Hydrofluorocarbon + ionic liquid is a potential working pair for the absorption refrigeration cycle. A pressure decay technique was used to measure the diffusion coefficients and Henry's constants of six hydrofluorocarbons (R32, R125, R161, R143a, R1234yf and R152a) in 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM] [PF₆]) in the temperature range from 303.15 K to 343.15 K. The experimental results show that the diffusion coefficients and Henry's constants of six hydrofluorocarbons in [HMIM] [PF₆] increase with the increasing temperature. Compared with other five hydrofluorocarbons, R32 not only exhibits higher solubility but also higher diffusivity. Therefore, R32 + [HMIM] [PF₆] is very suitable for the absorption refrigeration cycle. The Arrhenius equation was applied to correlate the diffusion coefficients and Henry's constants of six hydrofluorocarbons in [HMIM] [PF₆]. The average absolute relative deviations between the calculated results and the experimental data were less than 2.5% and 6.0%, respectively.

The three-dimensional solubility parameters(HSP) of raw coal were determined by inverse gas chromatography (IGC) in the temperature range 433.15 to 473.15 K. The HSP concept was applied to determine components (δ_d, δ_p and δ_h) of corrected solubility parameter (δ_t), and the HSP of raw coal was derived as δ_d=20.83(J·cm^-3)^1/2, δ_p=11.95(J·cm^-3)^1/2, δ_h=11.08(J·cm^-3)^1/2 and δ_t=26.44(J·cm^-3)^1/2 by extrapolation method at room temperature (298.15 K), the HSP of raw coal that was measured as δ_d=19.92(J·cm^-3)^1/2, δ_p=11.18(J·cm^-3)^1/2, δ_h=11.47(J·cm^-3)^1/2 and δ_t=25.56(J·cm^-3)^1/2by the HSPiP method at room temperature. The results are consistent through two approaches. The results of the study provide a reference for the study of the thermodynamic properties of coal and the choice of its swelling agent.

By using the microcalorimetry techniques, thermogravimetric analysis and LC-MS, the mechanism of the thermal degradation of aconitine, hydrolysis mechanism and the heat change of aconitine in the soil environment was explored, and the half-life of aconitine was determinated (t_1/2=0.973 h). While, aconitine is unstable and easily degradable in air, also easy to hydrolyze in alkaline solution. The thermal decomposition of aconitine in air displays three stages. The temperature range in the three stages, respectively, is 185-213℃, 248-468℃, 484-579℃. The corresponding reaction order is n=1/4, n=4, n=2 in the three stages; the activation energy in the three stages is 154.53 kJ·mol^-1, 100.97 kJ·mol^-1, 120.08 kJ·mol^-1. Aconitine should be stored as far as possible in the low temperature, dry and isolated air environment.

A new type ultra-thin flat heat pipe (UTFHP) with a total thickness of 1.30 mm was prepared by using multiscale composite structures composed of porous layer (PL) and porous wire (PW) as wicks. After chemical modification treatment, the nanostructures modified the surface of the wick, which had super-hydrophilic properties. The thermal performance of UTFHP was investigated with deionized water used as the working fluid. The effects of the nanostructures, filling ratios and inclination angles on thermal properties of UTFHP were analyzed at different heating powers. The results show that the nanostructures can greatly increase the critical heat flux (CHF) and reduce the total thermal resistance of UTFHP when the filling ratio is 25%. Compared with the sample without nano, the CHF is increased by 255% and the minimum total thermal resistance is reduced by 43.2% at the horizontal angle. In addition, when the filling ratio is low, the nanostructures can reduce the thermal resistance of condensation in the entire heating power range but increase the thermal resistance of the evaporator because of greater flow resistance at low heating power. But the nanostructures inhibit the heat transfer performance of UTFHP when the filling ratio is relatively high. The inclination angles effectively influence the heat transfer characteristics. When the evaporation section is located directly below the condensation section, the thermal performance of UTFHP is optimal. The unmodified and modified heat pipes both have great heat transfer performance, the maximum heating power is 83.7 and 44.3 W respectively.

Based on simplified periodic model and RNG k-ε turbulence model, the flow characteristics and heat transfer properties of shell-side fluid in perforated-baffle heat exchangers were numerically simulated by using CFD software FLUENT. The feasibility and accuracy of numerical simulation method was verified by experiment. The heat transfer and resistance performance of trefoil-baffle, four-leaf-hole baffle, five-leaf-hole baffle, big-hole baffle and small-hole baffle are analyzed. Then the influences of structural parameters on heat transfer and resistance performance were discussed. Furthermore, heat transfer enhancement mechanism of perforated-baffle structure heat exchangers was investigated based on the field synergy principle. The results showed that the fluid flow in the shell-side of the perforated-baffle structure heat exchanger can be accurately simulated by using the RNG k-ε turbulence model and the simplified periodic model. The heat transfer coefficient of five-leaf-hole baffle is the best while the resistance the greatest. The heat transfer coefficient of the small-hole baffle is the worst, while the resistance is the least. The heat transfer coefficient and pressure drop decrease when baffle pitch and hole-height increase. Behind the support plate, the angle between the velocity vector and the temperature gradient varies violently, which enhances the heat transfer in the shell-side. The field synergy angle of five-leaf-hole baffle has the largest fluctuation range, and the enhancement of heat transfer effect is the best.

Carbon dioxide plume geothermal system (CPGS) can be used to exploit geothermal energy and realize carbon dioxide geological sequestration simultaneously. The thermal compensation from the rock formation around the geothermal reservoir is one of the important factors that affect the performance of CPGS. Based on a three dimensional base and cap rocks enclosed heat reservoir model, the influences of the thermal compensation on the temperature evolutionary process of the rock and fluid in the geothermal reservoir and the heat collection performance of CPGS were studied. The distribution of geothermal reservoir temperature and the temperature of production fluid were compared with that without consideration of the thermal compensation. The results show that the thermal compensation reduces both the production fluid temperature variation along the vertical direction and its temperature decreasing rate in the later period of system operation, therefore extends the lifetime of CPGS and gains better heat collection performance. With consideration of the thermal compensation, the heat production is improved significantly. The results also show that the thermal compensation of the base rocks is stronger than that of the cap rocks.

A kind of shell-and-tube heat exchangers with fold helical baffles was proposed to eliminate the triangular leakage zones between adjacent baffles and shell. The effect of helical angle and overlapped degree on flow and heat transfer for shell-and-tube heat exchanger with fold helical baffles was studied based on investigation. The experimental correlations of convection heat transfer coefficient and resistance coefficient in shell side were obtained. The results show that the shell-side total pressure drop, shell-side tube bundle pressure drop, shell-side heat transfer coefficient and comprehensive performance all increase with the decrease of helical angle and the increase of overlapped degree under same shell-side volume flow rate. The flow and heat transfer performance of shell-and-tube heat exchanger with helical baffles is the best when helical angle is 18° and overlapped degree is 50%. The helical angle and overlapped degree as correction factor are added into experimental correlations. It is found that the average relative error between experimental values and experimental correlation of Nusselt number is 1.13%, the average relative error is 6.84% between experimental values and experimental correlation of resistance coefficient, which illustrates the fitting is correct and reliable. The results have a degree of theoretical guidance for design of shell-and-tube heat exchangers with fold helical baffles.

Based on framework combined discrete element method and computational fluid dynamics, a gas-solid flow model in three-dimensional spouted bed was established and Fortran numerical simulation program was further developed. The mixing characteristics of two different diameter-sized wet or dry particles in three-dimensional spouted bed were simulated and the mixing mechanism of binary particles in the spouted bed was analyzed. Lacey mixing index was introduced to quantitatively analyze degree of mixing in whole bed and specific regions of the bed. The influences on mixing different sized particles were studied by volume of liquid bridge, ratio of particle densities and superficial gas velocity. The results show that both wet and dry particles flow similarly in single jet spouted bed without obvious agglomeration of wet particles. Liquid bridge had a greater influence on small particles than large ones, which reduced difference of velocity between wet particles with different diameters. Particle mixing in circular groove was critical to mixing across whole bed. Liquid bridge volume had a more significant influence on particle mixing, compared to ratio of particle densities and superficial gas velocity.

The total deformation and equivalent stress of impeller, and hydrodynamics of solid-liquid suspension process in a stirred tank with RDT-PBDT, R-RDT-PBDT, RF-RDT-PBDT, PR-RDT-PBDT and PRF-RDT-PBDT were investigated using bidirectional fluid-structure interaction (FSI) method. Results showed that, at the same power consumption, the total deformation of PRF-RDT-PBDT was 1.984×10⁶, 1.247×10³, 1.169, 1.041×10³ times of RDT-PBDT, R-RDT-PBDT, RF-RDT-PBDT and PR-RDT-PBDT, respectively. The equivalent stress of PRF-RDT-PBDT was larger than that of RDT-PBDT, R-RDT-PBDT and RF-RDT-PBDT, and was more homogeneous than that of PR-RDT-PBDT. The maximum U_z/U_tip value of solid particle and maximum ε/D²N³ value in PRF-RDT-PBDT system were 53.08% and 80.84%,38.03% and 28.42%,22.14% and 20.16%,10.85% and 5.725%, which are higher compared with RDT-PBDT, R-RDT-PBDT, RF-RDT-PBDT, PR-RDT-PBDT, respectively. Therefore, PRF-RDT-PBDT can enhance mutual coupling effect with fluid, increase axial velocity of solid particles and turbulent energy dissipation rate, reduce the accumulation of solid particles at the bottom of stirring tank, and improve the solid-liquid mixing performance.

An experimental study was carried out on basic phenomena, pinch-off characteristics and penetration depth of underwater gas jet ejecting out of a vertical annular nozzle. The process of gas jet development was recorded by a high-speed camera, and jet interfaces were tracked by processing pictures with an edge detection algorithm. The pinch-off spatial distribution was determined by summation of downstream position across all recorded times. The gas jet penetration distance was calculated by counting transient pixel values divided by measured time duration of gas observed for all pixel locations. The color contour was used to indicate time percentage for gas to occupy a certain location in the field of view. The results show that underwater annular-nozzled gas jets exhibit two stages of continuous jet and centralized pinch-off. More pinch-off occurs near nozzle and less pinch-off occurs further away from nozzle in the study conditions. Pinch-off frequency at momentum jet section for all nozzles is reduced with the increase of gas flow rate. Back-attack phenomenon upon pinch-off is the result of axial obstruction and transverse expansion of subsequent gas instead of gas flowing backwards and impinging on nozzle end. The jet penetration distance is proportional to gas flow rate for ring seams of same sizes.

The study on flow boiling frictional pressure drop characteristics of CO₂ in horizontal micro tube which internal diameter is 1.5mm was made. Experimental conditions:heat flux(7.5-30 kW·m^-2), mass flow rate(300-600 kg·m^-2·s^-1), and saturation temperature(-40~0℃). Experimental results show:The increase of heat flux makes little effect on frictional pressure drop, almost zero; mass flow rate is the main factor that affects frictional pressure drop; the frictional pressure drop decreases as the saturation temperature increases; the effect of vapor quality on the frictional pressure drop is mainly caused by the change of the flow pattern in the tube. The trend of the experimental measured frictional pressure drop is plotted in CO₂ flow regime chart and it is found that the theoretical prediction of the maximum value of the frictional pressure drop falls in the end of the annular flow region. Making visible study on flow regime change in each working condition during the experiment process and the theoretical pattern is consistent with the flow pattern of the actual CO₂ in the micro tube in general.

In order to study effect of particulate circulating flow rate on pressure drop in riser, a cold experiment system of double circulating fluidized bed was established with differential pressure transmitters to probe axial pressure drop in riser. Based on various calculation methods of particulate velocity and different pressure drop mechanisms in different areas, pressure drop models were built for acceleration area, fully developed area, and whole riser. Pressure drop in the acceleration area by slip coefficient calculation was consistent with experimental value, while pressure drop in the fully developed area was relatively accurate upon assuming particulate slip velocity equal to terminal velocity. Therefore, pressure drop calculation in riser by comprehensive pressure drop models in the acceleration and fully developed areas could be good reference for pressure drop to be used in prediction of axial particulate concentration distribution in riser during production and provide guidance for on-line pressure drop monitoring in riser.

Mixing power were characterized by torque sensor. The largest Lyapunov exponents were computed by Matlab software. The fluid mixing performances were observed by the fluid field's visualization technology. A comprehensive experimental study on the effects of impeller type, the distance between impeller and bottom, the length of flexible wire, and the diameter of flexible wire on the number of mixing efficiency (C_e), and the largest Lyapunov exponents (LE_max) was carried out. Results showed that, single-wire flexible impeller can regulate and control the flow field structure and the way of energy dissipation, and effectively enhance the chaotic mixing. At rotation speed 120 r·min⁻¹, compared with the traditional rigid impeller, C_e was decreased by 87.4% and LE_max was increased by 53.2% with single-wire flexible impeller, C_e was decreased by 43.8% and LE_max was increased by 10.8% compared with single-wire rigid impeller. In addition, at the same agitation speed, the longer the flexible wire, the more conducive to the chaotic mixing, but its power consumption would also increase obviously. The diameter of flexible wire was measured at 0.8 mm, while C_e was less than the others and LE_max was larger than the others, which indicated that the degree of chaotic mixing was the largest in the case. Increasing the diameter of flexible wire led to the increase of fluid motion irregularity and the degree of chaotic mixing. If the diameter of flexible wire is more than 0.8 mm, the disturbance of flexible wire was reduced, which was close to the traditional rigid impeller, resulting in the decrease of chaotic mixing characteristics. It was not conducive to fluid mixing while the distance between impeller and bottom was too high or too low, the optimal distance between impeller and bottom was at 0.25T (T was used to express the inner diameter of stirred vessel).

Gas mixing flow in willow leaf-like static mixer was studied on both velocity and concentration field. The experimental results showed that deviations of velocity and concentration fields were reached to ideal range and were better than those of national standards. CFD simulation on the mixer flow field exhibited good consistencies in numerical values and distribution of concentration cloud diagram between experiment and simulation. Subsequent studies showed that mixing was promoted by longitudinal and hairpin vortices appeared in tailing wake zone of the mixing element. When gas was passing through the mixing element, a high turbulent flow energy dissipation region formed by turbulence-induced increase of kinetic energy dissipation rate could drive much frequent material transfer. Flow resistance of the entire static mixer also occurred mainly in this high energy dissipation region. To some extent, back mixing after the high energy dissipation region strengthened mixing effect.

The working lifetime of SAPO-34 for dimethyl ether to olefins (DTO) reaction was increased by non-contact La₂O₃. Increasing ratio of La₂O₃ to SAPO-34 prolonged working lifetime of SAPO-34. When the mass ratio of La₂O₃ to SAPO-34 was 1:1, the working lifetime of SAPO-34 was almost twice as much as that of SAPO-34 alone. La₂O₃ sandwiched in SAPO-34 had improvement, whereas La₂O₃ in upstream and downstream of SAPO-34 did not. Reaction kinetics and coke amount on SAPO-34 indicated that La₂O₃ decreased coking rate of SAPO-34. A synergetic mechanism for SAPO-34 and La₂O₃ was proposed that a coke precursor created on SAPO-34 during DTO was converted to non-coke forming species (such as CO, CO₂ and H₂) upon traveling onto La₂O₃ surface such that SAPO-34 coking rate was decreased and its working lifetime was increased.

The interaction of limestone calcination and sulfation in simultaneous calcination/sulfation under circulating fluidized bed furnace conditions was studied by constant-temperature thermogravimetric setup. The sulfation reaction took place simultaneously with calcination and CaSO₄ was formed in the particles when SO₂ was present. Compared to pure calcination condition, the mass loss rate of limestone calcined in the presence of SO₂ was lower but the final mass was higher. Limestone calcination was slowed down by SO₂ presence and the calcination rate decreased with increase of SO₂ concentration within the range of 0-0.3%. A probable mechanism was proposed that CaSO₄ formation by SO₂ sulfation with CaO of limestone particles upon calcination may fill or plug pores in CaO layer, impede CO₂ transfer, and hinder calcination reaction. The mechanism of SO₂ inhibition on limestone calcination was supported by product pore structure analysis and calculation that some pores were plugged and effective CO₂ diffusion coefficient in pores was reduced. However, the calcination rate of limestone was increased with particle size decreased from 0.4-0.45 mm to 0.2-0.25 mm, no matter whether there was SO₂ or not. Temperature also largely affected calcination, SO₂ impeding effect was less pronounced at 880℃ than at 850℃, which was probably due to reduced pore plug of CaSO₄ at 880℃.

Release-slowing mechanism of anisole desorption on glucose-based porous carbon materials was investigated. Porous carbon materials were prepared by using glucose as carbon source, and then characterized. Kinetic curves of anisole desorption on glucose-based porous carbon materials were measured. Model for estimating diffusion coefficient of anisole desorption from the carbon materials was established. Results showed that the specific surface area of the prepared samples reached as high as 1133-3153 m²·g⁻¹, and the anisole adsorption capacity of the adsorbents reached as high as 1050 mg·g⁻¹. Anisole desorption from the samples took place by mechanism of bulk diffusion, Knudsen diffusion and surface diffusion. The textural structure of the porous carbons had influence on the diffusion mechanism of anisole desorption. The high proportion of micropores would make the more anisole molecules desorb in the form of surface diffusion. Knudsen diffusion and surface diffusion played an important role in release-slowing anisole from the samples. About 78%-83% of anisole desorbed from the porous carbons in the forms of Knudsen diffusion and surface diffusion.

A high-efficiency sieve tray with bubble crusher was proposed. A layer of bubble crusher device was added in the height range of the foam layer on the sieve tray. The device could decrease the volume of the bubble and force the interphase to renovate, improve mass-transfer efficiency of trays in the trace distillation, and strengthen the gas-liquid mass transfer. The numerical simulation of gas-liquid two-phase flow field is carried out on the micro-bubble tray and sieve tray by Euler-Euler two fluid model, which was verified by test. The results showed that the bubble crusher device can effectively break the large bubbles, which made the gas distribution in those regions characterized by the small fraction of gas volume and evident back-mixing phenomenon more uniform, the regional area with large bubble content larger, and the gas hold-up distribution was gradient. The bubble crusher device in the foam layer can increase the interfacial area for vapour-liquid contact and residence time, improve the mass transfer efficiency and reduce the gas entrainment. The turbulence intensity near the bubble crusher device was high. The gas sprayed while large bubbles broken will further tear the liquid layer and increase the height of the foam layer, and bubble coalescence was restrained. The quick interphase renovation could enhance mass transfer process. The results can provide guidance for the design and optimization of industrial trays.

Conventional mechanical steam compression(MVR) heat pump distillation for separating mixed xylene exists shortcomings of high compressor power consumption and overhead sensible heat unused. Organic Rankine cycle(ORC) power generation technology can transform the low-temperature waste heat into electricity for compressor, in view of the above, the MVR heat pump distillation processes coupled by the ORC power generation technology and combined with exhaust steam regenerative cycle(EGC) were applied to separate the system. Taking total annual cost(TAC) and energy consumption as the evaluation indexes of separation process, net output power and cycle thermal efficiency are used as evaluation indexes of ORC system. Simulations for the above two kinds of distillation process were performed and the results were compared with the conventional MVR heat pump distillation process. The results show that compared with the conventional MVR heat pump distillation process,the MVR heat pump distillation processes coupled by ORC power generation technology and combined with EGC power generation technology both have certain energy saving and economic advantages, can reduce energy consumption by 9.64% and 9.89%, and save TAC by 3.19% and 3.50% respectively.

Wet vacuum distillation was used to separate oil and residue from one kind of rolling oil sludge. The effects of the three main factors (temperature, vacuum degree and steam flowrate) on the oil yield were studied by using the quadratic general spinning design. The results showed that the wet vacuum distillation could significantly mitigate the oil destruction and promote the oil recovery rate comparing with simple distillation. Within the range of the experimental condition, the optimal conditions were 321.4℃ in temperature, 90 kPa in vacuum degree and 1 ml·min⁻¹ in steam flowrate, at which the oil recovery rate of 57.2% could be reached. Both the excessive temperature and steam flowrate could cause the oil decomposition. If the temperature was too high, it promoted the conversion of oil from resin to aromatics and saturates because of pyrolysis. If the steam partial pressure was too high, oil transformed to aromatics from resin due to the ester-type bonds hydrolysis and the oxidation of heavy oil with co-effect of Fe₂O₃. As for the heavy organic matters, such as asphaltene, which were difficult to be removed from the distillation residuals. By raising the temperature and steam flowrate, especially raising temperature, they can be effectively decomposed and carbonized to achieve a low oil content in the residues, and thus benefitting to their recovery.

Oxygen concentration in penicillin vials is currently detected by destructive measurement of off-line samples, which has many limitations including long lead time, low precision, and high missing detection rate. Using tunable diode laser absorption spectroscopy (TDLAS), a theoretical correlation model between oxygen concentration, temperature, and second harmonic signal strength was constructed, and an on-line detection method to determine vial's oxygen concentration was proposed by temperature parameter. The experimental design and procedure were described in detail, angle of incidence and main parameters of the system were optimized. Under condition of 1 atm (101.325 kPa) air pressure and 296 K temperature, a conventional oxygen concentration inversion model was established on vials of different oxygen concentrations. At the same time, the second harmonic signal amplitude of 21% oxygen concentration sample was used as reference for quantitative prediction by temperature parameters. Experimental results show that temperature parameter for detecting vial's oxygen concentration can effectively overcome direct influence of large temperature variation on concentration inversion. The root mean square error of prediction (RMSEP) was reduced by 80.33%, compared to prediction method of relative direct concentration inversion.

The performance of liquid film seals is significantly affected by non-Newtonian behavior of lubricating fluids at seal interface. A mathematical model of spiral groove non-Newtonian liquid film seal was established by combination of mass conservation at JFO cavitation boundary condition and power law model of non-Newtonian fluids. The governing equation was discretized by finite difference method and solved by SOR iterative algorithm to obtain liquid film pressure distribution. The effects of non-Newtonian fluids on sealing performance were analyzed, including load-carrying capacity, leakage, friction torque, and cavitation occurrence in liquid film. The results indicate that with the increase of power law index, the load-carrying capacity first increases then decreases but the leakage and cavitation rate always increase and the friction torque consistently decreases. At power law index n=0.96, non-Newtonian fluids had increase by 4.6% in the load-carrying capacity and 0.3% in the friction torque but decrease by 98.6% in the cavitation rate of sealing face and 5.8% in leakage than Newtonian fluids. When operating parameters were changed, non-Newtonian fluids with various power law indices showed similar trending behavior of liquid film hydrodynamic performance. Suitable lubricant selection is important to improve sealing performance of liquid films.

The exit pressure boundary was determined by Chen's real gas equation of hydrogen and choked flow condition of gas exit speed reaching to the sound speed. Then, dynamic characteristics of spiral groove dry gas seal (S-DGS) at various operating parameters was analyzed by perturbation method, and compared to those of ideal gas and coercive exit pressure boundary models. The results show that real gas and choked flow effects should be taken into account for studying dynamic characteristics of S-DGS at high pressure. Both effects reduced direct stiffness coefficients of hydrogen S-DGS but increased direct damping coefficients. The influence of these two effects on dynamic gas film stiffness gradually enhanced with the increase of squeeze number and inlet pressure. In addition, when frequency ratio was varied, these two effects had a significant influence on gas film dynamic stiffness but minimal influence on gas film dynamic damping. Compared to models of ideal gas and coercive pressure boundary condition at the studied operating circumstance, these two effects caused three gas film dynamic damping coefficients (C_zz, C_αα, C_αβ) by mean standard deviations of 2.28%, 1.93%, 2.79% when squeeze number is variable and 4.08%, 2.07%, 1.82% when inlet pressure is variable.

Candida antarctica lipase B(CALB) is immobilized by entrapment in a hydrophobic silica xerogel. Firstly, the stability and reuse of immobilized enzymes are investigated and can be stored for at least 40 d at 25℃ without any significant loss of enzyme activity. Then, the transesterification of ethyl acetate with n-butanol in the presence of immobilized CALB is considered in a batch stirred tank reactor. The reaction kinetics is experimentally determined for different stirring rate, catalyst dosage, concentration and temperature. The suitable operating conditions are determined and a pseudo homogeneous kinetic model is established. The calculation data are in better agreement with the experimental data which shows that the kinetic equations are reasonable and suitable for simulation calculation.

The resource recycling of flue gas pollution is the developing direction of exhaust pollutant treatment. In order to explore the feasibility of the direct electrolysis process for resource recycling of the absorption solution from the ammonia-based wet desulfurization and denitrification, the effect of electrolyte compositions and concentrations, temperature, current densities, flow rate, electrolytic time and impurities of absorption on current efficiency of persulfate production were investigated in a two-compartment electrolytic cell under batch recirculation. The experimental results indicated that urea and ammonia has inhibitory effect on current efficiency, while ammonium sulfite and nitrite existing in anode chamber showed no significant influence on current efficiency. The current efficiency of simulated absorbent solution decreased to 69.88%, which was much lower than 86.98% by the pure ammonium sulfate electrolysis process under the optimal condition. Therefore, necessary pretreatments for the absorption solution, which contained the removal of heavy metal ions and urea, the oxidation of sulfite and the adjustment of pH, must be adopted before entering the electrolysis system. Using the pretreated absorption solution, the current efficiency could reach to 85.12%. The electrolytic reactor could effectively produce persulfate in anodic chamber and hydrogen by-product in cathodic chamber at the same time. Furthermore, the remainder solution after crystallization could be coupled with circulation absorption solution, and thus improving the denitrification efficiency. Therefore, it is a novel environmentally effective technology for flue gas cleaning with great prospects for development.

Thermodynamic vent system (TVS) is deemed as an efficient pressure control technique for long-term on-orbit storage of cryogenic propellants through fluid mixing and a combination of throttling and heat exchanging before venting. Three control strategies have been proposed to automate the mixing mode and venting mode of the TVS. The effects of these control strategies on liquid temperature, stratification and mass loss are investigated on a TVS simulator, which works at room temperature with R141b as the working fluid. The results show that the TVS can not only achieve a significant vent loss but also lower liquid temperatures and weaker stratification when one of the strategies is applied whose mixing mode operates based on ullage pressure and the vent mode is controlled based on both the ullage pressure and the bulk liquid temperature. This investigation provides guidance for the design and operation of cryogenic TVS.

A small scale pumpless ORC (organic Rankine cycle) system which can recover waste heat from low temperature heat resource is established to investigate the performance of the cycle. The system is mainly composed of two high efficient heat exchangers, one scroll expander, one generator, four refrigerant valves and eight water valves. The flow direction of the water and refrigerant is controlled by the valves. The water heated by electric heating boiler is used to simulate the low temperature heat resource. The temperature of the hot water ranges from 75℃ to 95℃ and the temperature gradient is 5℃. The cooling water from the cooling tower is 25℃ accordingly. The refrigerant R245fa is selected as the working fluid. The results show that the largest power output is 232 W, and the stable power output is about 230 W when the inlet water temperature is 95℃. The total time of power generation last 380 s. One more thing is that the higher inlet water temperature, the less time of power generation process. For the average steady power generation, the maximum energy efficiency is 3.92% and the minimum energy efficiency is 3.02% when the inlet water temperature is 95℃ and 85℃, respectively.

Currently, selective catalytic reduction (SCR) denitrification technology is the most effective technique to control emissions of nitrogen oxides from coal-fired power plants and it is widely utilized. The SCR catalyst is the core of SCR denitrification technology, which often encounters inactivation problems. The amount of harmful inactivated SCR catalyst is increasing with the increase in operation time of these power plants. V₂O₅ is the main active ingredient in the deactivated catalyst, and needs to be recovered. Three reducible organic acids, citric acid, tartaric acid, and oxalic acid were chosen to create an optimal experiment for recovery V₂O₅ from deactivated catalyst, and X-ray fluorescence was used to analyse the recovery result. The results demonstrated that oxalic acid has high acidity and strong reducibility, which provides a stronger acid environment for recovery V₂O₅ in the experiment. The oxalic acid recycling method only to control the reaction conditions, and no agent is needed to assist the recovery process. The experiment processes of oxalic acid simplify recovery method and are cost-effective.

The feasibility of the completely autotrophic nitrogen removal over nitrite (CANON) process for removal of nitrogen from mainstream wastewater (~60 mg NH₄⁺-N·L^-1) at room temperature (25℃) was investigated using bio-augmentation batch enhanced (BABE) controlling strategy. The results indicated that through changing 40% sludge of the mainstream reactor from sidestream reactor every 7 d, the total nitrogen removal rate (TNRR) and the total nitrogen removal efficiency (TNRE) stabilized at about 80 g N·m^-3·d^-1 and 70%.The specific anammox activity in mainstream reactor increased continuously. 16S rDNA gene high-throughput sequencing results showed that the functional microorganisms involved in both mainstream and sidestream reactor were Candidatus Jettenia like anammox bacteria and Nitrosomonas like ammonia-oxidizing bacteria (AOB), and the abundance of Nitrospira like nitrite-oxidizing bacteria (NOB) always maintained below 1% during 60 days' operation. It can be concluded that the operational mode of changing sludges between mainstream and sidestream every 7 d guarantees anammox activity and good nitrogen removal performance of mainstream CANON reactor under the experimental conditions herein.

Glycogen accumulating organisms (GAOs) has been enriched in the anaerobic-aerobic sequencing batch reactor (AO-SBR) (drained after anaerobic) with glucose as the carbon source and the P/C ratio less than 2/100. PRA was less than 1.0 mg·L^-1. The content of gly was 1.2 times the initial stage of GAOs enrichment. The domesticated GAOs cultured in anaerobic-anoxic operation could proceed endogenous denitrification reaction with NO₂^--N and NO₃^--N as endogenous carbon source. GAOs used intracellular poly-β-hydroxyvalerate (PHV), poly-β-hydroxyvalerate (PHB) and glycogen (gly) in turns as carbon source in endogenous denitrification process. The average endogenous denitrification rate of DGAOs using NO₂^--N and NO₃^--N as electron acceptors were 0.067 g N·(g VSS)^-1·d^-1 and 0.023 g N·(g VSS)^-1·d^-1 at 22℃, respectively. Short-range endogenous denitrification rate was about three times as much as endogenous denitrification rate at normal temperature.

The circulation and regeneration experiments were employed to evaluate the lifetime of the two different catalysts (HZSM-5 and 0.3 mol·L^-1 NaOH modified HZSM-5). The spent and regenerated catalysts were characterized by N₂ adsorption-desorption and NH₃-TPD techniques to analyse the reason of deactivation, and the spent catalysts were characterized by SEM,TGA, FTIR and UV-Vis techniques to analyse the coke deposited on the catalyst. The deactivation of the two different zeolites was become more and more serious along with the increase of the number of cycles. The difference was that the performance of 0.3 mol·L^-1 NaOH modified HZSM-5 was better than the one of unmodified HZSM-5 after four cycles. The coke of the spent catalysts was removed through calcination in air at high temperature and the catalytic activity was recovered to a large extent. The performance of 0.3 mol·L^-1 NaOH modified HZSM-5 was still better than the one of unmodified HZSM-5 after regeneration. The amount of coke deposited on the modified HZSM-5 was less than the one of unmodified HZSM-5. The coke of the modified HZSM-5 contains more condensed aromatics relatively.

Cutinase is capable of hydrolyzing soluble esters, insoluble triglycerides and various polyesters, and thus it can hydrolyze the binder in the ink and have the potential to replace lipase in the field of waste paper deinking. Cutinase and self-made surfactant was synergically used in deinking of office waste paper. The deinking effect and optimum process were discussed and compared with the conventional commercial lipase. The results showed that the optimal effect of cutinase could be achieved under the conditions of enzyme dosage of 10 U·g^-1, enzyme treatment time of 30 min, enzyme treatment temperature of 50℃ and surfactant dosage of 0.2%. Compared with lipase/surfactant and surfactant deinking, the brightness and ink removal rate of paper after cutinase deinking were higher and the mechanical strength of paper was also greatly improved. By comparison of the paper performance and scanning electron microscopy (SEM) analysis, the deinking effect of cutinase was better than that of lipase.

In the present study, microwave-H₂O₂ (MW-H₂O₂) process was applied for the treatment of Cu-EDTA containing wastewater. The effects of reaction time, initial pH, H₂O₂ dosage, microwave power and coexistent substances were investigated in detail. The corresponding degradation mechanism of Cu-EDTA was also described. The results showed that for the elimination of 1.57 mmol·L^-1 Cu-EDTA, the highest removal efficiencies of Cu (97.0%) and TOC (60.7%) were achieved under the optimum conditions (i.e. initial pH 3, H₂O₂ dosage 41 mmol·L^-1, microwave power 210 W, and reaction time 10 min). In this situation, the effluent conductivity decreased to 1.8 mS·cm^-1, and only 0.15 g·L^-1 of the sludge yield was generated. The presence of coexistent substances such as NO₃^- had nearly no effects on the degradation processes, while Cl^-, H₂PO₄^- and tartaric acid were unfavorable to the oxidation degradation of Cu-EDTA. After treated for 4 min, Cu-EDTA was almost totally oxidized to various Cu-intermediates, which rapidly degraded within 4-6 min, leading to the final formation of low molecular organic acids, NH₃-N, and inorganic carbon. The solid sludge mainly presented in the forms of CuO. Compared with traditional Fenton process, MW-H₂O₂ process exhibited more excellent performance in terms of oxidation efficiency, effluent conductivity and sludge yield.

Petroleum coke as a kind of by-product in petrochemical industry was chosen to prepare the mercury removal adsorbent with high sulfur and activity by SO₂ activation. The effects of adsorption temperature, inlet Hg⁰ concentration, flue gas composition and thermal regeneration on mercury removal characteristic were investigated in a fixed bed reactor system. Meanwhile, the removal mercury mechanism was put forward by applying characterization methods, including surface area and porosity analyzer, elemental analyzer and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the physical and chemical properties of SAPC were significantly improved. And carbonyl, ester and non-oxidized sulfur were the main active sites of Hg⁰ capture. Furthermore, the mercury removal capacity decreased with increasing adsorption temperature. The mercury adsorption rate was faster, while the initial mercury removal efficiency became lower at elevated initial Hg⁰ concentration. SO₂ had unconspicuous effect on mercury removal. Hg⁰ on or close to surfaces was oxidized by the adsorbed oxygen, and mercuric ions were more readily bound to sulfur via the Hg-S bond, while some will bind to oxygen. The absorption capacity of regenerated petroleum coke was weakened because of the loss of active sites in the regeneration process.

Viscose ash deposition and dewpoint corrosion in an industrial coal-fired boiler were investigated by field study of temperature-controlled mild steel 20^# test probes under different wall temperatures of 90℃, 80℃, 70℃, 60℃, 50℃ and 40℃. Ash deposits and metal samples were analyzed by X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDS). The results showed that when wall temperature fell to 70℃, viscose deposits and dewpoint corrosion began to form on probes due to condensation of H₂SO₄ on wall surface. The deposit accumulation and corrosion depth increased with the decrease of wall temperature, when wall temperature was lower than 80℃. At wall temperature of 40℃, HCl started condesing on wall surface which further enhanced ash deposition and corrosion. The coupling mechanism of viscose ash depostion and dewpoint corrosion was discussed and it was proposed that fly ash in flue gas could absorb and react with acid condensation to reduce viscose ash deposit and corrossion. Therefore, in order to avoid or reduce deposition and corrosion, it is recommended that low-temperature heating surface in industrial coal-fired boilers should be maintained above 70℃.

The effects of variable ammonia concentration on the removal efficiency of organic matter and ammonia nitrogen were examined by conducting sequencing batch experiments. Meanwhile, the soluble microbial products (SMP), loosely bound extracellular polymers (LB-EPS), and tightly bound extracellular polymers (TB-EPS) of anaerobic granular sludge were analyzed by using ultraviolet-visible spectroscopy (UV-Vis), excitation emission matrix fluorescence spectroscopy (EEM), and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that the removal rate of COD reduced from 94.19% to 93.33% by anaerobic granular sludge, when the influent concentration of ammonia nitrogen reached to 1000 mg·L^-1, which indicated that anaerobic granular sludge had an insignificant impact on the removal efficiency of COD. However, at the same time, the removal rate of ammonia nitrogen substantially decreased from 40.6% to 7.9%, due to its influent concentration. UV-Vis spectra analysis showed that a strong absorption band appeared at 205-210 nm scope of the LB-EPS and TB-EPS, and it was demonstrated that the LB-EPS and TB-EPS contained benzene ring and double bond structure. EEM spectra analysis showed that with increase of concentration of ammonia nitrogen, the intensity of aromatic protein adsorption peak decreased in the SMP, and the humic acid adsorption peak at E_X/E_M=370-390/420-450 nm enhanced. For the LB-EPS, the coenzyme F₄₂₀ absorption peak disappeared. It was illustrated that high concentration of ammonia nitrogen had an adverse effect on the activity of methanogens. In addition, the protein-like fluorescence peak in the TB-EPS has occurred red shift. At the ammonia nitrogen concentration of 1000 mg·L^-1, it was showed the existence of carboxyl in the LB-EPS. By using UV-Vis, FTIR and EEM spectra, the SMP, LB-EPS and TB-EPS of anaerobic granular sludge were analyzed comprehensively, which could provide scientific reference for the operation of anaerobic reactor.

A thorough understanding of fine particles clogging mechanisms is one of the critical issues during artificial recharge. This study was conducted to examine the effects of solution ionic strength (IS) and flow velocity on colloid transport and deposition in saturated porous media. Column transport experiments were carried out with different flow rate at various solution IS. These experiments were designed to obtain the long-term breakthrough curves (BTCs) in order to determine parameters by Hydrus-1D modeling. The results indicated that the BTCs were rising with increasing flow rate at given solution IS during attachment stage and values of key parameters. The results showed that these parameter values were controlled by the effects of solution IS at given flow velocity conditions and the parameter value increases with the increase of ionic strength. The effect of flow velocity was more significant for the chemical conditions when IS equaled to 30 and 50 mmol·L^-1. An explanation for these observations was obtained from extended interaction energy calculations that considered chemical heterogeneity on the sand surface. Interaction energy calculation showed that the size of the energy barrier to attachment in the primary minimum (Φ_T) reduced with increasing IS. The enhanced residence time available at low flow velocity allowed the bacteria to gain enough thermal energy to overcome the strength by realizing a primary minimum attachment. In addition, the hydrodynamic torques were small at microscopic roughness locations and grain-grain contacts. Therefore, a subsequent increase in flow velocity followed by retention phase had a negligible effect on the particles deposited at these favorable attachment locations. Hence, this study provided a very systematic experimental and theoretical evidence that the colloidal retention depended on the chemical feature and the flow velocity. On the whole, the migration and retention behavior of colloidal particles during the recharge process was mainly controlled by the ionic strength. However, the hydrodynamic characteristics interrupted the control of ionic strength. During the artificial recharge engineering, the two factors should be considered together to against the clogging.

Surfactants is one of the effective methods to promote hydrate formation. The influence of Sodium dodecyl sulfate (SDS) on the formation of hydrate was studied in an autoclave. The microscopic properties for SDS hydrate samples were detected with Raman spectroscopy and powder X-ray diffraction. It was found that the presence of SDS decreased the induction time and enhanced the hydrate growth rate. The microcosmic results showed that the presence of SDS did not change the sI-type hydrate lattice structure and had less impact (a few thousandths) on the crystal spacing compared with ideal sI-type structure and pure methane hydrate. The Raman shift of C-H stretching mode from CH₄ encapsulated in large and small cages are all 2904 and 2915 cm^-1, which illustrate SDS did not change the large and small cages structure. SDS improved the absolute small cages occupancy (q_L) as the absolute large cages occupancy (q_S) approached saturation, and this is also demonstrated that SDS can reduce hydration number and increase storage capacity.

Silver electrode with a three-dimensional surface (3D-Ag) was synthesized by a facile oxidation-reduction cycle method. The structure and properties of the electrode were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM) and potential steps. The results showed that Ag nanoparticles with {100} and {111} facets exposed and a diameter of 30-150 nm dispersed uniformly on the as-prepared 3D-Ag. In comparison to untreated Ag plate, the synthesized 3D-Ag electrode exhibits superior activity, selectivity and stability toward electrocatalytic reduction of CO₂ to CO. Moreover, the 3D-Ag electrode could maintain its high activity during three successive periods of two hours, while the bulk silver electrode gradually lost its activity. The high performance of 3D-Ag electrode could be ascribed to that the Ag nanoparticles are beneficial to the stabilization of the surface adsorbed COOH species, and to the desorption of the reduction intermediates of adsorbed CO species during the reduction of CO₂.

The heavy metal ion pollution of hexavalent chromium (Cr(Ⅵ)) in water is serious in China. An electrochemical sensor for hexavalent chromium (Cr(Ⅵ)) detection is proposed based on graphene nanomaterial. The graphene nanomaterial modified gold electrode (rGO/Au) was prepared by using the method of electrochemical reduction of graphene oxide (GO). The surface morphology and structure of rGO/Au were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM) technologies. The direct electrocatalytic reduction of Cr(Ⅵ) on the surface of rGO/Au was studied by using electrochemical methods such as square wave voltammetry (SWV), cyclic voltammetry (CV) and linear sweep voltammetry (LSV), etc. The preparation conditions were optimized which include GO reduction potential and reduction time, as well as the detection parameters, such as detection potential, pH and concentration of electrolyte. Without preconcentration step, the linear relationship between Cr(Ⅵ) concentrations and current responses on the rGO/Au was investigated by using amperometry method. The experimental results showed that graphene nanomaterial has electrocatalytic activity for Cr(Ⅵ) reduction. A good linear relationship between Cr(Ⅵ) concentrations and current responses was obtained from 5 to 2000 μg·L^-1, with a low detection limit of 0.5 μg·L^-1 (S/N ≥ 3). The modified electrode was resistant to some common metal interference ions, such as Cr(Ⅲ), Ni(Ⅱ), Cu(Ⅱ), Mg(Ⅱ) and Mn(Ⅱ). And the response current decreased less than 10% compared to the initial value after 11 successive measures, which showed a relative good stability. The advantages of the proposed electrochemical sensor are simple, fast, friendly environmental and reusable, which made it possible to apply the sensor for rapid detection of Cr(Ⅵ) in water.

This work mainly uses the one pot to synthesis RGO/δ-MnO₂ composites, which is characterized using X-ray powder diffraction (XRD), low pressure nitrogen adsorption stripping (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), energy spectrum (EDS) and thermal gravimetric analyzer (TGA). The electrochemical performance is tested by the cyclic voltammetry (CV), constant current charge/discharge test (GCD) and loop test. Results show that the RGO/δ-MnO₂ composites possess more excellent electrochemical performance than pure δ-MnO₂ and pure graphene. When the current density is 1 A·g^-1, the specific capacitance of RGO/δ-MnO₂ composite can reach 322.6 F·g^-1, which is higher than that of the pure δ-MnO₂ (234.2 F·g^-1) and the pure graphene (212.1 F·g^-1). Moreover, the specific capacitance retention of RGO/δ-MnO₂ composites remains 79.1% when current density increases to 10 A·g^-1. The specific capacitance of RGO/δ-MnO₂ composite is still as high as 252 F·g^-1 (99.6%) even after 1000 times constant current charge/discharge tests. These results indicate that the composite will be a kind of promising supercapacitor electrode material.

Cellulose nanofibers/graphene conductive membrane (CG) was prepared by vacuum filteration and the as-prepared CG was then coated with polylactic acid (PLA). FT-IR results show that a certain interaction exists between graphene and cellulose nanofibers. The optimal condition is that the composite ratio of cellulose nanofibers to graphene is 1:2, the electrical conductivity is 12 S·cm^-1, the tensile strength reaches 13.62 MPa and its hydrophilic angle is 80.6°. Thermogravimetric analysis (TGA) confirms the mass loss of PLA-based cellulose nanofibers/graphene conductive composite membranes (CGP) at 300℃ are below 10%, which is 20% less than that for pure cellulose nanofibers, suggesting that the introduction of graphene can greatly enhance the thermal stability of cellulose nanofibers. PLA possesses special advantages of mechanical property and degradability. The tensile strength of the CGP increases by 15-23 times as compared with the CG, after being buried in soil for 5 weeks, the mass loss of PLA-based cellulose nanofibers/graphene conductive composite membranes(CGP) was 3.7%. Therefore, CGP has a promising application in the flexible conductive material field.

A standard 20 L sphere chamber was modified to be adapted for measuring the explosion parameters of hybrid mixtures of ethylene and polyethylene dust. The change rules of the lower flammability limits and explosion severity of the hybrid mixtures were analyzed systematically. The explosion severity of ethylene, polyethylene and their mixtures were compared with each other. The results show that the addition of ethylene induces an obvious decrease in the minimum explosion concentration of polyethylene dust. Mixtures of ethylene below its lower flammability limit and polyethylene dust below its minimum explosion concentration were still explosible. Adding ethylene to polyethylene dust cloud of different concentrations increases both the explosion pressure p_ex and the rate of explosion pressure rise (dp/dt)_ex. But the increase range decreases with the increase of dust concentration. The maximum explosion pressure p_max and explosion index K_st of ethylene and polyethylene mixtures increase with the increase of ethylene concentration. While the maximum explosion pressure p_max and explosion index K_st of the hybrid mixtures of ethylene and polyethylene are higher under all ethylene concentrations than those of the pure polyethylene, but lower than those of the pure ethylene.

In order to improve the applicability of probabilistic estimation methods for process safety accidents, the propagation process of deviations should be considered in the basic event stage. A method for estimating the probability of process safety accidents based on scale effects is proposed. A new basic event solving model is established from the point of view of process deviations. Multi-scale ideas are introduced to modify the basic event probability, on the large scale, by considering the effects of human errors on process deviations. The fuzzy Petri net model is used to estimate the accident probability. Finally, the model is analyzed and verified by the case analysis of the fractionating tower accident. The results show that the participation of human has a great influence on the probability of process deviations. The proposed method is more suitable for the practical conditions and process safety. Since the probability estimate is based on the statistical data, the deviation probability is calculated and the subjectivity of the calculation parameters is avoided.

Fire alarm and gas detector system (FGS) is the important safety barrier to prevent gas leakage. Combustible gas leaks and forms combustible gas cloud mixing with air, and its explosion belongs to volume explosion. The gas cloud has complexity and variability subject to a variety of factors, so it is converted into equivalent gas cloud and the threshold size calculation method is proposed. The threshold is key input index to realize the quantitative layout of detector network of FGS. The control room is selected as a receptor for analysis. Based on the critical value of shock wave overpressure which takes load of control room, the corresponding equivalent gas cloud size is calculated as the detecting threshold of combustible gas cloud by using multi-energy method in reverse order. Then the critical detecting time of the FGS is calculated by using equivalent air cloud computing method and Gaussian diffusion model. Through one LNG tank industry case analysis, the maximum cloud size which can be carried by the industry and the critical time of diffusion can be quantitatively determined. The numerical calculation shows that the equivalent gas cloud size threshold can not only be used as the quantitative input indicators for detector design of FGS, but also provide theoretical support for the detection time setting and the prevention and control measures of gas leakage and explosion.

The effect of static rupture pressure (p_ST) on overpressure loadings caused by gasoline-air mixture deflagration was obtained based on experimental research in a vessel with a weak roof. The results showed that Δp-t profiles under different p_ST were divided into four types, and the main overpressure peaks were burst peak (Δp₁), vent flow peak (Δp₂), external deflagration peak (Δp₃) and locally instable combustion peak (Δp₄). The maximum overpressure peak inside the vessel was Δp₃ when p_ST was greater than or equal to 2.5 kPa, however, the maximum overpressure peak was Δp₁ when p_ST was greater than or equal to 5 kPa and less than or equal to 30 kPa. For the external overpressure, the maximum overpressure peak was Δp₃. Induced by the coupling of external deflagration and negative pressure, pressure oscillation occurred when p_ST was greater than or equal to 2.5 kPa and less than or equal to 20 kPa, and the frequency as well as the duration of pressure oscillation were related to p_ST. Duration of burst stage showed an increasing trend with the increase of p_ST, while duration of venting stage, external deflagration stage, and pressure oscillation stage showed an opposite trend. The value of internal and external overpressure peaks were both proportional to p_ST. With the increase of the p_ST, the internal pressure peak Δp₁ and Δp₂ increased in linear and the external pressure peak Δp₃ increased in quadratic.

In order to investigate the effect of the ignition position on deflagration characteristics of premixed methane/air mixture with hydrogen addition, an experimental study was conducted in a transparent pipe with the cross-section of 100 mm×100 mm and the length of 1000 mm with the variation of ignition position (IP) and hydrogen addition ratio (φ). The results indicated that the changing of the flame structures was dependent on both IP and φ when the flames propagated to the vent and the closed end. The formation of the tulip flame was mainly affected by IP when the flame propagated to the vent. Whereas, it was influenced by both IP and φ when the flame propagated to the closed end. The evolution of the flame front could be divided into three categories according to IP and φ. Hydrogen addition had no obvious effects on the flame propagation velocity when φ was less than 0.25. When φ was less than 0.75, the overpressure presented periodic oscillation only under the conditions that the ignition position was in the middle or the rear of the pipe. Moreover, the closer the ignition position was to the vent, the longer the oscillation time would be. With regard to the pure hydrogen explosion, the pressure oscillation disappeared and the arrival time of the maximum peak pressure was basically the same for all ignition positions. The changing trends of the maximum peak pressure with the ignition position were different for various hydrogen addition ratios.

Based on the assumption that waxy crude oil is deemed as the porous medium system under the temperature of losing flow point, the additional specific heat capacity method is used to describe the wax crystallization heat, and the momentum source term method is adopted to represent the flow resistance on the liquid oil due to the formation of network structure made by waxy crystal. The finite volume method is used to simulate the gelatinization process of waxy crude oil. The result shows that the gelatinization evolution is mainly conducted by the heat transfer mechanism and boundary condition. Affected by natural convection, the gelled crude oil first generates in the region surrounded by the sidewall and base wall, which is always the most serious gelled region in the tank. The integrated gelled oil layer first appears on the top wall, then it experiences two steps which include the slow growth and fast growth. Moreover, the gelled oil layer is gradually tends to be even when the cooling advances. Later after it appears on the top wall, the gelled oil layer covers the base wall which has the opposite development process from that on the top wall. The gelled oil layer covers the sidewall at the last step. On the sidewall the evolution of gelled oil layer has the trait of advancing from the base wall to the top wall along the sidewall. When natural convection gets stronger, the increasing rate of gelled oil layer turns to be smaller on the top wall, but it has the opposite behavior on the base wall. Based on the temperature profile and evolution of gelled structure, the cooling process can be divided into three states. Natural convection dominates the heat transfer behavior in the first stage. In the second stage, heat conduction gradually replaced the dominant role of natural convection. Finally the heat transfer behavior is conducted by heat conduction and boundary condition in the third stage. In the meantime, the rule of temperature profile and heat loss is also provided.