To study the influence of hydrogen mixing ratio on the leakage of natural gas pipelines, a mathematical model for the leakage and diffusion of directly buried high?pressure hydrogen mixed natural gas pipelines was established based on computational fluid dynamics theory and numerical simulation method.The leakage status, volume fraction distribution of hydrogen mixed gas,and the distribution of soil pressure and gas velocity around the pipeline were analyzed under different hydrogen mixing ratios.The results show that with the increase of hydrogen mixing ratio, the explosion radius of hydrogen mixed gas in the atmosphere will gradually decrease,and the range of high?pressure area around the pipeline will gradually decrease,and the gas flow rate at the leakage port will gradually increase.When the hydrogen mixing ratio is 30%,the explosion radius in the atmosphere is reduced by 43%,and the gas flow rate at the leakage port is increased by 68%.This provides a theoretical reference for the safety and emergency repair of hydrogen?doped natural gas pipelines and has important practical significance for promoting the large?scale application of hydrogen?doped natural gas.

In this paper, a kind of composite phase change material (capric?lauric acid/expanded vermiculite) using expanded vermiculite as the matrix and capric?lauric acid binary eutectic as the adsorbent was fabricated by vacuum impregnation technology. The chemical compatibility, morphology, stability，thermal?physical properties and reliability of the prepared composite capric?lauric acid/expanded vermiculite were investigated by fourier transform infrared spectrum (FT?IR), scanning electronic microscope (SEM), thermal gravimetric analyzer (TGA), differential scanning calorimeter (DSC) and thermal cycling test. The melting and solidification phase transition temperatures of capric?lauric acid/expanded vermiculite are 18.42 ℃ and 17.51 ℃, respectively. The latent heat of melting and solidification phase transition are 66.9 J/g and 62.9 J/g, respectively. Besides, the encapsulation amount of capric?lauric acid in expanded vermiculite can reach 52.97%, and it has good thermal stability between working temperature. Moreover, the capric?lauric acid/expanded vermiculite was used to substitute for a certain proportion of fine sand to prepare thermal storage mortar, the mechanical and thermal performance of capric?lauric acid/expanded vermiculite?based mortar was evaluated. The test result shows that prepared capric?lauric acid/expanded vermiculite?based thermal storage mortar is a potential material for building heat regulation and energy saving.

This paper proposed a method to improve the safety of shell and tube heat exchangers by adding a heat insulation layer at the inlet end of the heat exchange tube. Based on the SIMPLE algorithm, the transient change model of end temperature difference of three?dimensional shell and tube heat exchanger was established, and the effects of the changes of insulation thickness and insulation material on the safety of heat exchanger were compared. The results show that the temperature difference between the two sides of the heat exchange tube is significantly reduced when the pipe end insulation layer is installed, regardless of the material of the pipe end insulation layer; The greater the thickness of the insulation layer at the pipe end and the thermal conductivity of the insulation material, the greater the reduction of temperature difference, instantaneous thermal shock stress and temperature difference thermal stress on both sides of the heat exchange tube, and the higher the safety of the heat exchanger; When the thickness of the pipe end insulation layer is 247.5 mm and the thermal conductivity is 2.090 0 W/(m?K), the maximum instantaneous temperature difference on both sides of the heat exchange pipe can be reduced by 10.1%, the maximum temperature difference can be reduced by 12.5% during stable operation, and the instantaneous thermal shock stress and temperature difference thermal stress can be reduced by 10.1% and 12.5%.

Energy shortage and environmental pollution have always been the focus of the world's attention. The use of oil, natural gas, and electricity to heat crude oil has high energy consumption and serious environmental pollution. Solar energy, as sustainable and clean energy, has become the focus of researchers from all over the world.Thus, a solar heating crude oil system was designed, and safe and easily available air was selected as the heat transfer fluid. The system consists of a solar receiver, a heat accumulator, a crude oil heat exchanger, and an electro?thermal furnace. The heat receiver receives solar radiation and the temperature rises. The air passes through the heat absorber to obtain high temperature, and the high temperature air enters the heat exchanger to heat the crude oil. A mathematical model for the analysis of the thermodynamic performance of the solar heating crude oil system was established, and the model was verified. Then, the Aspen Plus software was used to conduct thermodynamic analysis of the heatingprocess. The results show that the compressor and the preheater are the components with large exergy loss. When the pressure ratio of the compressor is 2.7, the system reaches its best state. At this situation, the thermal efficiency is 72.35%, the exergy efficiency is 73.89%, and the waste heat recovery efficiency is 72.33%.

In order to study the salt precipitation law of the NaCl?Na₂SO₄?H₂O ternary system at a temperature of 298.15 K, the Pitzer model was used to predict and calculate the activity coefficient and solubility of the system, and the variation of the activity coefficients of Na⁺, Cl^- and SO {}_{\mathrm{4}}^{\mathrm{2}-} and the corresponding phase diagram of the ternary system were analyzed. The results show that with the increase of the Na₂SO₄ mass fraction, the activity coefficients of Cl^- and SO {}_{\mathrm{4}}^{\mathrm{2}-} have no obvious change, while the activity coefficient of Na⁺ icreases first and then decreases. When the mass fraction of Na₂SO₄ in the liquid phase is less than 6.8%, the average change rate of the increase in the activity coefficient of Na⁺ is 4.4%. When the mass fraction of Na₂SO₄ in the liquid phase is between 6.8% and 14.9%, the average change rate of decrease in the activity coefficient of Na⁺ is 4.1%, when the mass fraction of Na₂SO₄ in the liquid phase reaches 14.9%, the activity coefficient of Na⁺ decreases fastest, and the average change rate is 8.0%; when the mass fraction of NaCl in the liquid phase is greater than 22.9% and the mass fraction of Na₂SO₄ is less than 6.8% ,as the water evaporates, NaCl precipitates first and Na₂SO₄ precipitates later; when the liquid phase mass fraction of NaCl is 14.0%～22.9% and the mass fraction of Na₂SO₄ is 6.8%～14.9%, the precipitation order is reversed.

In order to solve the problem that the angle of crack and magnetization direction was too small to identify in the pipeline magnetic flux leakage internal detection, the influence of crack angle on magnetic flux leakage detection signal and the characteristics of crack magnetic flux leakage signal under the condition of axial excitation of DC electromagnet were analyzed. Comsol finite element simulation software was used to simulate and analyze the crack defects of 0.2 mm in different angles of the inner wall of the pipeline. DC electromagnet axial excitation experimental platform was built, and EDM technology was used to process the specimens with different angles of crack to carry out the dragging experiment of the crack angle. Results show that the minimum detectable angle of crack and magnetization direction is 25°. The peak value of MFL signal decreases with the decrease of crack angle, larger the signal span, the greater the influence of noise signal. When the magnetization direction is perpendicular to the crack, the maximum span of MFL signal amplitude is the smallest, and when the magnetization direction is parallel to the crack, no MFL signal is generated.

The heat transfer effect of nanofluid in electric heater was studied. Fe3O4⁃water nanofluid was prepared by two⁃step method. The effect of Fe3O4⁃water nanofluid with various nanoparticle concentrations (mass fraction of 0.1%~2.0%) on heating efficiency of the electric heater with or without magnetic field was studied. Mechanism of enhanced heat transfer by Fe3O4⁃water nanofluids under a magnetic field was also discussed. Results show that the Fe3O4⁃water nanofluid with a mass fraction of 1.0% obtains 18.2% enhancement of heat transfer on environment temperature compares to without a magnetic field. The Fe3O4⁃water nanofluid with a mass fraction of 1.0% obtains 35.1% enhancement of heat transfer on environment temperature with an external magnetic field. This research provides an important reference for enhancements of natural convective heat transfer in nanofluid applications.

The composite material Hβ/OMC containing the mesoporous carbon (OMC) and Hβ zeolite was synthesized. This composite was characterized with XRD, BET, FITR, SEM and TEM. The adsorption desulfurization performance of Hβ/OMC was investigated with benzothiophene (BT) as the probe molecule. The adsorption thermodynamics and kinetics of the BT on Hβ/OMC were studied. The characterization results showed that Hβ/OMC has the micro⁃mesoporous hierarchical pore structure, its specific surface area, pore volume and pore diameter are all higher than those of OMC. The saturated sulfur capacity of BT on Hβ/OMC is higher than OMC. Compared with Freundlich adsorption isotherm model, the adsorption of BT on Hβ/OMC is more consistent with Langmuir model. The adsorption of BT on Hβ/OMC is a process of spontaneous, exothermic and degree of confusion reduction, which is described better by pseudo⁃two⁃kinetic equations than pseudo⁃one⁃kinetic equations.

In order to enhance the edge features of pipeline weld magnetic flux leakage image, an edge enhancement method based on Laplace and multi⁃scale mathematical morphology was proposed. Firstly, magnetic flux leakage data of pipeline magnetic flux leakage internal detector are collected for imaging, Then, using mathematical morphology algorithm, we construct multi⁃scale structural elements to detect the edge of the image, and use edge color constraints to delete non⁃edge points. Finally, edge is enhanced by Laplace operator. The results show that the method can accurately extract the weld and defect boundaries of the magnetic flux leakage signal image, and effectively separate the weld and defect. It has certain feasibility and practicability.

ZSM⁃5 molecular sieve was used as carrier, cerium (Ce), manganese (Mn), nickel (Ni) and copper (Cu) were used as active components to prepare metal⁃supported catalyst to catalyze ozonation treatment of phenol wastewater. The catalyst was prepared by impregnation method and characterized. The effects of active components, ozone dosage, catalyst concentration and pH on the treatment of phenol wastewater were investigated. The results showed that Ce⁃ZSM⁃5 had the best catalytic effect and COD removal rate under the conditions of pH=7, catalyst concentration of 1.00 g/L, ozone dosage of 44.0 mg/min and reaction time of 60 min. It is 85.74%. When Ce⁃ZSM⁃5 is added, about 80% of the ozone can be saved. It shows good stability which the COD removal ratio reached about 70% after the catalyst repeatedly used for 7 times.

The objective optimization function was set by the summary of the insulation materials' annual sharing cost and the annual heat losing cost after insulation and the calculating model of buried hot oil pipelines' insulation economical thickness was given. The model included the burying depth's influences on around pipelines ambient temperature, the heat transfer coefficient of the outer wall insulation, and the overall heat transfer coefficient. With the help of C# programming language, a computer program was developed to optimize the thickness of insulation layer of buried hot oil pipeline with EXCEL to work out economic evaluation procedures, combining with examples of calculation. The results showed that: The determination of buried hot oil pipeline insulation thickness would have some impact on the economic benefits of the project, and it should take the double requirements into account determining the thickness on both technology and economy. That could provide a theoretical reference to the hot oil transportation construction's optimizing design.

The main index factors of the soil corrosion detection， for the section of pipeline in service in Qinghai Oilfield Huatugou, included resistivity, natural corrosion potential, redox potential, pH, moisture content, salt content, chloride ion content and soil corrosion rate. Combined with three theories, gray correlation, fuzzy evaluation, and improved AHP, the appropriate comprehensive evaluation model was established, the 15point set of measured data was used in Huatugou areas of this field to clarify its application of this method, and evaluation results reached by the comparison model with the original evaluation results were contrasted. The results of this evaluation model showed that the evaluation results was closer to reality than the original evaluation results.

    Mesoporous carbon was prepared by loading four different metal ions Ag+/MC, Zn2+/MC, Cu2+/MC, and Fe3+/MC by impregnation method using mesoporous carbon (MC) as the carrier.The influence of the loading quality and the species of the metal ions on the adsorption were investigated.The results show that the adsorption capacity of two thiophene (DBT) can be improved by loading Ag+, Zn2+, Cu2+ and Fe3+ on the surface of mesoporous carbon.The optimum adsorption efficiency of mesoporous carbon with different metals is compared. The order of adsorption capacity of DBT is Ag+/MC>Zn2+/MC>Cu2+/MC>Fe3+/MC. Among them, the adsorption efficiency of loading 10% Ag+ on the mesoporous carbon is best. Compared with the untreated mesoporous carbon sulfur saturation capacity increases 1.11 mg/g, through the sulfur capacity also rises 1.93 mg/g.

The mass fraction of sulfur contained in the catalytic diesel was determined by microcoulometry measurement, the effects of the integral resistance and magnification to the measurement results were investigated, and in addition, the optimal conditions were confirmed. Under the optimized conditions，precision and recovery rate of the external standard samples on catalytic diesel were investigated, and showed that the sulfur content measured with pretty good accuracy and repeatability with a magnification of 200 times, integral resistance of 600 Ω. It was a simple, rapid and accurate method for measuring large quantities of samples.

A mathematical model was established, which is a three-dimensional and steady-state heat transfer and flow process mathematical model in top combustion stove. Then the temperature field and velocity field were obtained according to the model. Based on these, the temperature and velocity fields were discussed under the conditions of various air and gas inlet position. The results show that when the gas entrance in single-channel mode, the liquid's temperature and velocity distribution was uneven extremely and tilted toward the furnace wall of gas entrance side in the hot blast stove. On the other hand, when the air and gas entrance in interval mode, the liquid's temperature and velocity distribution is uniform, and this mode is beneficial to the top combustion stove to work steadily.

The deacidification of Liaohe straight-run diesel with combination solvent in the alcohol-ammonia process was carried out. Effects of solvent composition, demulsifier type and amount and the operating conditions on the deacidification ratio and the yields of diesel were all studied. The suitable mass composition of solvent mixture is 5% NH ₃·H ₂O, 50% ethanol, 45% water and 0.4 μL NP6 demulsifier for 20 mL diesel. Operating conditions are as followings, the volume ratio of solvent to diesel 0.2, the treatment temperature 50 ℃, the processing time 60 seconds and the phase separation time is 20 minutes. The acid value of the diesel after deacidification comes up to the standard GB/T264-83 (acid value<5 mg(KOH)/(100 mL)). The solvent can be recycled by distillation and no waste generates, the naphthenic acid can be obtained by heating the distillation residues.

SO2-4/ZrO2-SBA-15 catalyst was directly synthesized and characterized with XRD, BET and NH3-TPD. The results showed that this catalyst presents the typical mesoporous structure of SBA-15 and super acidity. This catalyst was used in the synthesis of ethyl tertiary butyl ether (ETBE) with ethanol and tert-butyl alcohol as raw materials on the fixed bed reactor. Its catalytic activity turns out superior to some other kinds of microporous zeolites, such as ZSM-5, USY and mordenite.