The objective of this paper is to investigate the influence of the surface properties of polymer film on dropwise condensation heat transfer of steam, in order to prepare a viable polymer film sustaining long- term dropwise condensation. The PTFE films are coated on the external surfaces of brass tubes, copper tube, stainless steel tube and carbon steel tube by using the dynamic ion- beam mixed implantation technique, under a variety of surface processing conditions. It is found that the surface properties are greatly dependent on the surface processing conditions, and hence leading to different condensation modes and heat transfer characteristics. The experimental results indicate that condensation heat flux and heat transfer coefficient are increased by 0.4-1.5 times and 1.6-28.6 times of film condensation values, respectively, for the brass tubes treated under different conditions. Meanwhile, the surface processing condition is also crucial to the adhesion between polymer film and metal substrate. The fact that different substrate materials require different optimal processing conditions and demonstrate different condensation heat transfer coefficient, can be drawn from the present results.

The effect of volumetric oxygen transfer coefficient (kL_a), on the performance of producing pyruvate by a multi - vitamin - auxotrophic yeast of Torulopsis glabrata , was investigated in batch fermentation process. High yield of pyruvate to glucose (0.797 g·g^-1) was achieved at higher kL_a (450 h^-1), while the glucose consumption rate was low (1.14 g·L^-1·h^-1). Glucose consumption was enhanced at lower kLa (200 h^-1), however, the yield of pyruvate to glucose decreased to 0.483 g·g^-1. Based on the characteristics of process parameters and carbon flux distribution, a two - stage oxygen supply control mode, in which kL_a was controlled at 450 h in the first 16 h then switched to 200 h after 16 h, was proposed and experimentally verified. Relative high concentration of pyruvate (69.4 g·L^-1), high yield of pyruvate to glucose (0.636 g· g^-1), and high glucose consumption rate (1.95 g·L^-1·h^-1) was achieved by applying this mode. The productivity (1.24g·L^-1·h^-1) was improved by 36% , 23% and 31% than the cases of constant KL_a (450 h^-1, 300 h^-1 and 200 h^-1), respectively. Experimental results indicate that the difference between the performance of producing pyruvate under favorable state of oxygen- supply was caused by the different energy state of cell, which may be due to the different regenerated pathways of NADH generated from glycolysis.

The effects of different fed-batch methods on the biomass and ergosterol content in Saccharomyces cerevisiae were studied. The relationships of such parameters as pH, DO and concentration of glucose with biomass and ergoterol content were discussed under the circumstances of constant feed rate fed - batch, constant glucose - concentration fed - batch, exponential fed - batch, DO - control exponential fed - batch, pulse fed -batch, DO-control pulse fed-batch. Explanations and analysis of these phenomena were provided. According to the results of experiments, DO -control pulse fed- batch is an effective method for the fermentation of ergoterol. Compared with the traditional method, the actual yield (the product of biomass and ergoterol content) could be improved by 20% .

Aminotransferase is one kind of important enzymes for the enzymatic preparation of amino acid. In the paper, the condition of fermentation for aminotransferase is optimized by low sensitivity robustness design according to the stability of fermentation process. After experiments, the volume of air and velocity of agitation are the two main factors affecting the production of enzyme, while other factors such as bath, pH value and temperature do not affect the fermentation result. The optimium condition is: air 0.6 L·min^-1, agitation 500 r·min^-1, pH6.5, 35℃, C. S. L2%. The results of fermentation with aminotransferase are very stable.

The activities of cellulase in 10%-40% ethanol- water solution were investigated at temperatures of 20-40 ℃ and at pressures of 0.49-4.41 MPa. These data obtained are essential to purify cellulase by high pressure CO₂. The experimental results indicate that CO2 pressure is not the key factor of the loss of enzyme activities, but ethanol concentration and temperature markedly influence recovered activities. The optimum operating conditions are 30 % ethanol concentration solution and 35 ℃ for cellulase- ethanol- water systems using high pressure CO₂.

The initial formation process of mixed fouling of Pseudomonas fluorescent and CaCO₃ on the different solid surfaces in a simulated cooling water system was investigated. The mixed fouling behavior on different solid surfaces under the conditions of different CaCO₃ saturation levels and bulk velocities was examined, and the growth curves of mixed fouling were obtained. The results showed that the average mass of mixed fouling was less than that of biofouling. In the unsaturated CaCO₃ solution, the average mixed fouling mass was little; but in the saturated CaCO₃ solution, with the saturation level of CaCO₃ and bulk velocity increasing, the average mass and induction period of the mixed fouling decreased. The mixed fouling mass on non- metallic material surfaces was more than that on metal material surfaces. It was also found that CaCO₃ particles were adsorbed to the surfaces firstly, then microbes were adsorbed. The existence of CaCO₃ inhibited the combination of microbes with surfaces, on the other hand, the adsorption and growth of microbes suppressed CaCO₃ fouling development.

Experiments were conducted to investigate the influence of additives CaO, Fe2O3 and Al2O3 on bed sintering, while waste salty liquids are treated in fluidized bed with sand or coal ash as bed material. The results show that CaO and Fe2O3 can solve successfully bed sintering problems, provided Na2CO3 is formed in sand or coal ash bed, however, Al2O3 can cause serious bed sintering at bed temperature. If NaCl is formed in the sand bed, Al2O3 can solve successfully the bed sintering, CaO and Fe2O3 have some effect on preventing bed from sintering, but these two additives can’t solve the problem completely. If NaCl is formed in coal ash bed, CaO and Fe2O3 can solve successfully the bed sintering, however, Al2O3 can cause bad bed sintering. These results provide the base for the design and operation of fluidized bed incinerator for treating waste salty liquids.

The irregular A301 ammonia synthesis catalyst is spheroidized by means of shape factor and equivalent diameter. The tortuosity factor of irregular A301 catalyst is determined by single pellet string reactor method (SPSRM). So a one - dimensional isothermal multi- component diffusion ?reaction model is established in the irregular A301 ammonia synthesis catalyst based on the intrinsic kinetics under high pressure. The orthogonal collocation method as well as Broyden method was used to solve the model equations. The intraparticle diffusion efficiency factor and the concentration distributions of individual components in the catalyst are obtained. The model is verified by the global kinetics data under high pressure obtained in a gradientless reactor. The calculation data agree well with experimental data, so the spheroidized model can be used to describe the diffusion- reaction process in the irregular catalyst and to calculate the intraparticle diffusion efficiency for engineering design.

The reaction kinetics for the liquid phase synthesis of methyl acetate for the removal of dilute acetic acid in waste water using a macroporous sulfonic acid ion exchange resin as catalyst was determined experimentally in a continuous stirred tank reactor in temperature range 308-328 K at 101. 325 kPa. The experimental results could be described by a model based on Langmuir- Hinsewood rate expression in liquid phase activities from Wilson method. Based on the model, it was indicated by the simulation of the reaction that catalytic distillation is an effective method for the removal of the acid from waste water.

Roughing method to obtain symbol series of time series is refined in this research. Pressure fluctuation time series under various operating conditions, such as different flow regimes, static bed heights and average particle diameters, are analyzed in various scales through algorithm complexity for the first time. The result indicates that different trends of algorithm complexity in different scales correspond to the dynamic characteristics in fluidized bed. Algorithm Complexity C ( n ) is an explicit indicator of different fluidization regimes and different scales are distinct expressions of different fluidized phases. The larger scales are sensitive to bubble phase, and the smaller scales are sensitive to milk phase. Therefore, it reflects the dynamics of fluidized beds in various dimensions and gives more information than that of single scale. It is a new method for nonlinear analysis of pressure fluctuation time series.

By using wavelet decomposition, filtering and reconstructing, noise signal could be deleted from thermogravimetry signal. It can help researchers to gain true parameters about kinetic characteristics. Different process methods were compared; several rules of threshold selection for wavelet noise removal were studied. Some parameters of processed signal curve were calculated by different threshold selection rules. By utilizing this information, the characteristics of this processed signal by different threshold selection rules were confirmed. Power-spectrum analysis was used to change the time- varying information into frequency distribution information. Quantitative comparison of signals could be made. Wavelet transform is an effective and accurate method, which can be used in thermogravimetry signal processing.

Pressure fluctuations are always the focus of discussion in fluidized field for a long time because their measurement is easy and ample information on fluidized state is included. Many investigators have studied fluidized-bed system by measuring pressure fluctuations. Recently, many researchers have recognized that fluidized-bed systems exhibit chaotic characteristics by analyzing pressure fluctuations. However, there are always noises in pressure fluctuations due to many unexpected reasons. As everyone knows, noises would affect the accuracy and result of chaotic computation and nonlinear analysis. So, different authors filtered firstly the noises by applying different threshold of low-pass filtering frequency such as Pence et al[11] , using 40 Hz as threshold of low-pass filter in order to eliminate high-frequency line noise, Bai et al[2] , Daw and Halow[12], using 20 Hz as threshold of low-pass filter, and so on. But no researches have been conducted to clarify what threshold of low-pass filter is exactly in pressure fluctuations. Because too low threshold of low-pass filter would make the information contained in pressure signals lose, and too high threshold of low-pass filter would induce noise and make a mess of analysis results.In this paper, the signals of pressure in abubbling fluidized bed, 0.30 m in diameter and 3.8 m in height are decomposed into signals of different frequency band including 0-10 Hz, 10-20 Hz, 20-30 Hz, 30-40 Hz, 40-50 Hz, 50-60 Hz and more than 60 Hz by Fourier transform. The linear and nonlinear correlation characteristics of signals of different frequency band are studied using auto- correlation function and mutual information function, respectively. It is the fist time that the signals of more than 30 Hz in frequency are confirmed to be not of linear correlation and the signals of more than 40 Hz in frequency to be not of nonlineal correlation . Therefore, the signals of more than 40 Hz in frequency could be considered as noise for no correlation in any time interval. Meanwhile, the signals of less than 40 Hz in frequency should be considered rather than 20 Hz as before if more details on fluidized bed are to be obtained by studying pressure signals.

The products of the square - root of internal pressure A and the molar volume of the repeated unit Vm for various polymeric liquids at 298.15 K are plotted against their van der Waals volumes . A straight line through the origin of coordinates is obtained. This means that the A Vm of polymers has good group additivity . Therefore, a method of group contribution which can be used to predict the internal pressure of polymeric liquids is established. Combining with Small’s molar- attraction constants , the values of new solubility parameter defined by the authors’ previous work for various polymers at 298.15 K can be obtained from this method.

With the rapid progress of nonlinear theory and experimental technique, chaotic dynamics has been widely used in a lot of fields of science and technology. Correlation dimension is an important parameter to characterize the nonlinear time series produced from a dynamical system. Now, wavelet analysis is a rapidly developing domain of applied mathematics. So, in this paper, a new method to calculate the correlation dimension of a nonlinear time series has presented with wavelet analysis. Based on emulation calculation with Henon map and Ikeda map, it is found that the correlation dimension of the small- scale wavelet transform modulus of a nonlinear time series produced from a chaotic dynamical system is the same as the system itself. The calculation results show that calculating the correlation dimension with the small- scale wavelet transform modulus can efficiently eliminate the effect of strong large- scale noise because of the high- pass filtering characteristic of small - scale wavelet transform. At last, it is also found that this method can be used to estimate the correlation dimension of the fluctuant velocity of hydrogen jet flow.

It is very important to find a effective method to extract the extracelluar polymeric substances (EPS) including polysaccharides, proteins and DNA, which have a significant role in the metabolism of the cells and the mass transfer of substrate within the biofilms, from biofilms without destroying its structure. In this study, a novel method to extract the EPS from intact biofilm was set up, based on the enhancement of external alternating electric field. The results showed that the current had insignificant effect on the cells structure, but it could enhance the extraction rate when charged extractant is used. In the range from 10 Hz to 500 Hz, the extraction rate increased with current frequency.

A new technique of lower electricity consumption electrolysis producing H₂ has been developed, and the factors affecting producing H₂ production were investigated. The results found that under the same electrolysis conditions, H₂ production on the cathode increased with increasing electrolyte solution alkalinity; but decreased with increasing zinc ion concentration in the electrolyte solution. The results also revealed that H₂ production on the cathode fluctuated with increasing electrolysis voltage, and reached a maximum when the voltage was at 0. 6 V. In a certainty range, it would be favorable to reduce the electricity consumption in H₂ production with increasing electrolyte solution alkalinity; but the electricity consumption would be increase when electrolysis voltage was higher. Compared with producing H₂ from H₂O, the electrolysis voltage was lower by about IV, and the electricity consumption of H₂ also decreased by 50% .

Based on the principle of exergy- economics, an approach of synchronized design for thermal pipeline and its insulation from the point of profit is proposed. An equation for annual net profit of thermal pipeline and its insulation is derived by taking into account the convective heat transfer inside the pipe. By this equation, the effect of pipe diameter and insulation thickness on the annual net profit is analyzed. In addition, to increase the annual net profit of transporting the working media in the thermal pipeline, an equation is proposed to calculate the optimal pipe diameter and insulation thickness.

A fluid flow model of distributor was set up to investigate the effectof distributor configuration on the fluid flow distribution in plate- fin heat exchanger. At the same time, a mathematical equation was developed to generate different types of fluid flow maldistribution models considering the possible deviations in fluid flow. Using these fluid flow models, the fluid flow distributions in plate- fin beat exchanger were calculated for different configurations and operating conditions. The computational results show that nonuniform inlet velocity, inlet angle, and orifice diameter on the fin are the main factors affecting the distribution performance of distributor. The fluid flow distribution in plate- fin heat exchanger can be effectively improved by changing the distributor configuration. The distributor reaches the best distribution performance when the orifice diameter is 2 mm. The computational results are in good agreement with experimental ones.

The pervaporation of organics from dilute aqueous solution through a novel plate composite silicone rubber membrane was investigated. The measured and derived data indicated that the composite membrane possessed very high permeation flux and stable selectivity for dilute organic aqueous solution. Based upon the well- known resistance-in- series model, diffusive mass transfer behavior in membrane was investigated by calculation from the measured data with different skin layer thickness of membranes. The experimental results showed that the diffusive mass transfer coefficient conformed to Arrhenius correlation with temperature and was independent of the flow status. The diffusivities of the given alcohols in membrane had an order of magnitude 10 m-10·s-1 at a wider range of temperature, which is similar to those reported in literatures.