The optimal position( l _opt ) of isolating the heat conduction axially through the oscillatory tube wall is investigated in the present paper. The maximum moving distance( L _max ) of the contact surface inside the tube is studied and a calculating formula of L max is derived. Based on the formula of L _max , the influences of some factors such as expansion ratio, ratio of filling time and discharge time, number of nozzle, and jet flow exciting frequency on l opt are analyzed. It is shown that the value of l opt predicted by the formula is higher than that of experiments. The formula of L max can only be used to calculate the approximate value of l opt . The relation between lopt and the axial temperature distribution of the tube wall is also investigated. Both the theoretical and experimental results show that the position where the axial temperature gradient of the tube wall reaches the maximum value is exactly the position of l _opt So the value of l opt can be determined simply by means of measuring the axial temperature distribution of the tube wall.

The plate-fin heat exchanger is normally designed with the assumption that the fluid is uniformly divided among all the core passages.However,the fluid flow maldistribution in plate-fin heat exchanger may be caused by many factors,such as improper entrance configuration,poor header design,manufacturing tolerance of passages and the heat transfer process itself.The objective of this paper is to study the effects of different inlet angles on the distribution performance of distributor.It is found that there is fluid flow maldistribution in plate-fin heat exchanger and the flow maldistribution in crosswise direction is more serious than that in ordinate direction.The experimental results also show that inlet angle and Reynolds number are the main factors affecting distributor performance and the distributor reaches the best performance when its inlet angle equals 45° under the experiment.The conclusions of this paper are of great significance for the optimum design of plate-fin heat exchanger.

Experiment results of the effect of internals in high density circulating fluidized bed (HDCFB) on gas dispersion were reported in this paper .Gas dispersion behavior was investigated by using steady gas tracer (propylene) technique and FCC particles (particle density 1398 kg·m ^-3 , mean diameter 54 μm) for a 0.186 m ID,9.0 m high riser.Experiment results indicated that gas mixing could be well described by a two-dimensional dispersion model. Due to internals, fluid in HDCFB experienced violent roll flowing,and radial distribution of gas concentration was more uniform than in that free bed.The radial dispersion coefficient showed a value of 1000 cm ²·s ^-1 ,a one and a half order of magnitude larger than that in conventional HDCFB.

A physically accurate and computationally effective implicit algorithm for injection mold process simulations is presented. The governing equations involving the pressure field and fill factor which tracks the location of the front surface are developed in terms of mass conservation for each control volume. The transient equations are solved in an iterative manner for both pressure field and fill factor for tracking the progression of the resin front in the mold cavity. The present formulations accurately account for and capture the physical transient nature of the mold filling process while maintaining improved numerical and computational attributes. The selection of time steps is based on accuracy considerations and resolution of flow front locations, which is free from the restrictions that exist in the traditional explicit finite element control volume based formulations. The time increments of the traditional explicit methodology are restricted so that no more than one complete control volume region is updated and filled at each time increment. In certain cases, more than one control volume may be simultaneously filled. The present methodology does not have such a restriction and computes the position of the flow front at each of the selected discrete time intervals. The computed position of the flow front at the end of a certain time interval is independent of the time step size used to reach that time interval.In the end,the methodology is used successfully in two examples.

Based on the frequency spectrum of pressure fluctuation of gas-solid two-phase flow and tube cross-section image reconstruction algorithm, as well as improved code with fluctation-tomography fuzzy discriminant analysis, uniform flow and stratified flow and the flow at which blockage of tube might happen were effectively detected by some experiments. These tomographic results demonstrate,that it is feasible to detect the flow pattern in horizontal tube by use of pressure fluctuation spectrum signature and tube cross-section image reconstruction algorithm with fluctuation-tomography fuzzy discriminant analysis.

A correlation for calculating the mass transfer coefficient of the adsorption process in the electrophoretic affinity chromatography (EAC) was established. Adsorption of human serum albumin (HSA) on Blue Sepharose Fast Flow(Blue)in alternating electric field was conducted at different electric field strength and alternating frequency to illustrate the effects of electroosmosis on the adsorption process of the EAC. The experimental results showed that the increase in current density led to corresponding increases in both electrosmotic flux and dynamic binding capacity. The mass transfer coefficient was obtained as a function of electric field strength, as indicated by current density, and alternating frequency. The occurrence of electrosmotic flux inside the porous gel particle greatly increased the speed of the migration of biological molecules towards the ligand immobilized in the inner surface of the particle and consequently resulted in an improved adsorption behavior, as shown by the increase in mass transfer coefficient. The results described in the present paper demonstrated the high potential of electroosmosis in the development of large scale electrophoretic chromatography of biological molecules.

Supercritical fluid chromatography (SFC) was used to study the adsorption equilibrium and mass transfer properties for eicosapentaenoic acid(EPA) and docosahexaenoic acid(DHA) on C 18 by means of impulse response technique. In order to estimate the adsorption constant and rate constants, a kinetic model was established. Chromatographic curves were calculated by using the parameters obtained from experiments, and the agreement between the experimental and calculated curves was good. It was indicated that adsorption equilibrium, axial dispersion, mass transfer and effective diffusion are important factors that influence the separation of EPA and DHA by SFC.

The copolymer of carbon monoxide with styrene is of great interest, because as a monomer, carbon monoxide is particularly plentiful and inexpensive, the presence of the carbonyl groups in the backbone makes the copolymer photodegradable and the copolymer can be chemically modified to become excellent starting materials for other classes of functional polymers. Copolymerization of carbon monoxide/styrene was catalyzed by a catalytic system comprising palladium acetate as precursor. Kinetic study showed that copolymerization underwent a short transition period, in which the real active species were produced. The activity and life of the catalytic system are influenced by a number factors, such as the structure of ligands and their amounts. The mechanism of initiation and the catalytic cycle for the copolymerization were studied. Additionally, through parallel experiments, we concluded that different ligands and their amounts influenced the coordinating structure of the species as well as their catalytic activity and life.

Cylindrical pellet catalyst was made from strong acid cation exchange resin S-54 particles. Ethyl tert butyl ether (ETBE) was synthesized with this kind of catalyst by using ethanol (EtOH) and tert butyl alcohol (TBA) as the starting materials. Experiments were carried out in the liquid phase under atmospheric pressure with a stirred batch reactor. Mechanism studies have shown that three reactions (dehydration of TBA, EtOH with TBA, and isobutene(IB) with EtOH) take place simultaneously. It was found that catalyst size and stirring speed had no significant effect on reaction rate. Other influence factors, such as temperature, catalyst amount, molar ratio of ethanol to tert butyl alcohol and the effect of water inhibition on synthesis reaction were studied. A kinetics model, which included seven parameters, was obtained by curve fitting method. The experimental results agreed well with the model. The kinetics parameters of pellets catalyst was compared with particles catalyst. While the catalytic activity of pellets catalyst was lower than particles catalyst for the reason of the shield action of binder, however, it would be useful in the larger scale production of ETBE.

In a 0.5 meter diameter semicircular jetting fluidized bed with 42mm diameter semicircular nozzle,the transition of flow regime and the penetration depth were investigated.The penetration depth was recorded by a National M-7 video camera and analyzed frame to frame on a Panasonic HD-100 player.There were two flow patterns of jet and spout in a large jetting fluidized bed with increasing jet gas velocity.Spout appeared when jet gas velocity was high and static bed height was relatively low.The results from processing the signals of pressure fluctuation by multistage power spectrum analysis showed that the major frequency of pressure fluctuation increased with jetting gas velocity.On the basis of the experimental data,an equation describing flow regime transition was presented.Meanwhile,experimental data showed that penetration depth increased with increasing of jetting gas velocity.A correlation to calculate penetration depth was also proposed.

Biofilm is one of the main factors that influence metal corrosion in seawater environment.According to the structure and property of biofilm,a natural biopolymer gel,Calcium Alginate,an extracellular biopolymer containing carboxylate functional groups,was deposited on metal surfaces to form films.Simulated biofilm environment was produced.Corrosion behavior of carbon steel A3,low-alloyed steel E2,10CrMoAl and 1Cr18Ni9 stainless steel was studied by various electrochemical method,including measurements of corrosion potential, polarization curves, and electrochemical impedance spectra.Film coated sample surface was characterized by ESEM.The results show that such an approach is informative to reveal “how” and “to what extent” biofilm influences metal corrosion process during intial biofilm forming stage.

A flow apparatus for measuring heat of vaporization of liquids under pressure up to 6 MPa,and temperature from 260 K to 480 K is developed.Heats of vaporization of water are measured,and the differences of our experimental results with literature values are within 0.85%.The heats of vaporization HFC134a and HFC125 used as the alternatives of refrigerant Freon are determined, and 14 values of heat of vaporization are reported in this paper.

The relationship between mean inlet drop size and separation efficiency of reducing section,tapered section,parallel section and the whole hydrocyclone is discussed in this paper.The effect of operation parameters such as feed flowrate, split ratio on mean oil drop size in the wall of each part in hydrocyclone is also investigated.The result suggests that separation efficiency of the reducing section,tapered section and the whole hydrocyclone increased with increasing inlet droplet size,whereas the separation efficiency of parallel section does not vary very much.When inlet flowrate is high enough,mean droplet sizes in the wall of hydrocyclone decreases with increasing feed flowrate.The split ratio has little influence on mean droplet sizes on the wall of hydrocyclone,and mean oil droplet diameters decreases along the axial direction under same operation condition.

The kinetics of supercritical chelating extraction of heavy metal from a Chinese traditional medicine material was investigated.The extraction efficiencies of the heavy metals increased rapidly within the first 15min extraction at 40℃ and 20.0MPa by CO ₂ modified with 5% ethanol solution containing 1% diethylammonium diethyldithiocarbamate as chelating reagent.Then, the extraction efficiencies increased slowly with time while that of Pb leveled off.The results indicated that the contents of trace heavy metals in the sample had major effects on the extraction rates when the chelating reagent was excessive.The chelating reaction is the rate-controlling step.The extraction of trace heavy metals from the Chinese traditional medicine material is controlled by a pseudo-first-order chelating reaction.

Petroleum coke with high sulfur has high fixed carbon, high heating value and low ash content.Using it as fuel may not only alleviate energy shortage,but also convert it into a useful material.Its combustion characteristics and pollutant emission are not very clear.This paper investigates the combustion characteristics and pollutant emission of petroleum coke in circulating fluidized bed boiler.The results show that petroleum coke with high sulfur can be used as a fuel in industry,its combustion is stable and pollutant emission satisfies national environmental standard.

Vacuum residuum is mixed with FCC slurry oil and the mechanism of residuum modification FCC slurry oil is studied.In the course of mixed residuum with FCC slurry oil,there are two competitive processes of solution and adsorption.The solution process means that some components with similar structure and solubility parameter from FCC slurry oil and residuum will dissolve in each other and small molecules will be freed from the surface of big molecules;The adsorption process means that asphaltene adsorbs molecules with polarity similar to and some molecules with similar surface structure adsorb on each other with small particles aggregating into big ones.The process of solution is balance with process of adsorption.When the ratio of FCC slurry oil is lower;while the process of adsorption predominates,when the ratio of FCC slurry oil is higher.The combination of the two competitive processes changes the composition and compatibility of residuum colloidal system,which leads to the decrease of solvent power and stability of residuum.The properties of mixed residuum that change with temperature should be further studied.

Active carbon supported H ₃PW ₁₂ O ₄₀ (PW ₁₂ )solid acid catalysts are prepared and used in the etherification of light FCC gasoline with methanol.The effects of preparation conditions and the PW ₁₂ loading on the activities of PW ₁₂ (40)/C catalysts are studied.The results showed that the reflux time and the activating temperature influence the activity of the catalyst.As the loading of PW ₁₂ on active carbon is lower, the reaction of PW ₁₂ with the hydroxyl on the surface of active carbon makes the activity of the catalyst decrease.With the increase of loading of PW ₁₂ on active carbon, the activities of the catalysts increase.Using PW ₁₂ (40)/C as catalyst,under the conditions of reaction temperature 75℃,pressure 0.8MPa,molar ratio of methanol with tertiary carbonic olefins 1.0,and hourly space velocity 1.0 h ^-1 ,the ethers content in etherified light gasoline is up to 13.86%.