Study on temperature field of the drilling machine during the course of drilling in coal mine

The working conditions of the MK-3 type full hydraulic tunnel drilling machine during the course of drilling were analyzed. Based on the energy balance governing equations for the drill rod, the temperature field of drill rod at the normal and non-normal working conditions was numerically obtained. The numerical results show that the maximum temperature at the head of drill rod under the normal working circumstance is insufficient to ignite the gas. But under the non-normal working condition, the local high temperature can ignite the gas easily and cause the fire. In order to prevent the gas fire, the occurrence of the non-normal operating condition must be prevented as far as possible during the drilling.

Research on Temperature Field of the Support Structure for the Independent LNG Tank

The independent LNG(Liquified Nature Gas)containment is widely used for small or medium-sized LNG carrier and ship using LNG as fuels.The common tank pattern includes single-spherical-cylindrical tank and double-spherical-cylindrical tank,which is the key to design the hull structure and its support.The support is designed to connect the hull structure and LNG tank.Its main functions are heat transferring and force loading.This paper focus on the temperature field distribution of hull and its support structure.The thermal boundary conditions are simulated according to the heat transfer action,such as thermal convection,heat conduction and thermal radiation.The method on how to carry out thermal analysis is presented for an independent LNG containment.The case study is carried out with two typical independent LNG tanks.One is a tank with double spherical cylindrical in the LNG carrier,and the other is a tank with single spherical cylindrical on the deck of the ship using LNG as fuels.The result shows the method presented in this paper is a good reference for the structural design with independent LNG containment.

Numerical Simulation of Fluid Migration during Ore Formation of Carboniferous Exhalation-Sedimentary Massive Sulfide Deposits in the Tongling District, Anhui Province

Numerical simulation of fluid migration during the ore-forming process of the Carboniferous exhalation- sedimentary (Sedex) massive sulfide deposits in the Tongling district shows that fluid and thermal activities in lying-wall rocks were limited to a small area around the main draining passage, which led to weak mineralization and alteration in the lying-wall rock. Temperature and fluid fields indicate that mineralization and alteration in the lying-wall rock of the Sedex-type deposits are usually weaker than those of volcano-hosted massive sulfide deposits. Fluid migration involves the following processes: seawater penetrating and leaching the lying-wall rocks, then mixing with ascending hydrothermal fluids in the main draining passage, and finally jetting into seafloor. Although fluid activity-influenced area is rather small, the content of metals leached out from the lying-wall rocks is high enough to form large-scale ore deposits. Tensional contemporaneous faults accompanied with strong heat flows controlled the formation and distribution of Sedex deposits. The tensional tectonic regime on the northern margin of the Yangtze block during the Hercynian provided Sedex deposits with a prerequisite geodynamic condition.

Research on temperature field of non-uniform heat source model in surface grinding by cup wheel

To address the problems of thermal damage to a workpiece surface caused by the instantaneous high temperature during grinding and the difficulty in monitoring temperature in real time,the temperature field in the case of composite surface grinding by a cup wheel is studied.In order to predict the grinding temperature,considering material removal and grinding force distribution,a nonuniform heat source model with different function distributions in the circumferential and radial directions in the cylindrical coordinate system is first proposed;then,the analytical model is deduced and the numerical model of the temperature field is established based on the heat source model.The validation experiments for grinding temperature field are carried out using a high-definition infrared thermal imager and an artificial thermocouple.Compared to the temperature field based on the uniform heat source model,the results based on the non-uniform heat source model are in better agreement with the actual temperature field,and the temperature prediction error is reduced from approximately 23% to 6%.Thus,the present study provides a more accurate theoretical basis for preventing bums in cup wheel surface grinding.

Analytical Solution to Steady-State Temperature Field of Two Freezing Pipes with Diferent Temperatures

The existing analytical formulas to calculate the temperature field distribution of artificial frozen soil walls are all based on the conditions that the surface temperatures of all freezing pipes are equivalent. In this paper, analytical solution of steady state temperature field of two freezing pipes with diferent temperatures is deduced based on thermal potential superposition method. The correctness of the analytical formulas is verified by comparing the temperature field distributions of the analytical formulas and those of the numerical simulations in the same conditions. And discussions are made to analyze the influence of some parameters on temperature field distribution of this condition.