Centrifugal pump flow modifier
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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 shutdown and frequent cycling.
Innovation Solution
A centrifugal pump design incorporating a flow modifier with an annular portion and stabiliser cavity, featuring a liquid overflow outlet and vanes, which prevents air ingress by maintaining liquid pressure and flow direction transverse to the shaft axis, even when the water level falls below the shaft opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the shaft opening is positioned at the outer surface of the pumping chamber, then the shaft member can be mechanically connected to the impeller, but air ingress into the pump cavity occurs when water level drops below the shaft opening
Solution Approach 1:
The flow modifier acts as an intermediary component between the shaft opening and the pump cavity. It includes a stabilizer cavity that maintains liquid presence and flow direction control features that prevent air from entering the pump cavity through the shaft opening, thus mediating between the shaft connection requirement and air ingress prevention.
Solution Approach 2:
The flow modifier is pre-installed at the shaft opening position to establish liquid flow patterns before air ingress can occur. The stabilizer cavity is pre-filled with liquid to maintain a liquid barrier, and the flow direction features are pre-configured to guide liquid flow in a manner that prevents air entry, acting in advance to prevent the problem rather than correcting it.
2Productivity
If the pump operates continuously until water level reaches pump inlet, then productivity increases, but air ingress causes noise and reduced efficiency
Solution Approach 1:
The flow modifier converts the potentially harmful condition of low water level operation into a beneficial state by using the remaining liquid to create a controlled flow pattern through the stabilizer cavity and flow direction features. This converts what would be air ingress and noise into a controlled liquid flow that maintains pumping efficiency and allows continuous operation.
3Reliability
If the liquid overflow outlet is sized to prevent air ingress, then reliability improves, but liquid flow capacity may be restricted
Solution Approach 1:
The flow modifier applies local quality control at the shaft opening region specifically. The stabilizer cavity and flow direction features are localized at the shaft opening to control air ingress, while the rest of the pump system maintains its full liquid flow capacity. This localized intervention prevents air ingress without restricting overall liquid flow capacity.
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 solution effectively prevents air from entering the pump cavity, allowing continuous operation until the water level reaches the pump inlet, enhancing efficiency and reducing noise and operational frequency.
Implementation Method 1
maintaining liquid pressure and flow direction transverse to the shaft axis
Implementation Method 2
directing liquid flow in a direction substantially transverse to the shaft axis
Implementation Method 3
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
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).