A statistical signal processing technique was proposed and verified as independent component analysis(ICA) for fault detection and diagnosis of industrial systems without exact and detailed model.Actually,the aim is t...A statistical signal processing technique was proposed and verified as independent component analysis(ICA) for fault detection and diagnosis of industrial systems without exact and detailed model.Actually,the aim is to utilize system as a black box.The system studied is condenser system of one of MAPNA's power plants.At first,principal component analysis(PCA) approach was applied to reduce the dimensionality of the real acquired data set and to identify the essential and useful ones.Then,the fault sources were diagnosed by ICA technique.The results show that ICA approach is valid and effective for faults detection and diagnosis even in noisy states,and it can distinguish main factors of abnormality among many diverse parts of a power plant's condenser system.This selectivity problem is left unsolved in many plants,because the main factors often become unnoticed by fault expansion through other parts of the plants.展开更多
The air conditioning system in the Umm Al-Qura University (Albdiya Campus) was conceived to be a district cooling by a remote chilled water plant. Recently, there are two chilled water plants in the university install...The air conditioning system in the Umm Al-Qura University (Albdiya Campus) was conceived to be a district cooling by a remote chilled water plant. Recently, there are two chilled water plants in the university installed strategically to provide chilled water to all the academic and administrative buildings of the university through distribution network with total capacity approximately of 12,000 tons of refrigeration. The plants were built based on cooling towers with open water cycle as heat rejection system. Water treatment chemicals has been used to protect the cooling systems from corrosion, scaling and microbiological fouling accompanied with dissolved and suspended water impurities. Different methods are being used to determine and control the treatment chemical concentrations and system performance indicators. Traditional chemical controller has drawback of indirect measurements and set points. The purpose of this paper is to present a solution to overcome the problems of traditional and conventional chemical treatment and control sys-tems. Central cooling plant number (1) assigned to perform experimental setup using new chemical treatment technology. Advanced automatic chemical treatment controller installed on condensers (1, 2 and 3), and certain key performance indicators were selected and monitored such as chemical and water consumption, power, energy saving, and maintaining system integrity and efficiency. Satisfactory results were obtained in terms of performance and cost of operation.展开更多
The operating theory of an evaporative condenser was expatiated.The difference between an evaporative condensing refrigeration system and a general refrigeration system was analyzed.Compared with the air-cooled and th...The operating theory of an evaporative condenser was expatiated.The difference between an evaporative condensing refrigeration system and a general refrigeration system was analyzed.Compared with the air-cooled and the water-cooled,the virtues of energy-conservation and water-conservation of evaporative condensers were analyzed.Some questions existing in the application of evaporative condensers were pointed out,the corresponding solving methods were analyzed accordingly,and the development trend of evaporative condensing technique in mechanical refrigeration system field and the applied foreground of evaporative condensers in comfortable air conditioning were prospected.展开更多
<span style="font-family:Verdana;">Accord</span><span style="font-family:Verdana;">ing</span><span style="font-family:Verdana;"> to </span><span sty...<span style="font-family:Verdana;">Accord</span><span style="font-family:Verdana;">ing</span><span style="font-family:Verdana;"> to </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">study of basic Rankin thermal cycle, the steam exh</span><span style="font-family:Verdana;">aust pressure of a typical steam turbine toward </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">condenser, plays a great rol</span><span style="font-family:Verdana;">e</span><span style="font-family:Verdana;"> in the efficiency and the net output power of </span><span style="font-family:Verdana;">the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">steam turbine, so most surface conden</span><span style="font-family:Verdana;">sers </span></span><span style="font-family:Verdana;">that</span><span style="font-family:Verdana;"> are working in thermal power plants are kept at va</span><span style="font-family:;" "=""><span style="font-family:Verdana;">cuum condition so that the maximum power of thermal cycle can be achieved. The </span><span style="font-family:Verdana;">vacuu</span><span style="font-family:Verdana;">m pressure at condenser leads to </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">entering of air </span><span style="font-family:Verdana;">and Non-</span><span style="font-family:Verdana;">condensable gases from turbine gland seals to condenser so that the special air ejection equipment is being used to take apart air from steam and vent it to out of condenser.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">In this study</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> a special steam and air separator mechanism in </span><span style="font-family:Verdana;">an </span><span style="font-family:Verdana;">evacuating system called </span><span style="font-family:Verdana;">“</span><span style="font-family:Verdana;">Aircooler</span><span style="font-family:Verdana;">”</span><span style="font-family:Verdana;"> at a 16</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">MW steam turbine condenser is being studied and the Fluent CFD software is utilized to analyze the behavior of steam plus air in a typical aircooler system of 16</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">MW steam turbine condenser of Neka power plant to find a way to reduce the risk of cooling tube rupture in aircooler ducts. The critical condition which tube rupture happens is determined and it is demonstrated that in hot seasons of year, by increasing the seawater cooling temperature and increasing in turbine steam exhaust pressure and temperature, the risk of tube rupture due to more mixture velocity at the first row of aircooler cooling tubes increases and also</span><span style="font-family:Verdana;"> the effect of tube plugged condition on the performance of </span><span style="font-family:Verdana;">aircooler shows that the risk of other tubes rupture will increase and thus the efficiency of aircooler decreases due to more aircooler exhaust temperature. Finally</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> two modified plans at aircooler system design will be studied and simulated via Fluent CFD software which leads to reduce the risk of tube rupture. The results show that by modification of aircooler ducts and holes, the mixture air and steam flow velocity to first aircooler cooling tube row decreases significantly and causes the risk of tube rupture </span><span style="font-family:Verdana;">to </span><span style="font-family:Verdana;">decrease remarkably and also the exhaust temperature of aircooler decreases and causes the higher ejector performance.</span>展开更多
The relative permeability curve has been measured with simulation oil (refined oil) and gas (nitrogen or air) at room temperature and a lowpressure, both of which are very important parameters for depicting the flow ...The relative permeability curve has been measured with simulation oil (refined oil) and gas (nitrogen or air) at room temperature and a lowpressure, both of which are very important parameters for depicting the flow of fluid through porous media in a hydrocarbon reservoir. This basic measurement is often applied in exploitation evaluation, but the underground conditions with high temperature and pressure, and the phase equilibrium of oil and gas, are not taken into consideration when the relative permeability curve is tested. There is an important theoretical and practical sense in testing the diphase relative permeability curve of the equilibrium of oil and gas under the conditions of high temperature and pressure. The test method for the relative permeability curve is proposed in this paper. The relative permeability of the equilibrium of oil and gas and the standard one are tested in two fluids, and the differences between these two methods are stated. The research results can be applied to the simulation and prediction of CVD in long cores and then the phenomenon can better explain that the recovery of condensate gas rich in condensate oil is higher than that of CVD test in PVT. Meanwhile, the research shows that the relative permeability curve of equilibrium oil and gas is sensitive to the rate of exploitation, and the viewpoint proves that an improved gas recovery rate can properly increase the recovery of condensate oil.展开更多
A novel online process monitoring and fault diagnosis method of condenser based on kernel principle component analysis （KPCA） and Fisher discriminant analysis （FDA） is presented. The basic idea of this method is：...A novel online process monitoring and fault diagnosis method of condenser based on kernel principle component analysis （KPCA） and Fisher discriminant analysis （FDA） is presented. The basic idea of this method is： First map data from the original space into high-dimensional feature space via nonlinear kernel function and then extract optimal feature vector and discriminant vector in feature space and calculate the Euclidean distance between feature vectors to perform process monitoring. Similar degree between the present discriminant vector and optimal discriminant vector of fault in historical dataset is used for diagnosis. The proposed method can effectively capture the nonlinear relationship among process variables. Simulating results of the turbo generator＇s fault data set prove that the proposed method is effective.展开更多
In order to increase cooling or heating efficiency,a porous computational fluid dynamics（CFD）model is employed to predict the thermo-fluid status and optimize the placement of outdoor units.A full scale model is est...In order to increase cooling or heating efficiency,a porous computational fluid dynamics（CFD）model is employed to predict the thermo-fluid status and optimize the placement of outdoor units.A full scale model is established to validate the accuracy of CFD simulation in terms of velocity and temperature distributions.The comparison between the measurement and the simulation shows a good agreement.By evaluating the condensers＇ sucked air temperature with CFD for three units installed in a row,it is found that the minimum separation distance among neighboring units is 0.2 m;a vertical wall should be apart from the unit line by at least 0.8 m;and large different operating pressures among units do not impact the flow rate and the heat transfer of the other units meaningfully.展开更多
This paper is based on the rainwater collection project in the retrofit of the Dongyi teaching block in Zhejiang University Xixi Campus.The analysis incorporates the local meteorological data, recycling water utilizat...This paper is based on the rainwater collection project in the retrofit of the Dongyi teaching block in Zhejiang University Xixi Campus.The analysis incorporates the local meteorological data, recycling water utilization, and precipitation adjustment.The rainwater collection system in this program also adds the condensation water from the heating, ventilation and air conditioning （ HVAC） system and the concentration from the reverse-osmosis system used for watering greens and supplying waterscapes.By calculating, the quantity of the HVAC condensation water in summer is 3.48 m3/d, and the quantity of the reverse-osmosis concentrated water is 198 to 396 L/d.This method solves the water shortage caused by high evaporation in summer and low precipitation in winter.Supported by empirical monitoring data, the proposed method significantly increases the economic efficiency of the system during the summer period.展开更多
This paper introduces the development and industrial application of an on-line corrosion monitoring device for condenser tubes. Corrosion sensors are made up of representative condenser tubes chosen by eddy current te...This paper introduces the development and industrial application of an on-line corrosion monitoring device for condenser tubes. Corrosion sensors are made up of representative condenser tubes chosen by eddy current test, which enable the monitoring result to be consistent with the corrosion of actual condenser tubes. Localized corrosion rate of condenser tubes can be measured indirectly by a galvanic couple made up of tube segments with and without pits. Using this technology, corrosion problems can be found in time and accurately, and anticorrosive measures be made more economic and effective. Applications in two power plants showed the corrosion measurements are fast and accurate.展开更多
A new technique to fabricate silicon condenser microphone is presented.The technique is based on the use of oxidized porous silicon as sacrificial layer for the air gap and the heavy p+-doping silicon of approximately...A new technique to fabricate silicon condenser microphone is presented.The technique is based on the use of oxidized porous silicon as sacrificial layer for the air gap and the heavy p+-doping silicon of approximately 15μm thickness for the stiff backplate.The measured sensitivity of the microphone fabricated with this technique is in the range from -45dB(5.6mV/Pa) to -55dB(1.78mV/Pa) under the frequency from 500Hz to 10kHz,and shows a gradual increase at higher frequency.The cut-off frequency is above 20kHz.展开更多
Stress granules are membraneless organelles that serve as a protective cellular response to external stressors by sequestering non-translating messenger RNAs(mRNAs)and regulating protein synthesis.Stress granules form...Stress granules are membraneless organelles that serve as a protective cellular response to external stressors by sequestering non-translating messenger RNAs(mRNAs)and regulating protein synthesis.Stress granules formation mechanism is conserved across species,from yeast to mammals,and they play a critical role in minimizing cellular damage during stress.Composed of heterogeneous ribonucleoprotein complexes,stress granules are enriched not only in mRNAs but also in noncoding RNAs and various proteins,including translation initiation factors and RNA-binding proteins.Genetic mutations affecting stress granule assembly and disassembly can lead to abnormal stress granule accumulation,contributing to the progression of several diseases.Recent research indicates that stress granule dynamics are pivotal in determining their physiological and pathological functions,with acute stress granule formation offering protection and chronic stress granule accumulation being detrimental.This review focuses on the multifaceted roles of stress granules under diverse physiological conditions,such as regulation of mRNA transport,mRNA translation,apoptosis,germ cell development,phase separation processes that govern stress granule formation,and their emerging implications in pathophysiological scenarios,such as viral infections,cancer,neurodevelopmental disorders,neurodegeneration,and neuronal trauma.展开更多
Particulate matter emissions from ammonia-based wet flue gas desulfurization(AmmoniaWFGD)systems are composed of a filterable particulate matter and a condensable particulate matter(CPM)portion.However,the CPM part ha...Particulate matter emissions from ammonia-based wet flue gas desulfurization(AmmoniaWFGD)systems are composed of a filterable particulate matter and a condensable particulate matter(CPM)portion.However,the CPM part has been ignored for a long time,which results in an underestim ation of the aerosol problems caused by Ammonia-WFGD systems.In our research,the characteristics of the CPM that emits from an Ammonia-WFGD system are investigated experimentally for the first time,with the US Environmental Protection Agency Method 202 employed as the primary measurement.The influences of some essential desulfurizing parameters are evaluated based on the experimental data.The results show that CPM contributes about 68.8%to the total particulate matter emission.CPM consists mainly of ammonium sulfates/sulfites,with the organic part accounting for less than 4%.CPM is mostly in the submicron fraction,about 71.1%of which originates from the NH3-H2O-SO2 reactions.The appropriate adjustments for the parameters of the flue gas and the desulfurizing solution can inhibit CPM formation to different extents.This indicates that the parameter optimizations are promising in solving CPM emission problems in Ammonia-WFGD systems,in which the pH adjustment alone can abate CPM emission by around 49%.The opposite variations of the parameters need attention because they can cause tremendous CPM emission increase.展开更多
In this paper,a detailed investigation of water(Pr=7.0)convection in a chemical condenser is carried out.Two openings are located along one side of the cavity.The Navier-Stokes equations are solved in the frame of a c...In this paper,a detailed investigation of water(Pr=7.0)convection in a chemical condenser is carried out.Two openings are located along one side of the cavity.The Navier-Stokes equations are solved in the frame of a control volume method using the SIMPLEC algorithm to implement adequate coupling of pressure and velocity.Special emphasis is given to the influence of the Reynolds number,the tilt of the channel and the Rayleigh number on the convective heat transfer.Results are presented and discussed allowing the control parameters to span relatively wide intervals:Rayleigh number(10^(4)≤Ra≤5×10^(5)),channel inclination(0°≤90°)and Reynolds number(10≤Re≤1000).On the basis of these results,a new correlation of the Nusselt number is elaborated.展开更多
The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression...The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression ratio.Moreover,the following influential factors have been taken into account:evaporation temperature,condensation temperature and compressor suction-exhaust pressure ratio for different opening conditions of the compressor.The following quantities have been selected as the unit performance measurement indicators:refrigeration capacity,energy efficiency ratio(COP),compressor power consumption,and refrigerant flow rate.The experimental results indicate that the system refrigeration capacity and COP decrease with a decrease in evaporation temperature,increase of condensation temperature,and increase in pressure ratio.The refrigerant flow rate increases with the increase in evaporation temperature,decrease in condensing temperature and increase in pressure ratio.The compressor power consumption increases with the increase in condensing temperature and increase in pressure ratio,but is not significantly affected by the evaporation temperature.展开更多
A pH predictive model based on acid–base equilibria and ion equilibria was proposed to calculate the pH value of the overhead condensing system of crude distillation unit. The pH model could be used to predict the ap...A pH predictive model based on acid–base equilibria and ion equilibria was proposed to calculate the pH value of the overhead condensing system of crude distillation unit. The pH model could be used to predict the appropriate amounts of neutralizers by measuring the Cl-ion concentration of the overhead knockout drum. The pH values of various neutralized streams were estimated by this model. The results showed that the predicted pH values were in good agreement with the experimental ones. The trend of the corrosion inhibition efficiency decreases in the following order: ethylenediamine > N,Ndimethylethanolamine> triethylamine > 3-methoxypropylamine > morpholine. The difficulty in the accurate control of corrosion was solved, and a good instruction was provided for mitigating corrosion in refinery.展开更多
This paper presented an entropy evaluation method for the influences of condense heat recovery system on the environment.Aiming at the damage of the condense heat to the environment,an entropy of resource loss and an ...This paper presented an entropy evaluation method for the influences of condense heat recovery system on the environment.Aiming at the damage of the condense heat to the environment,an entropy of resource loss and an emission entropy from the condense heat recovery system in the air conditioning refrigerating machine were introduced.For the evaluation of the entropies,we developed a new algorithm for the parameter identification,called the composite influence coefficient,based on the Least Squares Support Vector Machine method.By simulation,the numerical experiments shows that the Least Squares Support Vector Machine method is one of the powerful methods for the parameter identification to compute the damage entropy of the condense heat,with the largest training error being-0.025(the relative error being-3.56%),and the biggest test error being 0.015(the relative error being 2.5%).展开更多
This study presents a facile and rapid method for synthesizing novel Layered Double Hydroxide(LDH)nanoflakes,exploring their application as a photocatalyst,and investigating the influence of condensed phosphates'g...This study presents a facile and rapid method for synthesizing novel Layered Double Hydroxide(LDH)nanoflakes,exploring their application as a photocatalyst,and investigating the influence of condensed phosphates'geometric linearity on their photocatalytic properties.Herein,the Mg O film,obtained by plasma electrolysis of AZ31 Mg alloys,was modified by growing an LDH film,which was further functionalized using cyclic sodium hexametaphosphate(CP)and linear sodium tripolyphosphate(LP).CP acted as an enhancer for flake spacing within the LDH structure,while LP changed flake dispersion and orientation.Consequently,CP@LDH demonstrated exceptional efficiency in heterogeneous photocatalysis,effectively degrading organic dyes like Methylene blue(MB),Congo red(CR),and Methyl orange(MO).The unique cyclic structure of CP likely enhances surface reactions and improves the catalyst's interaction with dye molecules.Furthermore,the condensed phosphate structure contributes to a higher surface area and reactivity in CP@LDH,leading to its superior photocatalytic performance compared to LP@LDH.Specifically,LP@LDH demonstrated notable degradation efficiencies of 93.02%,92.89%,and 88.81%for MB,MO,and CR respectively,over a 40 min duration.The highest degradation efficiencies were observed in the case of the CP@LDH sample,reporting 99.99%for MB,98.88%for CR,and 99.70%for MO.This underscores the potential of CP@LDH as a highly effective photocatalyst for organic dye degradation,offering promising prospects for environmental remediation and water detoxification applications.展开更多
A new reasonably perfect dynamic mathematic model has been established for condenser used in ship nuclear power plant according to its structural features and operating principle. The model has been solved by the Rung...A new reasonably perfect dynamic mathematic model has been established for condenser used in ship nuclear power plant according to its structural features and operating principle. The model has been solved by the Runge-Kutta method. And an analysis program has been developed for dynamic numerical simulation under steady operation condition, disturbance condition, and accident condition. The dynamic characteristics of condenser has been calculated and analyzed under several kinds of disturbances, and the results of calculation are in good agreement with the theoretical analysis.展开更多
The perovskite manganite sample La0.3Ca0.7Mn1-xWxO3 （x = 0.08, 0.12） was prepared by the solid-state reaction method. The effect of W doping on the Mn site to La0.3Ca0.7MnO3 charge ordering phase and the changing pr...The perovskite manganite sample La0.3Ca0.7Mn1-xWxO3 （x = 0.08, 0.12） was prepared by the solid-state reaction method. The effect of W doping on the Mn site to La0.3Ca0.7MnO3 charge ordering phase and the changing process of magnetic properties were studied through the measurement of the M-T curve, M-H curves, and ESR curves of the sample. The results showed that when x = 0.08, the charge ordering （CO） phase exists in the system, the transition temperature Tco= 275 K, and the system exhibits PM when T 〉 275 K. The system transforms from spin-disordering paramagnetism to spin-ordering antiferromagnetism in the charge ordering state with the temperature decreasing from 275 K to 230 K. The long-range antiferromagnetism forms and AFM/CO states coexist between 230 K and 5 K. There is a little ferromagnetic component in the AFM/CO background in a low temperature range. When x = 0.12, the CO phase in the system has almost melted completely. There is a little remnant of the CO phase below 150 K. The system exhibits paramagnetism when T 〉 150 K and transforms from paramagnetism to ferromagnetism when T〈 150 K.展开更多
This study investigates the corrosion properties of 0Cr11Ti and 0Cr11NbTi ferritic stainless steels （FSS） for automotive exhaust systems. The results indicate that the base metal and weld seam of 0Cr11NbTi steel exh...This study investigates the corrosion properties of 0Cr11Ti and 0Cr11NbTi ferritic stainless steels （FSS） for automotive exhaust systems. The results indicate that the base metal and weld seam of 0Cr11NbTi steel exhibit better intergranular and condensate corrosion resistant properties because carbon and nitrogen are stabilized by Nb and Ti, and the precipitation of Cr carbide is retarded in grain boundaries.展开更多
基金Project(217/s/458)supported by Azarbaijan Shahid Madani University,Iran
文摘A statistical signal processing technique was proposed and verified as independent component analysis(ICA) for fault detection and diagnosis of industrial systems without exact and detailed model.Actually,the aim is to utilize system as a black box.The system studied is condenser system of one of MAPNA's power plants.At first,principal component analysis(PCA) approach was applied to reduce the dimensionality of the real acquired data set and to identify the essential and useful ones.Then,the fault sources were diagnosed by ICA technique.The results show that ICA approach is valid and effective for faults detection and diagnosis even in noisy states,and it can distinguish main factors of abnormality among many diverse parts of a power plant's condenser system.This selectivity problem is left unsolved in many plants,because the main factors often become unnoticed by fault expansion through other parts of the plants.
文摘The air conditioning system in the Umm Al-Qura University (Albdiya Campus) was conceived to be a district cooling by a remote chilled water plant. Recently, there are two chilled water plants in the university installed strategically to provide chilled water to all the academic and administrative buildings of the university through distribution network with total capacity approximately of 12,000 tons of refrigeration. The plants were built based on cooling towers with open water cycle as heat rejection system. Water treatment chemicals has been used to protect the cooling systems from corrosion, scaling and microbiological fouling accompanied with dissolved and suspended water impurities. Different methods are being used to determine and control the treatment chemical concentrations and system performance indicators. Traditional chemical controller has drawback of indirect measurements and set points. The purpose of this paper is to present a solution to overcome the problems of traditional and conventional chemical treatment and control sys-tems. Central cooling plant number (1) assigned to perform experimental setup using new chemical treatment technology. Advanced automatic chemical treatment controller installed on condensers (1, 2 and 3), and certain key performance indicators were selected and monitored such as chemical and water consumption, power, energy saving, and maintaining system integrity and efficiency. Satisfactory results were obtained in terms of performance and cost of operation.
基金Supported by the combined project of the Science and Technology Ministry of Guangdong province and the Science and Tech-nology Ministry of Guangzhou city(2007A04020004,2007C13G0161)
文摘The operating theory of an evaporative condenser was expatiated.The difference between an evaporative condensing refrigeration system and a general refrigeration system was analyzed.Compared with the air-cooled and the water-cooled,the virtues of energy-conservation and water-conservation of evaporative condensers were analyzed.Some questions existing in the application of evaporative condensers were pointed out,the corresponding solving methods were analyzed accordingly,and the development trend of evaporative condensing technique in mechanical refrigeration system field and the applied foreground of evaporative condensers in comfortable air conditioning were prospected.
文摘<span style="font-family:Verdana;">Accord</span><span style="font-family:Verdana;">ing</span><span style="font-family:Verdana;"> to </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">study of basic Rankin thermal cycle, the steam exh</span><span style="font-family:Verdana;">aust pressure of a typical steam turbine toward </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">condenser, plays a great rol</span><span style="font-family:Verdana;">e</span><span style="font-family:Verdana;"> in the efficiency and the net output power of </span><span style="font-family:Verdana;">the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">steam turbine, so most surface conden</span><span style="font-family:Verdana;">sers </span></span><span style="font-family:Verdana;">that</span><span style="font-family:Verdana;"> are working in thermal power plants are kept at va</span><span style="font-family:;" "=""><span style="font-family:Verdana;">cuum condition so that the maximum power of thermal cycle can be achieved. The </span><span style="font-family:Verdana;">vacuu</span><span style="font-family:Verdana;">m pressure at condenser leads to </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">entering of air </span><span style="font-family:Verdana;">and Non-</span><span style="font-family:Verdana;">condensable gases from turbine gland seals to condenser so that the special air ejection equipment is being used to take apart air from steam and vent it to out of condenser.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">In this study</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> a special steam and air separator mechanism in </span><span style="font-family:Verdana;">an </span><span style="font-family:Verdana;">evacuating system called </span><span style="font-family:Verdana;">“</span><span style="font-family:Verdana;">Aircooler</span><span style="font-family:Verdana;">”</span><span style="font-family:Verdana;"> at a 16</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">MW steam turbine condenser is being studied and the Fluent CFD software is utilized to analyze the behavior of steam plus air in a typical aircooler system of 16</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">MW steam turbine condenser of Neka power plant to find a way to reduce the risk of cooling tube rupture in aircooler ducts. The critical condition which tube rupture happens is determined and it is demonstrated that in hot seasons of year, by increasing the seawater cooling temperature and increasing in turbine steam exhaust pressure and temperature, the risk of tube rupture due to more mixture velocity at the first row of aircooler cooling tubes increases and also</span><span style="font-family:Verdana;"> the effect of tube plugged condition on the performance of </span><span style="font-family:Verdana;">aircooler shows that the risk of other tubes rupture will increase and thus the efficiency of aircooler decreases due to more aircooler exhaust temperature. Finally</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> two modified plans at aircooler system design will be studied and simulated via Fluent CFD software which leads to reduce the risk of tube rupture. The results show that by modification of aircooler ducts and holes, the mixture air and steam flow velocity to first aircooler cooling tube row decreases significantly and causes the risk of tube rupture </span><span style="font-family:Verdana;">to </span><span style="font-family:Verdana;">decrease remarkably and also the exhaust temperature of aircooler decreases and causes the higher ejector performance.</span>
基金This paper was subsidized by the 15th National key Sci-Tech Project (NO.2001BA605A02-04-01)
文摘The relative permeability curve has been measured with simulation oil (refined oil) and gas (nitrogen or air) at room temperature and a lowpressure, both of which are very important parameters for depicting the flow of fluid through porous media in a hydrocarbon reservoir. This basic measurement is often applied in exploitation evaluation, but the underground conditions with high temperature and pressure, and the phase equilibrium of oil and gas, are not taken into consideration when the relative permeability curve is tested. There is an important theoretical and practical sense in testing the diphase relative permeability curve of the equilibrium of oil and gas under the conditions of high temperature and pressure. The test method for the relative permeability curve is proposed in this paper. The relative permeability of the equilibrium of oil and gas and the standard one are tested in two fluids, and the differences between these two methods are stated. The research results can be applied to the simulation and prediction of CVD in long cores and then the phenomenon can better explain that the recovery of condensate gas rich in condensate oil is higher than that of CVD test in PVT. Meanwhile, the research shows that the relative permeability curve of equilibrium oil and gas is sensitive to the rate of exploitation, and the viewpoint proves that an improved gas recovery rate can properly increase the recovery of condensate oil.
基金The National Natural Science Foundation of China(No60504033)
文摘A novel online process monitoring and fault diagnosis method of condenser based on kernel principle component analysis （KPCA） and Fisher discriminant analysis （FDA） is presented. The basic idea of this method is： First map data from the original space into high-dimensional feature space via nonlinear kernel function and then extract optimal feature vector and discriminant vector in feature space and calculate the Euclidean distance between feature vectors to perform process monitoring. Similar degree between the present discriminant vector and optimal discriminant vector of fault in historical dataset is used for diagnosis. The proposed method can effectively capture the nonlinear relationship among process variables. Simulating results of the turbo generator＇s fault data set prove that the proposed method is effective.
文摘In order to increase cooling or heating efficiency,a porous computational fluid dynamics（CFD）model is employed to predict the thermo-fluid status and optimize the placement of outdoor units.A full scale model is established to validate the accuracy of CFD simulation in terms of velocity and temperature distributions.The comparison between the measurement and the simulation shows a good agreement.By evaluating the condensers＇ sucked air temperature with CFD for three units installed in a row,it is found that the minimum separation distance among neighboring units is 0.2 m;a vertical wall should be apart from the unit line by at least 0.8 m;and large different operating pressures among units do not impact the flow rate and the heat transfer of the other units meaningfully.
文摘This paper is based on the rainwater collection project in the retrofit of the Dongyi teaching block in Zhejiang University Xixi Campus.The analysis incorporates the local meteorological data, recycling water utilization, and precipitation adjustment.The rainwater collection system in this program also adds the condensation water from the heating, ventilation and air conditioning （ HVAC） system and the concentration from the reverse-osmosis system used for watering greens and supplying waterscapes.By calculating, the quantity of the HVAC condensation water in summer is 3.48 m3/d, and the quantity of the reverse-osmosis concentrated water is 198 to 396 L/d.This method solves the water shortage caused by high evaporation in summer and low precipitation in winter.Supported by empirical monitoring data, the proposed method significantly increases the economic efficiency of the system during the summer period.
文摘This paper introduces the development and industrial application of an on-line corrosion monitoring device for condenser tubes. Corrosion sensors are made up of representative condenser tubes chosen by eddy current test, which enable the monitoring result to be consistent with the corrosion of actual condenser tubes. Localized corrosion rate of condenser tubes can be measured indirectly by a galvanic couple made up of tube segments with and without pits. Using this technology, corrosion problems can be found in time and accurately, and anticorrosive measures be made more economic and effective. Applications in two power plants showed the corrosion measurements are fast and accurate.
文摘A new technique to fabricate silicon condenser microphone is presented.The technique is based on the use of oxidized porous silicon as sacrificial layer for the air gap and the heavy p+-doping silicon of approximately 15μm thickness for the stiff backplate.The measured sensitivity of the microphone fabricated with this technique is in the range from -45dB(5.6mV/Pa) to -55dB(1.78mV/Pa) under the frequency from 500Hz to 10kHz,and shows a gradual increase at higher frequency.The cut-off frequency is above 20kHz.
基金supported by a grant from the Merkin Peripheral Neuropathy and Nerve Regeneration Center(to PKS)the Rutgers University Startup Fund(to PKS).
文摘Stress granules are membraneless organelles that serve as a protective cellular response to external stressors by sequestering non-translating messenger RNAs(mRNAs)and regulating protein synthesis.Stress granules formation mechanism is conserved across species,from yeast to mammals,and they play a critical role in minimizing cellular damage during stress.Composed of heterogeneous ribonucleoprotein complexes,stress granules are enriched not only in mRNAs but also in noncoding RNAs and various proteins,including translation initiation factors and RNA-binding proteins.Genetic mutations affecting stress granule assembly and disassembly can lead to abnormal stress granule accumulation,contributing to the progression of several diseases.Recent research indicates that stress granule dynamics are pivotal in determining their physiological and pathological functions,with acute stress granule formation offering protection and chronic stress granule accumulation being detrimental.This review focuses on the multifaceted roles of stress granules under diverse physiological conditions,such as regulation of mRNA transport,mRNA translation,apoptosis,germ cell development,phase separation processes that govern stress granule formation,and their emerging implications in pathophysiological scenarios,such as viral infections,cancer,neurodevelopmental disorders,neurodegeneration,and neuronal trauma.
基金supported by the National Key Research and Development Program of China(No.2016YFC0203703)the National Natural Science Foundation of China(Nos.51576039,51806107 and 21276049)+1 种基金the Scientific Research Foundation of Graduate School of Southeast University(No.YBJJ1610)the Research Innovation Program for College Graduates of Jiangsu Province(No.KYLX16_0283)。
文摘Particulate matter emissions from ammonia-based wet flue gas desulfurization(AmmoniaWFGD)systems are composed of a filterable particulate matter and a condensable particulate matter(CPM)portion.However,the CPM part has been ignored for a long time,which results in an underestim ation of the aerosol problems caused by Ammonia-WFGD systems.In our research,the characteristics of the CPM that emits from an Ammonia-WFGD system are investigated experimentally for the first time,with the US Environmental Protection Agency Method 202 employed as the primary measurement.The influences of some essential desulfurizing parameters are evaluated based on the experimental data.The results show that CPM contributes about 68.8%to the total particulate matter emission.CPM consists mainly of ammonium sulfates/sulfites,with the organic part accounting for less than 4%.CPM is mostly in the submicron fraction,about 71.1%of which originates from the NH3-H2O-SO2 reactions.The appropriate adjustments for the parameters of the flue gas and the desulfurizing solution can inhibit CPM formation to different extents.This indicates that the parameter optimizations are promising in solving CPM emission problems in Ammonia-WFGD systems,in which the pH adjustment alone can abate CPM emission by around 49%.The opposite variations of the parameters need attention because they can cause tremendous CPM emission increase.
文摘In this paper,a detailed investigation of water(Pr=7.0)convection in a chemical condenser is carried out.Two openings are located along one side of the cavity.The Navier-Stokes equations are solved in the frame of a control volume method using the SIMPLEC algorithm to implement adequate coupling of pressure and velocity.Special emphasis is given to the influence of the Reynolds number,the tilt of the channel and the Rayleigh number on the convective heat transfer.Results are presented and discussed allowing the control parameters to span relatively wide intervals:Rayleigh number(10^(4)≤Ra≤5×10^(5)),channel inclination(0°≤90°)and Reynolds number(10≤Re≤1000).On the basis of these results,a new correlation of the Nusselt number is elaborated.
基金supported by the National Natural Science Foundation of China(No.41877251)the Key project of Natural Science Foundation of Tianjin City(No.6JCZDJC39000).
文摘The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression ratio.Moreover,the following influential factors have been taken into account:evaporation temperature,condensation temperature and compressor suction-exhaust pressure ratio for different opening conditions of the compressor.The following quantities have been selected as the unit performance measurement indicators:refrigeration capacity,energy efficiency ratio(COP),compressor power consumption,and refrigerant flow rate.The experimental results indicate that the system refrigeration capacity and COP decrease with a decrease in evaporation temperature,increase of condensation temperature,and increase in pressure ratio.The refrigerant flow rate increases with the increase in evaporation temperature,decrease in condensing temperature and increase in pressure ratio.The compressor power consumption increases with the increase in condensing temperature and increase in pressure ratio,but is not significantly affected by the evaporation temperature.
基金supported by the PetroChina Company Limited (20151191)
文摘A pH predictive model based on acid–base equilibria and ion equilibria was proposed to calculate the pH value of the overhead condensing system of crude distillation unit. The pH model could be used to predict the appropriate amounts of neutralizers by measuring the Cl-ion concentration of the overhead knockout drum. The pH values of various neutralized streams were estimated by this model. The results showed that the predicted pH values were in good agreement with the experimental ones. The trend of the corrosion inhibition efficiency decreases in the following order: ethylenediamine > N,Ndimethylethanolamine> triethylamine > 3-methoxypropylamine > morpholine. The difficulty in the accurate control of corrosion was solved, and a good instruction was provided for mitigating corrosion in refinery.
基金Supported by Program of Science and Technology of Hunan Province(2007FJ2006)Project the Program of Science and Tech-nology of Hunan Province(2007TP4030)Hunan Provincial Natural Science Foundation of China(08JJ3093)
文摘This paper presented an entropy evaluation method for the influences of condense heat recovery system on the environment.Aiming at the damage of the condense heat to the environment,an entropy of resource loss and an emission entropy from the condense heat recovery system in the air conditioning refrigerating machine were introduced.For the evaluation of the entropies,we developed a new algorithm for the parameter identification,called the composite influence coefficient,based on the Least Squares Support Vector Machine method.By simulation,the numerical experiments shows that the Least Squares Support Vector Machine method is one of the powerful methods for the parameter identification to compute the damage entropy of the condense heat,with the largest training error being-0.025(the relative error being-3.56%),and the biggest test error being 0.015(the relative error being 2.5%).
基金the National Research Foundation of Korea(NRF)funded by the Korean Government(MSIT)(No.2022R1A2C1006743)。
文摘This study presents a facile and rapid method for synthesizing novel Layered Double Hydroxide(LDH)nanoflakes,exploring their application as a photocatalyst,and investigating the influence of condensed phosphates'geometric linearity on their photocatalytic properties.Herein,the Mg O film,obtained by plasma electrolysis of AZ31 Mg alloys,was modified by growing an LDH film,which was further functionalized using cyclic sodium hexametaphosphate(CP)and linear sodium tripolyphosphate(LP).CP acted as an enhancer for flake spacing within the LDH structure,while LP changed flake dispersion and orientation.Consequently,CP@LDH demonstrated exceptional efficiency in heterogeneous photocatalysis,effectively degrading organic dyes like Methylene blue(MB),Congo red(CR),and Methyl orange(MO).The unique cyclic structure of CP likely enhances surface reactions and improves the catalyst's interaction with dye molecules.Furthermore,the condensed phosphate structure contributes to a higher surface area and reactivity in CP@LDH,leading to its superior photocatalytic performance compared to LP@LDH.Specifically,LP@LDH demonstrated notable degradation efficiencies of 93.02%,92.89%,and 88.81%for MB,MO,and CR respectively,over a 40 min duration.The highest degradation efficiencies were observed in the case of the CP@LDH sample,reporting 99.99%for MB,98.88%for CR,and 99.70%for MO.This underscores the potential of CP@LDH as a highly effective photocatalyst for organic dye degradation,offering promising prospects for environmental remediation and water detoxification applications.
文摘A new reasonably perfect dynamic mathematic model has been established for condenser used in ship nuclear power plant according to its structural features and operating principle. The model has been solved by the Runge-Kutta method. And an analysis program has been developed for dynamic numerical simulation under steady operation condition, disturbance condition, and accident condition. The dynamic characteristics of condenser has been calculated and analyzed under several kinds of disturbances, and the results of calculation are in good agreement with the theoretical analysis.
基金This project was financially supported by the National Natural Science Foundation Key Project of China (No. 19934003)the National Key Fundamental Research Project of China (No. 001CB610604)+1 种基金the Natural Science Research Project of the Education Department of Anhui Province (No. 2004KJ331)the Natural Science Research Project of Colleges and Universities of Anhui Province, China (No. 2005KJ234)
文摘The perovskite manganite sample La0.3Ca0.7Mn1-xWxO3 （x = 0.08, 0.12） was prepared by the solid-state reaction method. The effect of W doping on the Mn site to La0.3Ca0.7MnO3 charge ordering phase and the changing process of magnetic properties were studied through the measurement of the M-T curve, M-H curves, and ESR curves of the sample. The results showed that when x = 0.08, the charge ordering （CO） phase exists in the system, the transition temperature Tco= 275 K, and the system exhibits PM when T 〉 275 K. The system transforms from spin-disordering paramagnetism to spin-ordering antiferromagnetism in the charge ordering state with the temperature decreasing from 275 K to 230 K. The long-range antiferromagnetism forms and AFM/CO states coexist between 230 K and 5 K. There is a little ferromagnetic component in the AFM/CO background in a low temperature range. When x = 0.12, the CO phase in the system has almost melted completely. There is a little remnant of the CO phase below 150 K. The system exhibits paramagnetism when T 〉 150 K and transforms from paramagnetism to ferromagnetism when T〈 150 K.
文摘This study investigates the corrosion properties of 0Cr11Ti and 0Cr11NbTi ferritic stainless steels （FSS） for automotive exhaust systems. The results indicate that the base metal and weld seam of 0Cr11NbTi steel exhibit better intergranular and condensate corrosion resistant properties because carbon and nitrogen are stabilized by Nb and Ti, and the precipitation of Cr carbide is retarded in grain boundaries.
