Radiation noise control of a 90° rectangular elbow in ventilation and air conditioning systems

Zhang, Chi; Li, Angui; Li, Jiaxing; Hou, Yicun; Chen, Xing

doi:10.1016/j.jobe.2021.102157

Cited by 9 publications

(4 citation statements)

References 40 publications

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“…A variety of parts make up ducting construction, which supports channel function based on field requirements. These include valves [1], guide vanes [2,3], 90° elbows [4,5], and so on. These components also have different functions.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of turbulent flow through a square-sectioned duct and 90ᵒ square elbow by using circular turbulator

Putra,

Sutardi,

Widodo

et al. 2024

Eureka: PE

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The ducting system is made up of 90° elbows and a few other fittings and accessories in addition to straight ducts. The friction loss, separation loss, and secondary flow loss are the main causes of the pressure decrease in an elbow, and they all increase with the presence of elbows. Utilizing too much energy to propel the flow is a cost associated with pressure loss. The aim of this research is to investigate turbulent flow via 90° square elbows and a square-sectioned duct through experimental methods by adding a circular turbulator (CT) close to the elbow wall's inner radius. The Reynolds numbers (ReDh) used in this research are 1.6×104, 4.8×104, and 9.5×104, with average flow velocities of 2 m/s, 6 m/s, and 12 m/s. Circular turbulators are added to the inner walls with angular positions (α) of 5°, 10°, 15°, and 20°. The results showed that the turbulence intensity increased toward the inner radius wall of the elbow in ducting with CT. For this study, the flow within the ducting with the CT is generally more turbulent than the flow inside the ducting without the CT. By including CT, it was possible to reduce the overall pressure loss in ducting with an elbow. The pressure reduction at two ReDh values (1.6×104 and 4.8×104) was only lessened by CT positioned at α=10°, 15°, and 20° out of the four CT placements. Conversely, CT positioned at α=5° can only effectively mitigate pressure decrease at ReDh=1.6×104. CT installation cannot lessen the pressure drop that happens in the ducting at a value of ReDh=9.5×104. CT placement at the three α values often helps to lower the pressure drop in the ducting. Using the CT, positioned at α=15°, is the greatest strategy to reduce the overall pressure decrease

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Section: Introductionmentioning

confidence: 99%

Experimental investigation of turbulent flow through a square-sectioned duct and 90ᵒ square elbow by using circular turbulator

Putra,

Sutardi,

Widodo

et al. 2024

Eureka: PE

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“…10 As the most common air-to-air system, the air conditioning system is mature and widely used, while it is not satisfactory in terms of thermal comfort. Zhang et al 11 proposed a new technology to reduce the noise of the air conditioning system. The maximum total sound pressure level was reduced by about 5 dB, but the noise problem still cannot be completely solved.…”

Section: Introductionmentioning

confidence: 99%

Investigation of thermal comfort performance and optimization of a novel refrigerant-heated radiator

Zhang

Tao

Jiang

et al. 2022

Indoor and Built Environment

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In this study, a novel refrigerant-heated radiator (RHR) was introduced and a computational fluid dynamics (CFD) model was developed to investigate the influence of RHR structure parameters on indoor thermal comfort under heating and cooling conditions. Results show that the heating capacity and thermal comfort are improved with the increase of length-to-height ratio, while the thermal comfort is infringed if the length-to-height ratio is too large in cooling conditions. The length-to-height ratio of the RHR with 2.22–3.71 is recommended to meet the thermal comfort requirements in heating and cooling conditions. Comparisons were made between the RHR and air conditioner on indoor thermal comfort, which indicates that the RHR has a better thermal comfort in heating conditions in terms of temperature field, velocity field and thermal comfort indices. Under cooling conditions, the air conditioner has lower temperature distribution and more uniform vertical temperature distribution in human activity area, while the RHR has the excellent performance in the velocity distribution and thermal comfort indices. The findings show RHR has a better thermal performance than air conditioners in terms of overall thermal comfort. The research provides a guide to the benefit of RHR and improves the thermal comfort of ASHP system.

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“…The main principle is that the vortex generated by the airflow passing through the elbow is divided by the wall of the guide vane, and the large eddy current is decomposed into a small eddy current, thus reducing the fluid resistance in the local components. 10,11 Nowadays, many studies have been carried out on applying diversion vanes into duct elbow. Haskew studied the resistance reduction effect of the guide vane on the 80°elbow of a circular duct, and the results showed that the guide vane could effectively reduce the radial pressure gradient, thus reducing the intensity of the vortex.…”

Section: Introductionmentioning

confidence: 99%

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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Radiation noise control of a 90° rectangular elbow in ventilation and air conditioning systems

Cited by 9 publications

References 40 publications

Experimental investigation of turbulent flow through a square-sectioned duct and 90ᵒ square elbow by using circular turbulator

Experimental investigation of turbulent flow through a square-sectioned duct and 90ᵒ square elbow by using circular turbulator

Investigation of thermal comfort performance and optimization of a novel refrigerant-heated radiator

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

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