Screw compressor economizer plenum for pulsation reduction
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Solution Overview
Problem
Screw compressors in chillers experience pulsation propagation from the economizer port, leading to annoying sound and unwanted vibration due to the opening and closing of compression pockets, which existing solutions like mufflers and sound damping materials do not fully address.
Innovation Solution
A compressor design with a housing featuring a chamber between the economizer port and external port, having a volume of at least 0.8 liters, and a specific area ratio between the economizer and external ports, which dissipates pulsations by providing a larger volume for pulsation wave dissipation and reflection, effectively reducing noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a chamber with volume of at least 0.8 liter is provided between the economizer port and external port, then pulsation transmission loss is improved (at least 3 dB rms), but the compressor structure becomes more complex and occupies more space
Solution Approach 1:
The chamber is nested within the existing compressor housing structure, utilizing the space between the economizer port and external port. This integration approach allows the pulsation reduction function to be incorporated without adding external components, thereby reducing overall structural complexity while achieving the required volume of at least 0.8 liter for effective pulsation transmission loss of at least 3 dB rms
Solution Approach 2:
The chamber acts as an intermediary element between the economizer port and external port, providing a buffer volume that dissipates pulsation waves. This intermediate chamber with specific volume requirements serves as a mediator that reduces the direct transmission of pulsations while maintaining the functional connection between ports, achieving pulsation transmission loss without requiring complex active control systems
2Object-affected harmful factors
If the chamber volume is increased to at least 1.0 liter, then pulsation dissipation is improved, but the housing space requirement increases
Solution Approach 1:
The chamber is designed with specific local geometric features including a protuberant portion with a minimum cross-sectional area at least twice that of the external port, and surface portions that are generally radially outwardly convex. These localized geometric optimizations maximize the pulsation dissipation effectiveness within the constrained housing space, achieving at least 3 dB rms pulsation transmission loss with a volume of at least 1.0 liter without proportionally increasing overall housing volume
Solution Approach 2:
The chamber incorporates a protuberant portion that extends into the housing space, utilizing the third dimension to maximize volume efficiency. By creating a three-dimensional structure with varying cross-sectional areas (minimum cross-sectional area at least twice that of the external port), the design achieves enhanced pulsation dissipation in a compact form factor, fitting within the existing housing boundaries
3Object-affected harmful factors
If the area ratio of the economizer port to the external port is optimized to 0.130-0.170, then pulsation reduction is improved, but manufacturing precision requirements increase
Solution Approach 1:
The design specifies an optimized area ratio parameter range of 0.130 to 0.170 between the economizer port and external port, which has been determined to provide optimal pulsation reduction performance. By defining a range rather than a single precise value, the design balances performance optimization with manufacturing feasibility, achieving effective pulsation reduction while accommodating normal manufacturing tolerances
Solution Approach 2:
The chamber includes a protuberant portion with a minimum cross-sectional area at least twice that of the external port, and a cut plane area at least three times (up to eight times) the cross-sectional area of passageway legs. These dimensional specifications provide sufficient pulsation dissipation capacity with appropriate margins, ensuring effective pulsation reduction while maintaining reasonable manufacturing precision requirements
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 design achieves a pulsation transmission loss of at least 3 dB rms over a significant range of male rotor speeds, expanding the compressor's operational envelope and reducing equipment vibration and noise effectively.
Implementation Method 1
A compressor design with a housing featuring a chamber between the economizer port and external port, having a volume of at least 0.8 liters, and a specific area ratio between the economizer and external ports, which dissipates pulsations by providing a larger volume for pulsation wave dissipation and reflection
Implementation Method 2
dissipates pulsations by providing a larger volume for pulsation wave dissipation and reflection
Data Source
AI summary
A compressor (22) has a male rotor (52), a female rotor (54), and a housing (50). The housing has a first bore (114) and a second bore (116) respectively accommodating portions of the male rotor and the female rotor. The housing has an inlet (26), an outlet (28), an economizer port (150) along at least one of the first bore and the second bore, and an external port (46) communicating with the economizer port. The housing has a chamber (152) between the economizer port and the external port having a volume of at least 0.8 liter.