Monitoring and control of combustion flames in utility boilers are required in order to optimize combustion conditions.This paper presents an instrumentation system for the concurrent measurement of the temperature di...Monitoring and control of combustion flames in utility boilers are required in order to optimize combustion conditions.This 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.展开更多
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 m...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.展开更多
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...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.展开更多
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...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.展开更多
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 th...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.展开更多
To clarify whether the adsorption of water in MCM41 can be promoted by introducing some metal ions onto its surface, molecular dynamics simulations were carried out to investigate the behavior of some water molecules ...To clarify whether the adsorption of water in MCM41 can be promoted by introducing some metal ions onto its surface, molecular dynamics simulations were carried out to investigate the behavior of some water molecules confined in mesoporous MCM41 whose pore size was tailored to 2.5 nm. Pure silica MCM41 as well as those containing some metal ions such as Al3+, Cu2+, and La3+ was simulated, and by observing the local average density distribution of particles, we found that both the MCM41 containing Al3+ and that of La3+ performed higher adsorption and lower desorption temperature. It is concluded that the adsorption is improved mainly owing to the diversities of polarity, active sites, and structure imported by these metal ions.展开更多
基金the National High Technology Research and Development of China (863 Program) (2006AA05A103)the National Natural Science Fund (grant No. 40501017, grant No. 50706053)
文摘Monitoring and control of combustion flames in utility boilers are required in order to optimize combustion conditions.This 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.
基金supported by the National Basic Research Program of China (973 Program) under Grant No.2012CB933200the National Natural Science Fundation of China under Grant No.51276180
文摘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.
基金supports of the National Natural Seience Foundation of China (Grant No.50706053)the National High Teelmology Research and Development Program of China(863 Prograrn,Grant No.2007AA052259) are gratefully acknowledged.
文摘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.
基金supported by the National Natural Science Foundation of China (Grant No.50976118)the National Basic Research Program of China (973 Program) Grant No.G2010CB227302
文摘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.
基金supports of the National Natural Science Foundation of China (Grant No. 50976118)the Shandong Provincial Natural Science Foundation of China (Grant No. ZR2010EM056) are gratefully acknowledged
文摘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.
文摘To clarify whether the adsorption of water in MCM41 can be promoted by introducing some metal ions onto its surface, molecular dynamics simulations were carried out to investigate the behavior of some water molecules confined in mesoporous MCM41 whose pore size was tailored to 2.5 nm. Pure silica MCM41 as well as those containing some metal ions such as Al3+, Cu2+, and La3+ was simulated, and by observing the local average density distribution of particles, we found that both the MCM41 containing Al3+ and that of La3+ performed higher adsorption and lower desorption temperature. It is concluded that the adsorption is improved mainly owing to the diversities of polarity, active sites, and structure imported by these metal ions.
