Collagen is widely distributed in various tissues of living organisms and is one of the basic proteins that constitute living organisms. The structure of collagen is more complicated than that of general protein and it displays a more stable property so that normal proteases have no significant effect to deal with it. There are only two typical enzymes have ability to hydrolyze collagen in situ, one is called matrix metalloproteinase (MMP) and another is bacterial collagenase. In this review the collagen and hydrolase are introduced in briefly, then the development process and the hydrolysis mechanism to collagen between matrix metalloproteinase and collagenase are presented, then the particular aspects of the different enzyme activities will be contextualized within relevant areas of application, mainly about therapeutics, food processing, environmental protection and tissue engineering. In the end the development of the present research and guide further potential research orientation of the system of collagen & collagenase is summarized.

Accurate selection of vapor-liquid equilibrium thermodynamic model is essential to the design and operation of CO₂-C₂H₆ azeotrope separation process. On the basis of collected experimental data, the reliabilities of four types of cubic equations of state including vdW, RK, SRK and PR combined with vdW, Margles and CVD mixing rules for predicting vapor-liquid equilibrium properties of CO₂ pure substance, CO₂-C₂H₆ azeotrope and n-C₅H₁₂-CO₂-C₂H₆ ternary system are evaluated according to the principle of vapor-liquid fugacity equilibrium. In addition, average absolute deviation is adopted to select cubic state equations. The results show that the SRK equation of state calculates the vapor-liquid equilibrium property of CO₂ pure material with the highest precision. The PR equation of state combined with Margles mixing rule can accurately calculate the vapor-liquid equilibrium characteristics of CO₂-C₂H₆ azeotrope system. However, for n-C₅H₁₂-CO₂-C₂H₆ ternary system, the calculating accuracy of SRK combined with Margles mixing rule is obviously better than that of vdW, RK and PR. Furthermore, binary interaction parameters have obvious effects on the calculating accuracy of cubic equations of state for the mixture system. In order to improve the calculation accuracy, the binary interaction parameter is calibrated for all of the studied EOSs regarding CO₂-C₂H₆ azeotropic system and n-C₅H₁₂-CO₂-C₂H₆ ternary system.

In order to accurately measure the isobaric specific heat capacity of liquid n-decane, a flow adiabatic calorimeter was constructed for subcritical pressure and supercritical pressure. The isobaric specific heat capacity of n-decane was measured at temperatures ranging from 311 K to 570 K and pressures ranging from 0.12 MPa to 6.02 MPa. The results show that the isobaric specific heat capacity of n-decane increases as the temperatures rise. And the system pressures have little effects on the isobaric specific heat capacity of n-decane. The experimental results were compared with the reference data. The results show that the maximum absolute deviation (MAD) is within 5.0%, and the average absolute deviation (AAD) is below 1.39%. Meanwhile, the experimental results were compared with Guseinov and Garg models. Based on the two empirical models, the improved isobaric specific heat capacity model was proposed. The improved model has higher fitting accuracy, showing that the MAD is 1.32%, and the AAD is 0.53%, which provides a basis and reference for the calculation of isobaric specific heat capacity of other hydrocarbon fuels.

The miscibility of refrigerant and lubricating oil directly affects the service life and cycle performance of refrigeration system. To solve the problem of matching new refrigerant and lubricating oil, a refrigerant and lubricating oil compatibility test system was established. The experimental study on the miscibility of R290/R1234yf and mineral oil was carried out in the temperature range of 223.15—303.15 K. The results show when R290 mass fraction in mixed refrigerant R290/R1234yf changed from 25% to 35% and oil proportion was specified at 10%±0.5%, the critical miscibility temperature of R290/R1234yf and mineral oil decreased with increasing R290. In the test range of oil proportion, based on the common refrigeration conditions, when the mass fraction of R290 in solution changed between 20% and 30%, the critical miscibility temperature was sensitive to the change of components. When the R290 mass fraction in solution was over 30%, the refrigerant/oil solution was believed to be clear and transparent. When the R290 mass fraction in solution was below 20%, the obvious stratification or large flocs would appear. By means of the element contribution evaluation method, the theoretical critical miscibility temperature prediction equation was provided and given in the form of ternary diagram, which has practical guiding significance for the development of new environmental protection refrigerants.

Organic Rankine cycle (ORC) is one of the most promising technologies for medium and low temperature thermal energy-electric energy conversion, and has received more and more attention in recent years. Working fluid is the carrier for energy transport or conversion in the ORC. Because of the diversity of the heat source and working substances, the screening of working fluids and the optimization of the system are very important to improve the comprehensive performance of the ORC. Accurate prediction of working fluid properties is significant for the accurate prediction and optimization of the ORC performance. Based on the artificial neural network and group contribution method (ANN-GCM), a prediction method for the ORC performance is presented. A group table covering 11 groups established, 7958 of data are derived from REFPROP for ANN training, obtaining the correlation of the energy transform and entropy difference in DRC. The performance of the ORC is tested by using 21 common refrigerants in 1584 working conditions. The error of predicting the thermal efficiency, output power, and exergetic efficiency of the ORC system with the experimental data is 1.01%, 1.02% and 1.61%. Comparing with the traditional method, the prediction accuracy is significantly improved.

According to the multi-component system Na-K-Ca-Mg-Sr-Li-Cl-B₄O₇-Br-SO₄-I-H₂O of underground brine in Sichuan basin, the phase equilibrium relationships of quinary systems NaBr-KBr-MgBr₂-CaBr₂-H₂O at 298 and 323 K were studied by isothermal solution equilibrium method, the solubilities of the equilibria solution of the quinary system were determined under the corresponding temperatures, and the corresponding phase diagrams were plotted according to the phase equilibrium experiment data (saturated with KBr). The results of research show that the quinary system has complex salt at 298 K and 323 K. There is complex salt KBr·MgBr₂·6H₂O formation at 298 K and the phase diagram contains two co-saturated points, five dissolution isotherms and four solid crystallization regions (corresponding to KBr·MgBr₂·6H₂O, NaBr·2H₂O, NaBr and CaBr₂·6H₂O, respectively). There are two kinds of complex salts KBr·MgBr₂·6H₂O and 2MgBr₂·CaBr₂·12H₂O formation at 323 K and the phase diagram contains three co-saturated points, seven dissolution isotherms and five solid crystallization regions (corresponding to KBr·MgBr₂·6H₂O, NaBr·2H₂O, NaBr, CaBr₂·4H₂O and 2MgBr₂·CaBr₂·12H₂O, respectively).

Using density functional theory(DFT) of quantum chemistry, the gas reaction mechanism in TMG/NH₃/H₂ system is explored, especially the formation of amide DMGNH₂ and its following nano-nucleation path. By calculating the changes of Gibbs free energy along different reaction path under different temperature, the most probable gas products of nucleation of nanoparticles are determined both thermodynamically and kinetically. It is found that DMGNH₂ can be formed by elimination of CH₄ from the adduct or by bimolecular collision when T < 622 K. DMGNH₂ can be directly formed by the bimolecular collision reaction of TMG and NH₃ when T > 622 K. When 662.5 K < T < 939 K, the reactions of dimer [DMGNH₂]₂ to [MMGNH]₂ by successive elimination of CH₄ are easy to occur. When 389 K < T < 734.7 K, the reactions of trimer [DMGNH₃]₃ to [MMGNH]₃ by successive elimination of CH₄ are easy to occur too. However, further elimination of CH₄ from [MMGNH]₂ and [MMGNH]₃ to form [GaN]₂ and [GaN]₃ are both thermodynamically unfavorable, because the changes of Gibbs free energy of the reactions are greater than 0. Thus indicates that [MMGNH]₂ and [MMGNH]₃ are the two probable gas reaction products for the nucleation of oligomers in GaN-MOVPE growth.

Experiment was made to comprehensively analyze the effect of circulating water flow rate on organic Rankine cycle (ORC) waste heat power generation system based on a 3 kW experimental prototype in laboratory. Considering circulating water as energy transfer medium, the energy consumption analysis was carried out by the total energy system method, and the performance of system and main equipment with different heat source temperatures was evaluated. The results showed that the output power of generator, expander and ORC subsystem increased with the increase of heat source temperature and circulating water flow rate, as well as the thermal efficiency and exergy efficiency of ORC subsystem. The maximum values of net output power and exergy efficiency of system were obtained under the same conditions. As the temperature of heat source is 120℃ and the circulating water flow rate is 1.629 t·h^-1, the maximum values of net output power and exergy efficiency of the system are 0.731 kW and 11.81%, respectively. This study provided references for performance analysis of ORC waste heat power generation system with different boundary.

For the first time, the three-dimensional, full-size entrained flow gasifier was simulated by CPFD（computational particle fluid dynamics） simulation method, and a gasification simulation model suitable for CPFD simulation was established. This validated the model and CPFD simulation used in entrained-flow gasification. The detailed reaction process and the probability distribution of particle residence time were obtained through CPFD simulation. The results show that both particle short-circuit and re-circulation exist in the gasifier using single burner at top. The short-circuit flow is mainly located at the central region of the gasifier. In addition, the particle reaction rate is very fast in the central region but relatively slow near the wall region. Besides, the first amount of particles flowing out of the gasifier mainly consists of the fully-reacted particles.

The flow characteristics of the sphere under uniform flow in a large space have been extensively studied, but the influence of the wall on the flow characteristics of the sphere is not clear. The wake of the particle is focused. Results show that there are three regimes of the sphere wake, which are steady wake, unsteady symmetric wake and unsteady asymmetric wake. If Re<150, steady wake occurs, and the wake is symmetric with respect to a plane perpendicular to the wall. If 150<Re<400, the wake is still planar symmetric. When the Reynolds number is large, regular and periodic vortex shedding occurs behind the sphere, and the Strouhal number is about 0.26－0.33. The vortex is planar symmetric with respect to a vertical plane passing through the sphere center and the vortex. The frequency band of the power spectra of the sphere wake is wide. If Re>400, the vortex shedding is not symmetric and becomes chaotic as Reynolds number increases.

To investigate the enhanced effect of wave-absorbing material assisted microwave heating on traditional freeze-drying, a multiphase transport mathematical model conjugating temperature field, concentration field and electromagnetic field was developed and numerically solved. The sintered silicon carbide (SiC) was used as the absorbing material and the mannitol aqueous solution was used. Microwave freeze-drying experiments of mannitol aqueous solution were carried out, and dielectric properties of mannitol solid powder were measured. Both numerical and experimental results show that using wave-absorbing material as the supporting pad of sample can effectively enhance the microwave freeze-drying process. Under the typical operating conditions, microwave freeze-drying time of the initially unsaturated material can be 18% and 30%, respectively, shorter than the traditional freeze-drying process of the initially unsaturated and conventionally saturated samples. Excellent agreements were received between experimental measurements and model predictions. This indicates that the proposed freeze-drying method can achieve the simultaneous enhancement of heat and mass transfer. Based on the profiles of temperature, ice saturation and electrical field strength, mechanisms of heat and mass transfer, as well as electromagnetic wave propagation and dissipation inside a sample were analyzed during drying. The accumulatively absorbed energy of radiation and microwave during drying was almost the same as those of traditional freeze-drying of the initially saturated and unsaturated samples. This demonstrates that the proposed method only increases the energy utilization so as to largely reduce the freeze-drying time.

Based on the dielectric properties of liquid and vapor phases of cryogenic fluids, the modified linear inversion algorithms of electrical capacitance tomography (ECT) are obtained by introducing a correcting deviation into the linear approximate equation of the traditional capacitance-permittivity distribution function. The 8-electrode capacitance tomography sensor was used as the geometric model to simulate the two-phase flow in the liquid oxygen-oxygen tube. The original linear algorithm, the modified linear algorithm and the total variation 1 norm regularity were compared under four different flow patterns. The inversion results of four different flow patterns of original linear algorithms, modified linear algorithms and non-linear algorithms represented by total variation L ¹-norm regularization (TV L ¹-norm) are compared. The correlation coefficient and image error are taken to measure the quality of the inversion results. The results of numerical experiments show that compared with the original linear algorithms, the quality of the inversion results is greatly improved by the modified linear inversion algorithm. The TV L ¹-norm takes more than 10 times as much time as the modified linear inversion algorithm. And when 3% measurement noise is applied, the non-linear algorithm shows strong sensitivity to measurement noise. The modified linear algorithms have better anti-noise ability and accuracy of inversion results.

The application of supercritical CO₂ in solar thermal power generation system could effectively improve the efficiency, compactness and environmental friendly of the system. Therefore, it is necessary to optimize the comprehensive performance of solar collectors using supercritical CO₂. In this paper, a new calculation model for the effective thermal conductivity of foam materials is proposed. The effects of different foam filling types on the flow and heat transfer performance and wall temperature distribution in receiver tubes are studied. The results show that the flow-heat transfer performance index (j/j _c)/(f/f _c)^1/3 is optimal for the annular filling method (filled along the inner wall of the tube), the net heat absorption is the largest, the highest wall temperature is the lowest and the temperature distribution is the same.

The effects of high temperature and pressure on bubble formation under constant flow conditions in N₂-H₂O, He-H₂O and N₂-tetradecane were experimentally investigated. The experiment conditions covered orifice velocity from about 0 up to 1500 cm/s, temperature from 293 K up to 393 K, pressure from 0 up to 6 MPa, orifice diameter 1.12 mm up to 2.5 mm. The experiments were carried out in a stainless steel bubble column of 50 mm I.D with three pairs of high strength quartz windows. The bubble flow was visualized and recorded through high speed camera. The results show that bubble diameter decreases and aspect ratio increases with increase of pressure. The effect of temperature is complicated owing to the change of saturated vapor pressure, ratio to system pressure. When the ratio is larger, bubble diameter increases with temperature due to vaporization phenomenon. When the ratio is smaller, bubble diameter decreases with temperature. According to the experimental results, the bubble diameter model proposed by Gaddis was modified, and the saturated vapor pressure contribution was introduced to obtain a new estimation formula for the bubble diameter under high temperature and high pressure conditions.

Experiments are performed on the effect of local cooling by thermoelectric cooler on triggering solidification of supercooled sodium acetate trihydrate (SAT). Factors such as the water content, the SAT sample mass as well as the input power of the thermoelectric cooler are examined about their effects on the crystallization activation and discharging characteristics. The results showed that with the increase of water content, the overall crystallization induction period increased, the heat release temperature decreased, and the water content of 44% was used as the ideal system ratio. The crystallization induction period was 2 min and the stable exothermic temperature was 52.8℃. The higher the input power(P) is, the faster the unit is cooled and the induction time period for P=280 W is one third of that for P=70 W. The probability of nucleation of samples is increased for higher sample mass and then the induction time is shorter with higher discharging temperature and longer heat release time.

Based on genetic aggregation response surface models and multi-objective genetic algorithms, the effects of key structural parameters and inlet velocities on the shell-side flow and heat transfer of rod-baffle heat exchangers (RBHXs) with twisted oval tubes were investigated. The performance of twisted-oval-tube RBHXs was optimized. The results show that the heat transfer coefficient h decreases by 9.38% firstly and then remains constant with the increase of the pitch and it increases with the ratio of long axis to short axis under lower inlet velocities and decreases firstly and then increases when inlet velocities are higher. When the inlet velocity is 0.1 m/s, the heat transfer coefficient increases by 45.92% with the ratio of long axis to short axis. When the inlet velocity is 0.5 m/s, the heat transfer coefficient decreases by 12.96% firstly and increases by 7.74% then. The pressure drop Δp is constant with the increase of the pitch; the increase with the ratio of the long and short axes is reduced by 36.67%. The sensitivity analysis shows that inlet velocities influence the heat transfer coefficient and pressure drop more than structural parameters and the ratio of long axis to short axis of structural parameters influences output parameters more than the pitch, which provides theoretical guides for structure improvement and inlet velocities selection of RBHE given structure and inlet velocities. Three sets of optimal results were obtained by employing multi-objective genetic algorithms to maximize the heat transfer coefficient and minimize the pressure drop simultaneously on response surfaces. Compared with the original structure, the heat transfer coefficient increases averagely by 19.17%; the pressure drop decreases by an average of 5.74%; the comprehensive performance h/Δp is enhanced by 26.42%.

The high-speed imaging technique was used to observe the evaporation and nucleation process of the droplets of deionized water after impacting the surface of the micro-pillar structure. The results show that the evaporation time of droplet decreased with the increase of wall temperature. Compared with smooth surface, the heat transfer coefficient (HTC) of micro-pillar surface can be only enhanced under certain conditions. In this paper the temperature is 50, 60, 70, 80 and 120℃,and the strengthening effect is best at 120℃. The evaporation of droplet can be divided into two stages. In the first stage, the diameter of the droplets is constant, and the height changes. In the second stage, the thickness of the droplet is close to the height of micro-pillar structure and the droplet dry in a very short time. As the wall temperature increases, the period of the first stage decreases obviously, and the nucleation density and the bubble diameter increase accordingly. It is worth to note that nucleation bubbles show a radial distribution on the micro-pillar surface because of the structure of array micro-pillars and the impact of dropping down.

Paraffin phase change emulsion is a new type of functional fluid that integrates heat storage and heat transfer, and has broad application prospects. However, the application of phase-change paraffin emulsion suffers from subcooling phenomenon, which weakens its ability to store and transfer heat remarkably. The degree of subcooling in phase-change paraffin emulsion is conventionally determined by differential scanning calorimetry (DSC), the result of which is dependent on the heating / cooling rate. As the heating / cooling rate increases, the degree of subcooling is higher. Here an equilibrium volumetric method was presented to determine the degree of subcooling in phase-change paraffin emulsion by measuring its specific volume at different temperatures. The specific volume obtained was plotted against the temperature to identify the phase transition temperature of paraffin during heating / cooling process, then the degree of subcooling was deduced from the phase transition temperatures obtained. The results showed that the degree of subcooling in phase-change paraffin emulsion can be measured accurately using the equilibrium volumetric method presented in this work. The results also revealed the mechanism of subcooling in phase-change paraffin emulsion from the point of view of specific volume change.

The heat transfer and resistance characteristics of the detachable plate heat exchanger composed of two different corrugated depth plates were studied by experimental method and comparative method. Each kinds of corrugated depth plates were divided into three corrugated angle combination of the hard plate (63°/63°), or soft plate (29°/29°), or mixed plate (63°/29°). The test was divided into two working conditions, one was that flow velocity of hot side synchronize with cold side, both sides were equal in every moment; The other was that flow velocity of hot side was always 0.5 m/s, flow rate of cold side was increased from 0.2 m/s to 0.9 m/s. The medium of each side was water. The value of the total heat transfer coefficient and pressure drop of two conditions were calculated, and the corresponding curves were described. The experiment proved that the total heat transfer coefficient of the shallow density corrugated plate was higher than that of the ordinary corrugated plate at the same corrugated angle combination, the average value was higher than 140 W/(m²·K), so the heat transfer coefficient was increased by 1.9% on average, and the difference of the heat transfer coefficients in the mixed plates was above 300 W/(m²·K), which was up to 4.8%, and the change trend of flow resistance was the same as the heat transfer coefficient. The functions of Nusselt number and friction factor were obtained, the correctness of the experiment was proved by comparing with the existed research results, it also revealed that there was room for optimization of the heat transfer performance and resistance of the two kinds of corrugated plates, which pointed out the direction for further research. The experiment also shown that the difference of the functions of Nusselt and friction coefficient about two kinds of corrugated plates with the same geometry size except the depth and the same structure were obvious.

Studying the variable mass flow law of pressure swing adsorption (PSA) in the radial flow adsorber can help to accurately grasp the influence of the adsorption process and the variable factors in the bed on the oxygen production performance. An air-solid two-phase pressure swing adsorption model is established for the π-shaped centripetal radial flow adsorber, axial oxygen purity profiles, temperature wave and oxygen concentration for product gas are comparatively studied by using this model. The results show that the oxygen purity of 66.02% and the recovery of the production of 29.2% can be obtained in the outlet after the first PSA cycle. The oxygen purity increases from 66.02% to 97.5% and the recovery of the production increases from 29.2% to 38.5% during the unsteady state. The product oxygen purity and recovery are achieved to be 98.6% and 38.9% at the end of each steps in steady state, and finally the temperature difference of air-solid two-phase gradually decreases and reaches thermal balance. The mass and heat transfer between the air and the adsorbent are obtained, which provides reference for π-shaped centripetal in the PSA for oxygen production.

Thermo regulated phase-separable Ir nano catalyst was applied to the selective hydrogenation of α, β-unsaturated aldehydes and ketones and its catalytic hydrogenation performance was systematically investigated. Under the optimized reaction conditions, the Ir nano catalyst exhibited high selectivity of C═O bond for α, β-unsaturated aldehydes (>99%), while high selectivity of C═C bond for α, β-unsaturatedketones (>99%). The catalyst can be simply separated and directly reused for 5 times with the selectivity remaining >99%. Furthermore, the results of TEM showed that the particle size of Ir nano catalyst after four cycles was (1.9 ± 0.2) nm, which increased a little compared with the Ir nano catalyst newly prepared. The results of ICP-AES showed that the leaching of Ir in the upper organic phase was below the detection limit (the detection limit is 5 μg/L).

The CFD simulation of the egg-shell Co-based catalyst Fischer-Tropsch synthesis reaction system was carried out by Comsol-Multiphysics software. The effects of catalyst active component thickness on product and temperature distribution, conversion of F-T synthesis were studied by establishing a reasonable three-dimensional model of catalyst. The results show that the CO concentration has obvious difference between the outside and inside of catalyst due to strong diffusion limitation. And because the diffusion rate of H₂ is much larger than the diffusion rate of CO, the internal hydrogen-carbon ratio of the catalyst particles is very high, which is not conducive to the formation of oils and waxes. As the thickness of catalyst active components increases, the conversion of CO and the selectivity of methane and low hydrocarbons increases, while the selectivity of C₁₀H₂₂ and C₂₂H₄₆ decreases. The peak temperature inside the catalyst moves towards the inside of the catalyst, which isn’t conducive to the transfer of reaction heat. For the shell-type spherical catalyst with the size of 2.5mm, the optimum catalyst thickness of the active component is 0.125 mm.

As a typical high concentration saline wastewater, Na⁺,Mg²⁺//Cl^--H₂O solution system was treated via membrane distillation and crystallization to recycle the pure water and high NaCl crystal products with high property, simultaneously. The performance of membrane distillation and the properties NaCl product were explored under the different operation temperature and the various concentration of salts. The results indicate that, the permeate flux obviously increased with the increasing of the operation temperature, due to the increasing of the different vapour pressure with the temperature. Moreover, the permeate flux slightly decreased with the adding content of MgCl₂ to the solution, it was mainly due to the decrease of the mass fraction of water and the increase of solution viscosity. The surface crystal particle deposition was also evaluated via lunching the comparison experiments. In addition, the hollow fiber membrane used in the experiments presents favorable reusability with 20 cycles during the membrane distillation. The NaCl crystal products obtained under the operation temperature of 65℃ exhibited the narrow size distribution, the smooth crystal surface, the perfect cube structure and without agglomeration, and the average size was 91.04, 91.38 and 122.56 μm, and the coefficient of variation (C.V.) was 28.78, 30.63 and 36.77, respectively. Meanwhile, the conductivity recycled water was 5 μS?m^-1, and the purity of crystal products were higher than 98.15% after washing with the selective solution (ethanol). Therefore, by regulate the membrane permeate flux and interface function, the membrane distillation crystallization is a feasible technology to process the high concentration saline wastewater (Na⁺,Mg²⁺//Cl^--H₂O) to recycle the pure water and NaCl product with high purity, smooth surface and uniform size under the appropriate operation temperature and the lower Mg²⁺ concentration. This research can explore the potential approach for the ‘near zero discharge’ treatment of multiple ions high saline wastewater and the reuse of the inorganic salt resource.

Chlorophyll a is a basic substance involved in photosynthesis, and is one of the important indicators for measuring algae biomass in water and evaluating eutrophication of lakes. The traditional calculation formula for extracting chlorophyll a was modified when the standard chlorophyll a and chlorophyll b was extracted by these organic solvents including 90% acetone, anhydrous ethanol, anhydrous ethanol∶acetone (1∶1), anhydrous ethanol∶acetone (1∶2) and anhydrous ethanol∶acetone (2∶1). The effects of these five organic solvents on Chlorella vulgaris and Microcystis aeruginosa were analyzed under the ultrasonic treatment. It was determined that anhydrous ethanol∶acetone (2∶1) was most effective for extraction and anhydrous ethanol was considered as the best solvent in terms of efficiency, safety and environmental protection. The chlorophyll a in shallow water reservoir was monitored by multi-parameter water quality monitor at different times. The accuracy of the determination results of anhydrous ethanol under ultrasonic treatment was verified. The optimum extraction conditions of chlorophyll a by anhydrous ethanol were determined by orthogonal experiment. The optimization of chlorophyll a measurement makes the process of measuring chlorophyll a for large quantities in water more simple, fast and accurate.

Model-free adaptive control (MFAC) has four model parameters, and existing studies consider it to be uncorrelated and conserved throughout. The relationship among 4 parameters is found out in this paper by assuming an initial state of the controlled system at the initial moment, based on the rule of the first moment output value should be close to the target value with genetic algorithm (GA), making the issue of 4 parameters to be simplified into the one of single parameter. Further, an automatic estimation method on step-length factor is suggested according to whether the absolute value of difference between output value and target value is less than a default value, thus it is regarded as a parameter with characteristic of time-variable and its maximum value is also enlarged into positive infinity from 1. The proposed two changes improve the present MFAC greatly, resulting in a faster calculation speed at the early control stage as well as avoiding overshoot and vibration at the convergence stage. A case application in a unit of oil refinery shows that the improved MFAC only needs 14 iterations for reaching the optimal target, and the system’s maximum added-benefit (MAD) can reach 5.43 million CNY/a. The number of parameter adjustments for the maximum gain of the system is reduced from 33 to 14 times, and the maximum gain is increased from 4.134 million CNY/a to 5.429 million CNY/a.

Aiming at the problem that batch data synchronization in unequal-length batch process monitoring fails to fully exploit local information, this paper proposes a variable grouping dynamic time warping-multiway canonical variate analysis (VGDTW-CVA) algorithm for unequal-length batch process fault detection. First, the mutual information matrix is used to describe the correlation between variables of unequal-length batch process, and all the variables are divided into serval groups based on mutual information matrix. Then use the DTW algorithm to synchronize each variable group separately, and integrate the synchronized variable groups into a complete 3D data set. Finally, MCVA method is utilized to establish dynamic monitoring model for online monitoring of batch production process. The simulation results on the penicillin simulation system show that the VGDTW-MCVA has better monitoring effect for the unequal-length batch production process.

To achieve efficient operation of the wastewater treatment plant(WWTP), it is necessary to establish a model that accurately describes the behavior of the plan. In this paper, the radial basis function neural network (RBFNN) is utilized in the modeling of the WWTP basing on the available influent and effluent data. Considering the bounded modeling error, linear-in-parameters set membership identification algorithm is used to describe an uncertain set of each vector representing the weights of the links between all the hidden neurons and one output neuron. Comparing with the existing methods which are all proposed for a single effluent variable, the method here builds a predictor model which can compute confidence intervals for multiple effluent variables simultaneously according to the values of the influent variables. The confidence intervals can characterize the existence ranges of the effluent variables, such that reliable estimates of them are obtained. By the estimates, the effluent quality or the WWTP performance can be evaluated. Besides, the interval predictor model is also applied to the fault detection and isolation of the WWTP to realize reliable operation. The experiment results show the satisfying performance of the proposed method.

Aiming at the problem that the ion concentration cannot be detected online during the electrochemical wastewater treatment process, a soft-sensor modeling method based on K-means clustering algorithm of state transition is proposed. On the basis of analyzing the mechanism in the electrochemical process, the mechanism model of the electrochemical process was established according to the material balance and adsorption kinetics. Since single model cannot meet the requirements of accuracy, a K-means clustering algorithm based on state transition is proposed to cluster the original data set. This algorithm uses the state transfer algorithm to optimize the initial clustering center of the K-means algorithm,and introduce a matrix to realize clustering and outlier detection simultaneously during iterative process. Then,after clustering, the sub-models are established with the training subsets respectively, and the soft measurement model based on the multi-model switching method is obtained by synthesizing the sub-models.Finally,via field data verification of a wastewater treatment plant, the results show that the soft measurement model of ion concentration in electrochemical wastewater treatment process is reasonable and effective.

Sewage treatment is a complex nonlinear process, and chemical oxygen demand (COD) is one of the key indicators for evaluating the effectiveness of wastewater treatment. It is costly and time-consuming to get COD by traditional chemical approaches. By neural networks, it is faster, but it is not accurate enough. To address them, a soft sensor approach, which is based on the combination of self-organizing map (SOM) and radial basis function (RBF) neural network, is designed. SOM is taken to cluster data samples. The number of hidden layer nodes and the center vector of the nodes are determined by clustering results. By such disposal, the rate of convergence and fitting precision have been improved. Part data of water samples from a sewage treatment plant are taken to establish the soft sensor model of COD. Test results provided by numerical model and hardware show that, compared with the traditional BP, RBF and other networks, the soft sensor model of COD designed in this paper has short measurement time and relatively high prediction accuracy. It may be a promising soft sensor approach in applications.

In this work, four polymer-grafted Candida rugosa lipase (CRL) were synthesized via atom transfer radical polymerization by grafting hydroxyethyl methacrylate (HEMA), glycidyl methacrylate (GMA), propyl methacrylate (nPMA) and butyl methacrylate (BMA) onto CRL surface using N-(bromoisobutyryloxy) succinimide as the initiator. The results of CD and fluorescence emission spectra showed that the helical and sheet contents of CRL increased with polymer grafting, and exhibited a positive relation with the length of alkyl group in the monomer. Furthermore, a blue shift was also observed in fluorescence emission spectra of polymer-grafted CRL, meaning that polymer-grafted CRL had a more compact structure than wide-type CRL. Activity measurement of polymer-grafted CRL further showed that polymer grafting led to a significant increase of enzymatic activity of CRL in the order of CRL, HEMA-g-CRL = GMA-g-CRL, nPMA-g-CRL and BMA-g-CRL. With an increase of the length of alkyl group in the monomer, moreover, Michaelis parameter of CRL decreased from 0.17 mmol·L^-1 to 0.09 mmol·L^-1 whereas turnover number increased from 67 to 182 s^-1. Therefore, catalytic efficiency of polymer-grafted CRL enhanced greatly and the catalytic efficiency BMA-g-CRL was 3.28 times as high as that of wide-type CRL. It indicated that polymer grafting improved the movement of lid structure, leading to the exposure of the active site in CRL and enhancing the substrate transformation. Stability tests show that polymer grafting enhances the thermal stability of the CRL and broadens its pH range. The research proposed a novel methodology to regulate the CRL activity by polymer grafting, and exhibited the influence of alkyl groups of the monomers to CRL activity. The result in this research provided a benefit guidance for rational screening of monomer molecules to improve the performance of lipase in industrial biotransformation.

Absorption refrigeration using low-grade solar heat, geothermal heat or industrial waste heat as driving heat source is an effective way to achieve energy saving and emission reduction. A new working pair of CaCl₂-LiCl/H₂O, which has an excellent refrigeration absorption characteristic, was studied by measuring its crystallization temperature and vapor pressure with different mass ratios of CaCl₂∶LiCl. The results showed that CaCl₂-LiCl(2∶1)/H₂O with a mass ratio of 2∶1 was the most suitable working pair for an absorption refrigeration system. Compared with LiBr/H₂O, under the same refrigeration conditions, the required driving heat source temperature, that is, the required generation temperature for CaCl₂-LiCl(2∶1)/H₂O was 5.8℃ lower, COP and exergy efficiency for CaCl₂-LiCl(2∶1)/H₂O were 0.041 and 0.052 higher, respectively. Furthermore, the cost of working pair was greatly reduced. In addition, the crystallization temperature, saturated vapor pressure, density, viscosity, specific heat capacity, specific enthalpy, and corrosivity of CaCl₂-LiCl(2∶1)/H₂O were measured systematically. Compared with other working pairs using CaCl₂ as the main component, CaCl₂-LiCl(2∶1)/H₂O had a relatively low viscosity and low corrosion rates for carbon steel and copper, so it could meet the requirements of practical engineering application.

Aiming at the two main mechanisms of initial deposition layer of ash deposition, namely, condensation and thermophoresis mechanism, a mathematical model for the formation of initial deposition layer by K-containing species was established. The rationality of the model was validated by the experimental results in the literature which indicates that considering the changes of the thickness of the deposition layer and the surface temperature have a reasonable improvement. The model was used to study the deposition process of K-containing gas and aerosol particles on the heating surface, and to investigate the effects of K-containing species composition, flue gas temperature and velocity. The results show that, because of the difference in the relative concentrations of K-containing gas and aerosol particles, both condensation and thermophoresis deposition may play a major role in the formation of the initial deposition layer at the beginning of the deposition process, while thermophoretic deposition dominates the later stage. The effects of flue gas temperature and velocity on the deposition process is similar, that is, the higher flue gas temperature and velocity, the higher the initial deposition rate, the lower the later deposition rate, and the lower the thickness of the deposited layer.

To quickly realize the autotrophic denitrification of actual domestic sewage in the short term, the activated sludge from the actual sewage treatment plant containing anammox bacteria was used to study the removal effect of nitrogen in the process of hypoxia aeration for Fe²⁺/Fe³⁺ and Mn²⁺. The results showed that both Fe²⁺/Fe³⁺ and Mn²⁺ can increase the abundance of anammox bacteria (AnAOB) in activated sludge, but Fe²⁺/Fe³⁺ had a certain inhibitory effect on ammonia oxidizing bacteria (AOB); therefore, the total inorganic nitrogen removal rate was 25% in the presence of Fe²⁺/Fe³⁺ under short-term dosing, but the total inorganic nitrogen removal rate was 44% in the presence of Mn²⁺. Nitrogen balance analysis showed that nitrogen transformation was mainly denitrification under the condition of Fe²⁺/Fe³⁺; but was mainly anaerobic ammonium oxidation (anammox) process under the condition of Mn²⁺. Therefore, the anammox activity could be enhanced in traditional activated sludge by short-term addition of Mn²⁺, promoting the removal of nitrogen during the low-oxygen aeration, and facilitating the rapid achievement of integrated autotrophic nitrogen removal.

In the process of catalytic oxidation of Fe(Ⅱ) co-precipitated arsenic by hydrogen peroxide, different pH adjustments were used to adjust the pH of the solution. The effects of different pH adjustments on the precipitation of arsenic in wastewater and the properties of precipitated slag were studied. The results show that the pH adjustments of Na₂CO₃ and CaO are beneficial to the removal of arsenic from wastewater, and the arsenic in the coprecipitates is mainly in the form of amorphous bulk particles. When Na₂CO₃ is used as the pH adjustment, it is most favorable to the growth of particle size, the size of precipitates is the largest, but the stability of arsenic is the worst, and it is easier to release from the slag. The particle size of the precipitates obtained by CaO is relatively small due to the existence of CaSO₄ rod-like particles, but the existence form of arsenic is the most stable, and the fixation effect of arsenic is the best.

In this work, a solar thermal-photovoltaic hollow fiber membrane distillation system was designed. A 1.82 m² vacuum tube collector area was used in the solar photothermal system, and 1.63 m² polycrystalline silicon panel area was used in the solar photovoltaic system. Experimental aspects, the difference of membrane permeate flux in different flow modes of hot liquid under different working conditions was studied. The influence of solar irradiance on the system performance under different tracking systems was studied. The results show that the membrane permeate flux of the feed liquid flowing through the tube pass is greater than the membrane permeate flux of the shell pass, and the temperature of the inlet liquid of the vacuum membrane distillation is most suitably selected as 50—70℃. The temperature of the automatic tracking membrane module inlet is 2—3°C higher than that at the non-tracking mode. The automatic tracking can extend the running time of the membrane distillation system for 1—2 h than the non-automatic tracking system. At the same time, the maximum membrane permeate flux of the automatic tracking mode is 8.89 kg/(m²·h), which is higher than 4.26 kg/(m²·h) in the non-tracking mode in the same natural environment. Theoretical aspects, the heat and mass transfer process of hollow fiber membrane distillation with water as working fluid was analyzed. The heat transfer theoretical mathematical model of the heat transfer process was established. The quantitative relationship between irradiation intensity, temperature difference of membrane surface, heat transfer coefficient of inner surface of membrane, heat and mass transfer flux were analyzed. The membrane surface temperature and theoretical membrane permeate flux were calculated, and the experimental and theoretical values were compared. The system has stable operation, high energy utilization efficiency and reliable performance, which lays a theoretical and experimental foundation for engineering application.

Three kinds of alkyne monomers with ester groups and three kinds of alkyne monomers with ether groups were synthesized, and characterized by nuclear magnetic resonance spectroscopy(¹H NMR), fourier transform infrared spectroscopy(FT-IR), mass spectrometry (MS) and liquid chromatography (LC). Three poly(triazole ester) resins (PTAEs) and three poly(triazole ether) resins (PTAOs) were prepared from these alkyne monomers and polyfunctional azide monomers. The curing behavior, mechanical properties, heat resistance and thermal stability of the resins were characterized by differential scanning calorimetry (DSC), FT-IR, dynamic mechanical thermal analysis (DMA), mechanical tests, and thermogravimetric analysis(TGA). The results show that PTAE and PTAO resins can be dissolved in common organic solvents and can be cured at low temperature (60℃). The flexural strength of cured resins exceeds 100 MPa, and the highest 158 MPa. The glass transition temperature (T _g) of cured resins exceeds 180℃, and the highest 251℃. The thermal decomposition temperature(T _d5) exceeds 300℃, and the highest 360℃. The mechanical properties, heat resistance and thermal stability of the cured PTAO resins are higher than those of the cured PTAE resins.

Thermochromic coatings have great application potential in reducing the building’s heating and cooling load and improving the urban thermal environment. In order to investigate the factors influencing the optical properties of thermochromic coatings and optimize the material formulation, 12 different thermochromic coatings with the color-changing temperature of 31°C were prepared by incorporating thermochromic powder with other assistant components. The effects of rutile TiO₂ content on the spectral reflectance of the coatings were analyzed. The results show that the spectral reflectance of coatings increases with the content of TiO₂. The optimum mass fraction for thermochromic powder is 5%, and for TiO₂ is about 5%—10%, in which the solar reflectance of colorless phase is higher than that of colored phase by more than 0.2. At the same time, the effects of the particle size of TiO₂ on the reflectivity of the coatings in different bands were investigated. The results show that the reflectivity of the thermochromic coatings decreases with the increase of TiO₂ particle size in ultraviolet and visible light bands except red band. In the red and near-infrared bands, the reflectivity of the thermochromic coatings increases with the increase of TiO₂ ^{particle size.}

Artificial lotus leaves superhydrophobic hierarchical structure was obtained on epoxy resin substrates by improved molding method and zinc oxide hydrothermal growth method. The process of this method is simple and low-cost, and the natural micro-structure can be quickly reproduced on the artificial surface. The molding method is effectively used for lotus and rice leave with protuberant microstructures. And the effect of ZnO growth liquid concentration on nanostructure was also studied. Then, in order to study the influence of microstructures at different scale sizes on the hydrophobic properties of the surface, smooth surface, nanostructure surface and microstructure lotus replica surface were fabricated. the hydrophobic properties of these surfaces were measured. The date shows that the rough structure can improve the hydrophobicity of the surface, and the micro-nano hierarchical structure is more helpful to the formation of superhydrophobicity on the surface. When droplets contact with the surface in Cassie state, the larger the proportion of air on the contact area, the smaller the contact angle and the smaller the sliding angle on the surface.

A kind of composite phase change materials (PCMs) was prepared by the process of “melting blend - solidification and form-stable” to improve the comprehensive performance of PCMs. Palmitic acid (PA) is used as PCM and expanded graphite (EG) is used for the supporting material. Twenty-one kinds of form-stable composite PCMs were prepared with different contents of EG. The morphologies and structures were characterized microscopically by SEM. On this basis, heat transfer performance analysis, thermophysical test, thermal stability test and heat storage performance analysis were conducted. SEM morphological characterization showed that PA could be absorbed into the pores of EG and the distribution was uniform. DSC test results revealed that the melting enthalpy of PCMs is 193.01 J/g with the 70%(mass) PA corresponding to the melting point of 61.08℃. The melting enthalpy of pure PA is 275.35 J/g corresponding to the melting point of 59.53℃. The thermal conductivity of the PCMs is significantly improved by the addition of EG. When the sample density was 900 kg/m³ and the content of EG was 30%(mass), the thermal conductivity of the composite PCM is 14.09 W/(m·K), which is about 87 times higher than that of pure PA. Cycle stability tests were carried out, the results suggest the samples with 24% and 30% EG content have no any change in shape, and therefore show excellent cycle stability in repeating charging and discharging processes.

High performance graphene-based composite membranes have attracted great attentions, however, graphene-based nanofiltration membranes usually exhibit low water flux in removing salt ions, which limits its application in water desalination. Novel reduced graphene oxide (rGO)/ultrathin carbon nitride (uCN) composite nanofiltration membrane was prepared by self-assembling rGO and nanoporous uCN nanosheets on polydopamine (PDA) modified polysulfone (PSF) support via vacuum filtration. Field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy analysis (XPS) were applied to evaluate the changes in structure and morphology of membranes by introducing uCN. The effects of addition ratios of uCN, rGO content and operating pressure on the performance of composite membranes were also investigated. With 20 mg·L^-1 uCN content in 100 mg·L^-1 of rGO, the prepared rGO/uCN composite membrane not only maintained satisfied salt rejection rates (85.86% for Na₂SO₄, 30.17% for NaCl), but also possessed 2.15 times water permeance (88.50 L·m^-2·h^-1·MPa^-1) that of pure rGO membrane.

To improve the economic benefits of CO₂ capture in flue gas, a novel N₂ selective zeolitic imidazolate framework-8 (ZIF-8) composite membrane has been designed in this work. The zinc ion (Zn²⁺) was tightly adhered to the polysulfone support by chelating crosslinked chitosan matrix. The ZIF-8 seeding layer was prepared by zinc ion coordinated with 2-methylimidazole (Hmim), and then the dense ZIF-8 composite membrane was prepared by the secondary growth method. The morphological structure of ZIF-8 composite membrane was characterized by FTIR, XRD and SEM. And the results showed that the dense ZIF-8 composite membrane has been prepared. The effects of the time of secondary growth, the concentration of Zn²⁺ solution, the continuous test time and feed gas pressure on gas separation performance of ZIF-8 composite membrane were systematically investigated by pure gas, and the gas transport mechanism was analyzed. In addition, the separation performance of membranes was investigated by CO₂/N₂ mixed gas. At testing temperature of 25℃ and feed gas pressure of 0.1 MPa, N₂ permeance and N₂/CO₂ selectivity were 523 GPU and 19 for pure gas, respectively. While N₂ permeance and N₂/CO₂ selectivity were 517 GPU and 18 for mixed gas under the same condition, respectively. The results showed that the ZIF-8 composite membrane could preferentially permeate N₂ in the flue gas. The ZIF-8 composite membrane contained many CO₂ active adsorption sites, so that CO₂ was adsorbed in the membrane and was not easily desorbed from the downstream side of the membrane, and N₂ could preferentially permeate, which provided a new idea for the preparation of N₂ selective membrane.

Considering a large amount of expired foods such as expired bread are generated in the world every day, expired sliced bread activated carbon (EBAC) was prepared from expired sliced bread by carbonization, activation with 1 mol·L^-1 KOH, neutralized with dilute hydrochloric acid, and then washed with deionized water and ethanol. The surface morphology, phase structure, surface functional groups, specific surface area and pore size distribution of expired sliced bread activated carbon were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption and desorption (BET). The electrochemical properties of activated carbon electrode materials were tested in a three-electrode system with the 3 mol·L^-1 KOH electrolyte. The charge-discharge curves show that the specific capacitance of the electrode material reaches 352 F·g^-1 at 0.5 A·g^-1 current density. After 1000 cycles at 5 A·g^-1 current density, the specific capacitance remains 99.87%, which shows good cyclic stability. At last, the Nyquist and Bode diagrams obtained by AC impedance measurement also shows that the expired sliced bread activated carbon has good supercapacitor performance.

In our present work, a typical biomass, maize straw was used as precursor to prepare porous biochar under high temperature followed with etching by KOH solution. The prepared biochar was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy (Raman). The specific surface area of as-prepared biochar was calculated by the Brunauer-Emmett-Teller (BET) method. Under the optimal conditions, the specific surface area can reach 1228 m2·g^-1. Then the as-prepared biochar was employed as electrode materials to fabricate the flexible supercapacitor cooperating with the H₂SO₄/PVA gel as electrolyte. The electrochemical capacitance properties of the obtained supercapacitors were tested by cyclic voltammetry (CV) constant current charge-discharge (CD) and AC impedance spectroscopy (EIS) measurements in a two-electrode system. The results showed that the specific capacity reaches 125 F·g^-1 when the current density is 1.0 A·g^-1. Noteworthily, the fabricated supercapacitor demonstrates the perfectly flexibility and stability that the capacitance retention kept at 93.5% under different bending angles (from 0° to 180°) at a constant current density of 1.0 A·g^-1. Furthermore, the flexible supercapacitor also exhibits a satisfied long-term stability performance of 95.6% capacitance retention and 94.9% coulombic efficiency under 180° bending angle through 500 cycles. These very attractive mechanical properties and electrochemical performances enable this flexible supercapacitor to present a great potential for wearable devices as energy storage equipment and open up new avenues to high-value materials from waste maize straw.

To study effects of C₂H₆/C₃H₈ on explosion limits and chemical kinetics, a standard test device was employed to investigate effects of C₂H₆/C₃H₈ on explosion limits of CH₄ and determine the critical parameters of CH₄ explosion. In addition, Chemkin software was used to simulate the influence of C₂H₆/C₃H₈ mixed gas on the concentration of intermediates during methane explosion, and sensitivity analysis was carried out. Results indicated that the presence of C₂H₆/C₃H₈ decreased the explosion limits of CH₄ while increased its explosion risk. In the inerting process, the reducing upper explosion limit and the rising lower explosion limit of CH₄ merged at the same point where the critical concentration of CH₄ and N₂ all gradually decreased with the addition of C₂H₆/C₃H₈. Moreover, the production of CO and·H gradually increased while that of CO₂,·O and·OH declined after adding C₂H₆/C₃H₈. It is suggested that the addition of C₂H₆/C₃H₈ promoted CH₄ explosion to some extend by sensitivity analysis. By contrast, it is found that the higher content of C₃H₈ indicated the greater influence on the related parameters in the process of methane explosion, which can provide a certain theoretical basis for the safety production of industrial and mining enterprises.