, it is crucial to obtain the fuel temperature distribution in the heating system for fuel preheating process. For this purpose, the numerical analysis is adopted here to simulate the fuel preheating process at a cold start phase and explore the change of the fuel temperature field under different influence factors. The results indicate that the starting temperature has obvious impact on the temperature field distribution in the heating chamber and preheating time but has little effect on the volume of cold fuel in the connecting line at the end of heating. When the starting temperature is −5 °C, the preheating time is 8.3 s. When the starting temperature increases up to 15 °C, the preheating time will decrease as 4.9 s. Furthermore, the lower the starting temperature is, the higher the overall temperature of the heating chamber is. The installing angle of injectors has some influence on the temperature field distribution, and the cold fuel ratio reduces slightly when the angle increases from 30 deg to 60 deg. The calculation results indicate that the temperature of fuel at the injector inlet is above 20 °C, and the fuel injected during the first three cycles of the engine operation is hot fuel.

2014 ◽  
Vol 501-504 ◽  
pp. 1662-1667
Author(s):  
Lei Ning ◽  
Shu Hui Xu ◽  
Ling Fei Cui ◽  
Chang Liu

Underground highway is an effective measure to ease the traffic pressure. However, fire in underground highway is of great danger. This work investigated the instantaneous velocity field, gas field and temperature field distribution of the underground highway in case of fire theoretically. The smoke field and temperature field distribution was determined at the safe altitude. The expression of the critical flow velocity in the previous work was verified. The optimal escape time in the fire upstream and downstream is 30s and 90s, respectively. The optimal escape distance in the fire upstream and downstream is 35m and 200m, respectively. The best is to read these instructions and follow the outline of this text.


Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1792
Author(s):  
Bingbing Dong ◽  
Yu Gu ◽  
Changsheng Gao ◽  
Zhu Zhang ◽  
Tao Wen ◽  
...  

In recent years, the new type design of current transformer with bushing structure has been widely used in the distribution network system due to its advantages of miniaturization, high mechanical strength, maintenance-free, safety and environmental protection. The internal temperature field distribution is an important characteristic parameter to characterize the thermal insulation and aging performance of the transformer, and the internal temperature field distribution is mainly derived from the joule heat generated by the primary side guide rod after flowing through the current. Since the electric environment is a transient field and the thermal environment changes slowly with time as a steady field under the actual conditions, it is more complex and necessary to study the electrothermal coupling field of current transformer (CT). In this paper, a 3D simulation model of a new type design of current transformer for distribution network based on electric-thermal coupling is established by using finite element method (FEM) software. Considering that the actual thermal conduction process of CT is mainly by conduction, convection and radiation, three different kinds of boundary conditions such as solid heat transfer boundary condition, heat convection boundary condition and surface radiation boundary condition are applied to the CT. Through the model created above, the temperature rise process and the distribution characteristics of temperature gradient of the inner conductor under different current, different ambient temperatures and different core diameters conditions are studied. Meanwhile, the hottest temperature and the maximum temperature gradient difference are calculated. According to this, the position of weak insulation of the transformer is determined. The research results can provide a reference for the factory production of new type design of current transformer.


AIP Advances ◽  
2016 ◽  
Vol 6 (7) ◽  
pp. 075007 ◽  
Author(s):  
Ruixi Jia ◽  
Qingyu Xiong ◽  
Kai Wang ◽  
Lijie Wang ◽  
Guangyu Xu ◽  
...  

2021 ◽  
Vol 315 ◽  
pp. 3-9
Author(s):  
Yuan Gao ◽  
Li Hua Zhan ◽  
Hai Long Liao ◽  
Xue Ying Chen ◽  
Ming Hui Huang

The uniformity of temperature field distribution in creep aging process is very important to the forming accuracy of components. In this paper, the temperature field distribution of 2219 aluminum alloy tank cover during aging forming is simulated by using the finite element software FLUENT, and a two-stage heating process is proposed to reduce the temperature field distribution heterogeneity. The results show that the temperature difference of the tank cover is large in the single-stage heating process, and the maximum temperature difference is above 27°C,which seriously affects the forming accuracy of the tank cover. With two-stage heating process, the temperature difference in the first stage has almost no direct impact on the forming accuracy of the top cover. In the second stage, the temperature difference of the tank cover is controlled within 10°C, compared with the single-stage heating, the maximum temperature difference is reduced by more than 17°C. The two-stage heating effectively reduces the heterogeneity of the temperature field of the top cover. The research provides technical support for the precise thermal mechanical coupling of large-scale creep aging forming components.


Author(s):  
Sergei Kurashkin ◽  
Vadim Tynchenko ◽  
Aleksandr Murygin ◽  
Yuriy Seregin ◽  
Valeriya Tynchenko ◽  
...  

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