Connecting Pipe Venting Layout to Stop Cold Water Backflow
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Solution Overview
Problem
Existing washing machine and dishwasher designs experience a decline in energy efficiency due to cold water being pushed back into the tub when the waste water tank cools and expands, leading to excess pressure.
Innovation Solution
The first connecting line between the sump and waste water tank is not vented at its apex, allowing an air pocket to form and counteract the pressure, while the line itself slopes monotonically to facilitate drainage and prevent water from flowing back into the tub, ensuring that cold water is primarily directed towards the drain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the waste water tank is cooled down to extract heat, then energy efficiency is improved, but cold water expands and creates excess pressure that pushes water back into the tub, deteriorating energy efficiency
Solution Approach 1:
An air pocket is introduced as an intermediary substance between the waste water tank and the sump in the first connecting line. This air pocket acts as a buffer that absorbs the expansion pressure when waste water freezes, preventing cold water from being pushed back into the tub while maintaining the heat extraction function.
Solution Approach 2:
The system utilizes the phase change parameter of water (liquid to solid) and its associated volume expansion. By allowing the waste water to freeze and expand in the waste water tank, the system extracts heat energy while the expansion pressure is managed by the air pocket, preventing energy loss through cold water returning to the tub.
2Ease of operation
If the first connecting line is vented at the apex area, then air can escape, but water cannot be effectively drained when the pump is disabled due to lack of pressure counteraction
Solution Approach 1:
Instead of venting the apex area to allow air escape, the invention inverts the approach by creating a sealed air pocket at the apex. This inverted design uses the trapped air to provide pressure counteraction, enabling effective drainage when the pump is disabled while maintaining pressure control reliability during heat extraction.
Solution Approach 2:
The air pocket in the first connecting line provides self-service pressure regulation. When the pump is disabled, the trapped air automatically expands to counteract water pressure, enabling drainage without requiring additional active control mechanisms. During heat extraction, the same air pocket self-regulates the pressure from freezing waste water.
3Ease of operation
If the first connecting line slopes monotonically from apex to sump, then drainage is facilitated, but the apex area cannot retain an air pocket for pressure counteraction
Solution Approach 1:
The first connecting line is segmented into two functional zones: a monotonically sloping section for drainage facilitation, and an apex area with sufficient volume to retain the air pocket. This segmentation allows the line to simultaneously achieve effective drainage when the pump is disabled and maintain pressure counteraction during heat pump operation.
Solution Approach 2:
Different sections of the first connecting line have different local qualities: the apex area is designed with sufficient volume and positioning to retain the air pocket for pressure counteraction, while the rest of the line slopes monotonically to facilitate drainage. This local differentiation resolves the contradiction between drainage efficiency and energy efficiency.
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
This design enhances energy efficiency by preventing cold water from returning to the tub and improving drainage, allowing the heat pump to effectively transfer heat from the waste water tank to the process water without energy loss.
Implementation Method 1
a heat pump to extract heat from the waste water tank and feed it to the process water in the tub
Implementation Method 2
The waste water tank is cooled down to such an extent that part of the process water in the waste water tank freezes
Implementation Method 3
This air pocket is able to counteract excess pressure in the waste water tank thanks to the static pressure force of the water in the sump
Implementation Method 4
the first connecting line drops monotonously, in particular strictly monotonously, from the apex region to the sump. This facilitates drainage of water to the sump when the first pump is disabled
Data Source
Figure 1
AI summary
In a washing machine or a dishwasher, the tub (1) is followed by a waste water tank (6) for temporarily holding process water. A heat pump (7 - 10) extracts heat from the waste water tank (6) until the waste water in the waste water tank (6) partially freezes. In order to avoid backflow of cold water from the waste water tank (6) into the tub (1), the apex area (30) of the connecting pipe (25) between the sump (21) of the tub and the waste water tank (6) is not vented.