By means of numerical simulation and experimental verification, this article investigates the hyd... more By means of numerical simulation and experimental verification, this article investigates the hydraulic performance and pressure fluctuation of a tank-style axial-flow pump device. With orthogonal test, 16 schemes are designed concerning the different flow conditions of the inlet and outlet passages, and simulated calculations are done; then the non-steady numerical simulation of pressure fluctuation is carried out for the optimized pump device; a model test finally verifies the reliability of the simulated numerical values of the optimized scheme. The results show that using the orthogonal test, an optimized scheme of the inlet and outlet passages can be obtained; compared with the initial scheme, the optimized one reduces the hydraulic loss by 1.3 cm in the inlet passage and 7.96 cm in the outlet passage; numerical simulation witnesses the highest pump operating efficiency of 70.04%, efficiency of 66.82% with the design head of 1.36 m, and the corresponding flow of 34.31 m 3 /s; the model test verifies all the simulated values of the optimized scheme with the highest pump operating efficiency reaching 71.5% and the test efficiency arriving at about 64% when the design head is 1.36 m. Meanwhile, the highest pressure fluctuation appears at the entrance of the impeller; the main frequency of the impeller and guide vane pressure fluctuation is 5 Hz depending on the frequency of the blade. This study offers reference for similar pump station project.
U-value estimation is crucial for energy diagnosis of existing buildings.Heat flux meter method a... more U-value estimation is crucial for energy diagnosis of existing buildings.Heat flux meter method allows in situ measurements of actual U-value.In situ measurements of U-value can be affected by some relevant metrological issues.Uncertainties of in situ measurements of U-value depend on operative conditions.Energy audits and check of energy performances are more and more urgent for achieving energy saving in existing buildings. In this context, it is very important to estimate U-value of buildings and, to this aim, different approaches are available. U-value is mainly estimated from the knowledge of thermal properties of the single layers of the wall using design data or analogies with similar buildings. To get a more accurate estimation, field analyses should be made like endoscopic investigation or logs. Nowadays, also in situ measurement of U-value using heat flow meters are available. Such measurements involve quite simple operational and calculation issues but, on the other hand, the disadvantage of long duration times and not negligible measurement uncertainties. In this paper, the authors present the results of an experimental campaign aimed both to assess the metrological performance of HFMs and to evaluate the influence of the ambient conditions. Furthermore, in situ U-values have been compared with the estimated ones from design data and field analyses. The results of the test show a good behavior of HFMs when tests are conducted according to ISO 9869. Nevertheless, operative measurement conditions and characteristics of the envelope component under investigation can strongly affect in situ U-value accuracy.
By means of numerical simulation and experimental verification, this article investigates the hyd... more By means of numerical simulation and experimental verification, this article investigates the hydraulic performance and pressure fluctuation of a tank-style axial-flow pump device. With orthogonal test, 16 schemes are designed concerning the different flow conditions of the inlet and outlet passages, and simulated calculations are done; then the non-steady numerical simulation of pressure fluctuation is carried out for the optimized pump device; a model test finally verifies the reliability of the simulated numerical values of the optimized scheme. The results show that using the orthogonal test, an optimized scheme of the inlet and outlet passages can be obtained; compared with the initial scheme, the optimized one reduces the hydraulic loss by 1.3 cm in the inlet passage and 7.96 cm in the outlet passage; numerical simulation witnesses the highest pump operating efficiency of 70.04%, efficiency of 66.82% with the design head of 1.36 m, and the corresponding flow of 34.31 m 3 /s; the model test verifies all the simulated values of the optimized scheme with the highest pump operating efficiency reaching 71.5% and the test efficiency arriving at about 64% when the design head is 1.36 m. Meanwhile, the highest pressure fluctuation appears at the entrance of the impeller; the main frequency of the impeller and guide vane pressure fluctuation is 5 Hz depending on the frequency of the blade. This study offers reference for similar pump station project.
U-value estimation is crucial for energy diagnosis of existing buildings.Heat flux meter method a... more U-value estimation is crucial for energy diagnosis of existing buildings.Heat flux meter method allows in situ measurements of actual U-value.In situ measurements of U-value can be affected by some relevant metrological issues.Uncertainties of in situ measurements of U-value depend on operative conditions.Energy audits and check of energy performances are more and more urgent for achieving energy saving in existing buildings. In this context, it is very important to estimate U-value of buildings and, to this aim, different approaches are available. U-value is mainly estimated from the knowledge of thermal properties of the single layers of the wall using design data or analogies with similar buildings. To get a more accurate estimation, field analyses should be made like endoscopic investigation or logs. Nowadays, also in situ measurement of U-value using heat flow meters are available. Such measurements involve quite simple operational and calculation issues but, on the other hand, the disadvantage of long duration times and not negligible measurement uncertainties. In this paper, the authors present the results of an experimental campaign aimed both to assess the metrological performance of HFMs and to evaluate the influence of the ambient conditions. Furthermore, in situ U-values have been compared with the estimated ones from design data and field analyses. The results of the test show a good behavior of HFMs when tests are conducted according to ISO 9869. Nevertheless, operative measurement conditions and characteristics of the envelope component under investigation can strongly affect in situ U-value accuracy.
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Papers by Fabio Iannetta