Electric Water Heater Temperature Feedback for Dry-Fire Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for preventing dry fire events in electric water heaters are either complex and costly or unreliable, particularly when using float switches or temperature sensors with polymer tanks, which can lead to overheating and damage.
Innovation Solution
A system with a temperature sensor and controller that intermittently actuates the heating element to maintain it below a maximum temperature, ensuring it provides a measurable energy contribution when immersed in water, and disables the element if the temperature exceeds a predetermined increment, thereby preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If float switch-based protective systems are used to prevent dry fire events, then the heating elements are activated only when water level is sufficient, but the system becomes complex and costly with moving parts that adversely affect reliability
Solution Approach 1:
The patent replaces the mechanical float switch system with an electrical/electronic solution using a temperature sensor and controller. Instead of using a mechanical float that moves with water level to activate switches, the system uses a temperature sensor to monitor the temperature near the heating element and a controller to interpret temperature changes. This substitution eliminates moving parts while achieving the same protective function through electrical sensing and control logic.
2Device complexity
If temperature sensor-based protective systems are used to prevent dry fire events, then the system is simpler to implement, but the sensors may be unreliable with polymer tanks where damage may occur to the tank before the temperature sensor detects a dry fire condition
Solution Approach 1:
The patent applies preliminary action by continuously monitoring the temperature near the heating element even before a dry fire condition occurs. The controller is programmed to detect temperature changes that indicate the heating element is not properly immersed in water, and it can prevent or shut off heating before damage occurs to either the heating element or the polymer tank. This proactive approach allows the system to prevent dry fire events before they cause harm.
Solution Approach 2:
The system uses feedback by continuously monitoring the temperature near the heating element and using this information to control the heating element's operation. The controller receives temperature data from the sensor, compares it against expected temperature ranges, and adjusts the heating element's power accordingly. This closed-loop feedback ensures the heating element operates safely and shuts down if temperature indicates a dry fire condition.
3Productivity
If the heating element is continuously energized to heat water, then heating efficiency is maximized, but the heating element may overheat if not properly immersed in water
Solution Approach 1:
The system uses feedback by continuously monitoring the temperature near the heating element and using this information to control the heating element's operation. The controller receives temperature data from the sensor, compares it against expected temperature ranges, and adjusts the heating element's power accordingly. This closed-loop feedback ensures the heating element operates safely and shuts down if temperature indicates a dry fire condition.
Solution Approach 2:
The system applies dynamics by making the heating element's operation adaptive rather than static. The controller dynamically adjusts the heating element's power level based on real-time temperature feedback. When water is properly immersed, the heating element operates at full power for efficient heating. When temperature indicates dry fire conditions, the controller dynamically reduces or shuts off power to prevent overheating, allowing the system to adapt its behavior to current conditions.
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
Effectively prevents dry fire events by ensuring the heating element does not overheat when exposed to air, thus protecting the water heater and its components from damage, while maintaining reliability and reducing complexity and costs.
Implementation Method 1
a temperature sensor disposed with respect to the heating element so that the temperature sensor detects temperature of an area ambient to the heating element in the interior volume
Implementation Method 2
the heating element contributes at least a predetermined amount of energy to the area that is measurable by the temperature sensor when the heating element is immersed in water
Implementation Method 3
the heating element contributes at least a predetermined amount of energy to the area that is measurable by the temperature sensor when the heating element is immersed in water
Data Source
AI summary
A water heater has a tank defining an interior volume, a heating element disposed within the interior volume, and a temperature sensor disposed with respect to the heating element so that the temperature sensor detects temperature of an area ambient to the heating element in the interior volume. The heating element is actuated at a predetermined actuation rate and for a cumulative actuation period so that the predetermined actuation rate maintains the heating element below a predetermined maximum temperature in air and so that the actuation period contributes a predetermined amount of energy to the ambient area when the heating element is immersed in water.