In the beach well intake system, heat is transferred from soil to fluid when seawater is filtered through the aquifer, providing higher temperature source water to the seawater source heat pump (SWHP) system in winter...In the beach well intake system, heat is transferred from soil to fluid when seawater is filtered through the aquifer, providing higher temperature source water to the seawater source heat pump (SWHP) system in winter. A 3-D coupled seepage and heat transfer model for studying beach well intake system is established by adopting the computer code FLUENT. Numerical results of this model are compared with the experimental results under the same conditions. Based on the experiment-verified coupled model, numerical simulation of the supply water tem-perature is studied over a heating season. Results show that the minimum temperature of supply water is 275.2 K when this intake system continuously provides seawater with flow rate of 35 m3/h to SWHP. Results also indicate that the supply water temperature is higher than seawater, and that the minimum temperature of supply water lags behind seawater, ensuring effective and reliable operation of SWHP.展开更多
A series of experiments on the dynamic performance of the HPWH （heat pump water heater） unit with EXV （electronic expansion valve） under different environmental conditions were conducted. The dynamic heating capac...A series of experiments on the dynamic performance of the HPWH （heat pump water heater） unit with EXV （electronic expansion valve） under different environmental conditions were conducted. The dynamic heating capacity and COP （coefficient of performance） of the HPWH unit under different EXV openings were measured. The effects of the EXV opening on the performance of the HPWH unit were analyzed. Meanwhile, the dynamic performance of the HPWH with EXV was simulated and the results were compared with the experimental one. The experimental results indicate that during heating process, the COP increases firstly and then decreases for a fixed EXV opening, which is in good agreement with the numerical result. For different EXV openings, the COP and heating capacity of the system using larger EXV opening are superior to those using the smaller one in the initial heating stage. While in the late stage, the performance of system using smaller EXV opening is better. It is found that the system performance is improved significantly by changing the EXV opening in the different heating period and the average COP of the HPWH system is increased by 7.6%.展开更多
The performance of a reversible pump turbine with S-shaped characteristics is of great importance to the transition processes such as start-up and load rejection. In order to predict the S-shaped curve accurately and ...The performance of a reversible pump turbine with S-shaped characteristics is of great importance to the transition processes such as start-up and load rejection. In order to predict the S-shaped curve accurately and develop a reliable tool for design improvement, a shear stress transport model (SST) with various numerical schemes for pressure term in the governing equation was investigated in a whole pump turbine including spiral casing, stay vanes, guide vanes, runner and draft tube. Through the computation, it was shown that different zones in the curve should employ different schemes to get the solution converged. Comparison of discharge-speed performance showed that good correspondence is got between experimental data and CFD results. Based on this, internal flow analysis was carried out at three typical operating points representing turbine mode, shut-off mode and reversible pump mode, respectively. According to the flow field concerned, the mechanism for the speed-no-load instability was explained, which provides good guidelines to take countermeasures in future design.展开更多
Mini turbo-pumps having a diameter smaller than 100mm are employed in many fields;automobile radiator pump,ventricular assist pump,cooling pump for electric devices,washing machine pump and so on.Further,the needs for...Mini turbo-pumps having a diameter smaller than 100mm are employed in many fields;automobile radiator pump,ventricular assist pump,cooling pump for electric devices,washing machine pump and so on.Further,the needs for mini turbo-pumps would become larger with the increase of the application of it for electrical machines.It is desirable that the mini turbo-pump design is as simple as possible due to restriction to make precise manufactures.But the design method for the mini turbo-pump is not established because the internal flow condition for these small-sized fluid machineries is not clarified and conventional theory is not conductive for small-sized pumps.Three types of rotors with different outlet angles are prepared for an experiment and a numerical analysis.The performance tests are conducted with these rotors in order to investigate the effect of the blade outlet angle on performance and internal flow condition of mini turbo-pumps.It is clarified from the experimental results that head of the mini turbo-pump increases and maximum efficiency flow rate shifts to larger flow rate according to the increase of the blade outlet angle,however the maximum efficiency decreases with the increase of it.In the present paper,the performance of the mini turbo-pump is shown and the internal flow conditions are clarified with the results of the experiment and the numerical flow analysis.Furthermore,the effects of the blade outlet angle on the performance are investigated and high performance design with simple structure for the mini turbo-pump would be considered.展开更多
基金Supported by Tianjin Construction Committee Technology Project (No2007-37)
文摘In the beach well intake system, heat is transferred from soil to fluid when seawater is filtered through the aquifer, providing higher temperature source water to the seawater source heat pump (SWHP) system in winter. A 3-D coupled seepage and heat transfer model for studying beach well intake system is established by adopting the computer code FLUENT. Numerical results of this model are compared with the experimental results under the same conditions. Based on the experiment-verified coupled model, numerical simulation of the supply water tem-perature is studied over a heating season. Results show that the minimum temperature of supply water is 275.2 K when this intake system continuously provides seawater with flow rate of 35 m3/h to SWHP. Results also indicate that the supply water temperature is higher than seawater, and that the minimum temperature of supply water lags behind seawater, ensuring effective and reliable operation of SWHP.
文摘A series of experiments on the dynamic performance of the HPWH （heat pump water heater） unit with EXV （electronic expansion valve） under different environmental conditions were conducted. The dynamic heating capacity and COP （coefficient of performance） of the HPWH unit under different EXV openings were measured. The effects of the EXV opening on the performance of the HPWH unit were analyzed. Meanwhile, the dynamic performance of the HPWH with EXV was simulated and the results were compared with the experimental one. The experimental results indicate that during heating process, the COP increases firstly and then decreases for a fixed EXV opening, which is in good agreement with the numerical result. For different EXV openings, the COP and heating capacity of the system using larger EXV opening are superior to those using the smaller one in the initial heating stage. While in the late stage, the performance of system using smaller EXV opening is better. It is found that the system performance is improved significantly by changing the EXV opening in the different heating period and the average COP of the HPWH system is increased by 7.6%.
基金supported by the National Natural Science Foundation of China (Grant No. 50979095)
文摘The performance of a reversible pump turbine with S-shaped characteristics is of great importance to the transition processes such as start-up and load rejection. In order to predict the S-shaped curve accurately and develop a reliable tool for design improvement, a shear stress transport model (SST) with various numerical schemes for pressure term in the governing equation was investigated in a whole pump turbine including spiral casing, stay vanes, guide vanes, runner and draft tube. Through the computation, it was shown that different zones in the curve should employ different schemes to get the solution converged. Comparison of discharge-speed performance showed that good correspondence is got between experimental data and CFD results. Based on this, internal flow analysis was carried out at three typical operating points representing turbine mode, shut-off mode and reversible pump mode, respectively. According to the flow field concerned, the mechanism for the speed-no-load instability was explained, which provides good guidelines to take countermeasures in future design.
文摘Mini turbo-pumps having a diameter smaller than 100mm are employed in many fields;automobile radiator pump,ventricular assist pump,cooling pump for electric devices,washing machine pump and so on.Further,the needs for mini turbo-pumps would become larger with the increase of the application of it for electrical machines.It is desirable that the mini turbo-pump design is as simple as possible due to restriction to make precise manufactures.But the design method for the mini turbo-pump is not established because the internal flow condition for these small-sized fluid machineries is not clarified and conventional theory is not conductive for small-sized pumps.Three types of rotors with different outlet angles are prepared for an experiment and a numerical analysis.The performance tests are conducted with these rotors in order to investigate the effect of the blade outlet angle on performance and internal flow condition of mini turbo-pumps.It is clarified from the experimental results that head of the mini turbo-pump increases and maximum efficiency flow rate shifts to larger flow rate according to the increase of the blade outlet angle,however the maximum efficiency decreases with the increase of it.In the present paper,the performance of the mini turbo-pump is shown and the internal flow conditions are clarified with the results of the experiment and the numerical flow analysis.Furthermore,the effects of the blade outlet angle on the performance are investigated and high performance design with simple structure for the mini turbo-pump would be considered.
