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Table of Content
05 January 2015, Volume 65 Issue z2
    CIESC Journal(HUAGONG XUEBAO)Vol.65 No.S2 December 2014
    2014, 65(z2):  0-0. 
    Abstract ( 41 )   PDF (6623KB) ( 186 )  
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    Research and applications of control technology of temperature and humidity in relic environment
    ZHANG Xuejun, ZHENG Youming, WANG Hengxu, SUN Daming, LI Xun
    2014, 65(z2):  1-8.  doi:10.3969/j.issn.0438-1157.2014.z2.001
    Abstract ( 170 )   PDF (2973KB) ( 343 )  
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    Relic protection requires high quality control of the temperature and relative humidity of the environment. Due to the large energy compensation caused by the fixed dew point on the cooling coil (CC) in the conventional constant temperature and humidity air-conditioning system, a decoupling method of temperature and humidity applying to the cooling coil is proposed, as well as the temperature and humidity control method for multi-zone. A new system employing a temperature and humidity independent control (THIC) device in the CC and a method of PID split-range control are developed. Experiments show that the temperature and relative humidity can be well controlled with a high precision. Now this system has been successfully applied to more than 10 relic protection projects of museums in Zhejiang province, with 30.7% energy-saving rate on average practically.

    Advances in mixed-gases Joule-Thomson refrigerators operating at low temperature ranges
    GONG Maoqiong, WU Jianfeng
    2014, 65(z2):  9-18.  doi:10.3969/j.issn.0438-1157.2014.z2.002
    Abstract ( 108 )   PDF (3802KB) ( 169 )  
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    Utilizing various refrigerants with different boiling points, multicomponent mixed-gases Joule-Thomson refrigerators (MJTRs) are suitable for refrigeration applications at temperatures ranging from liquid nitrogen to the lowest effective refrigeration temperature of the single-stage vapor compression refrigeration system. There are extensive and significant requirements for this refrigeration technology in fields of biomaterials, medicine, energy, material sciences, and even the state security. This paper gives a detailed review of our team's achievements on the MJTR for 20 years, including component selection and thermophysic properties of mixed-refrigerants, recuperator features, cycle configuration optimization, composition shift, as well as developments of -186℃ cryo-chamber and skid-mounted natural gas liquefier.

    Thermodynamic analysis of absorption refrigeration cycle using two working pairs
    XU Mengfei, YIN Yonggao, ZHANG Xiaosong
    2014, 65(z2):  19-24.  doi:10.3969/j.issn.0438-1157.2014.z2.003
    Abstract ( 159 )   PDF (1276KB) ( 161 )  
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    An absorption refrigeration cycle using two working pairs was presented, taking LiBr solution with low saturated vapor pressure as the working pair for the low-pressure stage and LiCl solution with higher saturated vapor pressure for the high-pressure stage. The thermodynamic performance of the cycle was investigated and evaluated with variable operation conditions. It shows that the single stage absorption chiller with LiCl solution as the working fluid has a higher COP than LiBr solution when the driven heat temperature is low. The low grade solar energy driving the absorption chiller can be extended to 55—75℃ and the maximal COP can reach up to 0.47 owning to two working fluids. Consequently, the available operation time is increased and the efficiency of solar collector is improved. In particular, the intermediate pressure has a significant influence on the COP of the system, and there is an optimal intermediate pressure making the COP of the system maximum. The theoretical analyses reveal that the optimal intermediate pressure for the system lies from 2.5 kPa to 4.0 kPa.

    Phase equilibrium property analysis of N2/O2/CO2 based on several state equation models
    LI Shuhong, LI Xianliang, YANG Wenchao, ZHANG Yongxin, ZHANG Xiaosong
    2014, 65(z2):  25-32.  doi:10.3969/j.issn.0438-1157.2014.z2.004
    Abstract ( 119 )   PDF (2658KB) ( 211 )  
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    CO2 capture is imperative currently, cryogenic separation is one of the important methods of CCS(carbon dioxide capture and storage). The accuracy of CO2-N2 phase equilibrium property is related to the liquefied CO2 recovery and recycling purity in cryogenic method, and it will affect the choice of the system and energy consumption analysis further. N2-CO2 phase equilibria calculation based on several state equation models were made in this article. The calculation results show that the PR state equation combined with Vdw mixing rules is most suitable for N2-CO2 phase equilibrium calculation, the maximum deviation is 7.37%, the average deviation is about 3%. Then the CO2 bubble point, dew point and the temperature of sublimation at the condition of 2 MPa with the PR equation model were calculated. An energy consumption analysis about cryogenic system was made, the results show that the method combined liquefaction and sublimation achieved higher recovery and recycling purity, and compared with sublimation separation method, the former method reduce energy consumption by more than 9%. At last, an analysis about the impact of O2 on the CO2-N2 phase equilibrium property was made.

    Molecular dynamics simulation of Ni thermal conductivity
    XIN Gongming, QI Jinsheng, LI Xin, WANG Yifei, JI Wanxiang, CHENG Lin
    2014, 65(z2):  33-37.  doi:10.3969/j.issn.0438-1157.2014.z2.005
    Abstract ( 57 )   PDF (959KB) ( 129 )  
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    The investigations of thermal conductivity of materials are important to understand their characteristics and their influences. In simulation-based studies, many researchers used molecular dynamics (MD) simulation to analyze the thermodynamic properties. In this paper, non-equilibrium molecular dynamics (NEMD) simulations based on uniform internal heat source are performed to determine the thermal conductivity of nickel material by using Lenard-Jones potential model and EAM potential model. Simulation results based on different potential models are achieved and analyzed. Based on this, the thermal conductivity of copper and nickel-copper solid solution were simulated. The EAM potential model was further validated by achieving reasonable results for copper. And the optimized Ni-Cu ratio for lower thermal conductivity of solid solution were modeled based on the EAM model.

    Numerical investigation of slush hydrogen flow in horizontal pipes
    ZHANG Peng, SHI Xinjie
    2014, 65(z2):  38-44.  doi:10.3969/j.issn.0438-1157.2014.z2.006
    Abstract ( 102 )   PDF (2684KB) ( 199 )  
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    The flow characteristics of slush hydrogen in horizontal pipes are investigated numerically using 3D Euler-Euler model. The pressure drops obtained by the numerical calculation are compared with experimental results from the open literature, in order to validate the numerical method. In addition, the models with proper parameters are adopted to simulate the flow of slush hydrogen with different volume fractions (10%, 20%, 30%) and flow rates (1.0 m·s-1, 2.0 m·s-1, 3.0 m·s-1) in horizontal pipes with different diameters (10 mm, 16.6 mm, 23 mm). The volume fraction distributions of slush hydrogen in the pipe are obtained. It is found that the solid volume fraction distribution of slush hydrogen is more heterogeneous at lower flow rate, lower average volume fraction and larger pipe diameter.

    Computational fluid dynamic analysis on flow and cavitation characteristics of R134a in centrifugal pump with straight blades
    LAI Tianwei, YANG Shanju, ZHANG Xingqun, CHEN Shuangtao, HOU Yu
    2014, 65(z2):  45-51.  doi:10.3969/j.issn.0438-1157.2014.z2.007
    Abstract ( 142 )   PDF (6187KB) ( 181 )  
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    The performance of refrigerant circulation centrifugal liquid pump is of great importance for the stability and reliability of free cooling system. Emergence of cavitation is crucial for the liquid pump, especially for that works near liquid saturation. In this paper, flow and cavitation characteristics in centrifugal liquid pump with straight blades are analyzed numerically with computational fluid dynamic (CFD) tools CFX based on Rayleigh-Plesset cavitation model, and the effect of rotational speed on the flow field distribution and cavitation is evaluated. Numerical results indicate that cavitation appears firstly in the upstream region around leading edge of blade with rotational speed, and that the adherent cavitation area enlarges near the suction surface of blade with the increase of rotational speed. Meanwhile, flow streamline turbulence is prominent and the secondary flow is obvious in the pump with straight blade.

    A novel compressed air drying method based on pressurized liquid desiccant dehumidifier and experimental verification
    ZHENG Baojun, YIN Yonggao, ZHANG Xiaosong
    2014, 65(z2):  52-57.  doi:10.3969/j.issn.0438-1157.2014.z2.008
    Abstract ( 184 )   PDF (1529KB) ( 262 )  
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    A novel compressed air drying method based on a pressurized liquid desiccant dehumidifier is proposed in this paper. An experimental setup of pressurized liquid desiccant dehumidifier associated with a compressed air module is established to verify the novel air drying method and further test the performance. The results show that, under the pressure of 0.5 MPa, the outlet moisture content of air can reach 0.9 g·kg-1. The moisture removal rate increases with the increase of air velocity, solution flow rate and solution concentration under certain pressure. The feasibility of applying liquid desiccant technology to drying compressed air in related fields is verified.

    Effect of humidifying amount on defrosting of air cooler in low-temperature cold storage
    WANG Dong, TAO Leren, TAO Leren
    2014, 65(z2):  58-63.  doi:10.3969/j.issn.0438-1157.2014.z2.009
    Abstract ( 137 )   PDF (3642KB) ( 157 )  
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    Experimental study of electricity defrosting and hot gas defrosting was done based on a low-temperature cold storage existing. The design of partition device was introduced. The effect of humidifying amount on defrosting time, defrosting load, temperature field around the air-cooler when defrosting were discussed at two kinds of situation with partition device or no. The results show that, with the increasing amount of humidification, defrosting energy consumed also increases accordingly, more than 18% when the humidifying capacity is 1000 g. Electricity defrosting was bigger to the damage degree of cold storage temperature field. The cold storage temperature is increased by 5℃ to 10℃. After the partition device was set up, there was a notable energy conservation effect, the temperature field of cold storage was less destroyed. The maximum change of cold storage temperature is decreased by 5℃ with electricity defrosting. The influence of the partition device to hot gas defrosting was relatively smaller.

    Analysis on cooling performance of porous pipes with water soaking-up ability for combining wall
    CHEN Wei, ZHAO Qunli, WANG Ji
    2014, 65(z2):  64-70.  doi:10.3969/j.issn.0438-1157.2014.z2.010
    Abstract ( 150 )   PDF (2428KB) ( 170 )  
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    The porous pipes with high water soaking-up ability have been combined for evaporative cooling wall. Due to the influences of the temperature and humidity outside, the evaporative cooling occurs on the porous pipe surface, which connects with the temperature and its gradient as well as the moisture content and its gradient in the porous pipe, and the temperature drop of 5—8℃ can be achieved in the experiment. The water sucked up by the porous pipes causes the continuation of the evaporative cooling. As the wind speed coupled with the relative humidity influences the evaporative cooling, the temperature drop of 2℃ on the pipe surface can be obtained at 2.5 m·s-1 than that at 1 m·s-1. The rise of gaseous phase in the porous pipe leads to the reduction of the evaporative area. The experiments have also been conducted to study the water soaking-up performance of the porous pipe and the influence of the porous pipe arrangement on the cooling of the combined wall.

    Mechanism of heat transfer during melting of lauric acid in horizontal annulus
    HU Chunyan, YUAN Yanping, CAO Xiaoling, YANG Xiaojiao
    2014, 65(z2):  71-77.  doi:10.3969/j.issn.0438-1157.2014.z2.011
    Abstract ( 103 )   PDF (3181KB) ( 152 )  
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    Numerical investigations on the melting process of lauric acid in a horizontal annulus heated isothermally from the inside wall is presented. The simulation is verified by comparing with the results by experiment. The mechanism of heat transfer of the melting process is analyzed through the melting phase front and the average Nusselt changes with Fourier number in different boundary temperatures. The result shows that the average Nusselt decreased with the increase in Fourier number first, and then decreased gradually, the lowest point before the average Nusselt changes with Fourier number in different boundary temperatures. The result shows that the average Nusselt decreased with the increase in Fourier number first, and then decreased gradually, the lowest point before the average Nusselt increased is the transition point of heat transfer mechanism. A clear separation of melt fraction curve is manifested in comparison with the pure heat conduction model diagram. It is found that the Fourier number of the transition point from pure heat conduction to natural convection is 0.028 when Rayleigh number and Stefan number are 1.33×107, 0.206 respectively.

    Simulation of cabbage seeds with heat pump drying
    ZHAO Haibo, YANG Zhao
    2014, 65(z2):  78-82.  doi:10.3969/j.issn.0438-1157.2014.z2.012
    Abstract ( 120 )   PDF (2394KB) ( 203 )  
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    To investigate the drying characteristics of multi-layer-arrangement cabbage seeds with heat pump drying, a cabbage seed heat pump drying model was built in this paper. It consists of the heat and mass transfer model of both drying air and cabbage seeds. The model was used to simulate the drying characteristics of cabbage seeds with three-layer orderly arrangement. The mean moisture content and temperature of overall cabbage seeds, internal moisture content and temperature of cabbage seeds were calculated and analyzed. Results show that seeds in the top layer dry faster than those in the bottom layer. So, the moisture content of different seeds rises gradually, while temperature decreases both along and across the flow direction of drying air. The moisture contents of seeds in the top layer rise from 12.67% to 12.80% along the flow direction of dry air in 3000 s, with temperatures decrease from 39.8℃ to 39.5℃. And the moisture contents of seeds in the eighth column rise from 12.73% to 12.78% across the flow direction of dry air in 3000 s, with temperatures decrease from 39.7℃ to 39.5℃.

    Heat transfer performance test and analysis of thermosyphon heat exchanger
    ZHANG Shuang, MA Guoyuan, ZHANG Sichao, ZHOU Feng
    2014, 65(z2):  83-87.  doi:10.3969/j.issn.0438-1157.2014.z2.013
    Abstract ( 105 )   PDF (1077KB) ( 247 )  
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    A calculation method of an air-to-air thermosyphon heat exchanger was reported in this paper. The face velocity, number of rows and inclination angle of heat exchanger were tested and studied in an air enthalpy type psychrometric calorimeter including indoor and outdoor chambers. The error of the calculation method and experimental data was within 15%. Thus, the calculation method can be applied in engineering design of the air-to-air thermosyphon heat exchanger.

    Characteristics of flooding with counter-current LN2/VN2 flow in inclined tube
    CHEN Jianye, WANG Yuchen, XIONG Wei, ZHAO Dongfang, XU Lu, ZHANG Xiaobin
    2014, 65(z2):  88-94.  doi:10.3969/j.issn.0438-1157.2014.z2.014
    Abstract ( 132 )   PDF (2874KB) ( 293 )  
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    Experiments with liquid nitrogen and the vapor (LN2/VN2) in an inclined tube were conducted to investigate the flooding mechanisms. The flow patterns during flooding were analyzed and compared with those of water/air. The results showed that the interfacial waves kept their shape and the slug flow was formed with water/air when flooding occurred. As a comparison, the interfacial waves were crushed and the mist flow was formed with LN2/VN2. The Fast Fourier Transform (FFT) of pressure drops between the two ends of the tube was carried out to evaluate the frequencies of interfacial waves and the flooding intensity. The influence of inclination on the critical gas superficial velocities was investigated. It was indicated that the frequencies of the biggest waves triggering flooding were almost the same between the two working fluid pairs,and the inclination angles had little effects on the flooding intensity but had great influence on the critical gas superficial velocities.

    Flow boiling pressure drop characteristics of refrigerant-oil mixture inside metal-foam filled tubes
    HU Haitao, ZHU Yu, PENG Hao, DING Guoliang, SUN Shuo
    2014, 65(z2):  95-100.  doi:10.3969/j.issn.0438-1157.2014.z2.015
    Abstract ( 133 )   PDF (2289KB) ( 125 )  
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    The pressure drop characteristics of refrigerant-oil mixture flow boiling inside metal-foam filled tubes were investigated experimentally. The experimental fluid is R410A/VG68 oil, and the oil concentration range is 0—5%. The structure of the metal foam used in the experiments include PPI of 5 and 10, and porosity of 95%. The experimental results show that, as the oil concentration and PPI increases, the pressure drop increases. The incomplete cells nearby tube wall decreases the flow turbulence, resulting in the decrease of pressure drop, with the decrease of tube diameter, the pressure drop in metal-foam filled tubes decreases, which is different from that in smooth or microfin tubes. Based on the experimental data, the pressure drop correlation for refrigerant-oil mixture flow boiling inside metal-foam filled tubes was developed, and it can predict the pressure drop characteristics in metal-foam filled tubes with different diameters.

    Mechanism and influence factors of frost melt water retention on fins
    WANG Feng, LIANG Caihua, YANG Mingtao, FAN Chen, ZHANG Xiaosong
    2014, 65(z2):  101-106.  doi:10.3969/j.issn.0438-1157.2014.z2.016
    Abstract ( 113 )   PDF (1851KB) ( 194 )  
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    In order to study the phenomenon of the frost melt water retention on fin surfaces of the air source heat pump during the defrosting process, the mechanism of the frost melt water retention was researched by theoretical analysis, and a frosting-defrosting experimental system was developed to study the frost melt water retention on four fin samples with different surface characteristics. Experimental results showed that there was obvious difference on retained water distribution between different fin surfaces: retained water formed a thin water film on the hydrophilic surface while only a few spherical droplets with small sizes stayed on the super hydrophobic surface. The retained water mass decreased with the increase of contact angle hysteresis, which on the super hydrophobic surface decreased by 79.82% compared with that on the hydrophilic surface. The frosting degree had a significant effect on the frost melt water retention of the bare surface while had no effect on that of the super hydrophobic surface. However, changing the defrosting temperature almost had no effect on the frost melt water retention of fin surfaces.

    Effectiveness of improving tent envelope thermal performance based on PCM
    WANG Jun, LONG Enshen, LIAO Xingyu, XU Long
    2014, 65(z2):  107-113.  doi:10.3969/j.issn.0438-1157.2014.z2.017
    Abstract ( 158 )   PDF (4552KB) ( 213 )  
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    Owing to effect of air permeability, thermal radiation adsorption and thin thickness, low thermal inertia and resistance of tent envelope become one fundamental reason causing poor indoor thermal environment of tent. For the sake of improving thermal performance of tent envelope, composite structure was proposed and applied in tent, including outer fabric layer, phase change material (PCM) layer and inner fabric layer. Meanwhile, the heat transfer model of this new type structure was established and verified. In addition, for the climatic conditions of Chengdu in China, the thermal performance of composite structure was evaluated and effectiveness of improving tent envelope thermal performance based on PCM was determined with the aid of numerical simulation under the influence of different PCM thermophysical properties, containing PCM thermal conductivity coefficient, latent heat, specific heat capacity and phase-transition temperature.

    Dynamic heat transfer characteristics of PCM-filled glass window and hollow glass window
    ZHONG Kecheng, LI Shuhong, ZHOU Yingying, ZHANG Xiaosong
    2014, 65(z2):  114-123.  doi:10.3969/j.issn.0438-1157.2014.z2.018
    Abstract ( 137 )   PDF (2955KB) ( 144 )  
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    In order to determine the effects of the phase change material filled glass window (PCMW) on building energy consumption in the hot summer and cold winter area of China, dynamic heat transfer process and heat transfer parameters of the PCM filled glass window and the hollow glass window (HW) exposed to different non-steady boundary conditions related to the climatic characteristic of the sunny and rainy days both in summer and winter were investigated. The experiments of the dynamic heat transfer process of PCMW and the hollow glass window (HW) in a representative sunny summer day were conducted, and the one dimensional numerical simulations under the same condition were conducted. The temperatures of the interior surfaces of the two kinds of window were obtained. The results of experiment and simulation were in good agreement. Then the validated numerical model was used to simulate the dynamic heat transfer processes of the two kinds of windows at more different weathers which were representative both in summer and in winter, the temperature and heat flux fluctuations on the interior surfaces of the two glass windows were analyzed based on simulation results. According to the obtained results, it was concluded that in the representative sunny summer day, the peak temperature on the interiorsurface of the PCMW (glauber's salt) reduced by 10.2℃, and the heat entered the building through the PCMW (glauber's salt) reduced by 39.5%, comparing with the hollow glass window. However, in the representative rainy summer day, the representative sunny winter day and the representative rainy winter day, the dynamic thermal performance of the PCMW (glauber's salt) was unsatisfactory as it cannot decrease the building energy consumption. Long period measurements and monitoring of the PCMW will be further researched to validate long term performance prediction based on numerical simulation.

    Flow rate measurement based upon temperature cross-correlation
    ZHANG Shaozhi, JIANG Qing, BAI Chongyan, CHEN Guangming
    2014, 65(z2):  124-128.  doi:10.3969/j.issn.0438-1157.2014.z2.019
    Abstract ( 34 )   PDF (1783KB) ( 170 )  
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    Preliminary experiments were carried out to study a non-intrusive method for measuring water flow rate based upon temperature cross-correlation. Through monitoring two temperature points in an insulated pipe, the data were analyzed with cross-correlation algorithm using Matlab software, and the delay time between the two points was estimated, thus the flow velocity and rate were obtained. The results showed that the estimated flow rate could agree with the measured value within an error of 10% if the minimum of the sum of square of the temperature differences was adopted as the optimization target. If combined with wireless temperature sensor network, the application of flow rate measurement based upon temperature cross-correlation may be anticipated in HVAC engineering.

    Performance analysis on air handling processes using desiccants
    LIU Xiaohua, ZHANG Tao, ZHENG Yuwei
    2014, 65(z2):  129-139.  doi:10.3969/j.issn.0438-1157.2014.z2.020
    Abstract ( 137 )   PDF (4690KB) ( 277 )  
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    Humid air handling process is a key part of the air-conditioning system. Air handling units using liquid desiccant or desiccant wheel are the common air humidity control devices using desiccants. Based on the basic air handling process using desiccants, similarity between the dehumidification units using liquid desiccant and desiccant wheel is analyzed in present research. Uniformity coefficient ξ is used to describe the uniformity of the driving force between air and desiccants for heat and mass transfer, then to investigate the diversity between liquid desiccant dehumidification and desiccant wheel. It is found that, for the desiccant wheel, distribution of the driving force are relatively uniform throughout the whole wheel. As to the liquid desiccant process, the uniformity characteristic of the driving force is significantly influenced by the relative position of the inlet air and solution states. Only when the inlet air and solution states are along the iso-relative-humidity line, the distribution of the driving force is uniform, with a uniformity coefficient ξ close to 1. Analysis on different air handling processes indicate that the distribution characteristic of the driving force offers an effective guidance for constructing an optimized actual process for air dehumification.

    Numerical simulation and experimental validation of water condensing and moving on plain-fin surface under dehumidifying conditions
    YANG Yifei, ZHUANG Dawei, HU Haitao, HAN Weizhe, DING Guoliang, XIONG Wei
    2014, 65(z2):  140-147.  doi:10.3969/j.issn.0438-1157.2014.z2.021
    Abstract ( 135 )   PDF (2097KB) ( 357 )  
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    In order to predict the performance of tube-finned heat exchangers under dehumidifying condition, the behavior of condensing liquid droplet on vertical plain-fin surfaces should be known. The objective of this article is to develop a model for liquid droplet condensation and motion on vertical plain-fin surfaces. To achieve this goal, the mechanisms of droplet condensation and motion are analyzed firstly. Then the equations for predicting the heat and mass transfer rate during the water condensation are established, and a Volume of Fluid-Continuous Surface Force model with varying contact angles along the contact line is developed to predict droplet movement. The prediction ability was verified by the experimental data, and verification results show that: the simulation results of jh agree with 96% of the experimental data within the deviation of ±15%, and the mean deviation is 6.9%; the simulation results of jm agree with 91% of the experimental data within the deviation of ±20%, and the mean deviation is 12.1%.

    Effect of helically coil diameter on thermal-hydraulic inhomogeneity in helically coiled tube
    LIU Shanghua, SUN Baozhi, SHI Jianxin, HAN Wenjing, ZHANG Guolei, GAN Yiran
    2014, 65(z2):  148-154.  doi:10.3969/j.issn.0438-1157.2014.z2.022
    Abstract ( 41 )   PDF (3156KB) ( 183 )  
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    A three-dimensional "unit pipe" physical model of helically coiled steam generator is established based on the similarity theory, two fluid model considering mass, momentum and energy transfer is used, and describe the process of two fluid phase through the bulk boiling model. Numerical investigation on the flow and phase change in the helically coil tubes with the helically coiled diameter 200 mm, 500 mm and 1718 mm is thereby carried out. Simulation results show that the obvious secondary flow is formed due to the centrifugal force, and the smaller the helically coiled diameter and the greater the velocity is, the more obvious the secondary flow is. In two-phase flow area, the helically coiled diameter has great influence on the distribution of two-phase flow. In addition, the smaller the helically coiled diameter is, the larger the temperature difference is due to the effects of vapor-liquid separation and the secondary flow. The temperature difference of circumferential wall temperature on the single-phase flow area is dramatically larger than that of two-phase flow area.

    On-orbit unusual temperature and analysis of thermal response of alpha magnetic spectrometer
    WANG Kun, LI Jinbo, CHENG Lin
    2014, 65(z2):  155-161.  doi:10.3969/j.issn.0438-1157.2014.z2.023
    Abstract ( 33 )   PDF (1978KB) ( 102 )  
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    The thermal control system (TCS) provides effective and stable support to the on-orbit running of the alpha magnetic spectrometer (AMS) running on the International Space Station (ISS). Long-time monitoring of the TCS presents temperature warnings occurred on the circulation box (Box-C) of the transitional radiation detector (TRD), tracker plane 1 and photomultiplier tube of lower time of flight detector in particular cases. The monitoring also presents that the operations of both starboard solar arrays and thermal radiator of the ISS can affect the local temperature of AMS. In this paper, by analyzing the temperature data in different cases, the influence of locking solar arrays of the ISS to the three components mentioned above is given. The most optimized angle factor of the starboard thermal radiator of the ISS reflecting solar irradiation to AMS is calculated, the calculation is verified by actual tests, the analysis of thermal response of the components is given, which indicates the validity of the TCS. Based on the analysis above, the approaches of controlling unusual temperature are proposed, which provides references to the on-orbit thermal control of AMS.

    Simulation for liquid phase bulk propylene polymerization in loop reactor by response surface methodology
    SUI Shuhui, HONG Dingyi, HONG Dongfeng
    2014, 65(z2):  162-168.  doi:10.3969/j.issn.0438-1157.2014.z2.024
    Abstract ( 52 )   PDF (2341KB) ( 174 )  
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    According to the mechanism of propylene polymerization, the process simulation for liquid phase bulk propylene polymerization in loop reactor was carried out by using Polymers Plus of ASPEN with the method of response surface methodology(RSM). The method of Levenberg-Marguardt was used in the GPC (Gel Permeation Chromatography) curve deconvolution of the polypropylene sample to calculate the active sites of Ziegler-Natta catalyst. The result showed that the catalyst was characterized by assuming existence of five active sites. By using Monte Carlo method, the multi-site's dynamic data was gotten on the base of a new model in which the catalyst was assumed as uniform sphere and the integral was made. The individual and interactive effects of temperature, pressure, mass flow of catalyst, mass flow of propylene, and volume fraction of hydrogen on Mw of PP was investigated and a quadratic model was developed for the prediction of Mw of PP. The Mw predicted by quadratic model was 2.142×105 very close to the experimental data with the deviation of 1.25%. The quadratic model and 3D tendency curves can be used to optimize operation and to improve PP quality conveniently.

    Concentration optimizations on small scale auto-cascade natural gas liquefier using rectifying column
    REN Bin, CHEN Fusheng, WANG Hui, SONG Qi, WANG Qin, XU Xiangguo, CHEN Guangming
    2014, 65(z2):  169-174.  doi:10.3969/j.issn.0438-1157.2014.z2.025
    Abstract ( 141 )   PDF (1248KB) ( 208 )  
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    The unconventional natural gas is very abundant in China. Small scale natural gas liquefiers can be effectively used for the extraction of the unconventional natural gas with a very promising future. In this study, a small scale auto-cascade natural gas liquefier using a rectifying column was simulated by HYSYS®. The influence of compositions of refrigerant mixtures on the energy consumption for the liquefaction of per unit LNG and the discharge temperature of the liquefier, was analyzed. Concentrations of the refrigerant mixtures were optimized and the optimum concentrations for the specified operating condition were obtained. The temperature profiles of three recuperators in the system with the optimum concentrations were also investigated to analyze the efficiency elevation of the system.

    Control system of linear compressor for refrigerator
    ZOU Huiming, TANG Mingsheng, XU Hongbo, SHAO Shuangquan, TIAN Changqing
    2014, 65(z2):  175-180.  doi:10.3969/j.issn.0438-1157.2014.z2.026
    Abstract ( 140 )   PDF (1850KB) ( 310 )  
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    Three main key control technologies of linear compressor—stroke detection, top dead center (TDC) detection and performance improvement are investigated by the experimental research theoretical analysis. Based on the above control technologies, a control strategy of linear compressor for refrigerator is designed according to the control target of linear compressor for refrigerator. The coupling cooling operation results show that the control strategy can fulfill the control target well and the cooling COP of the linear compressor under the rating working condition of refrigerator is around 1.74.

    Building system performance diagnosis and optimization based on data mining techniques
    XIAO Fu, FAN Cheng, WANG Shengwei
    2014, 65(z2):  181-187.  doi:10.3969/j.issn.0438-1157.2014.z2.027
    Abstract ( 38 )   PDF (1322KB) ( 137 )  
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    Buildings are becoming not only energy-intensive, but also information-intensive. Today's building automation system (BAS) has provided an enormous amount of data about the actual building operation. Valuable insights could be gained from such data. However, due to the data complexity and the lack of advanced analytic tools, only limited and rather simple applications have been found. Data mining (DM) is a promising technology which has great efficiency and effectiveness in discovering hidden knowledge from massive data sets. This study investigates the utilization of DM in analyzing massive BAS data for enhancing building energy efficiency. The DM-related research in the building field is firstly reviewed and then the challenges of practical applications are discussed. A generic DM-based analysis framework is proposed. The framework is applied to analyze the building operational data retrieved from the tallest building in Hong Kong. Two case studies are presented to show the capability of DM in developing robust energy prediction models, identifying building operating behaviors, and evaluating operational performance. The results show that, DM, together with domain knowledge, could be very powerful in the knowledge discovery in massive building operational data and valuable for enhancing the building energy efficiency.

    Novel temperature and humidity independent control system
    JIANG Yu, HUANG Yi, GE Tianshu, WANG Ruzhu
    2014, 65(z2):  188-194.  doi:10.3969/j.issn.0438-1157.2014.z2.028
    Abstract ( 111 )   PDF (2830KB) ( 136 )  
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    A novel temperature and humidity independent control system (THIC) is proposed in this paper, and then experimental investigation of this system is conducted to evaluate its system performance. The THIC system is constituted of a novel solid desiccant heat pump (DESICA) to deal with the latent load and a variable refrigerant flow air conditioning system (VRV) to handle the sensible load. In order to verify the actual performance of this novel joint DESICA and VRV system (JDVS), operation performance of this system is experimentally tested and compared with commonly adopted joint heat recovery ventilator (HRV) and VRV system (JHVS). These two hybrid systems are installed in an office room and operated on adjacent days during typical winter (Dec, 2012 to January, 2013) and summer (July, 2013 to August, 2013) season in Shanghai. From the experiment results, it is found that the proposed JDVS can provide better indoor thermal comfort while consuming less energy in both winter and summer season, compared with the traditional JHVS.

    Economy analysis of hybridgas engine heat pump in winter operating conditions
    JIANG Wenxiu, CAI Liang, DENG Weiwei
    2014, 65(z2):  195-201.  doi:10.3969/j.issn.0438-1157.2014.z2.029
    Abstract ( 111 )   PDF (2441KB) ( 201 )  
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    Hybrid gas engine heat pump (HPGHP) combines hybrid-power technology with heat pump technology to increase the fuel efficiency of the system. Based on a hybrid gas engine heat pump platform, this paper performed experiments under the winter heating condition to analyze operating economy of the system. The outdoor dry bulb temperature was 7℃, the evaporating and condensing temperature was -5℃ and 46℃, respectively. The optimization curve control strategy was adopted to control the engine operating in the economical zone and distribute requiring power between the engine and battery. The fuel consumption flow, fuel consumption rate, fuel conversion rate and recovered wasted heat were indicators of economic research. The system performance was tested under low, medium and high load separately and compared with conventional gas heat pump (GHP). Analysis results show that under low load, the average fuel conversion efficiency of hybrid gas heat pump is about 0.195, 16.7% higher than that of GHP. In high load range, average fuel conversion efficiency of hybrid gas heat pump is about 0.151, 12.1% higher than that of GHP under the same load.

    Impact of ground water seepage on ground temperature distribution and performance of GSHP
    ZHENG Xiaohong, QIAN Hua, LIANG Wenqing, ZHANG Lei
    2014, 65(z2):  202-207.  doi:10.3969/j.issn.0438-1157.2014.z2.030
    Abstract ( 115 )   PDF (2005KB) ( 193 )  
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    A coupling prediction model is developed for predicting buried pipes' geothermal field existing water advection and coefficient of performance of ground-source heat pump in this paper. The prediction results were validated by the data from literature. Results show that this model can accurately predict the geothermal field existing water seepage. This validated model was used to study the impact of ground water seepage on the performance of geothermal heat exchangers in ground-source heat pump systems. It was found that whether there is water seepage, the COP would continue to fall when the ground temperature is rising. The COP of the heat pump dropped 49% after 90 days' continuous operation when there is no water seepage. While the COP of heat pump dropped 44.7% when there is seeping water. It indicates that water advection can significantly improve the operation effect of the working unite, and it is also helpful to recover the geothermal field.

    System configuration and experimental study on LFG based biogas engine driven heat pump
    WU Jiying, MA Yimin
    2014, 65(z2):  208-214.  doi:10.3969/j.issn.0438-1157.2014.z2.031
    Abstract ( 96 )   PDF (1521KB) ( 121 )  
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    The system equipment configuration of a landfill gas (LFG) fueled biogas engine driven heat pump energy-saving system was studied, and the LFG collecting and purifying flow process was analyzed. By constructing an experimental plant, the performance of the system was tested. The results of experiments indicated that when the biogas engine operated at 70%—90% of its rated speed, the energy efficiency of the system would reach its maximum. That is because the waste heat recovery rate of exhaust fume was relatively higher, although the heat supplied by the system was not the maximum. Compared with other heating systems, biogas engine driven heat pump system can significantly reduce the consumption of fossil fuels and improve heating capability. Therefore, the heating system developed can lower energy consumption and utilize renewable energy sources comprehensively.

    Performance analysis of combined adsorption refrigeration and seawater desalination system
    WANG Yongqing, HE Hongzhou
    2014, 65(z2):  215-221.  doi:10.3969/j.issn.0438-1157.2014.z2.032
    Abstract ( 153 )   PDF (2949KB) ( 192 )  
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    Combined adsorption refrigeration and seawater desalination (ARSD) system is an emerging way to produce refrigeration and fresh water simultaneously. Focusing on several aspects that were not discussed in previous ARSD studies, the performance of refrigeration and water production and the energy benefit of two-bed ARSD under different conditions were studied using pure silica gel and composite CaCl2-in-silica gel as adsorbent. The results show that, comparing with separate refrigeration-only and water-only systems, the energy saving rate of cogenerated ARSD is significant, typically at 9.9%—26.2% and 22.4%—35.4% for the two adsorbents. The effects of the main parameters on cooling and water production and energy saving of the system are consistent, and concretely, higher evaporation temperature and peak desorption temperature, and lower condensation temperature and bottom adsorption temperature, are more favorable. Composite adsorbents are good for the performance of ARSD, but further study is needed to clarify the stability of composite adsorbents and the influence of the salt component on fresh water quality. Increasing water recovery rate leads to decreased performance of ARSD system. The decrease rate is marginal when the recovery rate is lower than 70%.

    Analysis on impact factors of energy consumption of novel solid adsorptive dehumidification air-condition system
    TU Yaodong, JIANG Yu, GE Tianshu, WANG Ruzhu
    2014, 65(z2):  222-227.  doi:10.3969/j.issn.0438-1157.2014.z2.033
    Abstract ( 126 )   PDF (1761KB) ( 205 )  
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    The method for determining the best air state point is investigated for a given cooling load and the fresh air volume. Then the relationship between the heat of adsorption of water vapor and the overall energy consumption of solid desiccant air conditioning system is discussed, finally the energy consumption of the novel air conditioning system is compared with conventional condensation dehumidifier. The results showed that the energy consumption of solid desiccant air conditioner is closely related with the heat of adsorption, a reasonable choice hygroscopic agent, not only the energy consumption of the air conditioner condensation dehumidifier is less, especially when a large dehumidification load is treated, the energy saving effect is most obvious. Besides, the supply air temperature difference is smaller, which is helpful for a better comfort indoor air-conditioning environment.

    Research and development of multi-field coupling test chamber based on preservation of unearthed relics
    LU Zhao, MENG Xiangzhao, LUO Xilian, JIN Liwen, GU Zhaolin
    2014, 65(z2):  228-234.  doi:10.3969/j.issn.0438-1157.2014.z2.034
    Abstract ( 181 )   PDF (1886KB) ( 172 )  
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    The unearthed relics suffer deterioration in some archeology museums of China because of improper preservation environment. To acquire appropriate environmental factors for the conservation of the historical relics, this paper designs the multi-field coupling test chamber orientated to research the quantitative relationship between deterioration and environmental factors(including air temperature and humidity, light, gaseous pollutants, soil moisture and soluble salt).The test chamber is made up of test chamber body, air curtain and air-conditioning system, gaseous pollutants control system, solar radiation simulation system and soil regulation system, which can realize the complex environment of air-relic-soil. This paper focuses on clarifies the test chamber's design index, system composition, as well as implementation and function of each subsystem, and makes performance testing of air temperature and humidity. The experimental result shows that air temperature and humidity is 10-35℃ and 30%-95%, and the accuracy of temperature and relative humidity is ≤1℃ and ≤3%,respectively, which can meet air temperature and relative humidity testing requirements.

    Sensitivity analysis of configuration parameters of water-type PV/T module
    SUN Liangliang, YUAN Yanping, HU Wenju, CAO Xiaoling, LEI Bo
    2014, 65(z2):  235-239.  doi:10.3969/j.issn.0438-1157.2014.z2.035
    Abstract ( 21 )   PDF (564KB) ( 160 )  
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    The sensitivity analysis of main configuration parameters of water-type PV/T module including thickness of cover glass, thickness of air gap, thickness of thermal absorber, diameter of water tube, spacing of water tube and thickness of thermal insulation material has been conducted using normalized sensitivity coefficient method. The impact of solar radiation, outdoor air temperature and flow rate on sensitivity coefficients of these configuration parameters are also investigated. It indicates that thickness of cover glass, diameter of water tube and spacing of water tube are significant influence parameters in term of electrical power generation and thermal heat for hot water. Compared with solar radiation and flow rate, effect of outdoor air temperature on sensitivity coefficients is not obvious.

    Design and numerical simulation of floor radiant system with two layer phase change energy storage
    XIA Yi, YAO Wenchao, ZHANG Xiaosong, ZHANG Ruyi
    2014, 65(z2):  240-247.  doi:10.3969/j.issn.0438-1157.2014.z2.036
    Abstract ( 129 )   PDF (3572KB) ( 173 )  
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    This paper puts forward a new type end equipment of double capillary floor system with phase change material, and makes theoretical study and numerical simulation on it. The analysis of heat storage time, phase transition temperature and water temperature so as well as the temperature distribution of each floor layer. The results of this study provide guidance to such system.

    A novel double-stage open absorption heat pump system
    YE Bicui, CHEN Guangming, LIU Jun, ZHENG Jiao
    2014, 65(z2):  248-255.  doi:10.3969/j.issn.0438-1157.2014.z2.037
    Abstract ( 166 )   PDF (2532KB) ( 341 )  
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    Considerable amount of energy provided for drying processes is rejected to the environment with the moisture in the discharged moist gas, which results in a significant energy inefficiency of the drying processes. In this paper, a new double-stage open absorption heat pump system has been proposed to recover the latent heat of the moist gas and produce high-temperature output, especially in the forms of steam, which is more practical for industrial application and more easier to store. A mathematical model was constructed to analyze the performance of the system. It was demonstrated that the secondary generator pressure pg2 had to be optimized to get a high energy-saving rate (RES), but heat recovery rate (η) of moist gas decreased with the increase of pg2. The optimized pg2 was 81.78 kPa when pressure of driven steam supplied to generators (pdsg) supplied to generators was above 750 kPa. The η increased with the increase of pdsg, and the highest η could achieve 49.5%. It was also found that the RES achieved from 16.47% to 60.3% when pdsg was from 550 to 850 kPa, which means that when 1 kg paper product was produced 60% of energy consumption could be saved.

    Simulation of CO2 heat pump water heater with hybrid heat sources
    LI Shanshan, LI Shuhong, ZHANG Xiaosong
    2014, 65(z2):  256-264.  doi:10.3969/j.issn.0438-1157.2014.z2.038
    Abstract ( 109 )   PDF (3082KB) ( 229 )  
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    To improve the performance of the heat pump water heater, CO2 is used to develop a heat pump water heater using the hybrid heat sources for its advantages of environment-friendly and the unique thermodynamic properties. The steady state models, including heating collector/evaporator, compressor, gas cooler, regenerator and throttle, are established according to the lumped parameter method. The operating characteristics of the CO2 heat pump water heater using the hybrid heat sources are analyzed, and the changes of COP were proposed on varied structural parameters, pressure, temperature of CO2,environmental temperature and solar radiation. The results show that a higher COP is achieved for the CO2 heat pump water heater at the appropriate structure parameters, enviromental parameters and operation parameters. The value of COP is 6.0 while the ambient temperature and the solar radiation are 35℃ and 900 W·m-2 respectively.

    Performance experiment and prediction simulation for air conditioning system with variable chilled water temperature
    JIANG Chuyao, LIANG Caihua, FAN Pengjie, ZHANG Xiaosong
    2014, 65(z2):  265-271.  doi:10.3969/j.issn.0438-1157.2014.z2.039
    Abstract ( 144 )   PDF (1761KB) ( 157 )  
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    To study the variation of performance of air conditioning system in the condition of variable chilled water temperature, a performance prediction model for air conditioning system including chiller and cooling coil which based on the modeling method making unknown parameter lumped and getting model parameters from measured data is developed. An experimental device is built up to validate this performance prediction mode, and simulation on performance of air conditioning system under variable chilled water temperature condition is studied. The results show that the relative errors of performance parameters such as cooling capacity and COP (coefficient of performance) between simulation and experiment are within 10%. The increase of COP caused by chilled water temperature increasing from 7℃ to 15℃ is 21.1% when return-air dry-bulb temperature of cooling coil is 28℃, and the dehydration quantity decrease 96.4%. It can be concluded that return-air dry-bulb temperature influences the energy saving effect and dehydration quantity of air conditioning system with variable chilled water temperature, the influence of chilled water temperature on performance of air conditioning system and comfort of indoorenvironment should be considered, and the variation range should be controlled based on setting indoor temperature and supply-air state.

    Performance of solar liquid desiccant regeneration
    QIAN Junfei, YIN Yonggao, ZHANG Xiaosong, GAO Longfei, ZHANG Youchao
    2014, 65(z2):  272-279.  doi:10.3969/j.issn.0438-1157.2014.z2.040
    Abstract ( 137 )   PDF (2413KB) ( 139 )  
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    To investigate the performance of solar liquid desiccant regeneration, experiments in the system of the solar liquid desiccant regeneration using LiCl solution as the liquid desiccant were performed. The effects of the important operating parameters on the performance of the system were analyzed experimentally. The results showed that,the air and solution mass flow rate had a big positive impact on the performance of the system. The regenerated rate and the energy utilization rate of the system were increased with the liquid desiccant regeneration temperature, but the heat collecting efficiency was decreased with the liquid desiccant regeneration temperature. The regenerated rate, the heat collecting efficiency and the energy utilization rate of the system would be reduced if the solution concentration increased. And the heat collecting efficiency increased when the solar radiation increased, the system energy utilization rate reduced on the other hand. In addition, the experimental results provided reliable data for the further analysis about how to make use of solar energy efficiently on solution regeneration process.

    A novel Z-type packing used for desiccant regenerator
    YIN Yonggao, ZHENG Baojun, GAO Longfei, ZHANG Xiaosong
    2014, 65(z2):  280-285.  doi:10.3969/j.issn.0438-1157.2014.z2.041
    Abstract ( 141 )   PDF (1481KB) ( 197 )  
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    Liquid desiccant air conditioning systems have become popular because of the advantage in removal of latent heat load. Regeneration performance is experimentally studied on a liquid regenerator filled with novel Z-type packing (specific surface area 160 m2·m-3) and corrugated structured packing (specific surface area 450 m2·m-3).The results show that, under the same operating condition in winter, the regeneration rate, the regeneration efficiency and the regeneration thermal efficiency of Z-type packing are about 40%,50% and 70% of the corrugated structured packing respectively. In addition, all the regeneration performance indicators have large space to improve through reducing the space between Z-type units. The Z-type packing in liquid desiccant regenerator is promising compared with the corrugated structured packing.

    Preparation and properties of lauric-palmitic-stearic acid eutectic mixture/ expanded graphite composite phase change material for energy storage
    YUAN Yaguang, YUAN Yanping, ZHANG Nan, LI Tianyu, CAO Xiaoling
    2014, 65(z2):  286-292.  doi:10.3969/j.issn.0438-1157.2014.z2.042
    Abstract ( 139 )   PDF (1896KB) ( 199 )  
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    Based on theoretical calculation, lauric acid-palmitic acid-stearic acid ternary eutectic mixture (LA-PA-SA) was obtained firstly. Then, the LA-PA-SA/expanded graphite (EG) composite phase change material (PCM) with an optimum mass ratio of LA-PA-SA: EG=15:1 was prepared by the porous structure of EG. The prepared LA-PA-SA/EG composite PCM are characterized by the scanning electron microscope (SEM), Fourier transformation infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermal cycling and thermal performance test. The results showed that LA-PA-SA uniformly distributed in the porous network structure of EG due to the capillary action and surface tension. The melting and freezing temperatures and latent heats of the LA-PA-SA/EG composite PCM were 32.1℃ and 30.3℃, and 143.2 J·g-1 and 143.1 J·g-1 respectively. Thermal cycling test results showed LA-PA-SA/EG had a good thermal and chemical reliability after 1000 thermal cycles. Thermal performance test results indicated that the rate of thermal energy storage and release was accelerated due to the high thermal conductivity of EG.

    Experimental performance of direct absorption collector using heat-transfer oil added with different nanoparticles
    XU Guoying, LI Lingzhi, ZHANG Xiaosong, SUN Yueming
    2014, 65(z2):  293-298.  doi:10.3969/j.issn.0438-1157.2014.z2.043
    Abstract ( 113 )   PDF (1197KB) ( 220 )  
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    A kind of direct solar heat collection system, in which heat-transfer oil added with nanoparticles as the absorbing medium in vacuum tube without coating was proposed. Different kind of oil based nanofluids respectively added with CuO、Fe3O4 and graphite nanoparticles for solar heat collection were experimentally investigated. Results show that a greatly enhancement achieved in the solar radiation absorption capacity when add nanoparticles into the heat-transfer oil. Within 80℃, direct absorption collecting efficiency using nanofluids is higher than that of using traditional film coating vacuum tube solar collector, while the heat loss increased rapidly on a higher temperature condition. Furthermore, efficiencies of oil-based CuO nanofluids with different mass fractions were also comparatively analyzed, and the optimum added mass fraction was obtained.

    Preparation and characteristics of magnetic porous starch microspheres
    QIAN Siriguleng, LÜ Yang, WANG Hongying, LI Chenghua
    2014, 65(z2):  299-303.  doi:10.3969/j.issn.0438-1157.2014.z2.044
    Abstract ( 28 )   PDF (1650KB) ( 116 )  
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    Magnetic microsphere is a composite magnetic material with rich surface functional group. Porous starch was prepared by corn starch hydrolysis using biological enzymatic method, then 10—15 μm magnetic porous starch microspheres can be obtained by mixing Fe3O4 magnetic fluid and porous starch by multiple shake and centrifugation. Oval or spherical magnetic microspheres with rich hydroxyl and carboxyl functional groups can be observed by SEM and FTIR. The obtained magnetic microspheres can be uniformly distributed in aqueous solution and have strong magnetic response in an external magnetic field.

    Synthesis and surface modification of ZSM-5 and Fe-ZSM-5 zeolite membranes
    LIU Xiufeng, XU Kai, ZHANG Baoquan
    2014, 65(z2):  304-309.  doi:10.3969/j.issn.0438-1157.2014.z2.045
    Abstract ( 33 )   PDF (1403KB) ( 120 )  
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    ZSM-5 and Fe-ZSM-5 membranes were synthesized on α-Al2O3 by secondary growth. The organic templates were removed at 450℃ in the flowing air environment. After ZSM-5 and Fe-ZSM-5 membranes were treated with NaOH or NaCO3 solution, the hydrophilicity of the membrane surface could be enhanced, leading to improved permeation flux and separation factor in prevoporation of aqueous ethanol solution. After treated by NaOH for 2 h, the permeation flux of Fe-ZSM-5 membrane could reach to 2.01 kg·m-2·h-1 with the separation factor of 21.0.