Low-Noise HVAC Airflow Design
137 patents in this list
Updated:
HVAC systems generate noise through multiple mechanisms: turbulent airflow in ducts can exceed 45 dBA at typical flow rates, while vortex formation at sudden expansions and contractions creates additional acoustic signatures. These issues are particularly challenging in commercial buildings, where larger air volumes and higher velocities amplify both broadband and tonal components.
The fundamental challenge lies in managing airflow transitions and velocities to reduce acoustic emissions while maintaining the thermal performance and energy efficiency of the system.
This page brings together solutions from recent research—including stepped volute designs for smooth flow transitions, strategic placement of sound attenuators, optimized diffuser geometries, and innovative duct partitioning approaches. These and other techniques demonstrate practical methods for achieving quieter operation in both new installations and retrofits of existing systems.
1. Blower with Integrated Diffuser for Vertical Airflow Conversion
LG ELECTRONICS INC, 2024
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.
2. Cabinet Air Conditioner with Split Airflow Path and Offset Heat Exchanger Outlet
TCL Air Conditioner Co., Ltd., TCL AIR CONDITIONER CO LTD, 2024
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.
3. Chassis Shroud with Airflow-Aligned Channels and Acoustic Attenuation Baffles
Dell Products L.P., 2024
A codesigned shroud for a chassis with components and fans that balances airflow for cooling and attenuates acoustic energy to protect sensitive components like hard drives from fan noise. The shroud has channels aligned with the airflow directions, with baffles in a noise attenuation channel perpendicular to the flow. The baffles have absorbent material to block direct acoustic paths. This balances cooling airflow while preventing noise from fan vibrations and flow turbulence.
4. Fan and Air Conditioner with Two-Section Stepped Volute Tongue Configuration
AUX Air Conditioner Co., Ltd., AUX AIR-CONDITIONING CO LTD, 2024
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.
5. Air Passage Silencer with Tapered Opening and Porous Material for Low Frequency Attenuation
FUJIFILM CORP, 2024
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.
6. HVAC Terminal Unit with Opposing Sound Attenuator and Internal Baffles for Balanced Airflow Distribution
TYCO FIRE & SECURITY GMBH, 2024
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.
7. Air Duct System with Divided Flow Path and Vortex Suppression Mechanism
TCL Air Conditioner Co., Ltd., TCL AIR CONDITIONER CO LTD, TCL Air Conditioner (Zhongshan) Co., Ltd., 2024
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.
8. Air Conditioner Fresh Air Module with Motor-Isolating Partition and Separate Compartment
GD MIDEA AIR-CONDITIONING EQUIPMENT CO LTD, 2024
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.
9. Air Outlet Panel with Grid and Sealing Sections for Floor-Type Indoor Air Conditioners
Guangdong Midea Refrigeration Equipment Co., Ltd., GD MIDEA AIR-CONDITIONING EQUIPMENT CO LTD, 2024
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.
10. Air Port Device with Perforated Silencing Cover and Airflow Guiding Cone
Zhuhai Gree Electric Appliances Co., Ltd., GREE ELECTRIC APPLIANCES INC OF ZHUHAI, 2024
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.
11. Air Duct with Detachable Volute Covers and Extendable Tongues for Controlled Airflow Expansion
AUX Air Conditioner Co., Ltd., AUX AIR-CONDITIONING CO LTD, 2024
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.
12. Air Conditioning Duct Noise Reduction Device with Air Guide Mechanism and Sound-Absorbing Panels
XIAN LEMON TREE GREEN CONSTRUCTION TECH CO LTD, XIAN LEMON TREE GREEN CONSTRUCTION TECHNOLOGY CO LTD, 2024
Device to reduce noise from air conditioning ducts at the air outlet. The device has features to address the two main sources of noise: contact friction between the air and duct walls, and friction between the air and dust. It uses an air guide mechanism with smaller diameter tubes that the air flows through before reaching the main duct. This reduces contact friction noise. The device also has sound-absorbing panels and angled air guide plates to intercept dust particles, concentrating friction noise there instead of the duct walls. The panels have ventilation holes to allow smooth airflow. By breaking up the duct into smaller ventilation areas with staggered features, noise reduction is improved.
13. Fan Fairing with Sequential Opposite Arc-Shaped Curved Sections for Noise Reduction
SUNGROW POWER SUPPLY CO LTD, 2024
Fan fairing, fan assembly, and air duct system to improve noise reduction of cooling fans. The fan fairing has an extension direction and is made of a cover body with arc-shaped curved sections connected in sequence. The sections bend in opposite directions. This rectifier shape guides airflow passing through the fairing. The opposite bending directions prevent eddy currents and turbulence compared to same-direction bends. The fairing can be used on fans, air ducts, and equipment to reduce fan noise.
14. Ventilation Duct with Noise-Reducing Deflector and Integrated Sound-Absorbing Components
CHINA ENERGY ENGINEERING GROUP TIANJIN ELECTRIC POWER DESIGN INST CO LTD, CHINA ENERGY ENGINEERING GROUP TIANJIN ELECTRIC POWER DESIGN INSTITUTE CO LTD, TIANJIN JINDIAN POWER SUPPLY DESIGN INST CO LTD, 2024
An air conditioning ventilation duct with good noise reduction for HVAC systems. The duct has an auxiliary pipe with a fan, filter plates, spiral duct, and noise-reducing deflector to capture and disperse airborne particles. The deflector and fan reduce noise by scattering and slowing airflow. The duct also has exhaust ducts with sound-absorbing cotton boards. The duct attaches to the main duct and has an outlet with a silencer plate.
15. Air Pipe with Golf Ball-Inspired Conical Air Guides and Integrated Flow Stabilization Components
HUNAN DACHUAN NEW BUILDING MAT CO LTD, HUNAN DACHUAN NEW BUILDING MATERIAL CO LTD, 2024
A multifunctional air pipe for reducing noise and wind resistance in applications like ductwork, that uses a golf ball-inspired design. The pipe has features like an adjustable scraping strip, conical air guides, a collecting box, a sprayer, and an interception system. These components inside the pipe clean impurities, stabilize flow, and capture debris to reduce noise and wind resistance compared to conventional ducts. The golf ball-shaped rear cones of the conical air guides further disturb the flow for noise reduction.
16. Duct Noise Suppression System Utilizing Closed Resonant Membranes with Higher Order Vibration Modes
FUJIFILM CORP, 2024
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.
17. Air Conditioner Outdoor Unit with Vent-Directed Airflow and Noise-Reducing Fin Configuration
MITSUBISHI ELECTRIC CORP, 2024
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.
18. Flow Duct Resonators with Tensioned Acoustically Resistive Screens for Noise Attenuation
DYSON TECHNOLOGY LTD, 2023
Reducing noise in air flow devices like compressors by using resonators in the flow ducts. The method involves forming holes in the duct wall, covering them with tensioned acoustically resistive screens that are fluid-contacted with the duct air and cavity gas. This creates noise-suppressing resonators that attenuate sound in specific frequency bands. The acoustic properties of the screens are optimized based on the duct geometry to maximize noise reduction.
19. Ceiling Air Conditioner with Noise-Reducing Internal Airflow Configuration Featuring Condensate Collection, Through-Flow Wind Wheel, and Wind Shielding Components
Guangdong Midea Refrigeration Equipment Co., Ltd., Midea Group Co., Ltd., GD MIDEA AIR-CONDITIONING EQUIPMENT CO LTD, 2023
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
20. Indoor Air Conditioner Unit with Fan Diameter to Duct Outlet Dimensional Ratios
Zhuhai Lingda Compressor Co., Ltd., Zhuhai Kaibang Motor Manufacturing Co., Ltd., ZHUHAI LAMDA COMPRESSORS CO LTD, 2023
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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