Centrifugal Pump Flow Modifier for Air Ingress Prevention
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Solution Overview
Problem
Centrifugal pumps in air conditioning equipment condensate systems face issues with air ingress into the pump cavity when the water level drops below the shaft opening, leading to reduced efficiency, increased operational volume, and noise generation, necessitating premature pump shutdown and frequent cycling.
Innovation Solution
A flow modifier comprising an annular portion with a stabiliser cavity and radially extending vanes that creates a pressure increase at the liquid overflow outlet, preventing air ingress by ensuring the outlet remains filled with water, even when the water level drops, and slowing down liquid flow to prevent air entry through the shaft opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the water level in the liquid tank drops below the shaft opening, then the pump can continue to operate, but air ingress into the pump cavity occurs leading to reduced efficiency and increased noise
Solution Approach 1:
The flow modifier acts as an intermediary component installed at the shaft opening to prevent air ingress. It includes a stabilizer cavity that maintains liquid presence and flow control features that regulate fluid passage, thereby mediating between the pump cavity and the liquid tank to eliminate air entry while allowing continuous operation.
Solution Approach 2:
The flow modifier introduces local quality changes at the shaft opening region by creating a stabilized liquid environment in the cavity and controlling flow characteristics through specific geometric features. This localized modification prevents air ingress at the critical interface without affecting the overall pump operation.
2Duration of action of moving object
If the water level drops below the shaft opening, then the pump can operate longer, but noise generation increases
Solution Approach 1:
The flow modifier serves as an intermediary that eliminates the harmful noise generation mechanism by preventing air ingress into the pump cavity. The stabilizer cavity and flow control features ensure liquid presence at the shaft opening, thereby mediating to prevent the air-liquid interaction that causes noise.
3Duration of action of moving object
If the water level drops below the shaft opening, then the pump can operate longer, but operational volume increases
Solution Approach 1:
The flow modifier applies local quality changes at the shaft opening by creating a concentrated liquid presence in the stabilizer cavity and controlling flow patterns. This localized approach prevents air ingress and maintains efficient operation without requiring increased overall pump volume.
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 flow modifier effectively prevents air ingress into the pump cavity, allowing continuous operation until the water level reaches the pump inlet, enhancing efficiency and reducing noise, while maintaining the pump's operational capacity and extending its lifespan.
Implementation Method 1
A flow modifier comprising an annular portion with a stabiliser cavity and radially extending vanes that creates a pressure increase at the liquid overflow outlet
Implementation Method 2
Centrifugal pumps operate by rotation of an impeller within the fluid to create a pressure differential across a fluid, whereby to move the fluid from a pump inlet to a pump outlet
Data Source
Figure 1~2
Figure 3
AI summary
There is provided a centrifugal pump comprising a pumping chamber (106). The pumping chamber (106) has an inner surface (108) defining a pump cavity (110); a pump inlet (112) defined in a first side of the pumping chamber (106); a shaft opening (116) defined substantially centrally in a second side of the pumping chamber (106), the second side substantially opposing the first side and arranged to be above the first side, in use; and a pump outlet (114). The centrifugal pump further comprises an impeller (120) retained within the pump cavity (110); and a shaft member (140) mechanically connected to the impeller (120) through the shaft opening (116), whereby rotation of the shaft member (140) causes rotation of the impeller (120) about a shaft axis (157) passing through the shaft opening (116) and movement of a pumping liquid from the pump inlet (112) towards the pump outlet (114). The centrifugal pump further comprises a flow modifier (150) provided adjacent to an outer surface (107) of the pumping chamber (106) at the shaft opening (116) to substantially prevent ingress of air into the pump cavity (110) through the shaft opening (116) during operation of the pump even when a water level in a liquid tank (104) surrounding the pumping chamber (106) drops below a level of the shaft opening (116). The flow modifier (150) comprises an annular portion (152) having defined therein a further shaft opening (156) spaced from the shaft opening (116) and having the shaft member (140) passing therethrough. The centrifugal pump comprises a spacing member (154) spacing the annular portion (152) from the outer surface (107). The flow modifier (150) defines a liquid overflow outlet (164) for liquid flow from the shaft opening (116) in a direction substantially transverse to the shaft axis (157). In one example, the liquid overflow outlet (164) is sized to substantially prevent the ingress of air into the pump cavity (110) through the shaft opening (116) during operation of the pump, even when the water level in the liquid tank (104) surrounding the pumping chamber (106) drops below the level of the shaft opening (116). In the same or an alternative example, the annular portion (152) comprises a first portion (158) having defined therein the further shaft opening (156) and a second portion (160) extending towards the outer surface (107) from the first portion (158) and defining the liquid overflow outlet (164). Also in the same or the alternative example, the annular portion (152) defines a stabiliser cavity (166) extending between the shaft opening (116) and the further shaft opening (156) and configured to remain filled with liquid during operation of the pump, even when the water level in the liquid tank (104) surrounding the pumping chamber (106) drops below the level of the shaft opening (116).