Pump Assembly with External Heating Element to Reduce Calcium Scaling
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Solution Overview
Problem
Household appliance pumps face inefficiencies in heating liquid recirculation, particularly due to calcium precipitation and scaling issues at heating elements, which affect heat transfer and appliance performance.
Innovation Solution
A pump assembly design featuring a motor, impeller, and housing with a heating element positioned on the exterior of the housing, utilizing convolutions to increase the heat transfer area and reduce watt density, thereby minimizing calcium precipitation and enhancing heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heating element is provided on the casing for heating the liquid within the liquid chamber, then the liquid can be heated, but calcium precipitation and scaling occur at the heating element
Solution Approach 1:
The heating element is moved from the interior liquid chamber to the exterior of the pump housing, changing the spatial dimension of heat application. This external positioning prevents direct contact between the heating element and the liquid, thereby eliminating calcium precipitation and scaling while still enabling liquid heating through thermal conduction via the housing walls.
Solution Approach 2:
The pump housing acts as an intermediary thermal conductor between the externally mounted heating element and the liquid. Heat is transferred from the heating element through the housing walls into the liquid chamber, allowing indirect heating that avoids the harmful effects of direct heating element contact with the liquid.
2Loss of energy
If the heating element is positioned inside the liquid chamber, then heat transfer is direct, but scaling reduces heat transfer efficiency
Solution Approach 1:
The heating element is extracted from the liquid chamber environment and repositioned on the exterior of the pump housing. This removal eliminates the scaling problem that would otherwise accumulate on the heating element surface and reduce heat transfer efficiency, while the housing walls serve as the new heat transfer interface.
3Device complexity
If a conventional heating element design is used, then the structure is simple, but heat transfer area is limited and watt density is high
Solution Approach 1:
The heating element is repositioned on the exterior surface of the pump housing, utilizing the external surface area as the heat transfer interface. This dimensional change allows the heating element to access a larger effective heat transfer area through the housing walls, reducing watt density while maintaining structural simplicity.
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 effectively reduces calcium precipitation and scaling by distributing heat over a larger surface area, increasing heat transfer efficiency and reducing the risk of scaling through thermal expansion and contraction.
Implementation Method 1
heat generated by the heating element is conducted into the volute chamber through the plurality of convolutions
Implementation Method 2
reducing the risk of scaling through thermal expansion and contraction
Data Source
Figure 1
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AI summary
A pump assembly (10) includes a motor (16) and a pump, with the motor having an output shaft (18) that extends into a volute chamber (24) defined by a housing of the pump. An impeller (26) may be mounted to the end of the output shaft. A heating element (14) maybe located within a projection formed in an end of the housing and defines a heat transfer area confronting the volute chamber, wherein heat generated by the heating element may be conducted into the volute chamber.