Discharge Muffler with Segmented Inner Duct for Compressor Noise
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Solution Overview
Problem
High-speed screw compressors in air conditioning and refrigeration systems generate higher noise levels compared to their standard speed equivalents, posing a challenge for efficient and quiet operation.
Innovation Solution
A noise reduction muffler design featuring an inner duct with strategically positioned holes and an offset outer duct, optimized to reflect acoustic waves across a wide range of frequencies, providing a chamber with a larger diameter around the inner duct to achieve effective noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor operates at higher speed to improve productivity, then the cooling capacity increases, but the noise level increases
Solution Approach 1:
The muffler is divided into an inner duct and an outer duct, creating segmented acoustic chambers. The inner duct contains holes that segment the acoustic path, allowing different frequency ranges to be treated independently. This segmentation enables the muffler to handle the broader frequency spectrum generated by high-speed compressors effectively.
Solution Approach 2:
The inner duct is nested within the outer duct, creating a compact dual-chamber structure. This nesting arrangement allows the muffler to provide effective noise reduction across wide frequency ranges while maintaining a space-efficient design suitable for integration with high-speed compressors.
2Ease of manufacture
If a conventional muffler design is used, then the manufacturing is simple, but the noise reduction effectiveness is insufficient for high-speed compressors
Solution Approach 1:
The muffler incorporates an inner duct with multiple holes at different positions along its length, segmenting the acoustic treatment into different zones. Each zone addresses specific frequency ranges, improving overall noise reduction effectiveness while maintaining a relatively simple cylindrical construction that is easy to manufacture.
Solution Approach 2:
The inner duct features holes with varying dimensions and positions along its length, creating local variations in acoustic impedance. This local quality variation allows different sections of the muffler to target different frequency ranges, enhancing noise reduction effectiveness across the broad spectrum generated by high-speed compressors.
3Object-generated harmful factors
If the muffler chamber volume is increased to improve noise reduction, then the acoustic treatment is enhanced, but the device size increases
Solution Approach 1:
The inner duct is nested within the outer duct, creating a compact dual-chamber structure. This nesting arrangement effectively doubles the acoustic treatment volume within a single external footprint, enhancing noise reduction capability without proportionally increasing the overall muffler size.
Solution Approach 2:
The invention utilizes the radial dimension by creating an annular chamber between the inner and outer ducts. This dimensional approach allows the muffler to provide effective acoustic treatment for broad frequency ranges while maintaining a compact axial length, effectively using space in multiple dimensions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The muffler significantly reduces noise levels by up to 10dBA across various speeds and operating conditions, effectively addressing the noise issue in high-speed compressors while maintaining low pressure drop.
Implementation Method 1
an inner duct with strategically positioned holes and an offset outer duct, optimized to reflect acoustic waves across a wide range of frequencies
Data Source
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AI summary
Disclosed is a discharge muffler for a compressor constructed as an inner duct extending inside an outer duct, the inner duct being open at each end and the outer duct being open only at the muffler inlet. The inner duct has a plurality of holes communicating with the outer duct. At least two of the holes are at different distances from the muffler outlet.