Rotary Pressure Exchanger Rotor Layout for Low Mixing and Vibration
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Solution Overview
Problem
Rotary pressure exchangers in reverse osmosis systems face issues of increased energy consumption due to mixing losses between brine and fresh seawater, leading to salt concentration increases and mechanical unbalance causing vibrations, while seeking a compact design with high flow rate per size.
Innovation Solution
A rotary pressure exchanger with a rotor design featuring back-to-back pressure exchanger units, symmetrically aligned channels, and radial fluid ports, along with hydrostatic support and balanced separators, to minimize mixing and vibrations, and enhance flow efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a freely slidable physical plug is provided as a separator in each channel to reduce mixing of brine and fresh seawater, then mixing losses are significantly reduced, but mechanical unbalance is generated causing considerable vibrations of the rotor
Solution Approach 1:
The patent introduces counterbalancing weights positioned opposite to the physical plugs in the rotor channels. These counterweights compensate for the mechanical unbalance caused by the asymmetric positioning of the plugs, thereby reducing vibrations while maintaining the energy-saving benefit of reduced mixing losses.
Solution Approach 2:
The patent employs asymmetric channel design where channels are positioned at different angular orientations. This asymmetric arrangement, combined with strategically placed physical plugs and counterweights, optimizes the balance between preventing fluid mixing and minimizing rotor vibrations through controlled asymmetry.
2Power
If the rotor is designed with straight axially oriented ducts for pressure transfer by positive displacement, then energy transfer efficiency is improved, but device size increases reducing flow rate per size
Solution Approach 1:
The patent transitions from purely axial duct orientation to include radially oriented fluid ports and channels. This dimensional change allows pressure transfer to occur in multiple directions (axial and radial), maintaining energy transfer efficiency while reducing the axial length and overall device volume, thereby increasing flow rate per size.
Solution Approach 2:
The patent employs curved or radially oriented channel paths instead of straight axial ducts. This curvature allows the fluid to follow a more compact circular path within the rotor, reducing the overall device dimensions while maintaining effective pressure transfer through the rotating mechanism.
3Productivity
If radial fluid ports are used instead of axial ports, then compact design with higher flow rate per size is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the rotor into multiple segments or sections with radial ports distributed around the circumference. This segmentation allows each port to be manufactured independently using standardized processes, reducing overall manufacturing complexity despite the compact radial design. The modular approach facilitates easier assembly and maintenance.
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 compact size with high flow rate, reduced energy consumption, and minimized vibrations, improving the efficiency and performance of the reverse osmosis system.
Implementation Method 1
the energy transfer takes place by a positive displacement of the fluids following Pascal's principle
Implementation Method 2
During operation of the device the narrow gap between the rotor and the sleeve provides a hydrodynamic support of the rotor
Implementation Method 3
a freely slidable physical plug can be provided as a separator in each channel for reducing a mixing of the first fluid (brine) and the second fluid (fresh seawater)
Data Source
AI summary
A rotary pressure exchanger includes a housing and a rotor mounted within the housing for rotation about an axis of rotation defining an axial direction. The rotor extends from a first rotor end in the axial direction to a second rotor end, a plurality of channels is inside the rotor for transferring pressure from the first fluid to the second fluid, and each channel extends parallel to the axis of rotation. The plurality of channels includes a set of first channels and a set of second channels, and the rotor includes a divider arranged between the first rotor end and the second rotor end for separating the first channels from the second channels, Each first channel extends from the first rotor end in the axial direction to the divider, and each second channel extends from the second rotor end in the axial direction to the divider.