M. Nakahara, Kodai Tanimoto, Hisanobu Kudo, Yuta Maruyama, Fumiaki Abe
{"title":"Effects of hydrogen addition and turbulence on ignition and meso-scale flames of propane mixtures","authors":"M. Nakahara, Kodai Tanimoto, Hisanobu Kudo, Yuta Maruyama, Fumiaki Abe","doi":"10.1299/jtst.22-00248","DOIUrl":"https://doi.org/10.1299/jtst.22-00248","url":null,"abstract":"","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66345573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Numerical investigation on performance improvement of CaSO4 solar chemical heat pump","authors":"Yawen Ren, H. Ogura","doi":"10.1299/jtst.22-00058","DOIUrl":"https://doi.org/10.1299/jtst.22-00058","url":null,"abstract":"","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66345177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daisuke Sato, Shuta Nakachi, Kaito Honda, Keisuke Obu, T. Katsumi, S. Kadowaki
{"title":"Experimental analysis on micro diffusion flames formed by oxygen combustion of H2-CO2 mixture using counterflow burners","authors":"Daisuke Sato, Shuta Nakachi, Kaito Honda, Keisuke Obu, T. Katsumi, S. Kadowaki","doi":"10.1299/jtst.22-00012","DOIUrl":"https://doi.org/10.1299/jtst.22-00012","url":null,"abstract":"","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66344762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Yatsufusa, Yuki Goto, Shota Hiroi, Kenji Yoshida, D. Shimokuri
{"title":"Analysis of flame detection data from multiple-ion probes using feature extraction","authors":"T. Yatsufusa, Yuki Goto, Shota Hiroi, Kenji Yoshida, D. Shimokuri","doi":"10.1299/jtst.22-00148","DOIUrl":"https://doi.org/10.1299/jtst.22-00148","url":null,"abstract":"","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66345068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1299/jtst.2021jtst0015
W. Yuan, F. Sun, Ruqing Liu, Xuehong Chen, Ying Li
The cooling process of circulating water in the NDWCTs is an extremely important process, which is achieved by the contact heat dissipation and evaporation heat dissipation in the NDWCT. For the NDWCTs, the water loss of cooling tower mainly includes evaporation loss, windage loss and blowdown loss. Evaporation loss makes up most of the water loss at thermal power plants. For this reason, the study on the prediction of evaporation loss in the NDWCTs lay a theoretical foundation for the thermal power plant to decrease the emission and save water. In the power industry, water is often used as a heat transfer medium to dissipate heat, and in many areas, water has become a scarce resource. How to take measures to reduce or recover water consumption of thermal power plants, many scholars have paid attention to this issue, and achieved remarkable results (Yuan et al., 2019; Bustamante et al., 2016; Wei et al., 2018; Saidi et al., 2010). The application of the direct air-cooled technology in power plants is a key measure to achieve water conservation. Factors such as wind direction, fan performance and blade installation angle have a great influence on the cooling capacity of a direct air-cooled system (Yang et al., 2011; Zhang et al., 2019a, 2019b; Zhang et al,. 2018a, 2018b). However, the direct air-cooled systems account for a small part of the cooling towers. Most cooling methods in thermal power plants are wet cooling. Several mathematical models for predicting evaporation loss had been established in the mechanical wet cooling towers. Kairouani constructed a mathematical model for the numerical prediction of the performance of cross flow cooling towers and used this model to predict the thermal behavior of six cooling towers located in the South of Tunisia. It was found that the actual water losses by evaporation represent 4% of the total water flow rate, which corresponds to 106 m per year (Kairouani et al., 2004). Based on ASHRAE’s rule of thumb Qureshi set an empirical formula, and it could accurately predict the evaporation loss of cooling tower (Qureshi et al., 2006; Qureshi et al., 2007). Effect of change factors on evaporation loss based on cold end system in natural draft counter-flow wet cooling towers
NDWCT循环水的冷却过程是一个极其重要的过程，它通过NDWCT内部的接触散热和蒸发散热来实现。对于无水冷却塔，冷却塔的水损失主要包括蒸发损失、风损损失和排污损失。蒸发损失占火力发电厂水损失的大部分。因此，ndwct蒸发损失预测的研究为火电厂减少排放、节约用水奠定了理论基础。在电力工业中，经常使用水作为传热介质来散热，在许多领域，水已成为稀缺资源。如何采取措施降低或回收火电厂的用水量，很多学者都关注了这个问题，并取得了显著的成果(Yuan et al.， 2019;Bustamante et al.， 2016;Wei et al.， 2018;Saidi et al.， 2010)。直接空冷技术在电厂的应用是实现节水的关键措施。风向、风机性能、叶片安装角度等因素对直接风冷系统的制冷量影响较大(Yang et al.， 2011;张等，2019a, 2019b;张等人，。2018年,2018 b)。然而，直接风冷系统只占冷却塔的一小部分。火力发电厂的冷却方式大多是湿冷却。建立了几种预测湿式机械冷却塔蒸发损失的数学模型。Kairouani构建了横流冷却塔性能数值预测的数学模型，并利用该模型对位于突尼斯南部的六座冷却塔的热行为进行了预测。研究发现，蒸发造成的实际水分损失占总水流量的4%，相当于每年106米(Kairouani et al.， 2004)。根据ASHRAE的经验法则，Qureshi设置了经验公式，可以准确预测冷却塔的蒸发损失(Qureshi et al.， 2006;库雷希等人，2007)。自然通风逆流式湿式冷却塔冷端系统蒸发损失变化因素的影响
{"title":"Effect of change factors on evaporation loss based on cold end system in natural draft counter-flow wet cooling towers","authors":"W. Yuan, F. Sun, Ruqing Liu, Xuehong Chen, Ying Li","doi":"10.1299/jtst.2021jtst0015","DOIUrl":"https://doi.org/10.1299/jtst.2021jtst0015","url":null,"abstract":"The cooling process of circulating water in the NDWCTs is an extremely important process, which is achieved by the contact heat dissipation and evaporation heat dissipation in the NDWCT. For the NDWCTs, the water loss of cooling tower mainly includes evaporation loss, windage loss and blowdown loss. Evaporation loss makes up most of the water loss at thermal power plants. For this reason, the study on the prediction of evaporation loss in the NDWCTs lay a theoretical foundation for the thermal power plant to decrease the emission and save water. In the power industry, water is often used as a heat transfer medium to dissipate heat, and in many areas, water has become a scarce resource. How to take measures to reduce or recover water consumption of thermal power plants, many scholars have paid attention to this issue, and achieved remarkable results (Yuan et al., 2019; Bustamante et al., 2016; Wei et al., 2018; Saidi et al., 2010). The application of the direct air-cooled technology in power plants is a key measure to achieve water conservation. Factors such as wind direction, fan performance and blade installation angle have a great influence on the cooling capacity of a direct air-cooled system (Yang et al., 2011; Zhang et al., 2019a, 2019b; Zhang et al,. 2018a, 2018b). However, the direct air-cooled systems account for a small part of the cooling towers. Most cooling methods in thermal power plants are wet cooling. Several mathematical models for predicting evaporation loss had been established in the mechanical wet cooling towers. Kairouani constructed a mathematical model for the numerical prediction of the performance of cross flow cooling towers and used this model to predict the thermal behavior of six cooling towers located in the South of Tunisia. It was found that the actual water losses by evaporation represent 4% of the total water flow rate, which corresponds to 106 m per year (Kairouani et al., 2004). Based on ASHRAE’s rule of thumb Qureshi set an empirical formula, and it could accurately predict the evaporation loss of cooling tower (Qureshi et al., 2006; Qureshi et al., 2007). Effect of change factors on evaporation loss based on cold end system in natural draft counter-flow wet cooling towers","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66342898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1299/jtst.2021jtst0007
Soumyadeep Paul, W. Hsu, M. Magnini, L. Mason, Yusuke Ito, Y. Ho, O. Matar, H. Daiguji
The increasing demands of computational power have accelerated the development of 3D circuits in the semiconductor industry. To resolve the accompanying thermal issues, two-phase microchannel heat exchangers using have emerged as one of the promising solutions for cooling purposes. However, the direct boiling in microchannels and rapid bubble growth give rise to highly unstable heat flux on the channel walls. In this regard, it is hence desired to control the supply of vapor bubbles for the elimination of the instability. In this research, we investigate a controllable bubble generation technique, which is capable of periodically producing bubble seeds at the sub-micron scale. These nanobubbles were generated in a solid-state nanopore filled with a highly concentrated electrolyte solution. As an external electric field was applied, the localized Joule heating inside the nanopore initiated the homogeneous bubble nucleation. The bubble dynamics was analyzed by measuring the ionic current variation through the nanopore during the bubble nucleation and growth. Meanwhile, we theoretically examined the bubble growth and collapse inside the nanopore by a moving boundary model. In both approaches, we demonstrated that by altering the pore size, the available sensible heat for the bubble growth can be manipulated, thereby offering the controllability of the bubble size. This unique characteristic renders nanopores suitable as a nanobubble emitter for microchannel heat exchangers, paving the way for the next generation microelectronic cooling applications.
{"title":"Analysis and control of vapor bubble growth inside solid-state nanopores","authors":"Soumyadeep Paul, W. Hsu, M. Magnini, L. Mason, Yusuke Ito, Y. Ho, O. Matar, H. Daiguji","doi":"10.1299/jtst.2021jtst0007","DOIUrl":"https://doi.org/10.1299/jtst.2021jtst0007","url":null,"abstract":"The increasing demands of computational power have accelerated the development of 3D circuits in the semiconductor industry. To resolve the accompanying thermal issues, two-phase microchannel heat exchangers using have emerged as one of the promising solutions for cooling purposes. However, the direct boiling in microchannels and rapid bubble growth give rise to highly unstable heat flux on the channel walls. In this regard, it is hence desired to control the supply of vapor bubbles for the elimination of the instability. In this research, we investigate a controllable bubble generation technique, which is capable of periodically producing bubble seeds at the sub-micron scale. These nanobubbles were generated in a solid-state nanopore filled with a highly concentrated electrolyte solution. As an external electric field was applied, the localized Joule heating inside the nanopore initiated the homogeneous bubble nucleation. The bubble dynamics was analyzed by measuring the ionic current variation through the nanopore during the bubble nucleation and growth. Meanwhile, we theoretically examined the bubble growth and collapse inside the nanopore by a moving boundary model. In both approaches, we demonstrated that by altering the pore size, the available sensible heat for the bubble growth can be manipulated, thereby offering the controllability of the bubble size. This unique characteristic renders nanopores suitable as a nanobubble emitter for microchannel heat exchangers, paving the way for the next generation microelectronic cooling applications.","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66342422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1299/jtst.2021jtst0035
T. Hirano, Daiki Tomonaga, T. Ogi, D. Shimokuri
{"title":"Direct spray combustion in a tubular flame burner toward fine particle synthesis","authors":"T. Hirano, Daiki Tomonaga, T. Ogi, D. Shimokuri","doi":"10.1299/jtst.2021jtst0035","DOIUrl":"https://doi.org/10.1299/jtst.2021jtst0035","url":null,"abstract":"","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66344243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abnormal combustion such as pre-ignition and knocking is becoming one of the biggest problems in the latest gasoline engines that have a higher compression ratio and boosting for higher efficiency. An ion-current sensor integrated in an ignition system is used for accurately detecting knocking cycles. First, the problem for accurate knocking detection with an ion-current sensor was clarified in the test engine. The oscillation in the ion-current signal was observed in knocking cycles as is commonly known in the previous research. However, heavy oscillation in the ion-current signal can be observed occasionally even in the small knocking cycles. This phenomenon leads to the misdetection of knocking cycles with the conventional signal-processing method, which defines the oscillation intensity of the change amount in the ion-current signal as a knocking indicator. Second, to solve the problem mentioned above, a new signal-processing method is proposed on the basis of the thermal characteristics of ion-current signals. This method defines the oscillation intensity of the “normalized ion-signal change rate” as a knock indicator in order to suppress the effect of temperature dependency in ion-current signals. Finally, the proposed method was applied to an actual gasoline engine, and the knocking detection performance was evaluated. The method enabled the misdetection of the knocking cycles to be avoided and enhanced the correlation factor with knock intensity compared with the conventional method. vibration sensor equipped on the engine block. Yang et al. (2010) developed a signal-processing method to detect the low intensity vibration from short data series, on the basis of kurtosis of vibration intensity. Momeni et al. (2016) proposed a normalization model that enables a fixed detection threshold in all head can be changed, and the signal intensity of the ion current can be adjusted.
在以更高的压缩比和增压来提高效率的最新汽油发动机中，预燃和爆震等异常燃烧正成为最大的问题之一。离子电流传感器集成在点火系统中，用于精确检测爆震周期。首先，澄清了在试验发动机中使用离子电流传感器进行准确爆震检测的问题。在以往的研究中，离子电流信号的振荡是在敲打周期中观察到的。然而，即使在小的敲打周期中，偶尔也可以观察到离子电流信号中的剧烈振荡。这种现象导致传统的信号处理方法将离子电流信号变化量的振荡强度定义为爆震指标，对爆震周期的检测存在错误。其次，针对上述问题，基于离子电流信号的热特性，提出了一种新的信号处理方法。该方法将“归一化离子信号变化率”的振荡强度定义为爆震指标，以抑制温度依赖性对离子电流信号的影响。最后，将该方法应用于一台实际汽油机，对其爆震检测性能进行了评价。与传统方法相比，该方法避免了爆震周期的误检，提高了爆震强度与爆震周期的相关系数。发动机缸体上装有振动传感器。Yang等(2010)基于振动强度峰度，提出了一种从短数据序列中检测低强度振动的信号处理方法。Momeni et al.(2016)提出了一种归一化模型，可以改变所有头部的固定检测阈值，并且可以调节离子电流的信号强度。
{"title":"Enhancement of knocking detection accuracy by an ion-current sensor integrated in the ignition system","authors":"Kengo Kumano, Hiroshi Kimura, Yoshihiko Akagi, Shinya Matohara, Yoshifumi Uchise, Y. Yamasaki","doi":"10.1299/jtst.2021jtst0037","DOIUrl":"https://doi.org/10.1299/jtst.2021jtst0037","url":null,"abstract":"Abnormal combustion such as pre-ignition and knocking is becoming one of the biggest problems in the latest gasoline engines that have a higher compression ratio and boosting for higher efficiency. An ion-current sensor integrated in an ignition system is used for accurately detecting knocking cycles. First, the problem for accurate knocking detection with an ion-current sensor was clarified in the test engine. The oscillation in the ion-current signal was observed in knocking cycles as is commonly known in the previous research. However, heavy oscillation in the ion-current signal can be observed occasionally even in the small knocking cycles. This phenomenon leads to the misdetection of knocking cycles with the conventional signal-processing method, which defines the oscillation intensity of the change amount in the ion-current signal as a knocking indicator. Second, to solve the problem mentioned above, a new signal-processing method is proposed on the basis of the thermal characteristics of ion-current signals. This method defines the oscillation intensity of the “normalized ion-signal change rate” as a knock indicator in order to suppress the effect of temperature dependency in ion-current signals. Finally, the proposed method was applied to an actual gasoline engine, and the knocking detection performance was evaluated. The method enabled the misdetection of the knocking cycles to be avoided and enhanced the correlation factor with knock intensity compared with the conventional method. vibration sensor equipped on the engine block. Yang et al. (2010) developed a signal-processing method to detect the low intensity vibration from short data series, on the basis of kurtosis of vibration intensity. Momeni et al. (2016) proposed a normalization model that enables a fixed detection threshold in all head can be changed, and the signal intensity of the ion current can be adjusted.","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66344410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1299/jtst.2021jtst0041
Suazlan MT AZNAM, N. Maruoka, R. Imai, S. Mori
Various surface modifications controlling wettability and wickability have effectively enhanced the critical heat flux (CHF) in saturated pool boiling. Among them, this paper focuses on the CHF enhancement using a honeycomb porous plate (HPP). The HPP, which is commercially available, was generally used to filter exhaust gases from combustion engines, and has micron-order pores and millimeter-order holes which is called as a “cell”. Once an HPP was installed on the heated surface, the CHF in saturated pool boiling of water was improved more than approximately three times compared with a bare surface. The enhancement may be caused by: (1) the liquid supply due to capillarity, (2) liquid flowing down through the cells of an HPP due to gravity onto the heated surface, and (3) the release of vapor generated through the cells. However, the liquid supply process to heated surface due to (1) and (2) has not been clarified yet. Therefore, it is necessary to elucidate the detailed liquid supply mechanism for further CHF enhancement. In the present paper, two separate sets of experiments have been designed to investigate the liquid supply effect to the heated surface independently, namely, (1) automatic liquid supply due to capillary action by the porous part and (2) bulk liquid flowing down through the cells of an HPP. In summary, the measured values from the experiment extracting the liquid supply due to capillarity were in good agreement with the proposed capillary limit model. Moreover, for the high heat flux region (more than 3.5 MW/m2), the liquid supply due to the capillary force is dominant in enhancing the CHF. It was concluded that the keys to further CHF enhancement were the promotion of gas-liquid circulation based on the capillary limit model and improvement of wickability of the heated surface.
{"title":"Process of liquid supply to heated surface by a honeycomb porous plate for critical heat flux enhancement","authors":"Suazlan MT AZNAM, N. Maruoka, R. Imai, S. Mori","doi":"10.1299/jtst.2021jtst0041","DOIUrl":"https://doi.org/10.1299/jtst.2021jtst0041","url":null,"abstract":"Various surface modifications controlling wettability and wickability have effectively enhanced the critical heat flux (CHF) in saturated pool boiling. Among them, this paper focuses on the CHF enhancement using a honeycomb porous plate (HPP). The HPP, which is commercially available, was generally used to filter exhaust gases from combustion engines, and has micron-order pores and millimeter-order holes which is called as a “cell”. Once an HPP was installed on the heated surface, the CHF in saturated pool boiling of water was improved more than approximately three times compared with a bare surface. The enhancement may be caused by: (1) the liquid supply due to capillarity, (2) liquid flowing down through the cells of an HPP due to gravity onto the heated surface, and (3) the release of vapor generated through the cells. However, the liquid supply process to heated surface due to (1) and (2) has not been clarified yet. Therefore, it is necessary to elucidate the detailed liquid supply mechanism for further CHF enhancement. In the present paper, two separate sets of experiments have been designed to investigate the liquid supply effect to the heated surface independently, namely, (1) automatic liquid supply due to capillary action by the porous part and (2) bulk liquid flowing down through the cells of an HPP. In summary, the measured values from the experiment extracting the liquid supply due to capillarity were in good agreement with the proposed capillary limit model. Moreover, for the high heat flux region (more than 3.5 MW/m2), the liquid supply due to the capillary force is dominant in enhancing the CHF. It was concluded that the keys to further CHF enhancement were the promotion of gas-liquid circulation based on the capillary limit model and improvement of wickability of the heated surface.","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66344637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1299/JTST.2021JTST0026
T. Katsumi, Y. Yoshida, R. Nakagawa, Shinya Yazawa, M. Kumada, Daisuke Sato, T. Aung, N. Chaumeix, S. Kadowaki
experimental data under a certain condition but also to create the mathematical model for the prediction of flame propagation velocity under various conditions. Thus, it is significant to understand the characteristics of dynamic behavior of hydrogen/air premixed flames and to elucidate the effects of addition of inert gas, i.e. carbon dioxide CO 2 and water vapor H 2 O. We performed the experiments of hydrogen explosion in two types of closed chambers to observe spherically expanding flames using Schlieren photography. Wrinkles on the flame surface were clearly observed in low equivalence ratios. Analyzing the Schlieren images, the flame propagation velocity depending on the flame radius was obtained. Increasing the addition of inert gas, the propagation velocity decreased, especially in the case of CO 2 addition. The propagation velocity increased monotonically as the flame radius became larger. The appearance of flame acceleration was found, which was caused by the evolution of wrinkles on the flame surface. Moreover, the Markstein length decreased as the concentration of inert gas became higher, indicating that the addition of inert gas promoted the instability of hydrogen flames. Furthermore, the wrinkling factor, closely related with the increment in propagation velocity, decreased as the inert-gas concentration became higher. The wrinkling factor normalized by the propagation velocity of flat flame increased, on the other hand, under the conditions of high inert-gas concentration, except for near the quenching conditions. This indicated that the addition of CO 2 or H 2 O promoted the unstable motion of hydrogen flames, which could be due to the enhancement of the diffusive-thermal effect. Based on the characteristics of dynamic behavior of hydrogen flames, the parameters used in the mathematical model on propagation velocity including flame acceleration was obtained, and then the flame propagation velocity under various conditions was predicted. Intrinsic
{"title":"The effects of addition of carbon dioxide and water vapor on the dynamic behavior of spherically expanding hydrogen/air premixed flames","authors":"T. Katsumi, Y. Yoshida, R. Nakagawa, Shinya Yazawa, M. Kumada, Daisuke Sato, T. Aung, N. Chaumeix, S. Kadowaki","doi":"10.1299/JTST.2021JTST0026","DOIUrl":"https://doi.org/10.1299/JTST.2021JTST0026","url":null,"abstract":"experimental data under a certain condition but also to create the mathematical model for the prediction of flame propagation velocity under various conditions. Thus, it is significant to understand the characteristics of dynamic behavior of hydrogen/air premixed flames and to elucidate the effects of addition of inert gas, i.e. carbon dioxide CO 2 and water vapor H 2 O. We performed the experiments of hydrogen explosion in two types of closed chambers to observe spherically expanding flames using Schlieren photography. Wrinkles on the flame surface were clearly observed in low equivalence ratios. Analyzing the Schlieren images, the flame propagation velocity depending on the flame radius was obtained. Increasing the addition of inert gas, the propagation velocity decreased, especially in the case of CO 2 addition. The propagation velocity increased monotonically as the flame radius became larger. The appearance of flame acceleration was found, which was caused by the evolution of wrinkles on the flame surface. Moreover, the Markstein length decreased as the concentration of inert gas became higher, indicating that the addition of inert gas promoted the instability of hydrogen flames. Furthermore, the wrinkling factor, closely related with the increment in propagation velocity, decreased as the inert-gas concentration became higher. The wrinkling factor normalized by the propagation velocity of flat flame increased, on the other hand, under the conditions of high inert-gas concentration, except for near the quenching conditions. This indicated that the addition of CO 2 or H 2 O promoted the unstable motion of hydrogen flames, which could be due to the enhancement of the diffusive-thermal effect. Based on the characteristics of dynamic behavior of hydrogen flames, the parameters used in the mathematical model on propagation velocity including flame acceleration was obtained, and then the flame propagation velocity under various conditions was predicted. Intrinsic","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66343229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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