The analysis on calculation model of heat-wave velocity during the process of crude oil storage tank fire
The formation mechanism of boilover fire in crude oil storage tank is very complex and harmful. Heat-wave velocity is an important research topic in the boilover fire. After introducing boilover mechanism, the models of heat transfer and heat-wave velocity was built by heat transfer analysis for oil layer. Comparing the calculation results of model with the experimental data, this heat-wave speed calculation model is reasonable. Through the research, several conclusions were found: the main factors that impact heat-wave rate are the viscosity and component of oil, heat of heat-wave comes mainly from thermal radiation of flame; Emulsified water in the oil will not trigger boilover fire normally. Only the heat-wave encountered bottom water cushion at the bottom of the tank, did boilover fire take place. In practice, the heat-wave moving speed can be valued 1m/h to estimate the occurrence time of boilover. The results of this study are important for control and security of boilover fire accident.
Study of time predicting model for boilover formation in crude oil tank fire
Boilover is a kind of mutational phenomenon,which can cause great casualties and property losses。The time prediction method of boilover formation was particularly concerned. According to the law of conservation of energy,the formation of heat transfer within oil layer was regarded as the unsteady heat transfer problem without heat resource,and a heat transfer model was established.The temperature distribution was predicted,Combining the experimental results of small scale oil tank fire test were combined,the prediction model of boilover formation was derived. The reliability of prediction model was tested. The results indicated that the model is right. Experiments results indicate that the influence of water layer thickness on the time of boilover formation decrease gradually with increase of oil tank diameter. The time of boilover formation directly related with the ratio of initial oil layer thickness and tank diameter through the prediction model calculation.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.