Condensate Tray Assembly with Capacitive Sensing for Complete Drainage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional condensate tray assemblies struggle with accurately detecting liquid levels near the bottom due to surface tension and contamination, leading to incomplete drainage and potential microbial growth, as non-self-priming pumps require residual liquid and can produce noise when over-operated.
Innovation Solution
A condensate tray assembly using capacitive sensors to measure the rate of change of liquid depth, integrated into a self-priming pump system with a sloped tray and filter, allowing precise control to empty the tray nearly completely while preventing contamination and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low level sensor is used to detect liquid level near the bottom of the tray, then the pump can be stopped earlier to reduce noise and energy consumption, but the sensor cannot reliably detect the liquid level due to surface tension and contamination effects
Solution Approach 1:
The patent replaces the mechanical/contact-based low level sensor with a capacitive sensor that measures liquid level without physical contact. The capacitive sensor detects changes in capacitance caused by the dielectric properties of liquid versus air, enabling reliable detection near the tray bottom without being affected by surface tension or contamination that plague contact sensors.
Solution Approach 2:
The capacitive sensor acts as an intermediary measurement mechanism that indirectly detects liquid level through electrical field interactions rather than direct mechanical contact. This intermediary approach allows the system to obtain accurate liquid level information without the sensor being subject to the harmful effects of direct contact with the liquid environment.
2Loss of substance
If the pump continues to run after the low level sensor is reached to empty the tray more completely, then less liquid remains in the tray, but it generates unpleasant noise and may over-operate
Solution Approach 1:
The capacitive sensor provides continuous feedback on the actual liquid level and rate of change to the control system. This feedback enables the controller to precisely determine when the tray is sufficiently empty and stop the pump at the optimal moment, avoiding both over-pumping (which causes noise) and under-pumping (which leaves excessive residual liquid).
Solution Approach 2:
The system dynamically adjusts pump operation based on real-time capacitive sensor readings. By monitoring the rate of change of liquid level, the control system can adaptively determine the optimal stop point, making the pump operation dynamic rather than static, thereby minimizing residual liquid without causing noise from over-operation.
3Device complexity
If a non-self-priming pump is used, then the pump structure is simpler, but an amount of liquid must be retained in the pump after pumping to maintain priming
Solution Approach 1:
The patent replaces the conventional non-self-priming pump with a self-priming pump that incorporates internal mechanisms (such as a priming chamber or air-lift mechanism) to automatically maintain priming conditions. This substitution eliminates the need for residual liquid to maintain pump operation, reducing residual liquid in the tray without complicating the overall system architecture.
4Quantity of substance
If the tray has a wide, shallow configuration to accommodate condensate, then more liquid can be collected, but a significant amount of liquid remains in the tray after pumping due to the inability to detect very low levels
Solution Approach 1:
The capacitive sensor replacement enables the wide, shallow tray design to achieve complete drainage. The non-contact measurement capability allows the sensor to detect the meniscus and residual liquid films that form in the corners and low areas of the wide tray, enabling the pump to continue until these remnants are removed, thus maintaining high condensate capacity while eliminating the residual liquid problem.
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 solution ensures accurate and efficient drainage, minimizing residual liquid and preventing microbial growth, with the capacitive sensors allowing for precise control of the pumping process to maintain a predetermined residual volume, thus reducing hygiene hazards and noise.
Implementation Method 1
the sensor is a capacitive sensor. This can be in the form of a pair of capacitive plates arranged vertically within the tray, such that the sensor determines the capacitance of the surrounding medium, whether it be air or liquid to provide a continuously varying indication of the liquid depth
Implementation Method 2
The tray preferably has a sloped lower surface which slopes towards the outlet, a sensor being positioned in the vicinity of the outlet. As well as causing the liquid in the tray to flow towards the outlet
Implementation Method 3
the low level sensor cannot reliably detect the level of the liquid very close to the bottom of the tray because of the effect of surface tension and contamination on the sensor
Data Source
AI summary
A condensate tray assembly for use below a condensate generating appliance, particularly a refrigeration unit. The assembly comprises a tray (1) with an inlet (3A) and an outlet (3) towards the bottom of the tray. A self-priming pump (5) is connected to the outlet for pumping liquid from the tray. A sensor (12) within the tray determines the rate of change of the depth of liquid. A control system (14) receives an input from the sensor (12) to control the pump (5) to pump liquid from the tray and to turn off the pump based on the rate of reduction of the depth of liquid in the tray. The invention also extends to a method of operating the pump.