Power plants release a massive amount of waste heat at very low temperatures. Posing a challenge for efficient conversion into useful work through conventional methods. By selecting appropriate working fluids, low-grade power cycles can solve this problem by converting waste heat to electricity. The present work dealt with waste heat utilization using the Organic Rankine Cycle (ORC) from a 400 MWe coal based supercritical Pressurized Pulverized Combined Cycle (PPCC). The working fluid for the ORC is the refrigerant R245fa. High-ash (HA) Indian coal and low-ash (LA) South African coal are used as fuel to assess the plant’s ability to produce electricity under ambient conditions in India. The simulation flowsheet program “Cycle-Tempo” models and simulates different plant layouts. The thermodynamic assessment unveiled that the standalone plant has energy and exergy efficiencies of 43.46% and 39.87% for HA & 45.42% and 43.84% for LA, respectively. According to this study, the proposed plant has energy and exergy efficiencies of 44.63% and 40.94% for HA & 46.69% and 45.07% for LA, respectively. Moreover, using ORC, the waste heat generates additional electricity of 9.38 MWe, with an energy efficiency of 12.92% and exergy efficiency of 34.63%.
发电厂在极低的温度下释放出大量废热。这给通过传统方法将废热有效转化为有用功带来了挑战。通过选择适当的工作流体，低品位动力循环可将余热转化为电能，从而解决这一问题。本研究利用有机郎肯循环（ORC）对 400 MWe 煤基超临界加压粉化联合循环（PPCC）中的废热进行利用。ORC 的工作流体是制冷剂 R245fa。高灰分（HA）印度煤和低灰分（LA）南非煤被用作燃料，以评估发电厂在印度环境条件下的发电能力。模拟流程图程序 "Cycle-Tempo "对不同的发电厂布局进行了建模和模拟。热力学评估结果表明，独立发电厂的能量效率和放能效率分别为：HA & 43.46% 和 39.87%；LA 45.42% 和 43.84%。根据这项研究，拟议的发电厂在 HA 和 LA 方面的能源效率和放能效率分别为 44.63% 和 40.94%；在 HA 和 LA 方面的能源效率和放能效率分别为 46.69% 和 45.07%。此外，利用 ORC，余热可产生 9.38 MWe 的额外电力，能源效率为 12.92%，放能效率为 34.63%。
{"title":"Waste heat utilization using organic rankine cycle from a pressurized pulverized combined cycle power plant","authors":"Nitesh Kumar Choudhary, Goutam Khankari, Sujit Karmakar","doi":"10.1177/09576509241240013","DOIUrl":"https://doi.org/10.1177/09576509241240013","url":null,"abstract":"Power plants release a massive amount of waste heat at very low temperatures. Posing a challenge for efficient conversion into useful work through conventional methods. By selecting appropriate working fluids, low-grade power cycles can solve this problem by converting waste heat to electricity. The present work dealt with waste heat utilization using the Organic Rankine Cycle (ORC) from a 400 MWe coal based supercritical Pressurized Pulverized Combined Cycle (PPCC). The working fluid for the ORC is the refrigerant R245fa. High-ash (HA) Indian coal and low-ash (LA) South African coal are used as fuel to assess the plant’s ability to produce electricity under ambient conditions in India. The simulation flowsheet program “Cycle-Tempo” models and simulates different plant layouts. The thermodynamic assessment unveiled that the standalone plant has energy and exergy efficiencies of 43.46% and 39.87% for HA & 45.42% and 43.84% for LA, respectively. According to this study, the proposed plant has energy and exergy efficiencies of 44.63% and 40.94% for HA & 46.69% and 45.07% for LA, respectively. Moreover, using ORC, the waste heat generates additional electricity of 9.38 MWe, with an energy efficiency of 12.92% and exergy efficiency of 34.63%.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"5 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140171716","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 : 2024-03-16DOI: 10.1177/09576509241236533
Leilei Ji, Haoming Li, Wei Li, Weidong Shi, Shuo Li, Yang Yang, Chensong Zhao, Ramesh K Agarwal
In recent years, it has been demonstrated for many two- and three-dimensional external and internal turbulent flows that the one-equation Wray-Agarwal turbulence model can compute the complex turbulent flow fields with high computational accuracy, excellent computational convergence and efficiency. In this paper, Wray-Agarwal (WA) turbulence model is employed as part of a detached eddy simulation (DES) method to predict the performance of a mixed-flow pump. By comparing the computations with the experimental results, the differences and similarities between the WA-DES model and the Shear Stress Transfer (SST) k-ω model in predicting the internal and external flow characteristics of the pump are analyzed. The results show that both the SST k-ω model and the WA-DES model can reasonably predict the performance of the pump between 0.6 Q and 1.2 Q, where Q is the design flow rate; however, they have their own merits and deficiencies in predicting head and efficiency of the pump at low and high flow rates. For the velocity field in the rotor-stator interaction region, the WA-DES model shows better prediction accuracy since it can accurately predict the large-scale recirculating vortex structure at the inlet of the guide vane. The SST k-ω model over-predicts the separated flow region, which leads to the emergence of a small vortex structure before the backflow region of the pump. Although the turbulent eddy viscosity predicted by the WA-DES model is higher than that of the SST k-ω model and there is small difference in the results for the scale of the tip leakage vortex (TLV) between the two models, the overall simulation results of the WA-DES model for the high turbulent viscosity region and the pressure increase in the impeller are consistent with the SST k-ω model results. The results of this paper demonstrate the potential of WA-DES model for prediction of flows in pumps.
{"title":"Application of a new DES model based on Wray-Agarwal turbulence model in flow simulation of a mixed-flow pump","authors":"Leilei Ji, Haoming Li, Wei Li, Weidong Shi, Shuo Li, Yang Yang, Chensong Zhao, Ramesh K Agarwal","doi":"10.1177/09576509241236533","DOIUrl":"https://doi.org/10.1177/09576509241236533","url":null,"abstract":"In recent years, it has been demonstrated for many two- and three-dimensional external and internal turbulent flows that the one-equation Wray-Agarwal turbulence model can compute the complex turbulent flow fields with high computational accuracy, excellent computational convergence and efficiency. In this paper, Wray-Agarwal (WA) turbulence model is employed as part of a detached eddy simulation (DES) method to predict the performance of a mixed-flow pump. By comparing the computations with the experimental results, the differences and similarities between the WA-DES model and the Shear Stress Transfer (SST) k-ω model in predicting the internal and external flow characteristics of the pump are analyzed. The results show that both the SST k-ω model and the WA-DES model can reasonably predict the performance of the pump between 0.6 Q and 1.2 Q, where Q is the design flow rate; however, they have their own merits and deficiencies in predicting head and efficiency of the pump at low and high flow rates. For the velocity field in the rotor-stator interaction region, the WA-DES model shows better prediction accuracy since it can accurately predict the large-scale recirculating vortex structure at the inlet of the guide vane. The SST k-ω model over-predicts the separated flow region, which leads to the emergence of a small vortex structure before the backflow region of the pump. Although the turbulent eddy viscosity predicted by the WA-DES model is higher than that of the SST k-ω model and there is small difference in the results for the scale of the tip leakage vortex (TLV) between the two models, the overall simulation results of the WA-DES model for the high turbulent viscosity region and the pressure increase in the impeller are consistent with the SST k-ω model results. The results of this paper demonstrate the potential of WA-DES model for prediction of flows in pumps.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"10 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140149497","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 : 2024-03-08DOI: 10.1177/09576509241237840
Francois D Boshoff, Sybrand J van der Spuy, Johannes P Pretorius, Christiaan J Meyer
An axial flow fan is designed for dry cooling of a sCO2 Brayton cycle for a CSP plant, and a scaled model of the fan is manufactured and tested experimentally in an ISO 5801:2017 Type A fan test facility. While the design procedure’s estimate of the total-to-static efficiency at the design flow rate is relatively high, at 74.4%, the experimental fan efficiency was found to be only 50.6%. This paper details an investigation into the causes of fan performance degradation, using both experimental and numerical methods. The investigation finds that the hub configuration, tip clearance size, and scale of the test fan is responsible for the reduced performance. Two alternative hub and casing configurations are identified which improve the fan’s performance significantly.
设计了一种轴流式风机，用于 CSP 电站 sCO2 布莱顿循环的干式冷却，并在 ISO 5801:2017 A 型风机测试设备中制造和实验测试了该风机的比例模型。虽然设计程序对设计流速下总静态效率的估算相对较高，达到 74.4%，但实验发现风机效率仅为 50.6%。本文采用实验和数值方法详细调查了风扇性能下降的原因。调查发现，测试风扇的轮毂配置、叶尖间隙大小和规模是性能下降的原因。本文确定了两种可供选择的轮毂和外壳配置，可显著提高风扇的性能。
{"title":"Investigation into the predicted performance of a cooling fan for an sCO2 concentrated solar power plant","authors":"Francois D Boshoff, Sybrand J van der Spuy, Johannes P Pretorius, Christiaan J Meyer","doi":"10.1177/09576509241237840","DOIUrl":"https://doi.org/10.1177/09576509241237840","url":null,"abstract":"An axial flow fan is designed for dry cooling of a sCO<jats:sub>2</jats:sub> Brayton cycle for a CSP plant, and a scaled model of the fan is manufactured and tested experimentally in an ISO 5801:2017 Type A fan test facility. While the design procedure’s estimate of the total-to-static efficiency at the design flow rate is relatively high, at 74.4%, the experimental fan efficiency was found to be only 50.6%. This paper details an investigation into the causes of fan performance degradation, using both experimental and numerical methods. The investigation finds that the hub configuration, tip clearance size, and scale of the test fan is responsible for the reduced performance. Two alternative hub and casing configurations are identified which improve the fan’s performance 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":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140075706","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 : 2024-03-02DOI: 10.1177/09576509241236825
Lijian Shi, Yiyu Chen, Xianlei Yu, Yi Han, Yao Chai, Muzi Xue
This paper investigates the energy dissipation mechanism of the internal flow field of the full tubular pump during reverse power generation and pump conditions, utilizing CFD and model test methods to research the device’s hydraulic characteristics, internal flow field and entropy production. The results indicate that the reverse power generation and pump conditions’ performance curves have opposite trends. Under PRPG conditions, the flow uniformity and weighted average angle of the impeller inlet flow field are smaller and the inlet flow field is poor. The stator-rotor gap flow under PRPG conditions increases with the increase in total flow, the gap flow under the design flow is 2.88 L/s, and the torque is 7.35 N·m. Under the PRPG condition, the turbulent and wall entropy production ratio increases gradually with the flow increase. Under the design flow rate, the entropy production rate of the impeller is 55.07%, and the entropy production rate of the impeller is the largest among the components under different flow rates. The entropy production of the outlet channel rises significantly with the flow rate. The research results of this paper provide a theoretical basis for the distribution of energy loss in reverse power generation of the full tubular pump.
{"title":"Energy loss mechanism of a full tubular pump under reverse power generation conditions using entropy production theory","authors":"Lijian Shi, Yiyu Chen, Xianlei Yu, Yi Han, Yao Chai, Muzi Xue","doi":"10.1177/09576509241236825","DOIUrl":"https://doi.org/10.1177/09576509241236825","url":null,"abstract":"This paper investigates the energy dissipation mechanism of the internal flow field of the full tubular pump during reverse power generation and pump conditions, utilizing CFD and model test methods to research the device’s hydraulic characteristics, internal flow field and entropy production. The results indicate that the reverse power generation and pump conditions’ performance curves have opposite trends. Under PRPG conditions, the flow uniformity and weighted average angle of the impeller inlet flow field are smaller and the inlet flow field is poor. The stator-rotor gap flow under PRPG conditions increases with the increase in total flow, the gap flow under the design flow is 2.88 L/s, and the torque is 7.35 N·m. Under the PRPG condition, the turbulent and wall entropy production ratio increases gradually with the flow increase. Under the design flow rate, the entropy production rate of the impeller is 55.07%, and the entropy production rate of the impeller is the largest among the components under different flow rates. The entropy production of the outlet channel rises significantly with the flow rate. The research results of this paper provide a theoretical basis for the distribution of energy loss in reverse power generation of the full tubular pump.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"12 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140017036","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 cooling problem of hot-end components has become an important factor restricting the aero-engine performance, life and reliability. In order to improve the cooling quality of the cooling air, the supercritical aviation kerosene was used as a heat sink to cool the cooling air in a spiral heat exchanger. The flow and heat transfer process of the air-oil heat exchanger with spiral tube were numerically simulated using Fluent software. The flow and heat transfer situation of air and aviation kerosene were analyzed in detail. The optimized spiral heat exchanger with the diaphragm was presented to enhance the heat transfer capacity of the air side. It is found that the heat transfer performance of the air-oil heat exchanger is greatly enhanced by the spiral tube due to the secondary flow effect. With the increase in the turning angle of the spiral tube, the effect of the secondary flow for the heat transfer enhancement is strengthened. The PEC index of the spiral heat exchanger increases with the increase in the air flow rate. The spiral heat exchanger with the diaphragm can effectively improve the heat transfer performance of the heat exchanger, and increase the PEC index of the air side by more than 20%.
{"title":"Heat transfer characteristics of the air-oil heat exchanger with spiral tube","authors":"Zhihai Kou, Baolin Cao, Qi Zhang, Binbin Li, Guangchao Li, Xunyan Yin","doi":"10.1177/09576509241237006","DOIUrl":"https://doi.org/10.1177/09576509241237006","url":null,"abstract":"The cooling problem of hot-end components has become an important factor restricting the aero-engine performance, life and reliability. In order to improve the cooling quality of the cooling air, the supercritical aviation kerosene was used as a heat sink to cool the cooling air in a spiral heat exchanger. The flow and heat transfer process of the air-oil heat exchanger with spiral tube were numerically simulated using Fluent software. The flow and heat transfer situation of air and aviation kerosene were analyzed in detail. The optimized spiral heat exchanger with the diaphragm was presented to enhance the heat transfer capacity of the air side. It is found that the heat transfer performance of the air-oil heat exchanger is greatly enhanced by the spiral tube due to the secondary flow effect. With the increase in the turning angle of the spiral tube, the effect of the secondary flow for the heat transfer enhancement is strengthened. The PEC index of the spiral heat exchanger increases with the increase in the air flow rate. The spiral heat exchanger with the diaphragm can effectively improve the heat transfer performance of the heat exchanger, and increase the PEC index of the air side by more than 20%.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"3 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009674","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 : 2024-02-23DOI: 10.1177/09576509241235977
Zhengshuai Du, Le Cai, Yingjie Chen, Songtao Wang, Hongfei Tang, Jun Zeng
The intensity and structure of the secondary flows have significant influences on the turbine cascade losses. Combining with the extension method of Non-linear Programming by Quadratic Lagrangian (NLPQLP), two endwall parametric methods respectively based on the B-spline surface and Fourier series are used to optimize the aerodynamic losses of a turbine cascade. The optimization processes are based on Computational Fluid Dynamics (CFD) analysis and two final designs are obtained by different methods. The endwall profile generated by the B-spline surface method (EW-B1) appears to relatively reduce the total pressure loss by 16.58% and the secondary kinetic energy coefficient ( C SKE) by 27.08%, while the endwall profile generated by the Fourier series method (EW-F1) relatively reduces the loss by 16.18% but increases C SKE by 8.99%. The radial movement of upper Passage Vortex (PV) and the weakening of the pressure branch of the Horseshoe Vortex (HVps) are confirmed to be the reasons of loss reduction in EW-B1, while the movement of PV is the main reason for EW-F1 to decrease the total pressure loss. In EW-B1, the weakening of HVps has a much more significant effect on the decrease in loss, which is affected by the non-axisymmetric shapes upstream of the vortex trajectory and the drop in C SKE generation near the throat.
二次流的强度和结构对水轮机级联损失有重大影响。结合二次拉格朗日非线性编程（NLPQLP）的扩展方法，分别采用基于 B 样条曲面和傅里叶级数的两种端壁参数方法来优化涡轮机级联的气动损失。优化过程以计算流体动力学（CFD）分析为基础，并通过不同的方法获得了两种最终设计方案。用 B-样条曲面法生成的端壁轮廓（EW-B1）似乎相对减少了 16.58% 的总压力损失和 27.08% 的二次动能系数（C SKE），而用傅里叶级数法生成的端壁轮廓（EW-F1）相对减少了 16.18% 的损失，但增加了 8.99% 的 C SKE。上部通道涡（PV）的径向移动和马蹄涡（HVps）压力分支的减弱被证实是 EW-B1 损失减少的原因，而 PV 的移动是 EW-F1 减少总压力损失的主要原因。在 EW-B1 中，HVps 的减弱对损失减少的影响更为显著，这是受漩涡轨迹上游的非轴对称形状和喉部附近 C SKE 生成量下降的影响。
{"title":"Investigation of non-axisymmetric endwall contouring in a high loaded turbine stator cascade","authors":"Zhengshuai Du, Le Cai, Yingjie Chen, Songtao Wang, Hongfei Tang, Jun Zeng","doi":"10.1177/09576509241235977","DOIUrl":"https://doi.org/10.1177/09576509241235977","url":null,"abstract":"The intensity and structure of the secondary flows have significant influences on the turbine cascade losses. Combining with the extension method of Non-linear Programming by Quadratic Lagrangian (NLPQLP), two endwall parametric methods respectively based on the B-spline surface and Fourier series are used to optimize the aerodynamic losses of a turbine cascade. The optimization processes are based on Computational Fluid Dynamics (CFD) analysis and two final designs are obtained by different methods. The endwall profile generated by the B-spline surface method (EW-B1) appears to relatively reduce the total pressure loss by 16.58% and the secondary kinetic energy coefficient ( C<jats:sub> SKE</jats:sub>) by 27.08%, while the endwall profile generated by the Fourier series method (EW-F1) relatively reduces the loss by 16.18% but increases C<jats:sub> SKE</jats:sub> by 8.99%. The radial movement of upper Passage Vortex (PV) and the weakening of the pressure branch of the Horseshoe Vortex (HV<jats:sub>ps</jats:sub>) are confirmed to be the reasons of loss reduction in EW-B1, while the movement of PV is the main reason for EW-F1 to decrease the total pressure loss. In EW-B1, the weakening of HV<jats:sub>ps</jats:sub> has a much more significant effect on the decrease in loss, which is affected by the non-axisymmetric shapes upstream of the vortex trajectory and the drop in C<jats:sub> SKE</jats:sub> generation near the throat.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"2017 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139952525","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 : 2024-01-29DOI: 10.1177/09576509241227754
Dharam Singh, Vikash Kumar
An outdoor experimental investigation was conducted to explore the thermohydraulic characteristic (Nusselt no. and friction factor) of artificial roughened solar air heater (ARSAH) having frustrum shaped roughened element on absorber plate. Data were recorded and further processed to generate Nusselt number and friction factor correlation to predict the effect of flow and roughness parameter on performance of ARSAH. The investigation was conducted by varying Reynolds number in range of 2500–12,500. Dimensionless parameter for Frustrum shaped roughness was relative frustum height (e/Dh) from 0.013 to 0.054, relative frustum pitch (p/e) from 8 to 14, Relative frustum height to base diameter (e/d1) from 0.37 to 0.75, relative frustum diametral ratio (d1/d2) from 1 to 3. Maximum performance for ARSAH was obtained corresponding to the optimum value of flow and geometric parameter. The geometric orientation of the proposed roughness geometry produced tremendous rise in Nu with an acceptable rise in friction (f). Maximum enhancement in Nu for varying p/e, e/Dh, e/d1, and d1/d2 was, 4.58, 5.21, 6.62 and 6.09 times and that of friction was 5.59, 4.69, 4.92 and 4.66 times respectively over conventional SAH. Maximum Thermohydraulic performance was 3.7, 3.6, 3.9 and 3.8 at p/e = 12, e/Dh = 0.054, e/d1 = 0.75 and d1/d2 = 3.
{"title":"Thermohydraulic performance parameter based experimental investigation of frustum shaped roughened solar air heater","authors":"Dharam Singh, Vikash Kumar","doi":"10.1177/09576509241227754","DOIUrl":"https://doi.org/10.1177/09576509241227754","url":null,"abstract":"An outdoor experimental investigation was conducted to explore the thermohydraulic characteristic (Nusselt no. and friction factor) of artificial roughened solar air heater (ARSAH) having frustrum shaped roughened element on absorber plate. Data were recorded and further processed to generate Nusselt number and friction factor correlation to predict the effect of flow and roughness parameter on performance of ARSAH. The investigation was conducted by varying Reynolds number in range of 2500–12,500. Dimensionless parameter for Frustrum shaped roughness was relative frustum height (e/D<jats:sub>h</jats:sub>) from 0.013 to 0.054, relative frustum pitch (p/e) from 8 to 14, Relative frustum height to base diameter (e/d<jats:sub>1</jats:sub>) from 0.37 to 0.75, relative frustum diametral ratio (d<jats:sub>1</jats:sub>/d<jats:sub>2</jats:sub>) from 1 to 3. Maximum performance for ARSAH was obtained corresponding to the optimum value of flow and geometric parameter. The geometric orientation of the proposed roughness geometry produced tremendous rise in Nu with an acceptable rise in friction (f). Maximum enhancement in Nu for varying p/e, e/D<jats:sub>h</jats:sub>, e/d<jats:sub>1</jats:sub>, and d<jats:sub>1</jats:sub>/d<jats:sub>2</jats:sub> was, 4.58, 5.21, 6.62 and 6.09 times and that of friction was 5.59, 4.69, 4.92 and 4.66 times respectively over conventional SAH. Maximum Thermohydraulic performance was 3.7, 3.6, 3.9 and 3.8 at p/e = 12, e/D<jats:sub>h</jats:sub> = 0.054, e/d<jats:sub>1</jats:sub> = 0.75 and d<jats:sub>1</jats:sub>/d<jats:sub>2</jats:sub> = 3.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"2 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139952492","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 : 2023-12-30DOI: 10.1177/09576509231225277
S. Zare, A. Tavakolpour-Saleh, Amirhossein Hosseininia, M. H. Sangdani
This work investigates the onset and steady-state conditions of diaphragm thermoacoustic Stirling engines using the averaging-based Lyapunov technique for the first time. First, the diaphragm thermoacoustic Stirling engine is introduced. Next, the startup conditions, including the onset condition and existence of a stable limit cycle (steady-state) of the engine are studied based on the alteration of the mass connected to the diaphragm of SUTech-SR-3 in the range of 88.2 g to 121.2 g. The simulation results obtained from the averaging-based Lyapunov technique show the engine can run only in the mass range of 90.4 g to 119 g. On the other hand, to validate the simulation outcomes, this assessment is carried out experimentally. The practical results confirm the extracted outcomes from this method. Based on the allowable range acquired from this technique, the effect of the change in the value of the mass connected to the engine diaphragm on the operating frequency is investigated experimentally. This work shows that the employed method can be a helpful means to investigate the startup conditions of the diaphragm thermoacoustic Stirling engines.
{"title":"Investigating the onset and steady-state conditions of a diaphragm thermoacoustic stirling engine","authors":"S. Zare, A. Tavakolpour-Saleh, Amirhossein Hosseininia, M. H. Sangdani","doi":"10.1177/09576509231225277","DOIUrl":"https://doi.org/10.1177/09576509231225277","url":null,"abstract":"This work investigates the onset and steady-state conditions of diaphragm thermoacoustic Stirling engines using the averaging-based Lyapunov technique for the first time. First, the diaphragm thermoacoustic Stirling engine is introduced. Next, the startup conditions, including the onset condition and existence of a stable limit cycle (steady-state) of the engine are studied based on the alteration of the mass connected to the diaphragm of SUTech-SR-3 in the range of 88.2 g to 121.2 g. The simulation results obtained from the averaging-based Lyapunov technique show the engine can run only in the mass range of 90.4 g to 119 g. On the other hand, to validate the simulation outcomes, this assessment is carried out experimentally. The practical results confirm the extracted outcomes from this method. Based on the allowable range acquired from this technique, the effect of the change in the value of the mass connected to the engine diaphragm on the operating frequency is investigated experimentally. This work shows that the employed method can be a helpful means to investigate the startup conditions of the diaphragm thermoacoustic Stirling engines.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":" 2","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139139455","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 : 2023-12-18DOI: 10.1177/09576509231222670
Yuqi Wang, Weixuan Jiao, Li Cheng, Heng Zhao, Yulan Zhu, C. Luo, Libo Dou
In order to improve the operation efficiency of low-head tubular pump, this paper studies the influence of shaft type in the shaft tubular pump on the flow characteristics and energy characteristics of the pump. To optimize the shaft structure of shaft tubular pumping systems and realize the efficient use of energy, numerical simulation and model test was employed to study the optimization of the entire pumping system. In this paper, the CFD method was used to numerically simulate the whole pumping system, and the effect of changing the shaft length, shaft head profile, and shaft tail profile on the internal flow and entropy production characteristics of the inlet passage and impeller position were analyzed. It is found that the tapered tail profile can make the inlet passage overflow area change more smoothly and thus make the flow pattern more favorable. The wall entropy production dissipation at the inlet passage position dominates the total entropy production, and the high-value area of mainstream entropy production at this position is distributed periodically. The mainstream entropy production dissipation at the impeller section accounts for a relatively large proportion. After the entropy production dissipation analysis, it is believed that the tapered can reduce the entropy production dissipation of the pumping systems. The change of the shaft tail profile will make the entropy production dissipation change more noticeable compared with other optimization factors. Therefore, the tapered tail profile with better transition in the actual project is recommended.
{"title":"Optimization of low-head shaft tubular pumping systems based on entropy production theory","authors":"Yuqi Wang, Weixuan Jiao, Li Cheng, Heng Zhao, Yulan Zhu, C. Luo, Libo Dou","doi":"10.1177/09576509231222670","DOIUrl":"https://doi.org/10.1177/09576509231222670","url":null,"abstract":"In order to improve the operation efficiency of low-head tubular pump, this paper studies the influence of shaft type in the shaft tubular pump on the flow characteristics and energy characteristics of the pump. To optimize the shaft structure of shaft tubular pumping systems and realize the efficient use of energy, numerical simulation and model test was employed to study the optimization of the entire pumping system. In this paper, the CFD method was used to numerically simulate the whole pumping system, and the effect of changing the shaft length, shaft head profile, and shaft tail profile on the internal flow and entropy production characteristics of the inlet passage and impeller position were analyzed. It is found that the tapered tail profile can make the inlet passage overflow area change more smoothly and thus make the flow pattern more favorable. The wall entropy production dissipation at the inlet passage position dominates the total entropy production, and the high-value area of mainstream entropy production at this position is distributed periodically. The mainstream entropy production dissipation at the impeller section accounts for a relatively large proportion. After the entropy production dissipation analysis, it is believed that the tapered can reduce the entropy production dissipation of the pumping systems. The change of the shaft tail profile will make the entropy production dissipation change more noticeable compared with other optimization factors. Therefore, the tapered tail profile with better transition in the actual project is recommended.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":" 7","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138994699","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 : 2023-12-13DOI: 10.1177/09576509231221007
Syed J Hoque, S. Lanjewar, Pramod Kumar
Inward flow radial (IFR) supercritical CO2 (sCO2) turbines are smaller in size and operate at considerably higher speeds in comparison to similar capacity conventional gas or steam turbines. The compact size and high speed of IFR turbines result in significant parasitic (leakage and disk friction) losses at the rotor backface. This paper presents CFD investigations to understand the mechanism of parasitic losses of IFR turbines in the kW to MW power scales. The first part of the paper presents a parametric study to quantify the effect of backface flowpath dimensions, rotor inlet radius, and rotational speed on the magnitude of parasitic losses. Subsequently, the paper proposes the implementation of a radial labyrinth seal on the rotor backface to curtail the parasitic losses. The second part of the paper examines how the power scale of the turbine and its design parameters, specific speed and velocity ratio, influence the magnitude of parasitic losses. The investigation reveals that parasitic losses cause an efficiency drop of 8%–15% for 100 kW and 4%–9% for 1 MW IFR sCO2 turbines. In addition, IFR turbines designed for low specific speeds and high velocity ratios result in notably higher parasitic losses, leading to a decline in turbine efficiency. Finally, the paper presents optimal turbine design parameters accounting for the parasitic losses to maximize turbine efficiency.
{"title":"Effect of parasitic losses on the design optimization of inward flow radial supercritical CO2 turbines","authors":"Syed J Hoque, S. Lanjewar, Pramod Kumar","doi":"10.1177/09576509231221007","DOIUrl":"https://doi.org/10.1177/09576509231221007","url":null,"abstract":"Inward flow radial (IFR) supercritical CO2 (sCO2) turbines are smaller in size and operate at considerably higher speeds in comparison to similar capacity conventional gas or steam turbines. The compact size and high speed of IFR turbines result in significant parasitic (leakage and disk friction) losses at the rotor backface. This paper presents CFD investigations to understand the mechanism of parasitic losses of IFR turbines in the kW to MW power scales. The first part of the paper presents a parametric study to quantify the effect of backface flowpath dimensions, rotor inlet radius, and rotational speed on the magnitude of parasitic losses. Subsequently, the paper proposes the implementation of a radial labyrinth seal on the rotor backface to curtail the parasitic losses. The second part of the paper examines how the power scale of the turbine and its design parameters, specific speed and velocity ratio, influence the magnitude of parasitic losses. The investigation reveals that parasitic losses cause an efficiency drop of 8%–15% for 100 kW and 4%–9% for 1 MW IFR sCO2 turbines. In addition, IFR turbines designed for low specific speeds and high velocity ratios result in notably higher parasitic losses, leading to a decline in turbine efficiency. Finally, the paper presents optimal turbine design parameters accounting for the parasitic losses to maximize turbine efficiency.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"28 30","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139006794","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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