Showing papers in "CIESC Journal in 2011"

Heat transfer characteristics of flat micro-heat pipe array

Abstract: Various flat micro-heat pipe arrays with miniature axially grooves for electric chip cooling are constructedA series of experiments including start-up time,temperature distribution and heat flux with different working fluids and filling factors are carried outThe result shows that flat micro-heat pipe arrays have advantages of quicker start-up,less temperature difference and better heat transferR141b,acetone,methanol and ethanol are used as working fluidsFlat micro-heat pipe arrays filled with methanol have the best heat transfer performanceThe maximum heat flux can reach 102 W·cm-2 while the chip is maintained at its working temperature,below 70℃The best filling factor of methanol is 03 for high heat flux

Multi-mode process monitoring method based on PCA mixture model

Abstract: Traditional multivariate statistical fault detection methods are designed for single operating conditions and may produce erroneous conclusions if used for multi-mode process monitoring.A novel multi-mode process monitoring approach based on PCA mixture model is proposed in this paper.First,the PCA technique is used to reduce the dimension of original variables and to guarantee the nonsingular covariance matrix.In order to overcome the limitations of EM(expectation-maximization),the BYY(Bayes Ying-Yang)scale-incremental EM algorithm is then adopted to automatically optimize the number of mixture components.With the obtained PCA mixture model,a novel process monitoring scheme is derived for fault detection of multi-mode processes.The validity and effectiveness of the proposed monitoring approach are illustrated by numerical example and the TE process.The results show that the proposed algorithm can achieve good parameter estimation of the mixture model with correct model selection.Therefore,it can achieve accurate and early detection of various types of faults in multi-mode processes.

Heat and mass transfer in vacuum membrane distillation

Abstract: Heat and mass transfer processes in a vacuum membrane distillation(VMD)were studied.A theoretical model that considers the temperature polarization and concentration polarization was used in the calculation of VMD process.It was found that as temperature increased,the mass transfer coefficient Km increased,the temperature polarization coefficient(TPC)decreased,the concentration polarization coefficient(CPC)increased,and the flux increased nearly exponentially.As the feed velocity increased,TPC and heat transfer coefficient hf increased,CPC decreased slowly,Km and the flux increased slowly.The flux decreased with the increase of number of fiber.As the vacuum increased,the TPC decreased,CPC and flux increased.The calculated results were in good agreement with the experimental data.

Dependent function analytic hierarchy process model for energy efficiency virtual benchmark and its applications in ethylene equipments

Abstract: The existed evaluation of energy efficiency of ethylene equipments does not consider the different raw materials,process technology and equipment sizes,and ignores the relative factors of energy efficiency index,so it cannot analyse the saving energy choice among energy consumption factors.The paper puts forward the energy efficiency analysis method for ethylene equipments according to technologies,scales and data distribution of energy consumption including fuel,power,steam and water inner ethylene process boundary.Furthermore,energy efficiency virtual benchmarking method is proposed based on dependent function analytic hierarchy process model(DFAHP),with which it can manipulate multi-factors and energy efficiency index together.It outweighs the traditional evaluation method such as the mean method and optimal index method.The applications of an ethylene equipment,even the whole ethylene industry for energy efficiency analysis are tested.The validity of proposed method is verified,which is more helpful to find the saving energy chance and quantified energy targets.

Cooling water fouling resistance prediction of plate heat exchanger based on partial least-squares regression

Abstract: A fouling test system was set up to measure water quality parameters of natural cooling water circulation from Songhua river,such as iron ions,chloride ions,total bacteria,pH,dissolved oxygen,turbidity and electric conductivity at different time,flow rates and water temperatures.A partial least squares regression(PLS)model was built,with a set of data measured as the input variables,to predict the fouling characteristics of the plate heat exchanger,which are iron ions,chloride ions,total bacteria,pH,dissolved oxygen,turbidity,conductivity,etc.The input water quality parameters were selected randomly.In the experiment,the hot water inlet temperature was between 43.5℃ and 44.5℃,cooling water inlet temperature was between 21.5℃ and 22.5℃,and water velocity was 0.104 m·s-1.The calculation shows that the PLS model contains four latent variables.Compared with the experimental results,the maximal relative error of the model was in 5.11%.The partial least-square regression algorithm of fouling model is reasonable and feasible.

Experiment and analysis of ammonia escape from decarburization absorbent inhibited by NHD

Abstract: CO2 is the most important greenhouse gas,and reducing its emission has caught wide attention.It is very important to develop CO2 capture technology for coal-fired power plants,which account for major greenhouse gas emission in China.Using ammonia solution to absorb CO2 from flue gas is expected to realize low cost and high efficiency.However,this technology faces a problem of escape of ammonia.This paper focuses on the problem of ammonia escape in ammonia decarburization process,through a series of experiments on NHD(polyethylene glycol dimethy ether)inhibiting effects in bubbling absorption of ammonia.The impacts of NHD and ammonia concentrations on ammonia escape were studied,and NHD inhibition mechanism of ammonia escape was analyzed.The results showed that NHD showed inhibition for ammonia escape and enhanced removal of CO2 at the same time.The amount of escaping ammonia was reduced by 24.86% and the removal efficiency for CO2 increased by about 10% when 5% NHD was added to decarburization solution.The results could provide reference for further research of ammonia method to capture CO2.

Effect of alkali metal on rate of coal pyrolysis and gasification

Abstract: The effect of alkali metal(AM)on crystallite structure of chars prepared by the pyrolysis of original and acid-washed coal without and with AM at 800—1050℃ in tubular furnace was investigated by XRD (X-ray diffraction) technique.The pyrolysis of coal samples and the gasification of chars were studied by PTGA (pressurized thermogravimetric analysis).The results show that both coal pyrolysis and gasification is affected by AM.At pyrolysis stage,the existence of AM inhibits the progress of char graphitizing,promotes the pyrolysis reaction and reduces its activation energy; at char gasification stage,AM is a catalyst,reduces gasification activation energy,goes up rate and prolongs the time to reach the maximum gasification rate.Modified random pore model can be used to describe the char-CO2 gasification process properly.

Mass transfer characteristics in heat-source tower

Abstract: Through analyzing the characteristics of equipment for cooling/heating,the superiority of a heat pump with heat-source tower for cooling/heating is presented.With different inlet air parameters and inlet solution temperatures,four different modes of mass transfer in the heat-source tower were discussed theoretically and the latent heat percentage,humidity difference of inlet and outlet air streams,and heating capacity with different inlet parameters were studied by experiments.The experimental results showed that as the inlet solution temperature increased from-2℃ to 4℃,the latent heat percentage reduced from 27% to zero.With the increase of the air flow rate and inlet air temperature,the latent heat percentage decreased and the total heat transfer rate increased.As the flow rate of solution increased from 2.9 L·min-1 to 6.4 L·min-1,the latent heat percentage was raised from 15% to 28% and the total heat transfer rate was also increased nearly 50%.Experimental data also showed that the latent heat percentage in the heat-source tower was usually less than 30%,which provided a guide for control of solution concentration and regeneration of solution.

Effect of seed particles on acoustic agglomeration efficiency

Abstract: Fine particle agglomeration technique is an effective method to control the air particle pollution,and acoustic agglomeration is considered as one of the most promising techniques.In this study,large size lime seed particles were introduced to the acoustic agglomeration experiment at low frequency(1000—2000 Hz).The distribution of fine particles was measured online by electrical low pressure impactor(ELPI)to investigate the effect of lime seed particles on acoustic agglomeration.The results show that the acoustic agglomeration with lime seed particles can attain higher agglomeration efficiency,with the best efficiency of 70.5%.For the cases with low acoustic agglomeration efficiency,the introduction of lime seed particles improves the agglomeration efficiency significantly,and the highest increment in agglomeration efficiency reaches 15.5%.The agglomeration efficiency depends on the sound frequency,sound pressure level,residence time,amount and size of seed particles.The introduction of lime seed particles can expand the "frequency window" and give a better agglomeration effect even at lower sound pressure level,and decrease the dependence on the size of agglomeration equipment,which improves the performance of acoustic agglomeration and reduces the energy consumption.The results show that the amount of seed particles should be appropriate and excessive seed particles will reduce the agglomeration efficiency.The size of seed particles should be moderate,otherwise the improvement of agglomeration efficiency is limited.

Laminar flow characteristics in in-line arranged micro-cylinder groups

Abstract: The flow field,pressure filed and friction characteristics of laminar flow in in-line arranged micro-cylinder groups were numerically investigated using de-ionized water as working fluid at low Reynolds numbers.The friction factors in the micro-cylinder group(cylinder diameter D=0.5 mm,cylinder height H=1.00,0.75,0.50 and 0.25mm)were measured.It was found that the friction factor decreased with the increase of micro-cylinder height due to the end-wall effect,and the correlations available could not predict the friction characteristics very well.A 3-D model was employed to simulate the vortex distribution in the in-line micro-cylinder groups with different geometrical parameters,including the diameter(0.5 mm)and height(0.25,0.50,0.75,and 1.00 mm)of micro-cylinder,pitch(0.75,1.00,and 1.25 mm),and number of rows(3,5,7,9)and columns(5,10,15,20)of micro-cylinder.It was found that the vortex number increased with the pitch ratio,so that the friction factor increased.The friction factor for the in-line arranged micro-cylinder group decreased with the increase of the cylinder height and the decrease of the column number,but the influence of the row number on the friction factor was negligible.A new correlation was obtained to predict the friction factor of laminar flow in the in-line arranged micro-cylinder group and the deviation of predictions from experimental results is 10%—25% at 40Re150.

Numerical study on temperature field of a large floating roof oil tank

Abstract: Accurate prediction of oil temperature in a large floating roof oil tank is very important for both strategic and commercial storage of crude oil.The oil temperature in the tank is influenced by many factors such as atmosphere temperature,thickness and conductivity of insulation coat,solar radiation intensity,soil physical property etc.In this study,these factors are considered in the model establishment to predict the temperature field of a large floating roof oil tank.A SIMPLE code is developed to calculate the coupled heat transfer among buoyancy chamber,oil,soil and insulation coat.The effects of solar radiation and thickness of insulation coat on oil temperature are studied.The numerical results are compared with and agreed well with field test data.

Optimization and simulation of sinter cooling process

Abstract: Through studying a 360 m2 sinter cooler in an iron and steel company,a mathematical model for heat transfer in sinter cooling process is established.This model is based on the porous medium model,in which the momentum equation is corrected by Ergun equation and the energy equation is corrected by the two energy equations for local non-equilibrium thermodynamics.This model is solved with the user defined functions(UDF)and the user defined scalars(UDS)in the platform of computational fluid dynamics software,Fluent6.3.The sinter size,inlet velocity,material height,porosity and inlet temperature are the main parameters affecting the waste heat recovery efficiency.The five parameters are simulated and their optimal combination is determined by orthogonal experimental method for improving the waste heat utilization,which are as follows: sinter size 0.025 m,inlet velocity 7.65 m·s-1,material height 1.8 m,porosity 0.45,and inlet temperature 414 K.This model is verified reliable by comparison with the test data.The method can be used for design of sinter coolers.

Coupling model of gas-steam-electricity and its application in steel works

Abstract: Based on periodical change of generation,storage and consumption of byproduct gases,the features of supply-demand change of steam and electricity for each period,aimed at minimizing energy consumption and optimal benefit of cost-effective,a multi-period coupling model of surplus byproduct gas,steam and electricity in iron and steel works was formulated.The model is implemented by ILOG Cplex and the optimal distribution scheme of byproduct gases,MP steam,LP steam and electricity is obtained.The results indicate: the model can distribute the energy medium reasonably,safely and efficiently,such as surplus byproduct gases,steam and electricity,for improving energy utilization efficiency and decreasing the product cost.

Online nonlinear process monitoring using kernel partial least squares

Abstract: To handle the nonlinear problem for process monitoring,a new technique based on kernel partial least squares(KPLS)is developed.KPLS is an improved partial least squares(PLS)method,and its main idea is to first map the input space into a high-dimensional feature space via a nonlinear kernel function and then to use the standard PLS in that feature space.Compared to linear PLS,KPLS can make full use of the sample space information,and effectively capture the nonlinear relationship between input variables and output variables.Different from other nonlinear PLS,KPLS requires only linear algebra and does not involve any nonlinear optimization.For process data,firstly KPLS was used to derive regression model and got the score vectors,and then two statistics,T2 and SPE,and corresponding control limits were calculated.A case study of the Tennessee-Eastman(TE)process illustrated that the proposed approach showed superior process monitoring performance compared to linear PLS.

Energy-saving analysis of solution regeneration in heat-source tower based on recovery of air energy

Abstract: The heat-source tower heat pump system was analyzed and the problem of solution regeneration in winter was presented.Considering the characteristics of low moisture absorption of the solution,a new regeneration design of heat-source tower based on recovery of air energy was proposed,and theoretical analysis of regeneration performance was conducted.Mathematical models of the components,including compressor,heat exchanger,expansion valve and regenerator of solution were built and the whole regenerative system was simulated.The results showed that with the increase of inlet solution temperature in the condenser from 18℃ to 28℃,the regeneration rate increased linearly from 17.7 kg·h-1 to 26.7 kg·h-1,the COP of the system kept constant at 4.3,the latent heat percentage increased from 68.3% to 82%,and the COP of latent heat increased from 2.8 to 3.5.Compared with the traditional regeneration system,this system consumed less energy,and had higher energy efficiency,promising huge energy-saving potential.

Gas explosion venting of premixed gases in linked vessels

Abstract: The experiment about explosion venting process of methane-air mixture in linked vessels was conducted.It was compared with the single closed container explosion process.The law of pressure variation in linked vessels and the influence of gas concentration and the way of explosion venting are studied.It was concluded that the maximum explosion pressure usually appeared at the end of the pipe.Vacuum appeared because of pressure vibration in the sphere vessel.The same as single vessel,the explosion pressure was higher when the volume concentration of methane was a little more than stoichiometric ratio comparing with the lower concentration.Two vent ports decreased the maximum pressure in the linked vessels better than only one port.The conclusions provided scientific basis in engineering for safety design of gas explosion venting of linked vessels.

Development and application of advanced process control system for ethylene cracking heaters

Abstract: The advanced process control systems for the SC-1 type ethylene cracking heaters at Lanzhou Petrochemical Company 460KTA Ethylene Plant were designed,including the average coil outlet temperature controllers,the pass outlet temperature balance controllers,the total throughout controllers.The software and hardware structure of the control systems,the switching logic between advanced control and DCS regular control,the DCS operation interface for advanced control were introduced.The control steadiness and control accuracy for cracking heaters are greatly improved by using the advanced process control systems,and remarkable economic benefit is obtained.

Factors influencing single drop deformation in high-voltage AC electric field

Abstract: Experiments were carried out to investigate the deformation of single drop in high voltage AC electric field with different types of white oil and waterThe effects of electric field strength,viscosity of oil,interfacial tension and droplet diameter on the deformation of droplet were studiedWith a micro high-speed camera system and image processing technology,the deformation of droplet was observed and analyzedThe results indicate that the deformation is mainly affected by electric field strength,drop diameter and interfacial tensionThe eccentricity of ellipsoid drop is approximately proportional to the power of the electric field strength,N(17N24),and the diameterThe drop with lower interfacial tension is more prone to deform in the electric fieldThe effect of oil viscosity on droplet deformation is not obviousWhen the deformation is small,the change of drop eccentricity is accordance with the change of Weissenberg number,but the phenomenon is different when the deformation is large

Numerical simulation for gas production from hydrate accumulated in Shenhu Area,South China Sea,using huff and puff method

Abstract: In this work,the gas production potential from hydrates at the SH7 drilling site of the Shenhu Area by means of the huff and puff method using a single horizontal well was estimated3 dimensional numerical model was established based on currently available data from site measurementsThe hydrate accumulations in Shenhu Area are similar to Class 3 deposits(involving only a HBL),and the overburden and underburden layers are assumed to be permeableThe simulation results indicate that the hydrate dissociated zone expands around the well,and the hydrate formation occurs during the injection stage of the huff and puff processReasonable injection and production rates should be adopted to avoid the over pressurization and depressurization during each huff and puff cycleThermal stimulation is shown to have an effect over a limited range around the wellThe gas production rate and gas to water production ratio in the Class 3 hydrate deposit at site SH7 in Shenhu Area in this work is not suitable for commercial production

Polymorphism,crystal structure and crystal habit of β-artemether

Abstract: Polymorphism is a key crystal product property.The effects of crystallization method and operating condition on polymorphism of β-artemether were investigated.Single-crystal X-ray diffraction and X-ray powder diffraction(XRPD)were performed to identify the crystal structure of β-artemether,and molecular dynamics simulation coupled with the direct-space approach was used to simulate the crystal structure based on XRPD pattern of β-artemether polymorph.Two crystal structures were confirmed,one was a monoclinic crystal with space group of P21,the other was a triclinic crystal with space group of P-1.DSC analysis and XRPD patterns showed that the polymorphs of β-artemether were enantiotropic,and temperature was the key factor that affected polymorphic transformation.The crystal habit of polymorph A was predicted based on AE model and BFDH model,and the results showed that the theoretical crystal habit based on AE model coincided with the observed crystal habit.

Effects of baffle connection manner on shell-side performance of heat exchanger with helical baffles

Abstract: A 3D numerical investigation for heat exchanger with helical baffles was carried out to study the effects of baffle connection manner on shell-side flow and heat transfer characteristics under the same helical pitch.The results show that both the shell-side heat transfer coefficient and pressure drop decrease with the increase of the overlap size at certain mass flow rate.The latter decreases more quickly than the former.When the baffles are arranged in a continuous manner,the leakage from the triangle zone increases the velocities of fluid flowing across the tube bundle perpendicularly and along the tubes in the central zone,but the overall velocity distribution is non-uniform and the flow on the leeward side is poor.As the overlap size increases,the leakage from the marginal triangle zone increases the velocity in the region near the shell so that the flow field is improved.The heat flux on the central tubes is much lower and the heat transfer is more uniform along the radial direction when the adjacent baffles are connected in an overlapped manner compared with the case when the adjacent baffles are arranged in a continuous manner.

Thin-film thermocouples for rapid measurement of transient surface temperature in cryogen spray cooling

Abstract: Pulsed cryogen spray cooling(CSC) has become an effective method to protect the epidermis from non-specific thermal injuries in laser treatments of vascular malformation such as port wine stains.Cooling experiments with a skin phantom are usually conducted to quantify the heat transfer of CSC from a skin surface.Due to the high cooling ability of CSC and poor thermal conductivity of the skin phantom,the skin surface usually experiences a fast variation of the surface temperatures during CSC.It is therefore desirable to have a fast response surface thermal sensor to measure such temperature change.In traditional methods,commercial thermocouples of round or plate-shaped joints are buried on the surface or within the skin phantom in the experiments and usually give a poor response of the surface temperature.In this study,a fast response,thin film thermocouple(TFTC) of type T on a skin phantom made of epoxy or plastic glass is developed.The thin film thermocouple is manufactured by the Magnetron Spurting technique with a precise control of the compositions of Cu and Ni as well as the film thickness from 0.5 to 2 microns.A 0.05 micron thick of SiO2 protection layer is deposited on the TFTC as protection.Careful calibrations of TFTCs indicate that the thermoelectric property of the TFTCs agrees well with that of standard T-type thermocouples.The time constant of the TFTCs is about 1.2 ms,determined by pulsed laser heating experiments.Due to its small thermal capacity,the TFTC is sensitive to environmental fluctuations and the original temperature data show large noises.A low pass Butterworth(BW) filter is then introduced in the data acquisition system to remove such noises.Effect of the cut-off frequency and sample rate on the filtered temperature data has also been investigated and optimal cut-off frequencies and sample rates are recommended.A typical result for the temperature variation of the epoxy phantom surface during CSC is presented to illustrate the effectiveness of our TFTCs.

Applications of synthetic biology in medicine and energy

Abstract: Synthetic biology is a new field under the guidance of engineering,which aims to redesign and rebuild natural biological systems,and meanwhile,design and synthesize new biological part,module and systemThe advent of synthetic biology represents the tendency of natural scienceSome marked achievements have been made in the areas of medicine and energy via synthetic biology methodsOn one hand,novel synthesizing pathways have been successfully constructed in engineered cells to produce amorphadiene and taxadiene,which are precursors of antimalarial drug artemisinin and anticarcinogen taxol respectivelyOn the other hand,the constructions of fatty acid ester,fatty alcohol and higher alcohols synthesizing pathways have also been realizedIn addition,several related synthetic bio-techniques accelerate reconstruction and evolution of engineered cells,which would offer convenient tools to construct novel functional cells for the purpose of bio-based manufacture

Flow condensation in tube filled with annular metal foam

Abstract: The tube with internally sintered annular metal foam layer is used to enhance the flow condensation heat transferThe pressure drop and heat transfer of flow condensation for refrigerant R134a in the tube partially filled with annular metal foam are experimentally investigated to overcome the disadvantage of large pressure drop for tubes fully filled with metal foamThe tube wall temperatures are measured with thermal couples to determine the heat transfer coefficientThe effects of mass flux and vapor quality of two-phase fluid on the pressure drop and heat transfer coefficient are analyzed accordinglyIt is found that the pressure drop of tubes partially filled with metal-foam is much higher than that of smooth tubes and the pressure drop increases non-linearly and greatly as the mass flux and vapor quality increaseThe flow regime is predicted by monitoring the distribution and fluctuation of cross-section temperatures,from which the stratified wavy flow and annular flow are detectedIt is also revealed that the flow condensation heat transfer coefficient for tubes partially filled with annular metal foam is about 2 times that of smooth tube and can be improved as mass flux or vapor quality increases

Discuss on estimation difficulties and numerical computation methods for short circuit flow in cyclone separators

Abstract: The short circuit flow at the bottom of the vortex finder is an important factor for evaluating the performance of cyclone separators,but it is difficult to determine the altitude range of the short circuit flow.General measuring method is not available and the calculation results are quite different with various computation methods.Thus,to design a new separator many experiments are usually needed,which is time consuming and always costs too much.Here a computation method of short circuit flow based on CFD software is proposed.With the inflection point of the centripetal and centrifugal flow on the cross-section of the position at the bottom of the vortex finder,appropriate range for computing short circuit flow can be determined.The shape of the range is approximately annular and the descending flow rate across this range may be regarded as the total short circuit flow value.The calculation process is easily completed through the simulation result and the computation for short circuit flow is reliable.This method can be applied to multi-inlet and single-inlet separators.

Relationship between water quality parameters and fouling in plate heat exchangers

Abstract: The relationship between fouling thermal resistance in a plate heat exchanger and water quality parameters such as iron,total bacteria,pH,dissolved oxygen,turbidity and conductivity in the Songhua River water was investigated.Results show that the value of the fouling thermal resistance in the plate heat exchanger is lower than that of Tubular Exchanger Manufacturers Association(TEMA),and the natural cooling water has no induction period.pH and dissolved oxygen influence the iron corrosion rate and total bacteria,which affects the turbidity and conductivity.All these parameters have considerable effects on the heat transfer performance in the initial period,and then the effects are less.There exists synergetic effects from different fouling causes,and the fouling can be inhibited by reducing the amount of dissolved oxygen and total bacteria.

Energy analysis for transition from Cassie state to Wenzel state

Abstract: This study analyzed the Cassie state to Wenzel state transition of droplets on surfaces decorated with assemblies of cylindrical pillars arranged on a silicon wafer from the point of view of energy.The relation curve between energy barrier of state transition on the cylindrical array of different parameters and droplet size was calculated.For droplets size larger than 2 μl,two methods could be used for the transition from Cassie state to Wenzel state: increasing the droplets' gravitational energy or maintaining constant droplets' size and increasing the cylindrical array spacing distance.The experimental results were consistent with theoretical analysis.

Sensitivity analysis of capacitance sensor with helical shaped surface plates

Abstract: The measurement and control of mass flow rate of gas/solid two-phase flows have not been effectively solved for a long time in the industryIn this paper,a novel helical shaped surface plates capacitance transducer is designed for industrial point of viewIt is based on the electrical capacitance tomography(ECT)The influence of the opening angle of electrode,the pipeline permittivity and pipeline thickness on sensitivity distribution and homogeneous error are analyzed by the method of finite element simulationThrough the simulation analysis,the range of model parameters can be fixedFurthermore,it can provide the theoretical basis for development of sensitivity distribution,optimization of sensor and the performance of transducer

Characterization and performance of rare-earth modified molecular sieve

Abstract: With acidic neodymium(Nd)salt and lanthanum(La)salt as modifying agents,the rare-earth ion-doped molecular sieves were prepared by impregnation,filtration,desiccation and calcination of 13X molecular sieveThe modified adsorbents were characterized using Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)The desorption performance of the rare-earth molecular sieves was evaluated by temperature programmed desorption(TPD)and thermogravimetry(TG),and their adsorptive performance was tested by static state adsorptionFTIR spectra and XRD spectra indicate that the rare-earth doping has no effect on the composition of molecular sieve,while the crystallinity of modified molecular sieve has a little declineXPS analysis shows that part of sodium in the molecular sieve is replaced by La atoms or Nd atomsDifferential thermogravimetry(DTG)and Temperature Programe Desorption(TPD) curves indicate that the desorption activated energy of rare-earth doped molecular sieve is lower than that of molecular sieve,which is proved by the reduction of the peak temperatures in DTG curve at the maximum thermogravimetric rate and in TPD curve at the maximum vapor desorption rate

Experimental study on wet air in supersonic condensation flows

Abstract: An experimental system was set up for wet air supersonic condensation research.The stability measurement tests were taken.The results showed that the experimental system at least needed 10 h to achieve stabilization.The supersonic condensation process of wet air in Laval nozzle was tested.The results showed that the droplet diameter is nearly 0.85 μm along the axial without obvious fluctuation,and the droplet number is nearly 3.0×1012#·kg-1,and the liquid fraction is neatly 8.0×10-4 when the inlet pressure of the nozzle was 0.46 MPa.Mathematical models of wet air were set up to simulate the process of homogeneous and heterogeneous condensation in Laval nozzle.The results showed that the experimental results were in agreement with heterogeneous condensation simulation results which validated the heterogeneous model.