Pub Date : 2024-07-23DOI: 10.1177/09576509241266284
Faiz T Jodah, Wissam H Alawee, Hayder A Dhahad, ZM Omara
Solving global water shortages has become an urgent challenge, hindering sustainable development. Therefore, comparing different solar still designs from application and economic perspectives is necessary. Solar distillation is considered a major innovation in the alternative energy sector for purifying brackish or brine water into clean water. Despite the extensive literature on improved solar stills, determining the most efficient designs for residential and industrial applications remains difficult. This review compares the productivity of spherical, hemispherical, and tubular solar still designs. The aim is to study the factors that influence the efficiency of each type and to analyze recent research and results obtained under different conditions. The results show that innovations in solar distillation design can take many forms to improve efficiency and productivity. For example, adding parabolic mirrors can increase productivity in spherical, hemispherical, and tubular stills by 35 to 70%. Likewise, innovative designs such as rotating spheres and changing bowl shapes significantly increased the productivity of spherical and hemispherical stills. Likewise, retrofitting a still with vacuum generation technology can significantly increase yields by 50 to 70%. In addition, using nanomaterials, especially nanophase change materials (NPCM), has increased the efficiency of the spherical and tubular stills by 116.5%, producing 7.62 kg/m2 per day. Therefore, the NPCM-equipped model was still the most efficient option among the three designs.
{"title":"Evaluating the performance of spherical, hemispherical, and tubular solar stills with various configurations - A detailed review","authors":"Faiz T Jodah, Wissam H Alawee, Hayder A Dhahad, ZM Omara","doi":"10.1177/09576509241266284","DOIUrl":"https://doi.org/10.1177/09576509241266284","url":null,"abstract":"Solving global water shortages has become an urgent challenge, hindering sustainable development. Therefore, comparing different solar still designs from application and economic perspectives is necessary. Solar distillation is considered a major innovation in the alternative energy sector for purifying brackish or brine water into clean water. Despite the extensive literature on improved solar stills, determining the most efficient designs for residential and industrial applications remains difficult. This review compares the productivity of spherical, hemispherical, and tubular solar still designs. The aim is to study the factors that influence the efficiency of each type and to analyze recent research and results obtained under different conditions. The results show that innovations in solar distillation design can take many forms to improve efficiency and productivity. For example, adding parabolic mirrors can increase productivity in spherical, hemispherical, and tubular stills by 35 to 70%. Likewise, innovative designs such as rotating spheres and changing bowl shapes significantly increased the productivity of spherical and hemispherical stills. Likewise, retrofitting a still with vacuum generation technology can significantly increase yields by 50 to 70%. In addition, using nanomaterials, especially nanophase change materials (NPCM), has increased the efficiency of the spherical and tubular stills by 116.5%, producing 7.62 kg/m<jats:sup>2</jats:sup> per day. Therefore, the NPCM-equipped model was still the most efficient option among the three designs.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"61 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141779383","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 : 2024-07-23DOI: 10.1177/09576509241264441
M. Sonachalam, V. Manieniyan, R. Senthilkumar
Researchers demonstrated that implementing new combustion technology and optimising fuel quantity results in a significant reduction in traditional fossil fuel usage and emission levels. The Reactivity Controlled Compression Ignition (RCCI) combustion strategy is one of the low temperature combustion technologies, and it is used to reduce the overall combustion temperature while also providing better combustion control. This study looks into RCCI combustion technology, which uses conventional diesel fuel as the high reactivity fuel (HRF) injected through the injector and acetylene gas as the low reactivity fuel (LRF) injected into the cylinder via a modified inlet manifold alongside air. The modified engine setup was tested for performance, emissions, and combustion under various load conditions, as well as different mass flow rates of acetylene gas, a low reactivity fuel that is injected with air. The flow field of the low reactivity fuel at the inlet manifold is analysed using the Computational Fluid Dynamics principle, which is used to determine the best flow rate for improving combustion quality. According to the simulation results, the optimal acetylene flow rate is 3 Litres Per Minute (LPM), and experimentation shows that at 3 LPM acetylene injection, the brake thermal efficiency (BTE) improves by about 3.2%, and emissions such as carbon monoxide (CO), hydrocarbon (HC), smoke intensity, and oxides of nitrogen (NOx) are reduced by about 35%, 17%, 10%, and 21%, respectively.
{"title":"Optimization on manifold injection in DI diesel engine fuelled with acetylene","authors":"M. Sonachalam, V. Manieniyan, R. Senthilkumar","doi":"10.1177/09576509241264441","DOIUrl":"https://doi.org/10.1177/09576509241264441","url":null,"abstract":"Researchers demonstrated that implementing new combustion technology and optimising fuel quantity results in a significant reduction in traditional fossil fuel usage and emission levels. The Reactivity Controlled Compression Ignition (RCCI) combustion strategy is one of the low temperature combustion technologies, and it is used to reduce the overall combustion temperature while also providing better combustion control. This study looks into RCCI combustion technology, which uses conventional diesel fuel as the high reactivity fuel (HRF) injected through the injector and acetylene gas as the low reactivity fuel (LRF) injected into the cylinder via a modified inlet manifold alongside air. The modified engine setup was tested for performance, emissions, and combustion under various load conditions, as well as different mass flow rates of acetylene gas, a low reactivity fuel that is injected with air. The flow field of the low reactivity fuel at the inlet manifold is analysed using the Computational Fluid Dynamics principle, which is used to determine the best flow rate for improving combustion quality. According to the simulation results, the optimal acetylene flow rate is 3 Litres Per Minute (LPM), and experimentation shows that at 3 LPM acetylene injection, the brake thermal efficiency (BTE) improves by about 3.2%, and emissions such as carbon monoxide (CO), hydrocarbon (HC), smoke intensity, and oxides of nitrogen (NOx) are reduced by about 35%, 17%, 10%, and 21%, respectively.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"44 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141779384","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 : 2024-06-21DOI: 10.1177/09576509241260795
Yutian Chen, Qun Zheng, Yuting Jiang, Bin Jiang
The application of inverse design in engineering is constrained by uncertainty over when to cease calculations owing to solution fluctuations and suboptimal aerodynamic parameter distribution. The proposed method for inverse design optimization incorporates active subspace assistance to effectively address these significant limitations. The optimal load distribution is achieved by the integration of sparse polynomial approximation and genetic algorithm. Furthermore, active subspace method is employed to solve the control zone of optimal static pressure/load distribution. The inverse design calculation is terminated when current load distribution falls completely within the control zone. Within the control zone, all static pressure/load distributions following a certain variance are guaranteed to provide nearly identical aerodynamic performance. The results indicate that the static pressure/load distribution of the final solution entirely falls within the control zone, while its aerodynamic performance approximates the optimal target value. In comparison to the initial solution, the final solution exhibits a significant decrease of 3.6% in the total pressure loss coefficient.
{"title":"Inverse design optimization of the compressor cascade airfoil assisted by active subspace approach","authors":"Yutian Chen, Qun Zheng, Yuting Jiang, Bin Jiang","doi":"10.1177/09576509241260795","DOIUrl":"https://doi.org/10.1177/09576509241260795","url":null,"abstract":"The application of inverse design in engineering is constrained by uncertainty over when to cease calculations owing to solution fluctuations and suboptimal aerodynamic parameter distribution. The proposed method for inverse design optimization incorporates active subspace assistance to effectively address these significant limitations. The optimal load distribution is achieved by the integration of sparse polynomial approximation and genetic algorithm. Furthermore, active subspace method is employed to solve the control zone of optimal static pressure/load distribution. The inverse design calculation is terminated when current load distribution falls completely within the control zone. Within the control zone, all static pressure/load distributions following a certain variance are guaranteed to provide nearly identical aerodynamic performance. The results indicate that the static pressure/load distribution of the final solution entirely falls within the control zone, while its aerodynamic performance approximates the optimal target value. In comparison to the initial solution, the final solution exhibits a significant decrease of 3.6% in the total pressure loss coefficient.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"26 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141546990","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 : 2024-05-30DOI: 10.1177/09576509241257727
Ramazan Şener, M Eşref Demir
Turbulators are used in heat exchangers to increase the contact surfaces of fluids and enhance heat transfer rates by promoting turbulence flow. This is particularly important in applications that require high productivity and capabilities. The use of turbulators can lead to maximum energy efficiency, resulting in high efficiency and lower costs. This investigation presents a comprehensive experimental and computational fluid dynamics (CFD) approach into the influence of turbulator-induced disturbances on heat transfer characteristics in a double pipe heat exchanger. In this study, two innovative turbulators (named TY and TZ) were designed to enhance the performance of heat exchangers. The turbulators are inserted into the inner pipe of the double pipe heat exchanger. According to the experimental and numerical results, compared to the plain pipe condition (without turbulator), it was observed that maximum temperature differences were reached with a 28% increase at velocity of 2.5 m/s with TY and 118% increase at velocity of 3 m/s with TZ. Nusselt numbers increased by 32% with TY and by 157.9% with TZ compared to the plain pipe condition. Therefore, TZ turbulator with a simple structure can significantly enhance the heat transfer performance of double-pipe heat exchangers, making it an ideal option for use in these exchangers.
{"title":"Heat transfer and flow characteristics of a novel turbulator design in heat exchanger: Experimental and numerical analysis","authors":"Ramazan Şener, M Eşref Demir","doi":"10.1177/09576509241257727","DOIUrl":"https://doi.org/10.1177/09576509241257727","url":null,"abstract":"Turbulators are used in heat exchangers to increase the contact surfaces of fluids and enhance heat transfer rates by promoting turbulence flow. This is particularly important in applications that require high productivity and capabilities. The use of turbulators can lead to maximum energy efficiency, resulting in high efficiency and lower costs. This investigation presents a comprehensive experimental and computational fluid dynamics (CFD) approach into the influence of turbulator-induced disturbances on heat transfer characteristics in a double pipe heat exchanger. In this study, two innovative turbulators (named TY and TZ) were designed to enhance the performance of heat exchangers. The turbulators are inserted into the inner pipe of the double pipe heat exchanger. According to the experimental and numerical results, compared to the plain pipe condition (without turbulator), it was observed that maximum temperature differences were reached with a 28% increase at velocity of 2.5 m/s with TY and 118% increase at velocity of 3 m/s with TZ. Nusselt numbers increased by 32% with TY and by 157.9% with TZ compared to the plain pipe condition. Therefore, TZ turbulator with a simple structure can significantly enhance the heat transfer performance of double-pipe heat exchangers, making it an ideal option for use in these exchangers.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"21 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141189928","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 : 2024-05-27DOI: 10.1177/09576509241256499
Xiaosong Xia, Shaogan Ye, Liang Hou, Dehui Wu, Quan Lin
Accurate calculation of instantaneous flow area is of great significance for modeling an axial piston pump. A point cloud based technique is developed to calculate the instantaneous flow area, and used to perform a parametric analysis of key parameters on the pump fluid dynamics. First, a model is developed to analyze the fluid dynamics of the axial piston pump. Second, three techniques used to obtain the instantaneous flow area are described, with focus on the detailed description of the point cloud technique. The instantaneous flow areas are compared, and the accuracy of the pump model using the obtained instantaneous flow areas are verified by comparing the output pressure. Last, a comprehensive parametric study is conducted concerning the effects of the fillet radius and diversion position of the triangular groove on the pressure in the piston chamber and flow rate at the output port based on the point cloud technique. The results shown that the computation time of the point cloud technique is only 1% of the Computational Fluid Dynamics (CFD) technique, with a total computational error of less than 2.5%, and the triangular groove inside the pitch circle with a small fillet radius is beneficial for reductions of pressure and flow rate ripples.
{"title":"Instantaneous flow area calculation for modeling an axial piston pump: A point cloud-based technique","authors":"Xiaosong Xia, Shaogan Ye, Liang Hou, Dehui Wu, Quan Lin","doi":"10.1177/09576509241256499","DOIUrl":"https://doi.org/10.1177/09576509241256499","url":null,"abstract":"Accurate calculation of instantaneous flow area is of great significance for modeling an axial piston pump. A point cloud based technique is developed to calculate the instantaneous flow area, and used to perform a parametric analysis of key parameters on the pump fluid dynamics. First, a model is developed to analyze the fluid dynamics of the axial piston pump. Second, three techniques used to obtain the instantaneous flow area are described, with focus on the detailed description of the point cloud technique. The instantaneous flow areas are compared, and the accuracy of the pump model using the obtained instantaneous flow areas are verified by comparing the output pressure. Last, a comprehensive parametric study is conducted concerning the effects of the fillet radius and diversion position of the triangular groove on the pressure in the piston chamber and flow rate at the output port based on the point cloud technique. The results shown that the computation time of the point cloud technique is only 1% of the Computational Fluid Dynamics (CFD) technique, with a total computational error of less than 2.5%, and the triangular groove inside the pitch circle with a small fillet radius is beneficial for reductions of pressure and flow rate ripples.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"46 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141165575","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 : 2024-05-25DOI: 10.1177/09576509241254416
Ruibing Wu, Zhuoxiong Zeng, Hong Liu, Kaifang Guo
In order to investigate the premixed combustion characteristics of CH4/H2/air in a micro-mixing combustor, the effects of different micro-mixing head-ends (HE1, HE2, HE3) and hydrogen mixing ratios on the temperature distribution, heat transfer process, emission characteristic, flames shape are analyzed. The results show that compared with swirl head-end combustion, the micro-mixing combustion performance is better. Among the three head-ends, HE3 has the best combustion characteristics and stable flames. The temperature distribution in the high-temperature zone is uniform, and low-temperature zone is concentrated near the jet, which can suppress the flashback. The velocity and temperature gradient near the central axis of jet streams show a strong synergistic effect. The flames are plume shaped and flames stability is mainly influenced by the H2 combustion process. Increasing the jet diameter, decreasing the jet spacing and increasing the hydrogen mixing ratio all contribute to the flames stability, but these three methods can stabilize the flames by affecting fluid Reynolds number, interaction between small flames and combustion rate, respectively. Moreover, small jet diameter and high hydrogen mixing ratio can reduce OTDF, which contributes to improve outlet temperature uniformity.
{"title":"Numerical investigation of CH4/H2/air micro-mixing combustion flow in a micro gas turbine combustor with different head-end structures","authors":"Ruibing Wu, Zhuoxiong Zeng, Hong Liu, Kaifang Guo","doi":"10.1177/09576509241254416","DOIUrl":"https://doi.org/10.1177/09576509241254416","url":null,"abstract":"In order to investigate the premixed combustion characteristics of CH<jats:sub>4</jats:sub>/H<jats:sub>2</jats:sub>/air in a micro-mixing combustor, the effects of different micro-mixing head-ends (HE1, HE2, HE3) and hydrogen mixing ratios on the temperature distribution, heat transfer process, emission characteristic, flames shape are analyzed. The results show that compared with swirl head-end combustion, the micro-mixing combustion performance is better. Among the three head-ends, HE3 has the best combustion characteristics and stable flames. The temperature distribution in the high-temperature zone is uniform, and low-temperature zone is concentrated near the jet, which can suppress the flashback. The velocity and temperature gradient near the central axis of jet streams show a strong synergistic effect. The flames are plume shaped and flames stability is mainly influenced by the H<jats:sub>2</jats:sub> combustion process. Increasing the jet diameter, decreasing the jet spacing and increasing the hydrogen mixing ratio all contribute to the flames stability, but these three methods can stabilize the flames by affecting fluid Reynolds number, interaction between small flames and combustion rate, respectively. Moreover, small jet diameter and high hydrogen mixing ratio can reduce OTDF, which contributes to improve outlet temperature uniformity.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"104 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141148889","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 : 2024-05-09DOI: 10.1177/09576509241252877
Tianxiao Zhao, Zhenyu Jiang, Guangyu Mo, GuoJie Wang, Jie Gao
Gas turbines cannot be directly reversed, and the astern operation of gas turbines still requires additional power transmission equipment to be achieved. To compensate for this deficiency, the application of turbine-blade-tip turbine in gas turbines was proposed. Turbine-blade-tip turbines have the characteristics of extremely low solidity and extremely high diameter-span ratio. Compared with conventional turbine blades, the capacity of turbine blades to restrain gas flow is greatly weakened, the separation flow is obvious when going astern, resulting in low efficiency. For the control problem of low solidity turbine-blade-tip turbines separation flow, a splitter blade control strategy is selected to suppress the separation flow. Adding a splitter blade between original rotor blades effectively improves the ability of rotor blades to restrain gas flow, significantly reduces separation phenomena, and significantly improves efficiency. As the axial chord length of the splitter blade shortens, the inhibitory effect on the separation flow decreases, and the ability of splitter blades to improve the efficiency gradually descends.
{"title":"Control of separation flows of turbine-blade-tip turbines by splitter blades","authors":"Tianxiao Zhao, Zhenyu Jiang, Guangyu Mo, GuoJie Wang, Jie Gao","doi":"10.1177/09576509241252877","DOIUrl":"https://doi.org/10.1177/09576509241252877","url":null,"abstract":"Gas turbines cannot be directly reversed, and the astern operation of gas turbines still requires additional power transmission equipment to be achieved. To compensate for this deficiency, the application of turbine-blade-tip turbine in gas turbines was proposed. Turbine-blade-tip turbines have the characteristics of extremely low solidity and extremely high diameter-span ratio. Compared with conventional turbine blades, the capacity of turbine blades to restrain gas flow is greatly weakened, the separation flow is obvious when going astern, resulting in low efficiency. For the control problem of low solidity turbine-blade-tip turbines separation flow, a splitter blade control strategy is selected to suppress the separation flow. Adding a splitter blade between original rotor blades effectively improves the ability of rotor blades to restrain gas flow, significantly reduces separation phenomena, and significantly improves efficiency. As the axial chord length of the splitter blade shortens, the inhibitory effect on the separation flow decreases, and the ability of splitter blades to improve the efficiency gradually descends.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"39 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140938220","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 : 2024-05-02DOI: 10.1177/09576509241249216
Cuizhen Zhang, Xuan Gao, Kun Zhu, Yongmei Wang, Yingjie Liu, Fengming Wang, Shuai Yin
This study aims to develop a reliable numerical model for predicting the supercritical heat transfer of aviation kerosene RP-3 in a tube under heating conditions, thereby providing a reference for revealing the mechanism behind the experimental phenomena. Based on validation studies between seven turbulence models and experiments, a numerical method using the Yang-Shih turbulence model is proposed. A detailed prediction of the turbulent flow process is obtained, and the heat transfer characteristics of RP-3 are analyzed. The evolution of parameters and properties in axial and radial directions is demonstrated, followed by investigations of the effects of system pressure, fuel inlet temperature, and mass flow rate. The drastic change in the specific heat of the fuel when its temperature is close to the pseudocritical value and the temperature difference between the area near the wall and the center of the tube are the main causes of the enhancement and deterioration of the heat exchange. A higher inlet temperature increases the heat transfer coefficient, but due to its different effects on decreasing the density and the viscosity, it increases the pressure drop. In addition, larger mass flow rates can promote turbulence intensity and heat transfer, but cause a higher pressure drop across the tube.
{"title":"Numerical investigations on heat transfer of supercritical RP-3 flowing in circular tube","authors":"Cuizhen Zhang, Xuan Gao, Kun Zhu, Yongmei Wang, Yingjie Liu, Fengming Wang, Shuai Yin","doi":"10.1177/09576509241249216","DOIUrl":"https://doi.org/10.1177/09576509241249216","url":null,"abstract":"This study aims to develop a reliable numerical model for predicting the supercritical heat transfer of aviation kerosene RP-3 in a tube under heating conditions, thereby providing a reference for revealing the mechanism behind the experimental phenomena. Based on validation studies between seven turbulence models and experiments, a numerical method using the Yang-Shih turbulence model is proposed. A detailed prediction of the turbulent flow process is obtained, and the heat transfer characteristics of RP-3 are analyzed. The evolution of parameters and properties in axial and radial directions is demonstrated, followed by investigations of the effects of system pressure, fuel inlet temperature, and mass flow rate. The drastic change in the specific heat of the fuel when its temperature is close to the pseudocritical value and the temperature difference between the area near the wall and the center of the tube are the main causes of the enhancement and deterioration of the heat exchange. A higher inlet temperature increases the heat transfer coefficient, but due to its different effects on decreasing the density and the viscosity, it increases the pressure drop. In addition, larger mass flow rates can promote turbulence intensity and heat transfer, but cause a higher pressure drop across the tube.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"71 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140836955","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 : 2024-05-02DOI: 10.1177/09576509241251909
Xuedi Hao, Zeyuan Zhang, Jinling Chi, Lei Sun, Jiajin Zhang
A compressor map is usually represented by a limited number of feature points to speculate the entire operating range. Also, accurate compressor map models can be obtained quickly by using the appropriate methods. In this paper, 9351FA gas turbine is used as the research object, and a set of targeted compressor map speculation scheme is proposed. At 15 data points, high-precision compressor maps are obtained based on BP neural network, and this method is suitable for a large number of data points. At 6 data points, compressor maps are obtained based on the parameter estimation method, and this method is suitable for a small number of data points. The mean square deviation of the compressor map obtained by the neural network is about 0.002, while the minimum mean square deviation of the results of the parameter estimation method is 0.026 and the maximum mean square deviation is 0.088. Since the corrected speed line of 106.4 is almost vertical, the maximum error mean squared deviation and the maximum standard deviation occur on this line. Both methods are suitable for different sample sizes, and the speculated compressor maps are more reliable. The combination of the two methods can provide a set of reference methods for compressor map speculation.
{"title":"Research on speculation method for compressor map of PG9351FA gas turbine","authors":"Xuedi Hao, Zeyuan Zhang, Jinling Chi, Lei Sun, Jiajin Zhang","doi":"10.1177/09576509241251909","DOIUrl":"https://doi.org/10.1177/09576509241251909","url":null,"abstract":"A compressor map is usually represented by a limited number of feature points to speculate the entire operating range. Also, accurate compressor map models can be obtained quickly by using the appropriate methods. In this paper, 9351FA gas turbine is used as the research object, and a set of targeted compressor map speculation scheme is proposed. At 15 data points, high-precision compressor maps are obtained based on BP neural network, and this method is suitable for a large number of data points. At 6 data points, compressor maps are obtained based on the parameter estimation method, and this method is suitable for a small number of data points. The mean square deviation of the compressor map obtained by the neural network is about 0.002, while the minimum mean square deviation of the results of the parameter estimation method is 0.026 and the maximum mean square deviation is 0.088. Since the corrected speed line of 106.4 is almost vertical, the maximum error mean squared deviation and the maximum standard deviation occur on this line. Both methods are suitable for different sample sizes, and the speculated compressor maps are more reliable. The combination of the two methods can provide a set of reference methods for compressor map speculation.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"99 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140837117","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}
The safe operation of closed-Bryton-cycle system is hindered by the nonlinear real gas properties in a supercritical carbon dioxide (SCO2) centrifugal compressor for waste heat recovery in a powertrain system. This paper aims to understand the influence of real gas properties on the aerodynamic stability of a shrouded SCO2 centrifugal compressor designed for waste heat recovery. Firstly, the numerical method was calibrated and validated using experimental results from the Sandia SCO2 centrifugal compressor. Next, based on the numerical method, the stability performance of an inhouse-design shrouded SCO2 compressor was discussed through a direct comparison with the identical compressor using air. The results showed that the performance of the SCO2 compressor was significantly different from that of the air compressor. Particularly, the impeller was the most unstable component featuring a notable recirculating region near the shroud at the leading edge. Further analysis is carried out to understand the discrepancies in the stability performance between the two compressors with different fluids. It is revealed that the boundary layer on the SCO2 impeller suction surface thickens at a faster rate, leading to stronger flow separation. Meanwhile, the stronger accumulation of low-momentum secondary flow near the SCO2 impeller outlet enhances the ‘wake’ structure near the shroud of suction surface at the impeller tailing edge, resulting in considerable backflow. The different behaviors of boundary layer were attributed to pressure gradient normal to the suction surface. Specifically, the pressure gradient on the suction surface for SCO2 impeller is orders of magnitude higher than that of the air impeller. The stronger gradient weakens momentum exchange in the boundary layer, thus increasing the thickness of boundary layer more rapidly along the streamwise direction. Moreover, the boundary layer is pushed towards the shroud of suction surface by the strong pressure gradient, resulting in the evident accumulation of secondary flow nearby. At the meantime, the low-momentum flow near the impeller outlet reduced the inlet flow velocity of the diffuser, causing more recirculation at the top of the vaneless diffuser in all circumferential directions, thus worsening its instability.
{"title":"Influence of real gas properties on aerodynamic stability of a SCO2 centrifugal compressor","authors":"Ruikai Cai, Mingyang Yang, Weilin Zhuge, Bijie Yang, Ricardo Martinez-Botas, Yangjun Zhang","doi":"10.1177/09576509241248885","DOIUrl":"https://doi.org/10.1177/09576509241248885","url":null,"abstract":"The safe operation of closed-Bryton-cycle system is hindered by the nonlinear real gas properties in a supercritical carbon dioxide (SCO<jats:sub>2</jats:sub>) centrifugal compressor for waste heat recovery in a powertrain system. This paper aims to understand the influence of real gas properties on the aerodynamic stability of a shrouded SCO<jats:sub>2</jats:sub> centrifugal compressor designed for waste heat recovery. Firstly, the numerical method was calibrated and validated using experimental results from the Sandia SCO<jats:sub>2</jats:sub> centrifugal compressor. Next, based on the numerical method, the stability performance of an inhouse-design shrouded SCO<jats:sub>2</jats:sub> compressor was discussed through a direct comparison with the identical compressor using air. The results showed that the performance of the SCO<jats:sub>2</jats:sub> compressor was significantly different from that of the air compressor. Particularly, the impeller was the most unstable component featuring a notable recirculating region near the shroud at the leading edge. Further analysis is carried out to understand the discrepancies in the stability performance between the two compressors with different fluids. It is revealed that the boundary layer on the SCO<jats:sub>2</jats:sub> impeller suction surface thickens at a faster rate, leading to stronger flow separation. Meanwhile, the stronger accumulation of low-momentum secondary flow near the SCO<jats:sub>2</jats:sub> impeller outlet enhances the ‘wake’ structure near the shroud of suction surface at the impeller tailing edge, resulting in considerable backflow. The different behaviors of boundary layer were attributed to pressure gradient normal to the suction surface. Specifically, the pressure gradient on the suction surface for SCO<jats:sub>2</jats:sub> impeller is orders of magnitude higher than that of the air impeller. The stronger gradient weakens momentum exchange in the boundary layer, thus increasing the thickness of boundary layer more rapidly along the streamwise direction. Moreover, the boundary layer is pushed towards the shroud of suction surface by the strong pressure gradient, resulting in the evident accumulation of secondary flow nearby. At the meantime, the low-momentum flow near the impeller outlet reduced the inlet flow velocity of the diffuser, causing more recirculation at the top of the vaneless diffuser in all circumferential directions, thus worsening its instability.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"21 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140837271","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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