Pub Date : 2023-05-24DOI: 10.1177/09576509231178900
R. Tao, Y. Heng, Fangfang Zhang, Jiale Pan, Di Zhu, Weichao Liu, R. Xiao, Z. Gui
The S region on the full characteristic curve of pump-turbine is one of the important key features that affect its operation stability. In S region, one specific rotational speed value ( n11) corresponds to three specific flow rate values ( Q11), which causes the unit to fluctuate between different operation conditions. In this paper, focusing on the special region of pump-turbine, based on the combination of model experiment and numerical simulation, the S-region dynamic model of pump-turbine is established. The internal flow mechanism of pump-turbine is analyzed in detail from the perspective of Flow Energy Dissipation (FED). The results show that the high FED component is different at different operating points, but the flow energy maintain balance in the pump-turbine unit. High FED area displayed in near-wall or inter-channel of different components under different flow conditions. Besides, the generation of S region is related to the dynamic balance of energy especially in the no-load region. The analysis results of this paper provide theoretical basis for scientific and stable operation of pump-turbine.
{"title":"Analyzing the S-characteristic of pump-turbine under the same head condition from the perspective of flow energy dissipation","authors":"R. Tao, Y. Heng, Fangfang Zhang, Jiale Pan, Di Zhu, Weichao Liu, R. Xiao, Z. Gui","doi":"10.1177/09576509231178900","DOIUrl":"https://doi.org/10.1177/09576509231178900","url":null,"abstract":"The S region on the full characteristic curve of pump-turbine is one of the important key features that affect its operation stability. In S region, one specific rotational speed value ( n11) corresponds to three specific flow rate values ( Q11), which causes the unit to fluctuate between different operation conditions. In this paper, focusing on the special region of pump-turbine, based on the combination of model experiment and numerical simulation, the S-region dynamic model of pump-turbine is established. The internal flow mechanism of pump-turbine is analyzed in detail from the perspective of Flow Energy Dissipation (FED). The results show that the high FED component is different at different operating points, but the flow energy maintain balance in the pump-turbine unit. High FED area displayed in near-wall or inter-channel of different components under different flow conditions. Besides, the generation of S region is related to the dynamic balance of energy especially in the no-load region. The analysis results of this paper provide theoretical basis for scientific and stable operation of pump-turbine.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"59 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75124417","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 : 2023-05-22DOI: 10.1177/09576509231177103
Junwei Zhong, Jingyin Li, Hui-zhen Liu
Dynamic mode decomposition (DMD) technology is used to analyze the control of dynamic stall on a pitching S809 airfoil using an off-surface rod. The unsteady flows around the original and the controlled airfoil are simulated by using the SST k-ω turbulence model. With the introduction of the off-surface rod, the hysteresis effect of the dynamic stall process of the original airfoil is considerably reduced, and the clockwise sub-loop of the pitching moment coefficient is eliminated. The improvement of the dynamic stall process is beneficial to the safe and high-efficiency operations of wind turbine. The coherent structure of the unsteady flow fields are decoupled by the DMD method compiled by an in-house code in MATLAB. Results reveal that the hysteresis effect is dominated by mode 2 with a pitching frequency and mode 3 with twice the pitching frequency. The global energy of the two modes is reduced by the off-surface rod, which alleviates the hysteresis effect for the original airfoil.
{"title":"Analysis of dynamic stall control on a pitching airfoil using dynamic mode decomposition","authors":"Junwei Zhong, Jingyin Li, Hui-zhen Liu","doi":"10.1177/09576509231177103","DOIUrl":"https://doi.org/10.1177/09576509231177103","url":null,"abstract":"Dynamic mode decomposition (DMD) technology is used to analyze the control of dynamic stall on a pitching S809 airfoil using an off-surface rod. The unsteady flows around the original and the controlled airfoil are simulated by using the SST k-ω turbulence model. With the introduction of the off-surface rod, the hysteresis effect of the dynamic stall process of the original airfoil is considerably reduced, and the clockwise sub-loop of the pitching moment coefficient is eliminated. The improvement of the dynamic stall process is beneficial to the safe and high-efficiency operations of wind turbine. The coherent structure of the unsteady flow fields are decoupled by the DMD method compiled by an in-house code in MATLAB. Results reveal that the hysteresis effect is dominated by mode 2 with a pitching frequency and mode 3 with twice the pitching frequency. The global energy of the two modes is reduced by the off-surface rod, which alleviates the hysteresis effect for the original airfoil.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"33 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74055315","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}
Pressure fluctuations caused by helical vortex rope in the draft tube is one of the main reasons for the instability of Francis turbines. Previous studies showed that drilling holes on runner cone can reduce the amplitude of pressure fluctuation. In this study, based on the runner cone which has been drilled one hole, two kinds of new runner cones are designed by means of drilling two more holes (2 holes runner cone) and drilling a slot (2 holes and 1 slot runner cone). Pressure fluctuation and flow pattern observation experiments as well as numerical simulations at partial load operation condition in a Francis turbine were carried out for the three types of runner cones. Analyses were performed to reveal the generation mechanism of the low frequency pressure fluctuations. The results showed that low frequency fluctuations are related to the cyclical rotation of helical vortex rope. Holes and slots on the runner cone have little impact on the efficiency of the Francis turbine. Slotting on the runner cone can reduce the amplitude of pressure fluctuation induced by vortex rope to a maximum of 29.41%. Hence, proper slotting on the runner cone can effectively reduce the low-frequency fluctuation caused by vortex rope in Francis turbines. These findings provide a new idea to improve the hydraulic instability of Francis turbines induced by vortex rope.
{"title":"Runner cone drilling and slotting to reduce vortex rope - induced pressure fluctuations in a Francis turbine","authors":"Yonglin Qin, Deyou Li, N. Zhang, Hongjie Wang, Qian Shi, Xianzhu Wei","doi":"10.1177/09576509231178387","DOIUrl":"https://doi.org/10.1177/09576509231178387","url":null,"abstract":"Pressure fluctuations caused by helical vortex rope in the draft tube is one of the main reasons for the instability of Francis turbines. Previous studies showed that drilling holes on runner cone can reduce the amplitude of pressure fluctuation. In this study, based on the runner cone which has been drilled one hole, two kinds of new runner cones are designed by means of drilling two more holes (2 holes runner cone) and drilling a slot (2 holes and 1 slot runner cone). Pressure fluctuation and flow pattern observation experiments as well as numerical simulations at partial load operation condition in a Francis turbine were carried out for the three types of runner cones. Analyses were performed to reveal the generation mechanism of the low frequency pressure fluctuations. The results showed that low frequency fluctuations are related to the cyclical rotation of helical vortex rope. Holes and slots on the runner cone have little impact on the efficiency of the Francis turbine. Slotting on the runner cone can reduce the amplitude of pressure fluctuation induced by vortex rope to a maximum of 29.41%. Hence, proper slotting on the runner cone can effectively reduce the low-frequency fluctuation caused by vortex rope in Francis turbines. These findings provide a new idea to improve the hydraulic instability of Francis turbines induced by vortex rope.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"16 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73713491","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 : 2023-05-19DOI: 10.1177/09576509231175944
Niveditha Porika, Shyama P Das, Bhamidi Vsss Prasad
Computational investigations are carried out on a high-speed centrifugal compressor with the vaneless diffuser to study the combined pinch and rotation effect. The axial inlet width of the rotating vaneless diffuser is reduced at diffuser inlet, either at the hub wall or at the shroud wall, or both the walls. The reduction is varied from 0% (base case) to 20% at an interval of 5%. Numerical simulations are conducted for different speed range by varying the rotating diffuser diameter ratio from 1.25–1.75. Among all these cases, the best performance of 25% increase in pressure recovery with uniform diffusion and 2.3% increase in isentropic efficiency is obtained with 15% shroud pinch at a diameter ratio of 1.375 at the design mass flow rate.
{"title":"Numerical investigation on the combined effects of pinching and rotation on the performance of a high-speed centrifugal compressor with a vaneless diffuser","authors":"Niveditha Porika, Shyama P Das, Bhamidi Vsss Prasad","doi":"10.1177/09576509231175944","DOIUrl":"https://doi.org/10.1177/09576509231175944","url":null,"abstract":"Computational investigations are carried out on a high-speed centrifugal compressor with the vaneless diffuser to study the combined pinch and rotation effect. The axial inlet width of the rotating vaneless diffuser is reduced at diffuser inlet, either at the hub wall or at the shroud wall, or both the walls. The reduction is varied from 0% (base case) to 20% at an interval of 5%. Numerical simulations are conducted for different speed range by varying the rotating diffuser diameter ratio from 1.25–1.75. Among all these cases, the best performance of 25% increase in pressure recovery with uniform diffusion and 2.3% increase in isentropic efficiency is obtained with 15% shroud pinch at a diameter ratio of 1.375 at the design mass flow rate.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"31 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84649889","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 : 2023-05-18DOI: 10.1177/09576509231174952
Jiajun Li, Dan Yu, Shuangtao Chen
This study investigates the spatial and temporal features of micropump cavitation. The numerical model is based on the k-Epsilon turbulence model and the Zwart cavitation model. Cases with different rotation speeds and flow volumes are carried out experimentally to validate the numerical model by changing rotation speed and flow rate separately. The periodic to chaos cavitation is observed by varying the cavitation number. Spatial modes of cavitation on the blade are identified by the dynamic mode decomposing. The frequencies of those modes are also obtained. The most energetic modes are presented and discussed. Cavitation of micropump on the suction side of the blade experiences growing, breaking, and shedding. With the decrease of cavitation number, the cavitation occurs at the leading-edge part, the middle part, and the entire blades. The leakage of cavitation can result in the interaction between cavitation between neighboring gaps of blades and the symmetrical distribution. The results also show that with the increase of cavitation number, there exists a downshift of frequency, and the bump point of the blade can influence the cavitation significantly.
{"title":"Spatial and temporal features of cavitation in micropump by dynamic mode decomposing","authors":"Jiajun Li, Dan Yu, Shuangtao Chen","doi":"10.1177/09576509231174952","DOIUrl":"https://doi.org/10.1177/09576509231174952","url":null,"abstract":"This study investigates the spatial and temporal features of micropump cavitation. The numerical model is based on the k-Epsilon turbulence model and the Zwart cavitation model. Cases with different rotation speeds and flow volumes are carried out experimentally to validate the numerical model by changing rotation speed and flow rate separately. The periodic to chaos cavitation is observed by varying the cavitation number. Spatial modes of cavitation on the blade are identified by the dynamic mode decomposing. The frequencies of those modes are also obtained. The most energetic modes are presented and discussed. Cavitation of micropump on the suction side of the blade experiences growing, breaking, and shedding. With the decrease of cavitation number, the cavitation occurs at the leading-edge part, the middle part, and the entire blades. The leakage of cavitation can result in the interaction between cavitation between neighboring gaps of blades and the symmetrical distribution. The results also show that with the increase of cavitation number, there exists a downshift of frequency, and the bump point of the blade can influence the cavitation significantly.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"9 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87087993","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 : 2023-05-17DOI: 10.1177/09576509231177333
R. Bahrampoury, Y. Pahamli, Ali Torbatinejad, M. Hosseini
In order to boost the cycles’ thermal efficiency, their power generations and reduce industrial equipment costs the growing need to develop and improve the performance of power generation cycles has provided the basis for research. Currently, there are quite a few investigations aiming to consider Kalina cycles as a power generation system using low-grade heat sources. In this research, firstly KCS-11 (Kalina Cycle System11) as well as Ekalina cycle (enhanced KCS-11 with ejector) has been studied. The SEKalina cycle, which is a modification of Ekalina cycle, is introduced, examined, and simulated by EES software. In the structure of the EKalina, the throttle valve and absorber are removed and the ejector is used instead. The use of the ejector reduces pressure at the turbine’s outlet and augments the difference between the enthalpy of two turbine ends, leading to enhancement of the thermal proficiency and net power output. Including an ejector and benefited from a split configuration, SEKalina cycle proposes a potential for efficiency improvement. Examining the results of the cycles, it is found that by employing the SEKalina cycle, compare to the two previously introduced cycles (EKalina and KCS-11), the thermal efficiency and net power output rise significantly. Moreover, as a result, the net power output in SEKalina cycle is 2% higher than that of EKalina cycle.
{"title":"Improved performance of Kalina cycle system 11 cycle with new arrangement of ejector cycle","authors":"R. Bahrampoury, Y. Pahamli, Ali Torbatinejad, M. Hosseini","doi":"10.1177/09576509231177333","DOIUrl":"https://doi.org/10.1177/09576509231177333","url":null,"abstract":"In order to boost the cycles’ thermal efficiency, their power generations and reduce industrial equipment costs the growing need to develop and improve the performance of power generation cycles has provided the basis for research. Currently, there are quite a few investigations aiming to consider Kalina cycles as a power generation system using low-grade heat sources. In this research, firstly KCS-11 (Kalina Cycle System11) as well as Ekalina cycle (enhanced KCS-11 with ejector) has been studied. The SEKalina cycle, which is a modification of Ekalina cycle, is introduced, examined, and simulated by EES software. In the structure of the EKalina, the throttle valve and absorber are removed and the ejector is used instead. The use of the ejector reduces pressure at the turbine’s outlet and augments the difference between the enthalpy of two turbine ends, leading to enhancement of the thermal proficiency and net power output. Including an ejector and benefited from a split configuration, SEKalina cycle proposes a potential for efficiency improvement. Examining the results of the cycles, it is found that by employing the SEKalina cycle, compare to the two previously introduced cycles (EKalina and KCS-11), the thermal efficiency and net power output rise significantly. Moreover, as a result, the net power output in SEKalina cycle is 2% higher than that of EKalina cycle.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"11 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89963115","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 : 2023-05-16DOI: 10.1177/09576509231173476
G. Müller, B. Mereš
There is a large but mostly unused energy resource available from low temperature waste heat with temperatures of 80–150°C. The lack of a cost-effective technology prevents the generation of power from this potential. Recently, the Condensing Engine, which employs the condensation of steam and the arising vacuum as the driving force, had been developed to address this problem. Its simplicity and the use of water as working fluid promises cost-effectiveness. In the context of this work, it was decided to investigate the Newcomen Engine to assess its potential. This engine is usually neglected because of is low efficiency, thought to be caused by the continuous cooling and re-heating of the cylinder. A thermodynamic model of the engine was developed. Surprisingly, the model indicated that 78% of the heat losses are caused by the re-heating of the injection water and only 22% by the cooling and re-heating of the cylinder. This finding allowed to conceptualise a new engine, the Internal Condensation Engine, where plastic material for the cylinder and the forced ejection of the water minimise losses. The engine would have a similar or better efficiency than competitive technologies whilst being simpler, and therefore more cost-effective.
{"title":"Assessment of the Newcomen engine’s development potential as heat engine for low temperature waste heat","authors":"G. Müller, B. Mereš","doi":"10.1177/09576509231173476","DOIUrl":"https://doi.org/10.1177/09576509231173476","url":null,"abstract":"There is a large but mostly unused energy resource available from low temperature waste heat with temperatures of 80–150°C. The lack of a cost-effective technology prevents the generation of power from this potential. Recently, the Condensing Engine, which employs the condensation of steam and the arising vacuum as the driving force, had been developed to address this problem. Its simplicity and the use of water as working fluid promises cost-effectiveness. In the context of this work, it was decided to investigate the Newcomen Engine to assess its potential. This engine is usually neglected because of is low efficiency, thought to be caused by the continuous cooling and re-heating of the cylinder. A thermodynamic model of the engine was developed. Surprisingly, the model indicated that 78% of the heat losses are caused by the re-heating of the injection water and only 22% by the cooling and re-heating of the cylinder. This finding allowed to conceptualise a new engine, the Internal Condensation Engine, where plastic material for the cylinder and the forced ejection of the water minimise losses. The engine would have a similar or better efficiency than competitive technologies whilst being simpler, and therefore more cost-effective.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"166 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84649892","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 : 2023-05-16DOI: 10.1177/09576509231176626
Bowen Zhang, Jian Xu, Wei Luo, Zhaohui Luo, Longyan Wang
In the wind farm control field, wind turbines are normally manipulated to maximize the individual power production which is named the greedy control. However, this greedy control method can lead to massive losses of total wind farm power production, mainly caused by the wake interference between multiple wind turbines. To this end, the cooperative wake control, which seeks the maximum total power production by coordinating each individual wind turbine at the global optimum operation point, can greatly improve the wind farm output performance. In this paper, we investigate the effectiveness of two different cooperative wake control strategies, i.e., instantaneous control and wind-interval based (WIB) control under variable wind speeds/directions scenario. These two cooperative control strategies are achieved based on the power de-rating operation to the upstream wind turbines. Taking three in-line wind turbines as an example, the control parameters of the two upstream wind turbines are cooperatively optimized while the downstream third wind turbine operates at the maximum power coefficient. To account for the multiple wind turbines wake interference, an artificial neural network (ANN) wake model characterized by the fast computational efficiency and great accuracy, in combination with the best wake superposition model chosen to quantify multiple wake effect, is proposed for the control optimization. By comparing to the baseline greedy control, it shows that both cooperative control strategies are effective in improving the power production of the wind farm. More specifically, the WIB control can maintain the power production at the same level of instantaneous control with a maximum difference less than 3%, while it reduces the operating difficulty to a large extent which greatly facilitates its application under realistic more complex wind scenarios.
{"title":"Study of cooperative wake control for multiple wind turbines under variable wind speeds/directions","authors":"Bowen Zhang, Jian Xu, Wei Luo, Zhaohui Luo, Longyan Wang","doi":"10.1177/09576509231176626","DOIUrl":"https://doi.org/10.1177/09576509231176626","url":null,"abstract":"In the wind farm control field, wind turbines are normally manipulated to maximize the individual power production which is named the greedy control. However, this greedy control method can lead to massive losses of total wind farm power production, mainly caused by the wake interference between multiple wind turbines. To this end, the cooperative wake control, which seeks the maximum total power production by coordinating each individual wind turbine at the global optimum operation point, can greatly improve the wind farm output performance. In this paper, we investigate the effectiveness of two different cooperative wake control strategies, i.e., instantaneous control and wind-interval based (WIB) control under variable wind speeds/directions scenario. These two cooperative control strategies are achieved based on the power de-rating operation to the upstream wind turbines. Taking three in-line wind turbines as an example, the control parameters of the two upstream wind turbines are cooperatively optimized while the downstream third wind turbine operates at the maximum power coefficient. To account for the multiple wind turbines wake interference, an artificial neural network (ANN) wake model characterized by the fast computational efficiency and great accuracy, in combination with the best wake superposition model chosen to quantify multiple wake effect, is proposed for the control optimization. By comparing to the baseline greedy control, it shows that both cooperative control strategies are effective in improving the power production of the wind farm. More specifically, the WIB control can maintain the power production at the same level of instantaneous control with a maximum difference less than 3%, while it reduces the operating difficulty to a large extent which greatly facilitates its application under realistic more complex wind scenarios.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79921429","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 : 2023-05-13DOI: 10.1177/09576509231174692
K. Z. Zarrag, F. Ismail, Tan E Sann, L. Habeeb
The goal of this review is to examine the current state of the art in nucleate pool boiling heat transfer in a variety of different fluids. The review is divided into many sections that discuss heat transfer in pool boiling, such as pool boiling of nanofluids, boiling behavior of water–glycerin combinations, and operational parameters. With the appropriate mixes of hydrocarbons and other commercial liquids, higher heat transfer coefficients may be produced. Coatings of nanoparticles with varying layer thicknesses applied to the heater surface may be optimized to improve heat transfer from the pool to the surrounding water. The heat transfer hypothesis elucidates the peculiarities of each pool’s boiling regime. It is also possible to expand it to flow boiling by combining pool boiling liquid motion with external mechanical force. Other phase transitions, such as condensation, solidification, and melting, can also be described using boiling heat flow processes. Pool boiling performance can be improved by making a variety of adjustments to the heating surfaces as well as by using pure liquids in the water. Improvements can be made to boiling parameters such as the heat flux, the critical heat flux, the heat transfer coefficient, bubble development and departure, and so forth. A nanoparticle addition to a pure liquid or a surface coating on a heating surface can improve heat transfer and boiling properties by increasing the surface area of the liquid. Pool boiling critical heat flux was enhanced with Al2O3-water nano fluid. Authors used three different powder sizes of Al2O3 which were 0.05, 0.3 and 1.0 μm. Addition of alumina particle in water increases the boiling heat flux. Critical heat flux (CHF) was significantly enhanced using Titania and Alumina nano particles in water as compared to pure water. Average size of nano particle used was 85 nm measured by scattering electron microscope. Enhancement in Critical heat flux is due to nano particle coating on heating surface. Characteristics of nucleate boiling are greatly affected by the operating pressure. Miniature flat heat pipe (MFHP) with evaporator having micro grooved heat transfer surface gives 50% increment in critical heat flux at atmosphere pressure whereas this value increases up to 150% at 7.4 kPa pressure. The addition of CNT (carbon nanotube) to the base liquid increases the critical heat flux. Transmission electron microscopy confirms the average size of a nanoparticle as 15 nm. Authors found that by decreasing pressure from atmosphere condition critical heat flux increases to 200% with CNT/water nano fluid as compared to deionized water. SiC-water nanofluids of 100 nm size were experimented with at volume concentrations of 0.001%, 0.001%, and 0.01%. The size of the nanoparticle was confirmed by a scattering electron microscope. Authors concluded that at 0.01% of nano particle enhances critical heat flux to 105%.
{"title":"A review of nucleate pool-boiling heat transfer in different liquids and nanofluids","authors":"K. Z. Zarrag, F. Ismail, Tan E Sann, L. Habeeb","doi":"10.1177/09576509231174692","DOIUrl":"https://doi.org/10.1177/09576509231174692","url":null,"abstract":"The goal of this review is to examine the current state of the art in nucleate pool boiling heat transfer in a variety of different fluids. The review is divided into many sections that discuss heat transfer in pool boiling, such as pool boiling of nanofluids, boiling behavior of water–glycerin combinations, and operational parameters. With the appropriate mixes of hydrocarbons and other commercial liquids, higher heat transfer coefficients may be produced. Coatings of nanoparticles with varying layer thicknesses applied to the heater surface may be optimized to improve heat transfer from the pool to the surrounding water. The heat transfer hypothesis elucidates the peculiarities of each pool’s boiling regime. It is also possible to expand it to flow boiling by combining pool boiling liquid motion with external mechanical force. Other phase transitions, such as condensation, solidification, and melting, can also be described using boiling heat flow processes. Pool boiling performance can be improved by making a variety of adjustments to the heating surfaces as well as by using pure liquids in the water. Improvements can be made to boiling parameters such as the heat flux, the critical heat flux, the heat transfer coefficient, bubble development and departure, and so forth. A nanoparticle addition to a pure liquid or a surface coating on a heating surface can improve heat transfer and boiling properties by increasing the surface area of the liquid. Pool boiling critical heat flux was enhanced with Al2O3-water nano fluid. Authors used three different powder sizes of Al2O3 which were 0.05, 0.3 and 1.0 μm. Addition of alumina particle in water increases the boiling heat flux. Critical heat flux (CHF) was significantly enhanced using Titania and Alumina nano particles in water as compared to pure water. Average size of nano particle used was 85 nm measured by scattering electron microscope. Enhancement in Critical heat flux is due to nano particle coating on heating surface. Characteristics of nucleate boiling are greatly affected by the operating pressure. Miniature flat heat pipe (MFHP) with evaporator having micro grooved heat transfer surface gives 50% increment in critical heat flux at atmosphere pressure whereas this value increases up to 150% at 7.4 kPa pressure. The addition of CNT (carbon nanotube) to the base liquid increases the critical heat flux. Transmission electron microscopy confirms the average size of a nanoparticle as 15 nm. Authors found that by decreasing pressure from atmosphere condition critical heat flux increases to 200% with CNT/water nano fluid as compared to deionized water. SiC-water nanofluids of 100 nm size were experimented with at volume concentrations of 0.001%, 0.001%, and 0.01%. The size of the nanoparticle was confirmed by a scattering electron microscope. Authors concluded that at 0.01% of nano particle enhances critical heat flux to 105%.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75058621","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 : 2023-05-08DOI: 10.1177/09576509231174975
Ning Bao, Zihan Zhao, C. Shao
In order to test the performance of the micro centrifugal pump and carry out performance analysis by using water instead of blood as the test medium, a modeling test method of the micro centrifugal pump was proposed in this paper. Dimensional analysis method was applied to study the dimensionless characteristic number of the micro centrifugal pump. The SST (Shear Stress Transport) k-ω model was used to simulate the flow in the prototype pump and model pump. The correctness of the similarity theory and modeling schemes was verified. The performance of the micro centrifugal pump for transporting water and blood was studied under the same working conditions, and the effect of Reynolds number on the performance of the micro centrifugal pump was discussed. The external characteristics of similar pumps can be converted to each other. For similar pumps under different modeling schemes, the pressure and velocity at the corresponding position is proportional. When the micro centrifugal pump that transports blood operates at low rotational speed and low flow rate, the performance of the micro centrifugal pump will change dramatically. The critical Reynolds number of the micro centrifugal pump is determined to be 1200. The similarity criterion between the prototype pump and model pump was established. The modeling schemes of the micro centrifugal pump were formulated. The critical Reynolds number of the micro centrifugal pump was determined. The research results provide a new method for the performance test of the micro centrifugal pump transporting blood.
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