The paper presents the results of comparative studies of thermal properties of various types of natural esters used as electroinsulating liquids in transformers. Adequate thermal properties of electro-insulating liquids ensure reliable work of transformers. Two natural esters were selected for the study – one commonly used in distribution transformers, the other characterized by low viscosity. Fourier Transform Infrared Spectroscopy and UV-Visible spectroscopy were used to examine the chemical structure of the examined esters. Properties such as thermal conductivity coefficient λ, kinematic viscosity υ, specific heat cp, density ρ, and thermal expansion coefficient β were analyzed. Heat transfer factor α of the liquid was calculated on the basis of obtained properties. This factor defines the ability of an insulating liquid to heat transport in the transformer, thus determining its reliability. The authors put forward a thesis that a low viscosity natural ester will have a higher heat transfer factor α due to its low viscosity, which affects the factor α. The analysis of thermal properties was carried out for the following temperatures: 25, 40, 60, and 80°C. On the basis of the calculated factor α, the temperature drops in the transformer filled with the analyzed types of natural esters were determined. It has been shown that if a low viscosity natural ester is used in the cooling system of the transformer, the temperature of the hot-spot will be lower. This fact may contribute to more reliable work of transformers and extend its service life.
{"title":"Thermal properties of natural ester and low viscosity natural ester in the aspect of the reliable operation of the transformer cooling system","authors":"G. Dombek, Z. Nadolny, A. Marcinkowska","doi":"10.17531/EIN.2019.3.4","DOIUrl":"https://doi.org/10.17531/EIN.2019.3.4","url":null,"abstract":"The paper presents the results of comparative studies of thermal properties of various types of natural esters used as electroinsulating liquids in transformers. Adequate thermal properties of electro-insulating liquids ensure reliable work of transformers. Two natural esters were selected for the study – one commonly used in distribution transformers, the other characterized by low viscosity. Fourier Transform Infrared Spectroscopy and UV-Visible spectroscopy were used to examine the chemical structure of the examined esters. Properties such as thermal conductivity coefficient λ, kinematic viscosity υ, specific heat cp, density ρ, and thermal expansion coefficient β were analyzed. Heat transfer factor α of the liquid was calculated on the basis of obtained properties. This factor defines the ability of an insulating liquid to heat transport in the transformer, thus determining its reliability. The authors put forward a thesis that a low viscosity natural ester will have a higher heat transfer factor α due to its low viscosity, which affects the factor α. The analysis of thermal properties was carried out for the following temperatures: 25, 40, 60, and 80°C. On the basis of the calculated factor α, the temperature drops in the transformer filled with the analyzed types of natural esters were determined. It has been shown that if a low viscosity natural ester is used in the cooling system of the transformer, the temperature of the hot-spot will be lower. This fact may contribute to more reliable work of transformers and extend its service life.","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131874587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Gorbunov, K. Kravchenko, G. Bureika, J. Gerlici, O. Nozhenko, G. Vaičiūnas, V. Bučinskas, S. Steišūnas
The desire for threshold of use of traction effort and power of locomotives is associated with an increased tendency of the driven wheelsets to slippage. This determines the need to use different means to increase the level of the adhesion of the locomotive wheels with rails and to ensure the stability of the traction [25, 26]. On the other hand, a high value of the adhesive coefficient is a major factor for realizing the maximum braking force of a train when using friction brakes and significantly increases the level of traffic safety [20]. This is especially true in case of emergency braking or an emergency stopping of trains before prohibitive traffic lights have turned on unexpectedly, i. e. it is essential to avoid the case of the railway station overruns or SPAD signal passing at danger [16]. The most common way to increase adhesion is to use silica sand or other mineral materials similar in hardness properties. This method, along with indisputable advantages (high efficiency, ease of use, relative cheapness) has obvious disadvantages: clogging of ballast, increased wear of wheels and rails [7, 23], increased resistance to movement in traction mode. Given the above disadvantages, the optimization of the use of sand is relevant. The spraying of sand into the wheel–rail contact is one of the most effective ways to enhance the friction between the driven wheels and rail under conditions of low adhesion, especially on intensive acceleration or emergency braking running modes. The scientific works carried out by worldwide researchers on reasons of low adhesion showed that wheel/ rail adhesion coefficient (the ratio of normal to friction force in the contact) varied between 0.04 and 0.55, averaging 0.3 in dry conditions. The impact of adding moisture to the rail reduced this average to 0.2, still the leaves can reduce the adhesion coefficient as low as 0.02 [23, 24]. Other causes of low adhesion have been identified as: general moisture/dampness combined with contaminants such as rust, ice, coal dust, leaf, spilled diesel fuel/ lubricating oils/flange lubricating grease/hydraulic fluid, airborne kerosene from nearby airports, or other chemicals from industrial sites [3]. Lewis S. R. et al. and Wang et al. [24, 35] carried out comprehensive research work using a full-scale laboratory rail–wheel test machine to find the position for the hose and sand flow rates that give optimum sand entrainment to the contact. It was found that ideGorbunov M, KrAvchenKo K, bureiKA G, Gerlici J, nozhenKo o, vAičiūnAs G, bučinsKAs v, steišūnAs s. estimation of sand electrification influence on locomotive wheel / rail adhesion processes. eksploatacja i niezawodnosc – Maintenance and reliability 2019; 21 (3): 460–467, http://dx.doi.org/10.17531/ein.2019.3.12.
对机车牵引力和动力使用阈值的要求与驱动轮对滑移趋势的增加有关。这就决定了需要采用不同的手段来提高机车车轮与轨道的附着程度，保证牵引的稳定性[25,26]。另一方面，较高的粘着系数是实现列车在使用摩擦制动器时制动力最大化的重要因素，可以显著提高交通安全水平[20]。特别是在禁止性交通灯未意外亮起前紧急刹车或紧急停车时，即必须避免发生火车站超限或SPAD信号危险通过的情况[16]。增加附着力最常用的方法是使用硅砂或其他硬度性质相似的矿物材料。这种方法虽然具有无可争辩的优点(效率高、使用方便、相对便宜)，但缺点也很明显:会堵塞镇流器，增加车轮和轨道的磨损[7,23]，增加牵引模式下的运动阻力。鉴于上述缺点，砂的优化使用是相关的。在低附着条件下，特别是在强烈加速或紧急制动运行模式下，向轮轨接触处喷砂是提高从动轮与轨道之间摩擦力的最有效方法之一。全球研究人员对低附着原因进行的科学研究表明，轮轨附着系数(接触中法向力与摩擦力的比值)在0.04至0.55之间变化，在干燥条件下平均为0.3。在钢轨中添加水分的影响下，这一平均值降至0.2，但叶片仍能将附着系数降低至0.02[23,24]。其他低附着力的原因已被确定为:一般的潮湿/潮湿与污染物结合，如铁锈、冰、煤尘、树叶、溢出的柴油/润滑油/法兰润滑油脂/液压油、附近机场的空中煤油或工业场所的其他化学品[3]。Lewis S. R.等人和Wang等人[24,35]使用全尺寸实验室轨道轮试验机进行了全面的研究工作，以找到软管的位置和砂流速率，从而为接触面提供最佳的含砂量。ideGorbunov M, KrAvchenKo K, bureiKA G, Gerlici J, nozhenKo o, vAičiūnAs G, bu inskas v, steišūnAs .砂电气化对机车轮轨黏附过程影响的估计。eksploatacja i niezawodnosc -维护和可靠性2019;21 (3): 460-467, http://dx.doi.org/10.17531/ein.2019.3.12。
{"title":"Estimation of sand electrification influence on locomotive wheel / rail adhesion processes","authors":"M. Gorbunov, K. Kravchenko, G. Bureika, J. Gerlici, O. Nozhenko, G. Vaičiūnas, V. Bučinskas, S. Steišūnas","doi":"10.17531/EIN.2019.3.12","DOIUrl":"https://doi.org/10.17531/EIN.2019.3.12","url":null,"abstract":"The desire for threshold of use of traction effort and power of locomotives is associated with an increased tendency of the driven wheelsets to slippage. This determines the need to use different means to increase the level of the adhesion of the locomotive wheels with rails and to ensure the stability of the traction [25, 26]. On the other hand, a high value of the adhesive coefficient is a major factor for realizing the maximum braking force of a train when using friction brakes and significantly increases the level of traffic safety [20]. This is especially true in case of emergency braking or an emergency stopping of trains before prohibitive traffic lights have turned on unexpectedly, i. e. it is essential to avoid the case of the railway station overruns or SPAD signal passing at danger [16]. The most common way to increase adhesion is to use silica sand or other mineral materials similar in hardness properties. This method, along with indisputable advantages (high efficiency, ease of use, relative cheapness) has obvious disadvantages: clogging of ballast, increased wear of wheels and rails [7, 23], increased resistance to movement in traction mode. Given the above disadvantages, the optimization of the use of sand is relevant. The spraying of sand into the wheel–rail contact is one of the most effective ways to enhance the friction between the driven wheels and rail under conditions of low adhesion, especially on intensive acceleration or emergency braking running modes. The scientific works carried out by worldwide researchers on reasons of low adhesion showed that wheel/ rail adhesion coefficient (the ratio of normal to friction force in the contact) varied between 0.04 and 0.55, averaging 0.3 in dry conditions. The impact of adding moisture to the rail reduced this average to 0.2, still the leaves can reduce the adhesion coefficient as low as 0.02 [23, 24]. Other causes of low adhesion have been identified as: general moisture/dampness combined with contaminants such as rust, ice, coal dust, leaf, spilled diesel fuel/ lubricating oils/flange lubricating grease/hydraulic fluid, airborne kerosene from nearby airports, or other chemicals from industrial sites [3]. Lewis S. R. et al. and Wang et al. [24, 35] carried out comprehensive research work using a full-scale laboratory rail–wheel test machine to find the position for the hose and sand flow rates that give optimum sand entrainment to the contact. It was found that ideGorbunov M, KrAvchenKo K, bureiKA G, Gerlici J, nozhenKo o, vAičiūnAs G, bučinsKAs v, steišūnAs s. estimation of sand electrification influence on locomotive wheel / rail adhesion processes. eksploatacja i niezawodnosc – Maintenance and reliability 2019; 21 (3): 460–467, http://dx.doi.org/10.17531/ein.2019.3.12.","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127062596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Reliability-based design optimization under fuzzy and interval variables based on entropy theory","authors":"Huiying Gao, Xiaoqiang Zhang","doi":"10.17531/EIN.2019.3.9","DOIUrl":"https://doi.org/10.17531/EIN.2019.3.9","url":null,"abstract":"","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124122660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jing Liu, Yajun Xu, Linfeng Wang, Zidan Xu, Changke Tang
Local defects in ball bearings may occur at the center line of raceway and its surrounding areas. However, most current studies were concentrated in studying the influence of the local defect located at the centerline of raceway on the bearing vibrations, where the effects of local defects surround the centerline were ignored. To overcome this problem, based on Hertzian point contact theory and multi-body dynamic algorithm, a multi-body dynamic model considering the offset and angular distributions for a ball bearing with a local defect on its outer raceway is established. The influences of offset distance and skew angle between the geometric center of local defect and the centerline of outer raceway on the bearing vibrations are investigated. The relationship between the offset distance and the impulse waveform characteristics is obtained, as well as that between the skew angle and the impulse waveform characteristics. The results show that the offset distance and skew angle of the local defect have a great influence on the time-domain impulse waveform characteristics of the bearing accelerations. This paper can provide a useful guidance for the accurate diagnosis of early local fault in the ball bearings.
{"title":"Influence of the local defect distribution on vibration characteristics of ball bearings","authors":"Jing Liu, Yajun Xu, Linfeng Wang, Zidan Xu, Changke Tang","doi":"10.17531/EIN.2019.3.15","DOIUrl":"https://doi.org/10.17531/EIN.2019.3.15","url":null,"abstract":"Local defects in ball bearings may occur at the center line of raceway and its surrounding areas. However, most current studies were concentrated in studying the influence of the local defect located at the centerline of raceway on the bearing vibrations, where the effects of local defects surround the centerline were ignored. To overcome this problem, based on Hertzian point contact theory and multi-body dynamic algorithm, a multi-body dynamic model considering the offset and angular distributions for a ball bearing with a local defect on its outer raceway is established. The influences of offset distance and skew angle between the geometric center of local defect and the centerline of outer raceway on the bearing vibrations are investigated. The relationship between the offset distance and the impulse waveform characteristics is obtained, as well as that between the skew angle and the impulse waveform characteristics. The results show that the offset distance and skew angle of the local defect have a great influence on the time-domain impulse waveform characteristics of the bearing accelerations. This paper can provide a useful guidance for the accurate diagnosis of early local fault in the ball bearings.","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"258 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133420936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper presents a modeling of angular bearing in the context of motion resistance. It was assumed that the motion resistance depends on the contact forces. For that reason, the main goal of modeling was an estimation of the forces and determination of the influence of such parameters, like rotational speed of the bearing ring, pre-displacement of the bearing and fit of the shaft and the inner ring, exerted on those forces. In the literature, when estimating the contact forces, such parameters are taken into account very rarely. The modelling was performed by means of a numerical method, viz. FEM. The modeling results show that the omission of such parameters will lead to big errors in estimation of contact forces, and those errors may be as high as 100%, or even higher. The real motion resistance will be bigger than calculated.
{"title":"An extended model of angular bearing - influence of fitting and pre-deformation","authors":"J. Kosmol","doi":"10.17531/EIN.2019.3.16","DOIUrl":"https://doi.org/10.17531/EIN.2019.3.16","url":null,"abstract":"The paper presents a modeling of angular bearing in the context of motion resistance. It was assumed that the motion resistance depends on the contact forces. For that reason, the main goal of modeling was an estimation of the forces and determination of the influence of such parameters, like rotational speed of the bearing ring, pre-displacement of the bearing and fit of the shaft and the inner ring, exerted on those forces. In the literature, when estimating the contact forces, such parameters are taken into account very rarely. The modelling was performed by means of a numerical method, viz. FEM. The modeling results show that the omission of such parameters will lead to big errors in estimation of contact forces, and those errors may be as high as 100%, or even higher. The real motion resistance will be bigger than calculated.","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129097283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The significant effect of path loss on the reliability of very high frequency (VHF) and ultrahigh frequency (UHF) bands propagation has drawn much attention. Previous works mainly focus on the reliability evaluation for infrastructures and basic equipment, however, its propagation reliability has not been taken into full consideration. This paper proposes a new method for evaluating the reliability of the wireless communication based on the analysis of the traditional outdoor wave propagation loss models. In the reliability evaluation of the radio communication, we firstly consider the transmission frequency, the antenna height, the cell type and the communication distance. Then, we use a lognormal distribution to fit the random distribution curve of the communication distance so that the relationship between the path loss value and the reliability can be analysed. We further derive the probability distribution function (PDF) and the cumulative distribution function (CDF) of the path loss value from different antenna correction factors, cell type correction factors and terrain correction factors. Finally, we calculate the radio communication reliability values at different frequencies based on the threshold of the propagation loss value. Compared with the reliability degree only considering the communication distance threshold, the influence of environmental factors on the reliability of the VHF and the UHF radio propagation has been analysed.
{"title":"Reliability evaluation for vhf and uhf bands under different scenarios via propagation loss model","authors":"Xiang Li, Hongzhong Huang, Yifan Li, Yanfeng Li","doi":"10.17531/EIN.2019.3.3","DOIUrl":"https://doi.org/10.17531/EIN.2019.3.3","url":null,"abstract":"The significant effect of path loss on the reliability of very high frequency (VHF) and ultrahigh frequency (UHF) bands propagation has drawn much attention. Previous works mainly focus on the reliability evaluation for infrastructures and basic equipment, however, its propagation reliability has not been taken into full consideration. This paper proposes a new method for evaluating the reliability of the wireless communication based on the analysis of the traditional outdoor wave propagation loss models. In the reliability evaluation of the radio communication, we firstly consider the transmission frequency, the antenna height, the cell type and the communication distance. Then, we use a lognormal distribution to fit the random distribution curve of the communication distance so that the relationship between the path loss value and the reliability can be analysed. We further derive the probability distribution function (PDF) and the cumulative distribution function (CDF) of the path loss value from different antenna correction factors, cell type correction factors and terrain correction factors. Finally, we calculate the radio communication reliability values at different frequencies based on the threshold of the propagation loss value. Compared with the reliability degree only considering the communication distance threshold, the influence of environmental factors on the reliability of the VHF and the UHF radio propagation has been analysed.","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126387974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fatigue crack propagation affects the operational reliability of engine turbo-fan blades. In this article, we integrate a Kriging regression model and a distributed collaborative response surface method (DCRSM) for the reliability assessment of turbo-fan blades, considering the relevant uncertainty. Following a series of deterministic analyses, such as steady-state aerodynamic analysis, harmonic response analysis and Campbell diagram, and based on the assumption that vibration stress is mainly from aerodynamic load, the fatigue strength is calculated for turbo-fan blades under coupling aerodynamic forces, according to a modified Goodman curve of titanium-alloy. Giving consideration to the uncertainty of the resonance frequencies and material properties, the fatigue strength of the turbo-fan blade is evaluated, including probabilistic analysis and sensitivity analysis. In the case study analyzed, the conclusions are that the fatigue strength reliability reaches 96.808% with confidence level of 0.95 for the turbo-fan blade under the coupling aerodynamic forces, and the first three-order resonant frequencies are found to have important influence on the fatigue performance of turbo-fan blades.
{"title":"Fatigue strength reliability assessment of turbo-fan blades by Kriging-based distributed collaborative response surface method","authors":"Haifeng Gao, Anjenq Wang, E. Zio, Wei Ma","doi":"10.17531/EIN.2019.3.20","DOIUrl":"https://doi.org/10.17531/EIN.2019.3.20","url":null,"abstract":"Fatigue crack propagation affects the operational reliability of engine turbo-fan blades. In this article, we integrate a Kriging regression model and a distributed collaborative response surface method (DCRSM) for the reliability assessment of turbo-fan blades, considering the relevant uncertainty. Following a series of deterministic analyses, such as steady-state aerodynamic analysis, harmonic response analysis and Campbell diagram, and based on the assumption that vibration stress is mainly from aerodynamic load, the fatigue strength is calculated for turbo-fan blades under coupling aerodynamic forces, according to a modified Goodman curve of titanium-alloy. Giving consideration to the uncertainty of the resonance frequencies and material properties, the fatigue strength of the turbo-fan blade is evaluated, including probabilistic analysis and sensitivity analysis. In the case study analyzed, the conclusions are that the fatigue strength reliability reaches 96.808% with confidence level of 0.95 for the turbo-fan blade under the coupling aerodynamic forces, and the first three-order resonant frequencies are found to have important influence on the fatigue performance of turbo-fan blades.","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126818647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Emergency Condenser (EC) is a heat exchanger composed of a large number of slightly inclined U-tubes arranged horizontally. The inlet header of the condenser is connected with the top part of the Reactor Pressure Vessel (RPV), which is occupied by steam during critical operation. The lower header in turn is linked with the RPV below the liquid water level during normal operation of the reactor. The tube bundle is filled with cold water and it is located in a vessel filled with water of the same temperature. Thus, the EC and RPV form together a system of communicating vessels. In case of an emergency and a decrease of the water level in the RPV, the water flows gravitationally from U-tubes to the RPV. At the same time the steam from the RPV enters to the EC and condenses due to its contact with cold walls of the EC. The condensate flows then back to the RPV due to the tubes inclination. Hence, the system removes heat from the RPV and serves as a highand low-pressure injection system at the same time. In this paper a model of the EC system is presented. The model was developed with Modelica modeling language and OpenModelica environment which had not been used in this scope before. The model was verified against experimental data obtained during tests performed at INKA (Integral Test Facility Karlstein) ̶ a test facility dedicated for investigation of the passive safety systems performance of KERENA ̶ generation III+ BWR developed by Framatome.
{"title":"Modeling of emergency condenser system response to loss of coolant accident in a BWR III+ generation","authors":"Rafał Bryk, H. Schmidt, T. Mull","doi":"10.17531/EIN.2019.3.13","DOIUrl":"https://doi.org/10.17531/EIN.2019.3.13","url":null,"abstract":"Emergency Condenser (EC) is a heat exchanger composed of a large number of slightly inclined U-tubes arranged horizontally. The inlet header of the condenser is connected with the top part of the Reactor Pressure Vessel (RPV), which is occupied by steam during critical operation. The lower header in turn is linked with the RPV below the liquid water level during normal operation of the reactor. The tube bundle is filled with cold water and it is located in a vessel filled with water of the same temperature. Thus, the EC and RPV form together a system of communicating vessels. In case of an emergency and a decrease of the water level in the RPV, the water flows gravitationally from U-tubes to the RPV. At the same time the steam from the RPV enters to the EC and condenses due to its contact with cold walls of the EC. The condensate flows then back to the RPV due to the tubes inclination. Hence, the system removes heat from the RPV and serves as a highand low-pressure injection system at the same time. In this paper a model of the EC system is presented. The model was developed with Modelica modeling language and OpenModelica environment which had not been used in this scope before. The model was verified against experimental data obtained during tests performed at INKA (Integral Test Facility Karlstein) ̶ a test facility dedicated for investigation of the passive safety systems performance of KERENA ̶ generation III+ BWR developed by Framatome.","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"165 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131896735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In reliability analysis of systems, multi-state systems are proposed instead of binary-state systems because they are more practical to use in real life situations. Especially multi-state models are useful in describing many engineering systems such as pipe-line systems, power generating systems or manufacturing systems, etc. Different from binary state systems, they have more than just two levels of working efficiency. A multi-state system and its components can have M (M>1) working states, from perfect functioning state φ(0)=M to less efficient states φ(t)∈{M-1,M-2,...,1,0}, where φ(t) denotes the state of the system at an arbitrary time point t. To have the general idea behind the multi-state theory and the basic evaluation methods on the reliability of such systems, see the works of Huang et al.[8], Tian et al. [24] and Eryilmaz [4]. Also for a detailed theory of multi-state modelling we refer to Kuo and Zuo [10]. This study examines a manufacturing system containing seriallyconnected workstations within its structure. Although the literature Funda IscIoglu Aydın KocAK
在系统的可靠性分析中，提出了多状态系统来代替二状态系统，因为它们在现实生活中更实用。特别是多状态模型在描述管道系统、发电系统或制造系统等工程系统时非常有用。与二元状态系统不同，它们的工作效率不止两个层次。一个多状态系统及其组成部分可以有M (M>1)个工作状态，从完美运行状态φ(0)=M到效率较低的状态φ(t)∈{M-1,M-2，…，1,0}，其中φ(t)表示系统在任意时间点t的状态。要了解多状态理论的一般思想和多状态系统可靠性的基本评估方法，请参见Huang et al.[8]、Tian et al.[24]和Eryilmaz[4]的著作。关于多状态建模的详细理论，我们参考了Kuo和Zuo[10]。本研究考察了在其结构中包含串行连接工作站的制造系统。虽然文献Funda IscIoglu Aydın KocAK
{"title":"Dynamic reliability analysis of a multi-state manufacturing system","authors":"Funda Iscioglu, Aydın Koçak","doi":"10.17531/EIN.2019.3.11","DOIUrl":"https://doi.org/10.17531/EIN.2019.3.11","url":null,"abstract":"In reliability analysis of systems, multi-state systems are proposed instead of binary-state systems because they are more practical to use in real life situations. Especially multi-state models are useful in describing many engineering systems such as pipe-line systems, power generating systems or manufacturing systems, etc. Different from binary state systems, they have more than just two levels of working efficiency. A multi-state system and its components can have M (M>1) working states, from perfect functioning state φ(0)=M to less efficient states φ(t)∈{M-1,M-2,...,1,0}, where φ(t) denotes the state of the system at an arbitrary time point t. To have the general idea behind the multi-state theory and the basic evaluation methods on the reliability of such systems, see the works of Huang et al.[8], Tian et al. [24] and Eryilmaz [4]. Also for a detailed theory of multi-state modelling we refer to Kuo and Zuo [10]. This study examines a manufacturing system containing seriallyconnected workstations within its structure. Although the literature Funda IscIoglu Aydın KocAK","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126488527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An analysis conducted by the World Bank [64] indicates that water shortages in some regions may reduce GDP by up to 6% and lead to increased migration and in some cases to a greater risk of conflict. Droughts and periods of water scarcity have become a more common and more frequent phenomenon in Europe [17]. The drought experiences in Europe in 2011, 2012, 2015 and 2018 were the worst in a century and affected not only Southern and Western Europe, but also the countries in Northern Europe (including Great Britain, France, Germany, Sweden and Poland). The difference between water supply and its growing demand also determines the key limitations of China’s economic development. It is estimated that before 2005 due to a shortage of water in production, China lost $ 28 511 million annually. Brown [7] concluded that the shortage of water in China will soon be a threat to global cereal demand. Therefore, water, alongside cereals and crude oil, is referred to as a strategic resource. Hence, it is suggested that public authorities should shape water pricing for users in order to reflect its true shortage or alternative costs [15]. Table 3. Steady state availability versus for Case 2
{"title":"Selected problems of ambiguity of the dual price of water in the post-optimization analysis of the water supply system","authors":"J. Wawrzosek, S. Ignaciuk, A. Bochniak","doi":"10.17531/ein.2019.2.18","DOIUrl":"https://doi.org/10.17531/ein.2019.2.18","url":null,"abstract":"An analysis conducted by the World Bank [64] indicates that water shortages in some regions may reduce GDP by up to 6% and lead to increased migration and in some cases to a greater risk of conflict. Droughts and periods of water scarcity have become a more common and more frequent phenomenon in Europe [17]. The drought experiences in Europe in 2011, 2012, 2015 and 2018 were the worst in a century and affected not only Southern and Western Europe, but also the countries in Northern Europe (including Great Britain, France, Germany, Sweden and Poland). The difference between water supply and its growing demand also determines the key limitations of China’s economic development. It is estimated that before 2005 due to a shortage of water in production, China lost $ 28 511 million annually. Brown [7] concluded that the shortage of water in China will soon be a threat to global cereal demand. Therefore, water, alongside cereals and crude oil, is referred to as a strategic resource. Hence, it is suggested that public authorities should shape water pricing for users in order to reflect its true shortage or alternative costs [15]. Table 3. Steady state availability versus for Case 2","PeriodicalId":309533,"journal":{"name":"Ekspolatacja i Niezawodnosc - Maintenance and Reliability","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124978126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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