A low-resistance elbow with a bionic sawtooth guide vane in ventilation and air conditioning systems

Zhang, Chi; Li, Angui; Che, Jigang; Li, Yue; Liu, Qi; Zhao, Yuhang

doi:10.1007/s12273-021-0782-y

Cited by 19 publications

(9 citation statements)

References 27 publications

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“…In order to reduce the flow resistance of an elbow, Ziganshin et al [3] provided a novel geometry with a profiled internal wall, which also significantly shortened the influence zone of the element. Yin et al [4] and Zhang et al [5] both investigated the effect of guide vanes mounted in an elbow: the former paper reports a computational fluid dynamics (CFD) based optimization process of the geometry and location of the guide vanes, using field synergy and viscous dissipation principles, while the latter one investigates the loss reducing capabilities of a guide vane with a sawlike trailing edge, designed using biomimetic principles, inspired by the wings of bats and the fins of humpback whales. As for T-junctions, biomimicry has as well been taken advantage of by Gao et al [6] to propose a novel shape -resembling tree junctions -with decreased losses.…”

Section: Introductionmentioning

confidence: 99%

Parameter Study of a Loss Reducing Passive Flow Control Method in a Square-to-square Sudden Expansion

Lukács,

Vad

2023

Period. Polytech. Mech. Eng.

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The energy consumption of mechanical ventilation in buildings needs to be reduced. An efficient way to achieve this goal is to reduce the hydraulic resistance of the ventilation duct system elements, for example, that of sudden expansions. Ventilation ducts and pipe fittings are frequently of rectangular cross-section. The present paper investigates a passive flow control method in order to reduce the loss coefficient of a square-to-square sudden expansion, where the loss-reducing appendages are short guide vanes, termed as miniflaps, placed at the step edge of the sudden expansion. The turbulent flow is examined numerically using the generalized k-ω model of the Ansys Fluent software for different area ratios of the sudden expansion, miniflap lengths, and miniflap angle setups. The Reynolds number is kept constant at 1.08·105. Based on the results of the numerical simulations, the loss coefficient of the sudden expansion can be reduced by ~20–25% for an optimum miniflap angle between 9° and 12°. Increasing the length of the miniflaps leads to a greater reduction of the loss coefficient up to a miniflap length of 0.3 dh1, where dh1 is the upstream hydraulic diameter of the duct.

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Section: Introductionmentioning

confidence: 99%

Parameter Study of a Loss Reducing Passive Flow Control Method in a Square-to-square Sudden Expansion

Lukács,

Vad

2023

Period. Polytech. Mech. Eng.

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“…However, the flowrate of clean air required for the airborne infection risk control can be generally higher than the capacity of existing ventilation systems since the existing ventilation systems are designed for the non-pandemic condition (Guo et al 2021;Nardecchia et al 2022;Zhang et al 2022e). For the non-pandemic condition, the required clean air from the outdoor is generally around 10 L/s per person (ASHRAE 2010).…”

Section: Introductionmentioning

confidence: 99%

Occupancy-aided ventilation for airborne infection risk control: Continuously or intermittently reduced occupancies?

2022

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Ventilation is an important engineering measure to control the airborne infection risk of acute respiratory diseases, e.g., Corona Virus Disease 2019 (COVID-19). Occupancy-aided ventilation methods can effectively improve the airborne infection risk control performance with a sacrifice of decreasing working productivity because of the reduced occupancy. This study evaluates the effectiveness of two occupancy-aided ventilation methods, i.e., the continuously reduced occupancy method and the intermittently reduced occupancy method. The continuously reduced occupancy method is determined by the steady equation of the mass conservation law of the indoor contaminant, and the intermittently reduced occupancy method is determined by a genetic algorithm-based optimization. A two-scenarios-based evaluation framework is developed, i.e., one with targeted airborne infection risk control performance (indicated by the mean rebreathed fraction) and the other with targeted working productivity (indicated by the accumulated occupancy). The results show that the improvement in the airborne infection risk control performance linearly and quadratically increases with the reduction in the working productivity for the continuously reduced occupancy method and the intermittently reduced occupancy method respectively. At a given targeted airborne infection risk control performance, the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the working productivity by up to 92%. At a given targeted working productivity, the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the airborne infection risk control performance by up to 38%.

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“…The maximum resistance of the new design could be reduced by about 9% compared with regular guide vanes. 21 In the industrial standard "Technical Specification for Ventilation Ducts" JGJ141-2017, the position and number of guide vanes are recommended for rectangular duct elbows whose internal and external bends are curved as commonly used in engineering application. Ito et al studied the influence of the position of the guide vane on the elbow resistance by experimental means, and the results showed that the best position of the guide vane was not necessarily in the center of the elbow.…”

Section: Introductionmentioning

confidence: 99%

“…The maximum resistance of the new design could be reduced by about 9% compared with regular guide vanes. 21…”

Section: Introductionmentioning

confidence: 99%

Simulation and experimental study on the elbow pressure loss of large air duct with different internal guide vanes

Wang

Tang³

et al. 2022

Building Services Engineering Research and Technology

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Air duct pressure loss, especially the duct elbow, is a significant component of building air-conditioning energy consumption. Improving the airflow uniformity in the duct elbow for large prefabricated air ducts can help reduce the local resistance loss. In this paper, the influence of guide vanes on the pressure loss of elbows in the duct was investigated through experimentally validated simulation results. According to similarity theory, the computational fluid dynamics (CFD) simulation results were employed to perform a parametric study to optimize the duct elbow guide vane. Different numbers, positions, and shapes of air guide vanes in the elbow were used to reduce the pressure loss and also played a crucial role in improving the uniformity of airflow in the elbow. Through CFD simulation, the optimized specifications of guide vanes in the elbow on the airflow and local pressure loss coefficients were explored. This study will provide a reference for numerical prediction and engineering application of using guide vane to minimize the local pressure loss of large prefabricated air ducts.

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A low-resistance elbow with a bionic sawtooth guide vane in ventilation and air conditioning systems

Cited by 19 publications

References 27 publications

Parameter Study of a Loss Reducing Passive Flow Control Method in a Square-to-square Sudden Expansion

Parameter Study of a Loss Reducing Passive Flow Control Method in a Square-to-square Sudden Expansion

Occupancy-aided ventilation for airborne infection risk control: Continuously or intermittently reduced occupancies?

Simulation and experimental study on the elbow pressure loss of large air duct with different internal guide vanes

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