Airflow Design Techniques for Noise Reduction in HVAC Systems

Blower design with a diffuser to convert the direction of airflow discharged by the fan into ascending airflow. This allows the blower to efficiently move air vertically without needing a separate upward fan or ducting. The diffuser extends vertically from the fan outlet and guides the air upward. It reduces noise and flow separation compared to conventional rising airflow generators. The diffuser shape and angles are optimized to balance noise reduction and efficiency.

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Cabinet air conditioner design that reduces noise by buffering the airflow out of the heat exchanger before it enters the ducts. The air conditioner has a shell with an air inlet in the rear and an air outlet in the front. The airflow path is split into two sections. The heat exchanger is between the cross-flow fan and rear shell. The air outlet of the heat exchanger is not opposite the air inlet of the through-flow duct. This causes the air to turn or shift as it leaves the heat exchanger before entering the ducts. This buffering reduces the peak air speeds and noise at the outlet.

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A fan and air conditioner design with improved airflow and reduced noise compared to conventional designs. The fan has a two-section volute tongue that steps in height. The first section extends along the air duct opening and the second section extends from the end of the first section. This smooths the airflow transition and reduces vortex formation compared to a single tongue. The air conditioner has a matching stepped volute tongue in the duct cover and seat. This joint configuration improves airflow in the duct and reduces noise compared to conventional ducts.

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Air passage silencer with improved low frequency attenuation and reduced wind noise compared to conventional expansion type silencers. The silencer has a tapered opening structure at the expansion to outlet connection, surrounded by a rear space. A porous material is added in the rear space opening to absorb sound. This provides resonance in the tapered space for low frequency attenuation, without backflow turbulence. The tapered opening reduces wind noise compared to a sudden expansion. The expansion size, tapered shape, and rear space dimensions are optimized for performance.

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Heating, ventilation, and air conditioning (HVAC) terminal unit with improved airflow distribution and noise reduction compared to traditional units. The terminal unit has a sound attenuator positioned opposite the air inlets that directs return airflow into the unit. This balances the airflow distribution to the blowers and reduces noise compared to uneven airflow. The attenuator has an inlet facing the return air inlet and outlet into the unit. Baffles inside the unit further direct the airflow. This balanced airflow reduces blower speeds, pressure losses, and noise compared to uneven flow.

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Air conditioner design with reduced noise by preventing vortex formation in the air ducts. The ducts are split using a dividing piece near the impeller inlet. This divides the airflow entering the impeller into two streams, one from each duct half. The stream entering from the second duct half passes through an angle formed by the duct shape, preventing vortex formation. This prevents pressure pulsations and noise caused by vortex interaction in the ducts.

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Fresh air module for air conditioners that reduces noise compared to conventional modules. The module has a housing with an inlet and outlet, a fan assembly with a motor and wind wheel, and a partition between the motor and fresh air duct. The motor is outside the duct in a separate compartment. This isolates the motor noise from the airflow, preventing amplification and reducing overall noise.

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Air outlet panel for floor type indoor air conditioners that improves airflow efficiency and reduces noise compared to conventional designs. The panel has a strip-shaped plate with a grid section for high airflow and a weaker air outlet section. Sealing strips around these sections weaken flow to adjacent areas, directing more air through the intended outlet. This prevents unnecessary flow losses and noise. The sealing strips also have fillers and brushes to further regulate airflow. The panel can switch between the grid and weaker outlet sections for different applications.

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Air port device and air conditioning unit with reduced noise. The air port device has a silencing cover inside the air duct between the inlet and outlet. The cover has holes for airflow and disperses it to reduce turbulence. It also has a cone to guide air uniformly. This reduces noise by scattering and refracting sound, lowering flow velocity, and absorbing noise with cotton.

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Air duct design for air conditioners that reduces vortex wind phenomenon, noise, and improves user experience compared to conventional spiral case air ducts. The duct has detachable volute covers and seats that form extendable tongues to gradually expand airflow from the inner duct to the outer duct. This reduces vortices and noise compared to sudden expansion in conventional ducts. The outer tongue extends further than the inner tongue and the outer duct opening is smaller. The tongues' lengths and angles are balanced to further reduce noise.

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Muffling noise in ducts using resonating membranes without openings to prevent wind noise. The membranes are integrated into the duct walls and vibrate in response to sound. They form closed resonant spaces that suppress duct end noise when excited by nearby sources. The membranes are designed to have higher order vibration modes for better absorption. The membrane positions are optimized for interference cancellation. This allows muffling specific frequencies without amplifying others. It avoids the drawbacks of open resonators like Helmholtz resonators that generate wind noise.

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Outdoor unit for an air conditioner that reduces noise generated by air entering the unit. The unit has fins on the heat exchanger, a vent in the casing wall facing the fins, and an air inlet. The vent allows straight airflow between the fins while the inlet has higher resistance. This prevents air from entering gaps between the fins and casing, reducing turbulence and vortices that could cause noise. The vent interrupts any inlet airflow in that direction.

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Reducing noise of a ceiling air conditioner by improving the internal airflow path. The ceiling air conditioner has a unique configuration that reduces noise compared to conventional centrifugal air conditioners. The improvements include: 1. A heat exchanger with a water pan below it to collect condensate. This prevents water dripping from the heat exchanger and reduces noise from dripping. 2. A through-flow wind wheel that generates negative pressure in the airflow path. This prevents dead angles and vortex formation in the airflow passage, which can cause noise. 3. A wind shielding part around the wind wheel that covers the airflow entry and exit points. This prevents air leakage and improves airflow efficiency. By combining these features, the ceiling air conditioner reduces noise compared to conventional centrifugal air conditioners. The water collection, airflow path improvements, and wind wheel en

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Indoor unit for air conditioners that improves airflow performance and reduces noise. The indoor unit has a duct with opposing walls and a fan inside. The fan diameter, duct outlet length, and width have specific relationships. This limits fan size based on outlet dimensions. It allows optimizing fan size for duct dimensions to improve airflow and reduce noise compared to arbitrary fan sizes. The relationships are: d = a*L2 - b*L2 = 2 - c (fan diameter vs outlet length) and d = a1 - e*a1^3 + f = 2 + g (fan diameter vs outlet width) with a=2.85-2.95, b=1.51e-3-1.61e-3, c=1241.3-1261.3, e=6.05-6.

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Air conditioner indoor unit and air conditioner with reduced noise at low airflow rates. The indoor unit has a volute with a pivoting section that can rotate to decrease the width of the airflow duct. This forces removal of the return flow area and prevents airflow discontinuities and drafts at low speeds. The pivoting duct section reduces noise by eliminating turbulent areas and airflow separation at low flow rates.

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Reducing fan noise in HVAC systems by using an acoustic shroud around the fan blades. The shroud has an inner wall inside the outer wall. An acoustic damping material is sandwiched between the walls. The inner wall is permeable to air flow. The shroud encircles the fan blades to attenuate noise as the fan spins. The inner wall allows air to pass through while the damping material absorbs vibrations and sound.

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Air conditioner with variable air discharge methods to optimize cooling and reduce noise. The air conditioner has a movable discharge blade that can close the outlet or guide the air flow. When closed, the blade has holes for discharging air. This allows adjusting the air speed and direction coming out of the unit. When open, the blade guides the air out the fixed outlet. This lets the user choose between slow, radiant cooling with minimal wind or fast, convective cooling with higher wind. The blade movement also helps control airflow when the blower fan is running.

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Air conditioner indoor unit with a mechanism to sweep the air outlet without blocking it when not needed. The unit has a wind sweeping mechanism at the air outlet with a blade that can move between positions facing and away from the outlet. When air sweeping is needed, the blade faces the outlet. When not needed, the blade folds back against the unit to avoid obstructing the airflow. This improves air quantity and reduces noise compared to fixed blade designs.

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Air duct assembly for mobile air conditioners that reduces noise compared to conventional designs. The duct has a spiral case with a wind wheel that rotates inside. The spiral case has two lateral walls forming the air outlet. The wind wheel extends into the outlet and creates a gap between the walls. The length of the outlet is 1.5-2 times the gap. This configuration allows the wheel to move freely without rubbing the walls, reducing noise.

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Air duct assembly for air conditioners that reduces noise while maintaining airflow. The assembly has a spiral case with a wind wheel inside that rotates. The wind wheel extends through an air outlet formed by adjacent lateral walls. The distance between the walls is in a range that balances airflow and noise. The contained angle between the walls is also optimized. This configuration allows efficient airflow without excessive noise.

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