Dry tank detection method for a water heater appliance
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Solution Overview
Problem
Existing water heater appliances lack effective and cost-efficient methods to detect water levels, leading to potential damage from prolonged heating element operation without immersion in water, as conventional solutions are either costly or have slow response times and are prone to errors.
Innovation Solution
A water heater system with a controller that measures electrical current during energization periods and uses a correlation filter to determine if the heating element is submerged, preventing damage by ensuring the element is immersed in water before operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional water level detection methods (conductivity sensors, mechanical sensors) are used, then water level can be detected, but the system complexity and cost increase, and response time is slow
Solution Approach 1:
The heating element serves dual purposes: heating water and detecting water level. By monitoring its own electrical characteristics (current, resistance, power consumption), the heating element autonomously determines whether it is submerged without requiring external sensors. This self-service approach eliminates complex sensor arrangements while maintaining reliable detection.
Solution Approach 2:
The heating element is made multi-functional by using it both for heating and for water level detection. The controller monitors the electrical characteristics of the heating element to infer water level status, thereby serving two functions with a single component and avoiding the need for dedicated detection sensors.
2Reliability
If conventional water level detection methods are used, then water level can be detected, but the response time is slow and errors occur
Solution Approach 1:
The controller continuously monitors the electrical characteristics of the heating element during operation and uses this real-time feedback to determine water level status. This continuous feedback mechanism enables quick response to water level changes and accurate detection by comparing measured characteristics against expected values for submerged and non-submerged states.
Solution Approach 2:
The patent replaces mechanical or physical sensors with an electrical measurement approach. By measuring electrical current, resistance, and power consumption of the heating element, the system achieves faster response time and higher accuracy without the mechanical inertia or calibration issues associated with conventional sensors.
3Device complexity
If no water level detection is implemented, then the system is simple, but the heating element may be damaged from prolonged operation without immersion
Solution Approach 1:
The heating element monitors its own operational conditions by measuring its electrical characteristics. When the heating element detects it is not submerged (through abnormal current or resistance readings), it automatically stops operation or alerts the user, preventing damage without requiring external protection systems.
Solution Approach 2:
The controller continuously monitors the electrical characteristics of the heating element and provides feedback control. When the heating element is not submerged, the abnormal electrical characteristics trigger a feedback response that stops heating operation, thereby preventing damage while maintaining system 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 solution effectively prevents heating element damage by quickly and accurately determining water levels, ensuring safe operation and reducing the risk of overheating, thus extending the lifespan of the appliance.
Implementation Method 1
heating elements, such as gas burners, electric resistance elements, or induction elements, heat water within the tank
Implementation Method 2
measuring electrical current passing through the heating element during the energization period
Data Source
AI summary
A method for controlling a water heater appliance includes energizing the heating element for an energization period, such as less than two seconds. During the energization period, the appliance controller measures the electrical current passing through the heating element. The measured electrical current and a base signal are passed through a correlation filter to determine a correlation value. The base signal may correspond to the electrical current passing through the heating element when the tank is full or when the tank is empty, and the correlation value may be used to determine to which base signal the measured electrical current more closely correlates. In this manner, the correlation value is used to determine whether the heating element is submerged in water.