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Methanol adsorption studies of electrified ACF by MD simulations

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Science China(Technological Sciences) 2004年第6期47卷 667-675页

作者： liang shiqiang XU Jingzhong Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100080China

In order to clarify whether static electricity can impose a control on physical adsorption of polar adsorbates, MD simulations were carried out to study the adsorption/desorption behavior of methanol in the nanopores of electrified activated carbon fiber (ACF). Some special phenomena were observed from the MD simulations for methanol adsorption in a mesopore of electrified ACF. For example it takes a shorter time for the adsorbates to reach the adsorption sites on the mesopore wall, the liquid-like methanol is highly condensed, the methanol molecules have a unique distribution of space orientation, and the total energy of equilibrium state dropped a lot. These phenomena indicate the static electricity reinforced the interaction between the polar methanol and the electrified ACF, so that the intensity, stability and regularity of adsorption were increased, and thus we predict that the adsorption capacity will be increased and the adsorption process will be accelerated. When adsorption equilibrium was reached at room temperature, eliminated the electric charges and heated the system, the desorption tendency was evidently observed from our simulations at 60°C or so.

关键词： ACF methanol adsorption MD static electricity

An Efficient Summer Operation Scheme for a Thermal Power Plant Air Cooling System based on Electric Peak Shaving

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Journal of Thermal Science 2020年第2期29卷 393-407页

作者： HU Hemin liang shiqiang JIANG Yuyan GUO Yongxian Heat and Mass Transter Research Center Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

We proposed a novel efficient operation scheme for a thermal power plant’s air-cooling system based on peak shaving, in order to cope with high ambient temperature in summer. We introduced an absorptiongeneration equipment with water/lithium working pairs into the air cooled condenser(ACC) to reconstruct the traditional thermal power plant, and established a dynamic thermodynamic model adopting Ebsilon code. We studied the thermodynamic performance variation of the reconstructed thermal power plant throughout a 24-hour cycle and found that the fluctuation ratio of the turbine back pressure decreased to 6% from 78%, which is beneficial for the stable and safe operation of the electric power system. The thermal performance improvement benefited from the exploitation of the heat transfer potential of ACC, which realized via cold duty schedule throughout the day, under different ambient temperature conditions. In this system, the generated power was higher at relatively high ambient temperature than that at relatively low ambient temperature, which solved the electricity demand-supply imbalance problem under high ambient temperature. Finally, the same optimization effects for power thermal plants with an indirect air-cooling system were obtained using the same operation scheme.

关键词： thermal power reconstruction air cooled condenser(ACC) indirect air cooling system peak-shaving absorption-generation equipment

Viscous Heating for Laminar Liquid Flow in Microtubes

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Journal of Thermal Science 2011年第3期20卷 268-275页

作者： Zhigang LIU shiqiang liang Chengwu ZHANG Ning GUAN Energy Research Institute of Shandong Academy of Sciences Jinan 250014 China Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China

Using de-ionized ultra-filtered water (DIUFW) as the working fluid, the effects of viscous dissipation in micro-tubes with inner diameters of 19.9μm and 44.2μm, respectively, have been studied by experiments, the theoretical analysis and the numerical simulation at laminar state. Based on thermal imaging technology of micro-area, the temperature rise resulted from the viscous dissipation in microtube is measured by employing IR camera with a specially magnifying lens at different Reynolds numbers. A 2-D model adapted to microtube is presented to simulate the viscous dissipation characteristic considering electric double layer effect (EDL). The investigation shows the calculating results are in rough agreement with the experimental data if removing the experimental uncertainties. Based on the experimental and the numerical simulation results, a viscous dissipation number which can describe the law of the viscous heating in microtube is summed up and it explains the abnormity of the flow resistance in microtubes.

关键词： viscous dissipation microtube IR camera numerical simulation electric double layer effect

n-Octadecanethiol Self-Assembled Monolayer Coating with Microscopic Roughness for Dropwise Condensation of Steam

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Journal of Thermal Science 2009年第2期18卷 160-165页

作者： liang CHEN shiqiang liang Runsheng YAN Yanjun CHENG Xiulan HUA Shuling CHEN Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China College of Mechanical and Electronic Control Engineering Beijing Jiaotong University Beijing 100044 China Institute of Light Industry Environment Protect Beijing 100089 China

Here we presented a novel technology to achieve a Super-hydrophobic coating with microscopic roughness on copper surface. First, make a layer of verdigris grow on the fresh pure copper surface. Gain it by exposing the copper to air and the mist of acetic acid solution. The green coating is a mixture of basic copper（II） carbonate and copper（II） acetate. Second heat the coating and make it decompose to CuO. Lastly, form an n-octadecanethiol self-assembled monolayers coating on the outermost surface. Contact angle test, scanning electron microscope analysis and electrochemical testing were carded out to characterize the surface, and a heat transfer experiment for dropwise condensation of steam was performed also. Results show that the modified surface bears a few Super-hydrophobic features, the static contact angle is higher than that in literatures, reaching 153.1±1.7°. The microscopic roughness can be seen in SEM images, differing much from H2O2 etched surface and bare copper surface. The condensation of steam on the surface is a typical form of dropwise condensation, in the measured range of temperature difference, under 0.1 MPa, the average convection heat transfer coefficients of the vertical surface are 1.7-2.1 times for those of film condensation. At the same time, the inhibition efficiency of surface is improved to some extent comparing with the same kind of SAMs, which suggests that the lifetime of maintenance dropwise condensation would have the possibility to surpass the existing record.

关键词： Dropwise condensation Self-assembled monolayers Microscopic roughness Super-hydrophobic surface Heat transfer coefficient

Effects of Chemical Reaction Caused by Cooling Stream on Film Cooling Effectiveness

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Journal of Thermal Science 2012年第1期21卷 60-65页

作者： Keyong Cheng shiqiang liang Xiulan Huai Wei Chen Yongxian Guo Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China Graduate University of Chinese Academy of Sciences Beijing 100049 China School of Mechano-electronic Engineering Xidian University Xi’an 710071 Shaanxi China

With the increase of inlet temperature of gas turbines, the benefits by using the conventional methods are likely to approach their limits. Therefore, it is essential to study novel film cooling methods for surpassing these current limits. Based on the theory of heat transfer enhancement, a film cooling method with chemical reaction by cool- ing stream is proposed. In order to test the feasibility of the proposed method, numerical simulations have been conducted. The classic flat plate structure with a 30 degree hole is used for the simulation. In the present study, the effects of the parameters in relation to the chemical reaction on film cooling effectiveness, such as chemical heat sink, volume changes, and reaction rate, are investigated numerically. The conventional film cooling is also calculated for the comparison. The results show that film cooling effectiveness is improved obviously due to the chemical reaction, and the reaction heat and reaction rate of cooling stream have an important effect on film ef- fectiveness. However, the effect of volume changes can be ignored.

关键词： Gas turbine Film cooling Chemical reaction Heat transfer Numerical simulation

Thermodynamic Performances of[mmim]DMP/Methanol Absorption Refrigeration

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Journal of Thermal Science 2012年第6期21卷 557-563页

作者： Wei Chen shiqiang liang Yongxian Guo Keyong Cheng Xiaohong Gui Dawei Tang Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

In order to study the theoretical cycle characteristic of [mmim]DMP （1-methyl-3-methylimidazolium dimethyl- phosphate）/methanol absorption refrigeration, the modified UNIFAC group contribution model and the Wilson model are established through correlating the experimental vapor pressure data of [mmim]DMP/methanol at T= 280~370 K and methanol mole fraction x= 0.529-0.965. Thermodynamic performances of absorption refrigera- tion utilizing [mmim]DMP/methanol, LiBr/H20 and H20/NH3 are investigated and compared with each other under the same operating conditions. From the results, some conclusions are obtained as follows： 1） the circula- tion ratio of the [mmim]DMP/methanol absorption refrigeration is higher than that of the LiBr/H2O absorption refrigeration, but still can be acceptable and tolerable. 2） The COP of the [mmim]DMP/methanol absorption refrigeration is smaller than that of the LiBr/H2O absorption refrigeration, while it is higher than that of the H2O/NH3 absorption refrigeration under most operating conditions. 3） The [mmim]DMP/methanol absorption refrigeration are still available with high COP when the heat source temperature is too high to drive LiBr/H2O absorption refrigeration.

关键词： Modified UNIFAC model Wilson model Thermodynamic performances Absorption refrigeration

Visual Flame Monitoring System Based on Two-Color Method

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Journal of Thermal Science 2009年第3期18卷 284-288页

作者： Fan Jiang Shi Liu shiqiang liang Zhihong Li Xueyao Wang Gang Lu Key Laboratory of Advanced Energy and Power Chinese Academy of Sciences (Institute of Engineering Thermophysics) P. O. Box 2706 Beijing 100190 China School of Energy and Power Engineering North China Electric Power University Beijing 102206 China Department of Electronics University of Kent UK

Monitoring and control of combustion flames in utility boilers are required in order to optimize combustion *** paper presents an instrumentation system for the concurrent measurement of the temperature distributionand soot concentration of flames developed on the two-color principle. This system consists of an endoscope,an optical assembly with optical filters, a CCD camera, a frame grabber and associated image processingsoftware. Experiments are performed on a methane-air combustor and the temperature fields and the soot concentrationscorresponding to the flame images are obtained. The results have demonstrated that the system is capableof performing on-line measurement of flame and temperature distribution, providing temporal and spatial characterizationof the combustion process. In addition, the combination of advanced optical sensing and digital imageprocessing technique can help to define the threshold by the analysis of the background noise. Furthermore, theutilization of the filter technique can enhance the image presentation effect to an extent.

关键词： Two-color method CCD camera Flame temperature fields Digital image processing

Film cooling with using the decomposition of an NH_3 cooling stream as a chemical heat sink

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Chinese Science Bulletin 2012年第27期57卷 3652-3659页

作者： CHENG KeYong CHEN Wei liang shiqiang GUO YongXian HUAI XiuLan GUI XiaoHong nstitute of Engineering Thermophysics Chinese Academy of SeiencesBeijing 100190China Graduate University of Chinese Academy of Sciences Beijing 100049 China

The inlet temperatures of gas turbines are generally increasing over time,so conventional cooling methods are likely to approach their useful *** is therefore essential to investigate novel cooling *** on the theory of heat transfer enhancement,a novel film cooling method for gas turbine blades using a chemical heat sink is *** this method,the endothermic reaction of an NH 3 cooling stream heated by the main gas stream takes place,reducing the convective heat transfer between the mainstream and the ***,film cooling effectiveness is *** test the feasibility of the proposed method,numerical simulations were conducted,using the classical flat plate with a 30 degree angled cylindrical hole(diameter,D).Film cooling effectiveness at different blowing ratios(M = 0.5,1.0,and 1.5) were computed and compared with the results of conventional cooling *** simulation results show that the proposed method can enhance film cooling effectiveness not only in the stream-wise direction,but also in the span-wise *** span-averaged film effectiveness is improved in the presence of a chemical heat sink,with the value of X/D(the ratio of downstream distance from the center of the film hole to the diameter of the film hole) increasing downstream of the film *** novel film cooling approach showed the best performance at M = 0.5.

关键词：薄膜冷却散热器 NH3 化学气膜冷却效率燃气涡轮机分解冷却方法

碳纤维负载纳米二氧化钛对空气中微量甲醛的吸附-降解性能研究

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精细石油化工 2006年第4期23卷 25-28页

作者：梁世强穆筱梅葛建芳仲恺农业技术学院化学与化工系广东广州510225

采用TiO2溶胶和活性碳纤维(ACF)制备的TiO2／ACF光催化剂吸附-降解空气中微量的甲醛。实验结果表明,在室温和无光照条件下,当甲醛浓度为0．4 mg／m3,流量为2．5 L／min时,ACF对甲醛的饱和净化量为43．8μg／g,净化量大于TiO2／ACF;在紫... 详细信息

采用TiO2溶胶和活性碳纤维(ACF)制备的TiO2／ACF光催化剂吸附-降解空气中微量的甲醛。实验结果表明,在室温和无光照条件下,当甲醛浓度为0．4 mg／m3,流量为2．5 L／min时,ACF对甲醛的饱和净化量为43．8μg／g,净化量大于TiO2／ACF;在紫外光照射下,TiO2／ACF对甲醛具有较优异的光催化降解能力,当催化剂中m(TiO2):m(ACF)=0．082 1时,降解速率为0．150μg／(g·min)。TiO2的负载量对催化剂的表面结构、吸附性能和光催化性能有显著的影响。

关键词：二氧化钛活性碳纤维光催化甲醛