Storage Water Heater Control With Variable Hysteresis Standby Heating
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Solution Overview
Problem
Conventional water heaters face inefficiencies in energy-saving modes, particularly during standby times, leading to increased heat losses and potential scalding risks due to unpredictable temperature fluctuations.
Innovation Solution
A water heater with a dual-control system, featuring a first control unit for normal mode with constant hysteresis and a second control unit for energy-saving mode with variable hysteresis based on water temperature, usage patterns, and time intervals, along with a redundant temperature sensor design for reliable measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the water temperature in the storage tank is lowered to save energy during standby time, then heat losses are reduced, but the risk of scalding increases when hot water is tapped
Solution Approach 1:
The patent applies dynamics by implementing a variable hysteresis control where the temperature difference between switching on and off the heater changes based on the operating mode. In energy-saving mode, a larger hysteresis is used, allowing the water temperature to drop to a lower threshold before reheating, thereby reducing standby heat losses while maintaining safety through controlled temperature variations.
Solution Approach 2:
The patent changes the control parameter from a fixed hysteresis to a variable hysteresis that adapts to different operating modes. By adjusting the hysteresis parameter based on whether the system is in normal or energy-saving mode, the controller optimizes energy efficiency while preventing scalding risks through appropriate temperature management.
2Device complexity
If a constant hysteresis control is used, then the control system is simple, but energy efficiency during standby time is poor
Solution Approach 1:
The control system transitions from static to dynamic by introducing mode-dependent hysteresis values. The controller adapts its behavior based on the operating mode, using a larger hysteresis in energy-saving mode to allow greater temperature fluctuations, thereby reducing energy losses without significantly increasing system complexity.
3Speed
If the water temperature is rapidly increased after being drawn off, then hot water is quickly available, but the user may scald themselves if the fitting temperature setting is not changed
Solution Approach 1:
The system performs preliminary action by pre-heating water to a higher temperature threshold before it is actually needed. This ensures that when hot water is tapped, the heater can quickly respond and restore the desired temperature, reducing waiting time while the mode indicator gives users advance warning to adjust their mixing valve settings.
4Loss of energy
If an energy saving mode is implemented with lower target temperature, then energy efficiency is improved, but the control precision is reduced
Solution Approach 1:
The patent changes the control parameters by implementing mode-dependent hysteresis values. In energy-saving mode, a larger hysteresis is used with a lower target temperature, accepting reduced precision for energy efficiency. In normal mode, a smaller hysteresis maintains tighter temperature control. This parameter adaptation resolves the contradiction between energy efficiency and control precision.
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 minimizes heat losses during standby periods while ensuring rapid re-heating when needed, and reduces the risk of scalding by maintaining a safe lower water temperature when not in use, enhancing overall energy efficiency and user safety.
Implementation Method 1
a temperature sensor (3) for detecting the water temperature in the storage tank (10)
Implementation Method 2
an electric heater (2) for heating the water in the storage tank
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
The heater has a controller (100) for controlling temperature of water with two control units (31, 32) based on a variable hysteresis that depends on parameter. The two control units are activated in two operation modes, respectively, where one of the operation modes represents a normal operation mode, and the other mode represents a standby operation mode. An electrical heating element, a temperature sensor and a hot water tank are provided in the heater, where the water is heated at small amount of temperature when the hot water tank is in the standby mode. The hot water tank is formed as a storage tank, and the temperature sensor is formed as printed temperature sensor.