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Table of Content
28 December 2012, Volume 63 Issue S2
    Coupling of lithium bromide absorption cycle inside and outside thermal physical parameters and refrigeration unit characteristics
    WANG Gang, XIE Guozhen, WANG Liangliang
    2012, 63(S2):  1-7.  doi:10.3969/j.issn.0438-1157.2012.z2.001
    Abstract ( 1368 )   PDF (453KB) ( 534 )  
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    LiBr absorption refrigeration units are paid more attention in the areas of energy saving and environmental protection because of its zero pollution,low energy consumption,stable operation and multi-function energy modes,etc.But LiBr refrigeration technology application is limited by its low refrigeration efficiency.The cooling property of LiBr refrigeration unit is analyzed by experiments,which is based on the balance of liquid phase and vapor phase in the liquor mixed by LiBr and H2O as well as the parameters of the refrigeration unit are modulated in the refrigeration circle.The experiments prove that evaporation temperature,the concentration of the LiBr liquor and the absorption pressure could improve the cooling capacity and the COP of the refrigeration which are impacted mostly by the absorption pressure and the absorption pressure could improves the COP by 100%,on the contrary,the upper temperature of the cooling water of the LiBr refrigeration unit,the lower cooling capacity and COP.Therefore,the proper setup of thermal properties in the refrigeration circle could improve the refrigeration character.
    Steady state characteristics of absorption-compression hybrid refrigeration cycle
    LI Jianbo, XU Shiming, KONG Shaokang
    2012, 63(S2):  8-13.  doi:10.3969/j.issn.0438-1157.2012.z2.002
    Abstract ( 1238 )   PDF (806KB) ( 479 )  
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    The distributed-parameters model of heat transfer between the gases and working fluids in the generator was established in the absorption-compression hybrid refrigeration system powered respectively by the exhaust heat and power from engine,as well as the lumped-parameters in the other units.The steady characteristics of the hybrid refrigeration cycle were analyzed at the condition of cooling load being 30 kW.The research results show that the compression refrigeration supplies primarily the cooling load for the bus when the bus drives at idle and low speed; and the absorption refrigeration sub-cycle supplies mainly the cooling load for the bus when it is at middle and high speed.
    Heat transfer characteristics of shell-tube latent thermal energy storage system
    ZHANG Peng, XIAO Xin, WANG Ruzhu, LI Ming
    2012, 63(S2):  14-20.  doi:10.3969/j.issn.0438-1157.2012.z2.003
    Abstract ( 1482 )   PDF (2033KB) ( 572 )  
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    The charging and discharging characteristics of a latent thermal energy storage(LTES)system using pure paraffin and composite paraffin/expanded graphite(EG)PCMs were experimentally investigated.The results showed that the thermal conductivity of the composite PCM was distinctly enhanced,whereas natural convection was hampered because the paraffin was confined in the porous structure of the EG.The time-durations of the charging and discharging processes with different flow rates for heat storage/retrieval were discussed.The time-duration of composite PCM during the discharging process was reduced more than that during the charging process,and the charging and discharging rates could be improved significantly with the higher flow rate.The charging process of the LTES system was numerically investigated with enthalpy method,which was verified by the experimental results.
    Theoretical analysis of uniform flow distribution in vertical radial adsorption bed
    LU Junliang, ZHANG Xuejun, QIU Limin, WANG Xiaolei
    2012, 63(S2):  21-25.  doi:10.3969/j.issn.0438-1157.2012.z2.004
    Abstract ( 1479 )   PDF (364KB) ( 500 )  
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    In order to improve adsorption efficiency for air separation,a cone is commonly designed in internal flow passage to keep equal pressure drop gradient along axial direction of internal and external flow passages to ensure that air is distributed uniformly in adsorbent.This paper concludes a dimensionless differential equation that adsorption bed parameters must meet when air is uniformly distributed in adsorbent by pressure drop analysis of vertical radial Π type flow adsorption bed.An experimental radial adsorption bed is also designed in this paper.The variation law of cone section radius along axial height is obtained by solving this dimensionless differential equation,which provides theoretical support for designing this kind of radial flow adsorption bed.
    Heat and mass transfer performance between liquid desiccant and air with parallel flow
    YIN Yonggao, PAN Xiongwei, CHEN Yao, ZHANG Xiaosong
    2012, 63(S2):  26-31.  doi:10.3969/j.issn.0438-1157.2012.z2.005
    Abstract ( 1570 )   PDF (425KB) ( 640 )  
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    Experiments on liquid desiccant dehumidification and regeneration were performed to investigate the characteristics of heat and mass transfer between aqueous solution of lithium chloride and air with parallel flow.Based on the NTU-Le model,the coupled heat and mass transfer coefficients were obtained according to the experimental results,and the effects of mass flow rates of air and liquid desiccant and liquid desiccant temperature were analyzed.The results provide reliable data for the related model validation and equipment performance analysis and calculation.
    Effects of face velocity of outdoor heat exchanger on frosting characteristics of air source heat pump system
    GUO Xianmin, WANG Dongli, CHEN Yiguang, WANG Weihua
    2012, 63(S2):  32-37.  doi:10.3969/j.issn.0438-1157.2012.z2.006
    Abstract ( 1423 )   PDF (700KB) ( 504 )  
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    The frost growth characteristics on the outdoor heat exchanger of an air source heat pump(ASHP)under different face velocity conditions were investigated experimentally.The dynamic frost thickness on the fins and the frost accumulation mass on the evaporator were measured,and the growth process of the frost layer was observed through a microscope.The experimental results indicate that the decrease in the face velocity of the outdoor heat exchanger accelerates the growth of the frost layer,the frosting duration reduces almost linearly with the decrease in the face velocity,further more,the lower the relative humidity is,the faster the frosting duration decreases.Therefore,the decrease in the face velocity of the outdoor heat exchanger will deteriorate the average performance of the ASHP unit in the frost/defrost period.The observation to the frost layer through a microscope shows that the acceleration of the frost layer growth under low face velocity condition is mainly attributed to the morphological variation of the frost crystal comparing with that under the high face velocity condition,which is resulted from the decrease in the wall temperature of the evaporator.Under the low face velocity condition,the column-shaped ice crystals grow mainly in its length in whole frosting period,which is similar with the form of the frost crystal under the low temperature and high face velocity conditions.The total frost accumulation mass reduces with the decrease in the face velocity,therefore,the average frost density is fallen down.
    Effect of 2-ethylhexanol additives on contact angle of water-metal surface
    SUN Han, YU Lihua, Imdad Hussain, MA Guoyuan
    2012, 63(S2):  38-41.  doi:10.3969/j.issn.0438-1157.2012.z2.007
    Abstract ( 1726 )   PDF (426KB) ( 356 )  
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    Adding a little bit 2-ethylhexanol additives to lithium bromide-water solution can enhance the absorption dramatically in LiBr-water chiller.As a result,COP of the chiller is improved.But the heat transfer is going bad in falling film evaporator where 2-ethylhexanol water solution is working.To find the reasons,this paper focuses on the contact angle by comparing the 2-ethylhexanol water solution and deionized water on the different metal plates.Experimental results show that adding a little bit 2-ethylhexanol additives to the water makes the contact angle bigger than no additives.Wettability is changed to be lower.Hence,the heat transfer in the falling film evaporator is decreased.It also shows that 40 mg稬-1 2-ethylhexanol water solution on the zinc coated steel has the smallest contact angle,next is stainless steel and the copper has the biggest contact angle.Concentration of the 2-ethylhexanol water solution has no obvious effect on the contact angle.
    Principle of designing fin-and-tube evaporator with small diameter tubes for air conditioner
    GAO Jingdan, WU Wei, DING Guoliang, GAO Yifeng, SONG Ji
    2012, 63(S2):  42-48.  doi:10.3969/j.issn.0438-1157.2012.z2.008
    Abstract ( 1833 )   PDF (572KB) ( 715 )  
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    The principle of designing fin-and-tube evaporator with small tubes is proposed in this study.The principle includes designing of fin configuration and designing of refrigerant circuits.In the designing principle,the suitable fin configuration is designed by computational fluid dynamic-based method,and the refrigerant circuits are designed by simulation-based method.To verify the designing results,experiments on air conditioner unit are carried out.The experimental results confirm the designing principle,and indicate that the optimal air conditioner with small diameter tubes has good performance.
    Performance of a novel tubular indirect evaporative cooler
    WANG Yugang, HUANG Xiang
    2012, 63(S2):  49-52.  doi:10.3969/j.issn.0438-1157.2012.z2.009
    Abstract ( 1519 )   PDF (459KB) ( 420 )  
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    The tubular indirect evaporative cooler coated water-absorbing material was tested,performance of heat and mass transfer was analyzed,affect of water content for the heat and mass transfer,and opportunity of supplying water for the water-absorbing material was analyzed.
    Numerical study of Ar-He cryoprobe
    ZHANG Shaozhi, WANG Hongyu, NIU Meimei, CHEN Guangming
    2012, 63(S2):  53-57.  doi:10.3969/j.issn.0438-1157.2012.z2.010
    Abstract ( 1395 )   PDF (489KB) ( 383 )  
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    JI Changfa, MU Hongyan, SUN Ruike, LI Lixia
    2012, 63(S2):  58-63.  doi:10.3969/j.issn.0438-1157.2012.z2.011
    Abstract ( 1361 )   PDF (453KB) ( 595 )  
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    Designed a new type of tube heat exchanger which insert spoiler components,and then at different velocity the pipe inner wall surface average heat transfer coefficient,heat transfer capacity,the average Nu and friction resistance variation characteristics of the new heat exchanger tube and corrugated tube,smooth tube are analyzed and compared.The results showed that the enhanced heat transfer capacity and the pressure loss of insert spoiler element heat transfer tube will be great,so its economy must be considered when choosing of heat exchange tube inserted by disturbance device in practical application.Under the same pump power consumption conditions,thermal efficiency for metal-wire inserts in heat exchanger tube and corrugated tube are very close.But for metal-wire inserts in heat exchanger tube the manufacturing process is convenient,flexible and more suitable for the existing heat exchanger transformation.Therefore,the heat exchange tube also has extensive application value.
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    ZHANG Xuelai, LIU Xiaowei, WU Yunyun
    2012, 63(S2):  64-68.  doi:10.3969/j.issn.0438-1157.2012.z2.012
    Abstract ( 1120 )   PDF (457KB) ( 431 )  
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    Photocatalytic oxidation of Hg0 in flue gas using TiO2-V2O5 nanofibers
    YUAN Yuan, ZHANG Junying, LI Xiaolong, ZHAO Yongchun, ZHENG Chuguang
    2012, 63(S2):  69-75.  doi:10.3969/j.issn.0438-1157.2012.z2.013
    Abstract ( 1337 )   PDF (1481KB) ( 432 )  
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    Nanofibers of TiO2 and TiO2-V2O5 prepared by an electrospinning method were used to remove Hg0 in flue gas,and characterized by SEM,TEM,XRD,BET as well as UV-Vis.The TiO2-V2O5 nanofiber is of anatase phase structure and V2O5 is highly dispersed in the fiber.Its average diameter is around 200 nm.The fiber is composed of a large number of nanoparticles with diameter around 10 nm. Compared with pure TiO2,UV-Vis absorption intensity of TiO2-V2O5 significantly increases and its absorption bandwidth also broadens.The mercury removal efficiencies under various illuminations,the optimum doping content of V2O5 as well as the capabilities to oxidize Hg0 for 8 cycles were also tested.In addition,mechanism analysis was used to reveal photocatalytic activity enhancement of TiO2-V2O5 nanofibers.The result shows that 66% of Hg0 removal efficiency can be reached under visible irradiation at the sample with 3% V2O5 doping,and much higher than 7% for pure TiO2.After eight cycles,Hg0 removal efficiencies over TiO2-V2O5 still remain stable at 80% and 65% under UV and visible light respectively,indicating that this fiber catalyst could be used for long time.The increase of photocatalytic activity under visible light could be attributed to its electron transition and better photoelectron-hole separation.
    Synthesis of cycloaliphatic epoxy-silicone oligomer with high refractive index
    ZHANG Xianshun, YE Hui, WANG Tao
    2012, 63(S2):  76-79.  doi:10.3969/j.issn.0438-1157.2012.z2.014
    Abstract ( 1584 )   PDF (419KB) ( 534 )  
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    Cycloaliphatic epoxy-silicone oligomer(Ep-Cz-SiO)with 1.577 of refrative index was synthesized via sequential hydrosilylation reactions of methylhydrogen silicone oil by attaching first N-allyl carbazole,followed by 4-vinyl-1-cyclohexene-1,2-epoxide in the presence of Lamoreaux catalyst.Ep-Cz-SiO was characterized by 1H NMR and IR.The refractive index of the obtained monomer were measured and the results showed that the carbazole ring can improve RIs.Thermal analysis showed that Ep-Cz-SiO had better thermal stability than methylhydrogen silicone oil.
    Configuration and flow process study of direct-fired heat pump system driven by biogas from sewage treatment plant
    WU Jiying, MA Yimin
    2012, 63(S2):  80-84.  doi:10.3969/j.issn.0438-1157.2012.z2.015
    Abstract ( 1499 )   PDF (450KB) ( 501 )  
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    To reclaim and utilize biogas produced during sludge treatment process in sewage treatment plants,the schemes and flow processes for utilizing the biogas were studied.A direct-fired heat pump heating system based on biogas from sewage treatment plant was structured,and the configuration and economic analysis of the system were also made.Results indicated that compared with coal-fired boiler,gas-fired boiler and electricity driven heat pump,a biogas direct-fired heat pump system of 600 kW input power,which was assumed to operate in heating mode for 300 days annually,could save 510 t of standard coal or 3.25?105 m3 of natural gas or 7.72?105 kW穐 of electricity.The initial cost of the system could be paid back in no more than 2.6 years.Therefore,this heating system was featured by good economic,energy saving and emission reduction properties,and the economic and environmental interests produced by the system should be significant.
    Analysis of sensor fault detection in chiller based on PCA method
    HU Yunpeng, CHEN Huanxin, ZHOU Cheng, YANG Xiaoshuang, XU Rongji
    2012, 63(S2):  85-88.  doi:10.3969/j.issn.0438-1157.2012.z2.016
    Abstract ( 1456 )   PDF (451KB) ( 741 )  
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    Chiller is a highly nonlinear complex system.The sensor fault in the automation system of chiller will cause it to operate in unmoral situation and waste energy.Based on the principal component analysis(PCA)method,one of the analytical methods in multivariate statistics,the data in normal condition have been used to establish the train matrix.The square prediction error(SPE)has been used to analyze the sensor fault.The detection efficiency has been analyzed by the PCA method with introducing different level faults into the chiller.The result shows that PCA-based fault detection method works well,but the fault detection efficiencies of different sensors with different level faults are inconsistent.
    Evaluation on air conditioning’s operating property of airport terminal based on hierarchal cluster
    FANG Xing, JIN Xinqiao, FAN Bo, DU Zhimin, ZENG Xiaoqing
    2012, 63(S2):  89-94.  doi:10.3969/j.issn.0438-1157.2012.z2.017
    Abstract ( 1044 )   PDF (562KB) ( 321 )  
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    Building energy simulation software-Energyplus was used to construct simulation model of an airport building and its air conditioning system in Hainan.Based on chiller system’s whole year operating data,the paper proposes a method of hierarchal cluster to categorize chiller’s operating condition by extracting operating parameters which have evident influence on chiller’s operation as the cluster parameters.It analyzes the relationship between chiller’s operation level and operating parameters,construct multivariate regression models in different clusters.By comparing every chiller’s COP in different cluster centers with the calculated COP of regression model,it illustrates that chiller’s operating property of a cluster center can be used as the representative of the cluster.It was found that hierarchal cluster can supply an effective and simple way to evaluate chiller’s operation level.
    Optimal control strategy for HVAC system of airport terminal based on optimal schedule time of AHU for pre-cooling
    FAN Bo, JIN Xinqiao, DU Zhimin, FANG Xing, ZENG Xiaoqing
    2012, 63(S2):  95-99.  doi:10.3969/j.issn.0438-1157.2012.z2.018
    Abstract ( 1147 )   PDF (514KB) ( 416 )  
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    An optimal control strategy for HVAC system of an airport terminal based on the optimal schedule time of AHU for pre-cooling is presented.According to this optimal control strategy,a BPNN model is established to predict the optimal schedule time of AHU for pre-cooling,which is used as references to control AHU operation.Comparing with the original control strategy,this optimal control strategy can maintain indoor thermal comfort and save the power consumption of HVAC system.And the sensitivity analysis of BPNN model shows that the indoor dry-bulb temperature has a great impact on prediction accuracy of this BPNN model.
    Self-tuning control algorithm with SMITH predictor for HVAC systems
    BAI Jianbo, ZHENG Yu, MIAO Guochang
    2012, 63(S2):  100-105.  doi:10.3969/j.issn.0438-1157.2012.z2.019
    Abstract ( 1050 )   PDF (423KB) ( 376 )  
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    At present,the phenomenon of low operation efficiency and wasteful of energy widely exists in HVAC systems.The main reason is that HVAC systems have nonlinear,time-delay and time-variable characteristics,which lead to poor control performance with traditional control methods.It is one of the important ways to improve the control performance of HVAC control loops with the attemption to overcome the unfavorable influences of time-delay and time-variable characteristics.A self-tuning control algorithm with SMITH predictor is put forward in the paper.In the presented control infrastructure,an online identification method is used to estimate HVAC models with time-delay parameter.Then,based on the estimated parameters,the SMITH predictor is adopted to compensate for the time-delay characteristic.Furthermore,a PI controller within the predictor is introduced to improve the robust performance.Also,the control parameters of the control algorithm are updated in real time.Simulation results demonstrate that the proposed control method is superior to traditional control methods.
    Model predictive control with input feedback and its controllability for unsymmetrical systems
    FENG Aixiang, WEI Minghui, LUO Xionglin
    2012, 63(S2):  106-111.  doi:10.3969/j.issn.0438-1157.2012.z2.020
    Abstract ( 1166 )   PDF (393KB) ( 329 )  
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    Model predictive control for nonlinear unsymmetrical system which exhibits gains and/or dynamics depending on the input or output direction has been studied.Theoretical results for these systems especially for its control aspects are very limited compared with their common occurrence in industry.Due to the differences between the positive/negative model predictive control structure for asymmetric system and the traditional predictive control structure,there may be model mismatch which would lead to bad control effect.In order to handle this problem,input feedback control algorithm is used to revise the positive/negative model predictive controller.The actual control action that applied to the object is joined into the calculation of the next step control law of the positive/negative controllers through the feedback form in order to eliminate the effect.Then the controllability of the positive/negative model predictive control system is analyzed in the unconstrained condition.Ultimately the control performance between the revised positive/negative model predictive control and the traditional positive/negative model predictive control was compared through the simulation of pH control.
    Design and analysis of surge active control for small-power FCCU rich gas compressor
    LUO Xionglin, ZHAO Juezheng, WANG Juan
    2012, 63(S2):  112-117.  doi:10.3969/j.issn.0438-1157.2012.z2.021
    Abstract ( 1351 )   PDF (448KB) ( 285 )  
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    When load reduced to a certain degree,compressor will produce dramatic surge phenomena.This will seriously damage the machine and lead to a serious consequence.In order to avoid the compressor surge of fluid catalytic cracking unit,high-power compressor is usually chosed to make its stable work,and the same time the problem of high fixed investment and lots of operating cost will bring.Active control can expand the stable work region of the compressor,and make compressor work in high performance areas,so this paper chooses a small-power compressor to work.The result of it maybe the compressor can not work in the steady areas in most time,but through the active control function the idea not only can make the compressor work in steadily,but also achieve the purpose of reducing the investment cost and operating cost.It respectively describes the control scheme and control algorithm. Finally,it proves the effectiveness of the proposed scheme by simulation of the actual cases.
    Dual time scales based dynamic simulation of surge control in FCCU rich gas compressor
    LUO Xionglin, ZHAO Juezheng, WANG Juan
    2012, 63(S2):  118-125.  doi:10.3969/j.issn.0438-1157.2012.z2.022
    Abstract ( 1657 )   PDF (647KB) ( 526 )  
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    When load reduced to a certain degree,compressor will produce dramatic surge phenomena.This will seriously damage the machine and lead to a serious consequence.The purpose of this paper is to simulate the surging phenomena and its control in rich gas compressor of fluid catalytic cracking unit.The surge will happen in a short time,and its operation step length is thousands of times different from catalytic cracking running time,so it will simulate in two different time scales.First,the compressor model applying in active control is established by using user unit model extension.In order to overcome the consumption in steady areas brought by active actuator,switching control scheme designed that compressor implements active control in surge region while compressor without active control in stable region only applying PID control can satisfy the technological requirements.Finally,the scheme is used in the dual time scales simulation.The whole process validates the effectiveness of the proposed scheme and proves that it can both solve the problem of compressor could not work in high performance area in the traditional anti-surge passive control and resolve the increasing of the energy consumption brought by active actuator.
    VO2+ permeation behavior for vanadium redox flow battery
    XU Bo, QI Liang, YAO Kejian, LIU Ran, YANG Chun, XIE Xiaofeng
    2012, 63(S2):  126-131.  doi:10.3969/j.issn.0438-1157.2012.z2.023
    Abstract ( 1708 )   PDF (429KB) ( 581 )  
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    UV-VIS spectrophotometer was employed to investigate the permeation behavior in transmembrane electrolyte ions for all-vanadium redox flow battery (VFB).Emphasis is placed on the impact on transmembrane osmosis of VO2+ ions with external factors such as concentration,temperature,state-of-charge (SOC),electric field and osmotic pressure.It was helpful to explore the effects of ion diffusion and side reactions on the capacity loss for VFB by correlating the osmotic coefficient of different vanadium ions.The results indicate that it could increase the energy efficiency and reduce the transfer rate of VO2+ ions by improving the electrolyte concentration.Lowering the system temperature helps inhibit the cross-contamination during long term use and eliminating the side reactions.The osmotic coefficient of VO2+ ions decreased when increasing the SOC.As positive electric field was employed in electrolyte solution,VO2+ ions transmembrane diffusion would be accelerated within the aggravation of self-discharge; The osmotic pressure between the anode and cathode acclerates the permeation of VO2+,leading to a capacity loss for VFB.
    Calculation of solvation free energies of VO2+/VO2+ ions in aqueous solution by using Cluster-Continuum model
    ZHAO Chengming, XIE Xiaofeng
    2012, 63(S2):  132-135.  doi:10.3969/j.issn.0438-1157.2012.z2.024
    Abstract ( 1277 )   PDF (579KB) ( 519 )  
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    The Cluster-Continuum model was employed to calculate the solvation free energy of VO2+,VO2+ ions in aqueous solution.The number of water molecules on the first solvation shell of VO2+,VO2+ ions was predicted to be 3 and 5 respectively with density functional theory (DFT) at B3LYP level.With the calculated values,the standard electrode potential of VO2+/VO2+ was computed to be 1.29 V,which was close to the theoretical value.The results showed that the Cluster-Continuum model was capable to simulate the solvation effects of VO2+,VO2+ ions.
    Performance of flat-plate PV/T integrated heat pump water heating system
    XU Guoying, ZHANG Xiaosong, ZHAO Shanguo
    2012, 63(S2):  136-141.  doi:10.3969/j.issn.0438-1157.2012.z2.025
    Abstract ( 1740 )   PDF (594KB) ( 795 )  
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    A solar photovoltaic/thermal integrated heat pump (PV/T-HP) system was proposed. Refrigerant,R134a flowing inside the tubes below the PV cells,absorbs the solar heat and evaporates.The heated water produced by heat pump could be used to supply domestic hot water services combined with space heating,or to assist solar cooling system in buildings.The system’s thermodynamic and photovoltaic output characteristics for heating 180 L water up to 60℃ were investigated experimentally on a summer sunny day in Nanjing,China.The performances of the prototype for both electricity generation and water heating vs that for electricity generation only were compared.Results show that,the performance of PV cells without cooling is deteriorated greatly at noon,because of its higher working temperature.While for the PV/T-HP system,the cells is operated on a stable and uniform temperature condition,and therefore output more electricity by 35%.
    Performance of generator of LiBr-H2O absorption cascading conversion system driven by waste heat for power,cool and heat
    BU Guangfeng, JIN Sumin, ZHANG Xiufang
    2012, 63(S2):  142-145.  doi:10.3969/j.issn.0438-1157.2012.z2.026
    Abstract ( 1300 )   PDF (371KB) ( 434 )  
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    A LiBr-H2O absorption cascading conversion system driven by waste heat for power,cool and heat was investigated.By the system,a part of energy of waste heat was transformed into power and a part of remaining energy was transformed into cool and heat so as to realize energy cascading conversion,thus achieving a more rational use of waste heat.Through analyzing the theoretical knowledge and the results of the thermodynamic calculations about the system,effect of the generator pressure and temperature on energy transformation was gained.
    Performance test and analysis of rotary type two-stage evaporative cooling air conditioning unit
    LUO Rong, HUANG Xiang, SHEN Boqing, LIU Xiaofeng, KANG Jian, LU Xiang
    2012, 63(S2):  146-150.  doi:10.3969/j.issn.0438-1157.2012.z2.027
    Abstract ( 1168 )   PDF (516KB) ( 488 )  
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    In order to study the operation of rotary two-stage evaporative cooling air conditioning unit in areas of high humidity,a 3000 m3·h-1 air volume rotary heat recovery-type indirect-direct evaporative cooling air conditioning unit was tested.When opened primary air side rotary indirect evaporative cooling section and filler segment,the pump of secondary air side filler segment was shut down,the supply air temperature of the unit was 23℃,which was lower than the outdoor air dew-point temperature of 24.5℃,the total average temperature drop of the unit was 7.1℃,the average temperature drop of the rotary indirect segment was 6.9℃,the average cooling efficiency of 76.9%,filler segment almost did not play a role in cooling,the dominant cooling rotary indirect segment.The contrast in a dry,moderate humidity areas,the average outdoor dry bulb temperature of 32.1℃,which played a major role in cooling air side filler segment,lower the average temperature up to 5.5℃.This showed whether the indirect,direct,or indirect-direct evaporative cooling could applied where refrigeration refrigeration cooling was expensive.
    Refrigeration dehumidification system with membrane-based total heat recovery
    LIANG Caihang, ZHANG Lizhi
    2012, 63(S2):  151-155.  doi:10.3969/j.issn.0438-1157.2012.z2.028
    Abstract ( 1303 )   PDF (364KB) ( 491 )  
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    An independent air dehumidification system is helpful for improving the indoor air quality.Refrigeration dehumidification system with membrane-based total heat recover is the key equipment to realize this goal.The system comprises of two subsystems:membrane total heat recover and refrigeration dehumidifier.The total heat exchanger has a membrane core where the incoming fresh air exchanges moisture and temperature simultaneously with the exhaust air.In this manner,the total heat or enthalpy from the exhaust air is recovered.Then the fresh air flows through a cooling coil where it is dehumidified below the dew point.Finally,the code and dry air are supplied to indoor.A prototype is built in laboratory.Experiments are conducted under variable operating conditions in the enthalpy laboratory.The effects of air flow rates,temperature,and air relative humidity on the air dehumidification rates,cooling capacities,electric power of compressor and COP are investigated under indoor temperature 27℃ and bulk wet-bulb temperature 19℃.The experimental results show that the prototype has a high air dehumidification rates and COP under hot and humid environment.
    Preliminary exploration for air-conditioning system of combination of evaporative cooling and semiconductor refrigeration
    SUN Zhe, HUANG Xiang, WANG Chao, SUN Tiezhu
    2012, 63(S2):  156-160.  doi:10.3969/j.issn.0438-1157.2012.z2.029
    Abstract ( 1661 )   PDF (428KB) ( 667 )  
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    In this paper the principle and the current status of semiconductor refrigeration are briefly introduced.Meanwhile,the influence of the difference between the cold and hot side temperature of the refrigeration was analysed.A brief introduction of the air conditioning system is characterized by a combination of evaporative cooling and semiconductor refrigeration,as well as doing the derivation of formula for the COP of the semiconductor refrigerating device in the system.Preliminary to the performance for semiconductor refrigerating device in the system was tested.The experimental results showed the semiconductor refrigerating device within the maximum coefficient of performance for 3.3.It lays the foundation for further research.
    Analysis of new system combining CO2 cryogenic capture and liquefaction with N2/O2 separation
    DING Jie, LI Shuhong, CHENG Deyuan, ZHANG Xiaosong
    2012, 63(S2):  161-165.  doi:10.3969/j.issn.0438-1157.2012.z2.030
    Abstract ( 1479 )   PDF (429KB) ( 533 )  
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    A novel CO2 cryogenic capture and liquefaction system is introduced and studied theoretically in this paper.The performance and advantages of the combined system are discussed theoretically in this research.This new system combines the CO2 cryogenic capture and liquefaction system with the N2/O2 separation together.The aim is to reduce the energy consumption of CO2 separation.Theoretical analysis and software-simulation of the combined system are carried out together.The results show that the energy consumption of the proposed new system is lower than the traditional amine solution capture system.When one ton CO2 is separated and liquefied,the total primary energy consumption of this combined system is 3.29 GJ,while the traditional amine solution capture system is 4.11 GJ.In addition,the byproducts N2 and O2 can be obtained as well.The study of this paper presents a new thought for the CO2 cryogenic capture and liquefaction system.
    Ejector used in transcritical CO2 heat pump system
    CHEN Qi, LÜ Yujie, TONG Yang, LI Tao, CHEN Guangming, TANG Liming
    2012, 63(S2):  166-169.  doi:10.3969/j.issn.0438-1157.2012.z2.031
    Abstract ( 1226 )   PDF (398KB) ( 453 )  
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    An experimental transcritical CO2 heat pump water heater system was designed,and the measurement and control system for testing was developed.The flow rate,entrainment ratio,compression ratio and efficiency of ejector were investigated.The experimental results showed that:the increase of both primary fluid pressure and entrained fluid pressure can improve the performance of the ejector,the decrease of primary fluid pressure or the increase of entrained fluid pressure can improve the ejector working perfection.Development of high efficient ejector was a critical factor on optimizing transcritical CO2 heat pump system.
    Performance analysis of boosting double-effect ammonia-water absorption refrigeration cycle
    CAI Xingchen, DU Kai, LI Yanjun
    2012, 63(S2):  170-175.  doi:10.3969/j.issn.0438-1157.2012.z2.032
    Abstract ( 1524 )   PDF (461KB) ( 458 )  
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    On the basis of double-effect NH3-H2O absorption refrigeration cycle,a boosting double-effect NH3-H2O absorption refrigeration cycle was proposed.Combined with Schulz’s ammonia-water state equation,mathematical model was established to simulate the process and analyze influencing factors of performance such as pressure ratio,refrigeration temperature,cooling water temperature and heat source temperature.A comparison with traditional double-effect ammonia-water absorption refrigeration cycle was also made.The result showed that pressure ratio was a very important factor,which directly affected performance coefficient of the cycle and without changing other factors,the cycle had the optimum pressure ratio.With the appropriate pressure ratio,the cycle could also have higher performance coefficient at lower refrigeration temperature and expanded the scope of refrigeration application of the double-effect cycle.Meanwhile,at the same refrigeration temperature,the cycle reduced the driven heat source temperature and expanded the scope of the available heat source.
    Pressure characteristics of auto-cascade refrigeration system
    RUI Shengjun, ZHANG Hua, HUANG Lihao
    2012, 63(S2):  176-180.  doi:10.3969/j.issn.0438-1157.2012.z2.033
    Abstract ( 1981 )   PDF (376KB) ( 762 )  
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    A pressure regulation and control system for auto-cascade refrigeration system was designed in order to solve the problem of too high exhaust pressure and exhaust temperature at the starting up process.It is on the basis of three-stage auto-cascade refrigeration system as the research object and including a buffer,an expansion tank,pressure control valve and pipeline.Buffer has the role of easing the impact of high pressure refrigerant gas and stabling the pressure of refrigerant gas.Expansion tank has the effect of receiving and storing refrigerant gas.The bypass branch from buffer may realize high and low pressure bypass through electromagnetic valve and expansion tank.The bypass branch from the upper of the two-phase separator can effectively control and regulation the compressor discharge pressure and exhaust temperature through manual ball valve and flow meter.Through the experimental research,the cabinet with bypass refrigerator system could accelerate initial cooling speed and had the effect of fast cooling refrigerant gas.The system bypass quantity could be adjusted through pressure control valve,and then the system pressure and temperature could be controlled in a reasonable range.It might avoid forced shutdown of pressure control system.
    Low-frequency vibration characteristic of gas bearing turbo-refrigerator
    ZHAO Chen, YANG Jinfu, HAN Dongjiang, QI Weijun, CHEN Changting
    2012, 63(S2):  181-186.  doi:10.3969/j.issn.0438-1157.2012.z2.034
    Abstract ( 1066 )   PDF (1492KB) ( 445 )  
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    Experimental studies on low-frequency vibration,which are apt to happen on the gas bearing turbo-expander in the air refrigerator system for the airplanes,are carried out in this paper.Tests are conducted at various journal bearing supply pressure and run-rate to research the characteristics of low-frequency vibration i.e.gas-film whirl and gas-film whip.The experimental results verify the impact of low-frequency vibration on stability,and appropriate bearing supply pressure and run-rate can abate and eliminate the low-frequency vibration.More importantly,the results reveal the relationship between low-frequency vibration and the mechanical efficiency of rotor-bearing system,and an effective calculation equation is proposed.
    Test analysis of semi-central evaporative cooling air conditioning system in office building
    HUANG Xiang, BAI Yanbin, HAO Hang, SUN Tiezhu
    2012, 63(S2):  187-192.  doi:10.3969/j.issn.0438-1157.2012.z2.035
    Abstract ( 1467 )   PDF (591KB) ( 373 )  
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    Introduced the design process of the semi-central evaporative cooling air conditioning system in an office building of Xinjiang,combined with the office building structure adopted tandem air -water system.Test results show that the outdoor dry bulb temperature is 35.0℃,and the tertiary evaporative cooling air unit can make the supply air temperature to 13.5℃.The water temperature of indirect-direct evaporative cooling composite chiller is 16.5℃,the indoor maintain in the air conditioning specification requirements of the comfort zone.The paper analyzes the semi-central evaporative cooling air conditioning system’s advantages and disadvantages,and provides some suggestions for evaporative cooling air conditioning system design.
    Influence of spray solution on novel non-frosting air source heat pump system performance
    FU Huiying, JIANG Yiqiang, YAO Yang, GAO Qiang
    2012, 63(S2):  193-198.  doi:10.3969/j.issn.0438-1157.2012.z2.036
    Abstract ( 1376 )   PDF (420KB) ( 407 )  
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    Based on the study of the mechanism of defrosting of air-source heat pump (ASHP),a novel non-frosting air-source heat pump (NASHP) and its test rig were developed.The NASHP system has been proved feasible by the experiment.When it ran in "frost prevention" mode,its temperature difference of air was 1.5℃ larger and its heat output was 6% higher than that of conventional system.Moreover,for the compression ratio and parameters of air almost kept the same in the running process,the compressor and system was stable.When the glycerol was selected as spray solution for NASHP,for ensuring the effect of frost prevention,glycerol content should be 31%-65%(mass) and its flow of unit windward area should be 0.53-0.64 t·(h·m2)-1.
    Analysis on energy consumption of freezing concentration in wastewater treatment
    WEN Ling, ZHANG Xu, ZHOU Xiang
    2012, 63(S2):  199-203.  doi:10.3969/j.issn.0438-1157.2012.z2.037
    Abstract ( 1672 )   PDF (379KB) ( 542 )  
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    As an energy saving and environment protecting wastewater treatment method,freezing concentration is a new way not only to solve the problems of water pollution but save energy and ease the water demand in water scarce areas.Compared with evaporating wastewater treatment,freezing concentration has a huge energy-saving potential.Through theoretical analysis and calculation under the design conditions,it is obvious that the freezing concentration method use 30.35% less energy than evaporating in wastewater treatment.It consumes about 45.7% less energy while using pre-cooling method in freezing concentration.Moreover,it consumes about 62.5% less energy while combining freezing concentration with pre-cooling method and ice thermal storage technology.
    Size effect of methane-air mixture explosion intensity in spherical vessels and pipelines
    CUI Yiqing, WANG Zhirong, JIANG Juncheng
    2012, 63(S2):  204-209.  doi:10.3969/j.issn.0438-1157.2012.z2.038
    Abstract ( 1013 )   PDF (531KB) ( 586 )  
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    Size effect on explosion intensity of methane-air mixture in spherical vessels and pipes was investigated.The experimental results suggested diameter of the spherical vessel,the length of connection pipes of single vessel and the length of connection pipes between two spherical vessels played a great role in explosion intensity of methane-air mixture in spherical vessels and pipes.The maximum explosion pressure and the maximum rate of pressure rise in single vessel with connection pipes both decrease due to the increase of the length of connection pipes.And the maximum explosion pressure and the maximum rate of pressure rise appeared at the end of connection pipes.For linked vessels,the explosion intensity in secondary vessel increased with the increasing of the length of connection pipes with linear relationships.The conclusions provided important reference for safety design of explosion venting and explosion resistance.