Pump Assembly Inducer and Straight Inlet for Boiling Water Cavitation
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Solution Overview
Problem
Pumps used in beverage dispensing systems face challenges when pumping liquids at temperatures close to boiling point, as the liquid can undergo phase change due to reduced pressure, leading to cavitation, reduced efficiency, and potential damage.
Innovation Solution
A pump assembly with a conduit inlet having a substantially straight length of at least five times its internal diameter, an inducer with a helical blade, and an impeller with radially extending vanes, all mounted on a ceramic shaft, to promote laminar flow and reduce the likelihood of cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pump inlet is used, then the pump structure is simple, but cavitation occurs due to reduced pressure causing phase change
Solution Approach 1:
The inlet conduit is designed with a substantially straight configuration of at least five times its internal diameter length before the water enters the impeller. This preliminary straight section allows the water flow to stabilize and maintain pressure before entering the high-velocity impeller region, preventing phase change and cavitation from occurring in advance
2Reliability
If the inlet conduit is made longer to promote laminar flow, then cavitation is reduced, but the device size increases
Solution Approach 1:
The patent specifies that the straight inlet conduit length should be at least five times its internal diameter, with the internal diameter preferably in the range of 5mm to 15mm. This parameter optimization achieves sufficient laminar flow promotion and cavitation prevention while controlling the overall device size within practical limits
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 pump assembly effectively prevents cavitation and maintains high efficiency and flow rate when pumping boiling water, ensuring consistent performance and reducing the risk of damage.
Implementation Method 1
The internal diameter of the inlet conduit is preferably in the range of about 5 mm to 15 mm, and more preferably about 10 mm. In a preferred embodiment, the inlet comprises a conduit having a substantially straight length of at least six times its internal diameter, and optionally even longer. This length of the inlet conduit acts to promote laminar flow through and along the inlet by providing a sufficient length of straight travel for the water.
Implementation Method 2
The inducer acts to raise the inlet pressure and, in this way, reduces the chance of a phase change occurring as the water is pumped by the impeller, thereby reducing or avoiding the occurrence of cavitation during operation of the pump.
Implementation Method 3
In a centrifugal pump, a rotating impeller draws the liquid through an inlet of the pump typically arranged on or near its rotational axis and accelerates the liquid radially outwards into the volute chamber or casing of the pump where it then exits through an outlet, thereby transferring rotational kinetic energy of the impeller to hydrodynamic energy.
Data Source
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AI summary
A pump assembly (10) for pumping boiling water to a dispenser in a drinking water dispensing system, the pump assembly (10) comprising: a pump housing (20) having an inlet (22) for the boiling water and an outlet (24) arranged in fluid communication with the inlet (22); an impeller (30) disposed in the pump housing (20) for rotation about a central axis (23) for driving the water from the inlet (22) to the outlet (24), wherein the inlet (22) is arranged on the central axis (23); and an inducer (40) arranged in the inlet (22) to the pump housing (20) and operatively connected to the impeller (40) for rotation therewith about the central axis (23) to induce the water at the inlet (22) towards the impeller (30) and raise the inlet pressure.