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Layout method and optimization of averaging Pitot tube in VAV terminal unit |
1.School of Energy and Power Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.Taizhou Hujiang Special Equipment Co., Ltd., Taizhou, Jiangsu 225300, China
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Abstract To improve the effectiveness of air volume control, the airflow field from the inlet to the rear duct in VAV terminal unit was numerically simulated. Combined with the velocity distribution at different cross section in the air duct, the reasonable method for the layout of the averaging Pitot tube was proposed by minimizing the mean relative error of air volume between the measured value and the theoretical value. Comparing the number and position of intersection points of the velocity distribution curves and the theoretical values on the cross section of the air duct under the conditions of air volume of 100300 m3·h-1 with different opening degrees of damper, the installation position of the averaging Pitot tube and the location of the measuring holes were determined. The results show that the optimal averaging Pitot tube is located on the section with X of 306 mm along the flow direction and with Y of 210 mm along the height direction of air duct, and the measuring hole coordinates are at Z of 116 mm, 188 mm, 264 mm and 330 mm, respectively. The measured value of the air velocity is well consistent with the theoretical value. The minimum relative error is only 2.25% at the opening degree of damper with 50%, and the maximum relative error is 9.04% at that with 30%.
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Received: 22 July 2020
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