Experiments were carried out to study the heat transfer performance of an impinging jet in a cross flow. Several parameters including the jet-to-cross-flow mass ratio (X 2%-8%), the Reynolds number (Re_d 1434-5735) and the jet diameter (d 2-4 mm) were explored. The heat transfer enhancement factor was found to increase with the jet-to-cross-flow mass ratio and the Reynolds number, but decrease with the jet diameter when other parameters maintain fixed. The presence of a cross flow was observed to degrade the heat transfer performance in respect to the effect of impinging jet to the target surface only. In addition, an impinging jet was confirmed to be capable of enhancing the heat transfer process in considerable amplitude even though the jet was not designed to impinge on the target surface.

The kinetics of forward extraction of boric acid from salt lake brine by 2-ethyl-1, 3-hexanediol in toluene was investigated using the single drop technique. The factors affecting the extraction rate include interfacial area between aqueous phase and organic phase, initial concentration of boric acid in aqueous phase, initial concentration of 2-ethyl-1, 3-hexanediol in organic phase, and extraction temperature. The experimental results show that the extraction rate increases with the increase of the initial concentration of boric acid and 2-ethyl-1,3-hexanediol, interfacial area of two phases, and temperature. With the temperature-dependence study, it is showed that the extraction is a diffusion-controlled process. The kinetic equation is presented for pH 1.0 in the aqueous phase and temperature of 318 K.

The presence of a limited amount of H₂S in H₂-rich feed adversely affects the Pd-Cu membrane permeation performance due to the sulphidization of the membrane surface. A theoretical model was proposed to predict the S-tolerant performance of the Pd-Cu membranes in presence of H₂S under the industrial water-gas-shift (WGS) reaction conditions. The ideas of surface coverage and competitive adsorption thermodynamics of H₂S and H₂ on Pd-Cu surface were introduced in the model. The surface sulphidization of the Pd-Cu membranes mainly depended on the pressure ratio of H₂S to H₂, temperature and S-adsorbed surface coverage, i.e., the occurrence of sulphidization on the surface was not directly related with the bulk compositions and structures [body centered cubic and face centered cubic (bcc or fcc)] of Pd-Cu alloy membranes because of the surface segregation phenomena. The resulting equilibrium equations for the H₂S adsorption/sulphidization reactions were solved to calculate the pressure ratio of H₂S to H₂ over a wide range of temperatures. A validation of the model was performed through a comparison between lots of literature data and the model calculations over a rather broad range of operating conditions. An extremely good agreement was obtained in the different cases, and thus, the model can serve to guide the development of S-resistant Pd alloy membrane materials for hydrogen separation.

Under oxygen transfer limitation and kinetic control, liquid-phase catalytic oxidation of toluene over metalloporphyrin was studied. An improved technique of measuring dissolved oxygen levels for gas-liquid reaction at the elevated temperature and pressure was used to take the sequential data in the oxidation of toluene catalyzed by metalloporphyrin. By this technique the corresponding control step of toluene oxidation could be obtained by varying reaction conditions. When the partial pressure of oxygen in the feed is lower than or equal to 0.070 MPa at 463 K, the oxidation of toluene would be controlled by oxygen transfer, otherwise the reaction would be controlled by kinetics. The effects of both oxygen transfer and kinetic control on the toluene conversion and the selectivity of benzaldehyde and benzyl alcohol in biomimetic catalytic oxidation of toluene were systematically investigated. Three conclusions have been made from the experimental results. Firstly, under the oxygen transfer limitation the toluene conversion is lower than that under kinetic control at the same oxidation conditions. Secondly, under the oxygen transfer limitation the total selectivity of benzaldehyde and benzyl alcohol is lower than that under kinetic control with the same conversion of toluene. Finally, under the kinetics control the oxidation rate of toluene is zero-order with respect to oxygen. The experimental results are identical with the biomimetic catalytic mechanism of toluene oxidation over metalloporphyrins.

Size-controlled Pd nanoparticles (PdNPs) were synthesized in aqueous solution, using sodium carboxymethyl cellulose as the stabilizer. Size-controlled PdNPs were supported on α-Al₂O₃ by the incipient wetness impregnation method. The PdNPs on α-Al₂O₃ support were in a narrow particle size distribution in the range of 1-6 nm. A series of PdNPs/α-Al₂O₃ catalysts were used for the selective hydrogenation of acetylene in ethylene-rich stream. The results show that PdNPs/α-Al₂O₃ catalyst with 0.03% (by mass) Pd loading is a very effective and stable catalyst. With promoter Ag added, ethylene selectivity is increased from 41.0% to 63.8% at 100℃. Comparing with conventional Pd-Ag/α-Al₂O₃ catalyst, PdNPs-Ag/α-Al₂O₃ catalyst has better catalytic performance in acetylene hydrogenation and shows good prospects for industrial application.

We have developed a process model to simulate the behavior of an industrial-scale pressurized Lurgi fixed-bed coal gasifier using Aspen Plus and General Algebraic Modeling System (GAMS). Reaction characteristics in the fixed-bed gasifier comprising four sequential reaction zones—drying, pyrolysis, combustion and gasification are respectively modeled. A non-linear programming (NLP) model is developed for the pyrolysis zone to estimate the products composition which includes char, coal gases and distillable liquids. A four-stage model with restricted equilibrium temperature is used to study the thermodynamic equilibrium characteristics and calculate the composition of syngas in the combustion and gasification zones. The thermodynamic analysis shows that the exergetic efficiency of the fixed-bed gasifier is mainly determined by the oxygen/coal ratio. The exergetic efficiency of the process will reach an optimum value of 78.3% when the oxygen/coal and steam/coal mass ratios are 0.14 and 0.80, respectively.

With CO combustion promoters, the role of combustion air flow rate for concerns of economics and control is important. The combustion air is conceptually divided to three parts: the air consumed by coke burning, the air consumed by CO combustion and the air unreacted. A mathematical model of a fluid catalytic cracking (FCC) unit, which includes a quantitative correlation of CO heterogeneous combustion and the amount of CO combustion promoters, is introduced to investigate the effects of promoters on the three parts of combustion air. The results show that the air consumed by coke burning is almost linear to combustion air flow rate, while the air consumed by CO combustion promoters tends to saturate as combustion air flow rate increases, indicating that higher air flow rate can only be used as a manipulated variable to control the oxygen content for an economic concern.

The processes of building dynamic and static relationships between secondary and primary variables are usually integrated in most of nonlinear dynamic soft sensor models. However, such integration limits the estimation accuracy of soft sensor models. Wiener model effectively describes dynamic and static characteristics of a system with the structure of dynamic and static submodels in cascade. We propose a soft sensor model derived from Wiener model structure, which is an extension of Wiener model. Dynamic and static relationships between secondary and primary variables are built respectively to describe the dynamic and static characteristics of system. The feasibility of this model is verified. Then the expression of discrete model is derived for soft sensor system. Conjugate gradient algorithm is applied to identify the dynamic and static model parameters alternately. Corresponding update method for soft sensor system is also given. Case studies confirm the effectiveness of the proposed model, alternate identification algorithm, and update method.

A dynamic experimental set-up was utilized to measure ibuprofen solubility in supercritical CO₂ at the pressure range of 8-13 MPa and the temperatures of 308, 313 and 318 K. Mole fraction values varied from 0.015×10^-3 to 3.261×10^-3 and correlated by using seven different semi empirical equations of state (Bartle, Modified Bartle, Mendez-Teja, Modified Mendez-Teja, Kumar-Johnson, Sung-shim and Gordillo) as well as seven cubic equations of state (van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, Peng-Robinson, Stryjek-Vera, Patel-Teja-Valderana and Pazuki). Single and twin-parametric van der Walls mixing rules (vdW1, vdW2) were applied in order to estimate the supercritical solution properties. The physicochemical properties were also obtained using Joback, Lydersen and Ambrose methods. Absolute average relatives deviation (AARD) were calculated and compared for all the correlating systems. Results showed that among the cubic equations of state (EOSs) the Pazuki equation (AARD 19.85% using vdW1 and AARD 8.79% using vdW2) and SRK equation (AARD 19.20% using vdW1 and AARD 10.03% using vdW2) predicted the ibuprofen solubility in supercritical CO₂ with the least error in comparison to the others. Among the semi-empirical EOSs the most desirable deviation (AARD<10%) was obtained by using Modified Bartle and Modified Mendez-Teja equations in all the studied temperatures.

The plasmid-expression system is routinely plagued by potential plasmid instability. Chromosomal integration is one powerful approach to overcome the problem. Herein we report a plasmid-free hyper-producer E. coli strain for coenzyme Q₁₀ production. A series of integration expression vectors, pxKC3T5b and pxKT5b, were constructed for chemically inducible chromosomal evolution (multiple copy integration) and replicon-free and markerless chromosomal integration (single copy integration), respectively. A coenzyme Q₁₀ hyper-producer Escherichia coli TBW20134 was constructed by applying chemically inducible chromosomal evolution, replicon-free and markerless chromosomal integration as well as deletion of menaquinone biosynthetic pathway. The engineered E. coli TBW20134 produced 10.7 mg per gram of dry cell mass (DCM) of coenzyme Q₁₀ when supplemented with 0.075 g·L^-1 of 4-hydroxy benzoic acid; this yield is unprecedented in E. coli and close to that of the commercial producer Agrobacterium tumefaciens. With this strain, the coenzyme Q₁₀ production capacity was very stable after 30 sequential transfers and no antibiotics were required during the fermentation process. The strategy presented may be useful as a general approach for construction of stable production strains synthesizing natural products where various copy numbers for different genes are concerned.

A new metal-organic framework of MIL-101 was synthesized by hydrothermal method and the powder prepared was pressed into a desired shape. The effects of molding on specific surface area and pore structure were investigated using a nitrogen adsorption method. The water adsorption isotherms were obtained by high vacuum gravimetric method, the desorption temperature of water on shaped MIL-101 was measured by thermo gravimetric analyzer, and the adsorption refrigeration performance of shaped MIL-101-water working pair was studied on the simulation device of adsorption refrigeration cycle system. The results indicate that an apparent hysteresis loop appears in the nitrogen adsorption/desorption isotherms when the forming pressure is 10 MPa. The equilibrium adsorption capacity of water is up to 0.95 kg·kg^-1 at the forming pressure of 3 MPa (MIL-101-3). The desorption peak temperature of water on MIL-101-3 is 82℃, which is 7℃ lower than that of silica gel, and the desorption temperature is no more than 100℃. At the evaporation temperature of 10℃, the refrigeration capacity of MIL-101-3-water is 1059 kJ·kg^-1, which is 2.24 times higher than that of silica gel-water working pair. Thus MIL-101-water working pair presents an excellent adsorption refrigeration performance.

Aqueous ammonia was used to pretreat wheat straw to improve biodegradability and provide nitrogen source for enhancing biogas production. Three doses of ammonia (2%, 4%, and 6%, dry matter) and three moisture contents (30%, 60%, and 80%, dry matter) were applied to pretreat wheat straw for 7 days. The pretreated wheat straws were anaerobically digested at three loading rates (50, 65, and 80 g·L^-1) to produce biogas. The results indicated that the wheat straw pretreated with 80% moisture content and 4% ammonia achieved the highest methane yield of 199.7 ml·g^-1 (based on per unit volatile solids loaded), with shorter digestion time (T₈₀) of 25 days at the loading rate of 65 g·L^-1 compared to untreated one. The main chemical compositions of wheat straw were also analyzed. The cellulose and hemicellulose contents were decomposed by 2%-20% and 26%-42%, respectively, while the lignin content was hardly removed, cold-water and hot-water extracts were increased by 4%-44%, and 12%-52%, respectively, for the ammonia-pretreated wheat straws at different moisture contents. The appropriate C/N ratio and decomposition of original chemical compositions into relatively readily biodegradable substances will improve the biodegradability and biogas yield.

Membrane fouling seriously restricts applications of membrane technology. A novel strategy was applied in this study to retard membrane fouling by changing operating pressure with the pressure responsibility membrane. A polyurethane-based hollow fiber membrane was used to treat surface water for evaluating the effect of operating pressure on membrane fouling. Some bench-scale tests in dead-end mode were carried out. In the experiments without backwashing, as operating pressure increased, severe membrane fouling occurred on membrane surface, while the permeate quality was improved obviously, which is considered to be due to shrinkage deformation. The total resistance, irreversible resistance and reversible resistance under different backwash pressures were determined in filtration/backwashing test. With the increase of backwash pressure, the total resistance decreased, and more importantly, the irreversible resistance also decreased, which implies that small particles deposited inside membrane pores and cake layers on membrane surface are effectively removed. Similar results could be obtained in mass balance tests. The results of the present study indicate that the application of pressure responsibility membrane in surface water treatment may be an effective strategy for reducing membrane fouling.

A facile and practical route was introduced to prepare LiFePO₄/C cathode material with nano-sized primary particles and excellent electrochemical performance. LiH₂PO₄ was synthesized by using H₃PO₄ and LiOH as raw materials. Then, as-prepared LiH₂PO₄, reduced iron powder and α-D-glucose were ball-milled, dried and sintered to prepare LiFePO₄/C. X-ray diffractometry was used to characterize LiH₂PO₄, ball-milled product and LiFePO₄/C. Differential scanning calorimeter-thermo gravimetric analysis was applied to investigate possible reactions in sintering and find suitable temperature for LiFePO₄ formation. Scanning electron microscopy was employed for the morphology of LiFePO₄/C. As-prepared LiH₂PO₄ is characterized to be in P21cn(33) space group, which reacts with reduced iron powder to form Li₃PO₄, Fe₃(PO₄)₂ and H₂ in ball-milling and sintering. The appropriate temperature for LiFePO₄/C synthesis is 541.3-976.7℃. LiFePO₄/C prepared at 700℃ presents nano-sized primary particles forming aggregates. Charge-discharge examination indicates that as-prepared LiFePO₄/C displays appreciable discharge capacities of 145 and 131 mA·h·g^-1 at 0.1 and 1 C respectively and excellent discharge capacity retention.

Based on modified silicon polyester resin in addition to several functional fillers such as corrosion-resistant fillers, heat-resistant fillers and thermal conductive fillers, a high thermal conductive coating can be made. On the basis of boronnitride (BN) and aluminum nitride (AIN) used as thermal conductive fillers and by means of the testing system of hot disk and heat transfer experiment, researches on the varieties of thermal conductive fillers and the effects of the contents of high-thermal conductive coating have been done, which shows that the thermal conductivity of coating increases with the increase of the quality fraction and the coefficient of thermal conductivity of the thermal conductive fillers of coating. With guaranteeing better heat resistance, stronger corrosion resistance and adhesive force, the coefficient of coating can reach a level as high as 3 W·m^-1·K^-1.

Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can affect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters.

Methyl N-phenyl carbamate (MPC), an important organic chemical, can be synthesized from aniline, CO₂ and methanol. Catalyst Cu-Fe/ZrO₂-SiO₂ was first prepared and its catalytic performance for MPC synthesis was evaluated. Then the influence of solvent on the reaction path of MPC synthesis was investigated. It is found that the reaction intermediate is different with acetonitrile or methanol as a solvent. With acetonitrile as a solvent, the synthesis of MPC follows the reaction path with diphenyl urea as the intermediate, while with methanol as a solvent the reaction occurs via the reaction path with dimethyl carbonate as the intermediate. The catalytic mechanism of cooperative catalysis comprising metal sites, Lewis acid sites and Lewis base sites is proposed according to different reaction intermediates.