Water Heater Flow Control for Faster Cold-Start Heating
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Solution Overview
Problem
Conventional water heaters require a long time to reach the preset temperature during a 'cold start,' leading to high water and fuel gas consumption.
Innovation Solution
An operation control unit compares the detected temperature with the preset temperature and reduces the water flow rate through the heat exchanger if it's lower, then resets it to the determined flow rate when the temperature approaches the preset, thereby controlling the temperature efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the water flow rate is set to a pre-determined flow rate at the time of starting operation, then the flow rate is sufficient for normal operation, but the time required to reach the preset temperature becomes long and water and fuel gas consumption increase
Solution Approach 1:
The water flow rate control unit dynamically adjusts the water flow rate based on the detected temperature. During cold start when the detected temperature is low, the flow rate is reduced to minimize heat loss and accelerate heating. When the detected temperature approaches the preset temperature, the flow rate is restored to the pre-determined level to ensure sufficient hot water supply for normal operation.
Solution Approach 2:
The system changes the water flow rate parameter according to the detected temperature condition. At the time of starting operation, when the detected temperature is lower than the preset temperature by a predetermined degree or more, the flow rate is changed from the pre-determined value to a reduced value. This parameter change optimizes the heating efficiency during cold start while maintaining normal operation performance.
2Loss of energy
If the water flow rate is reduced at the time of starting operation to shorten heating time, then water and gas consumption are saved, but the flow rate becomes insufficient for normal hot water supply
Solution Approach 1:
The water flow rate control unit dynamically adjusts the water flow rate based on the detected temperature. During cold start when the detected temperature is low, the flow rate is reduced to minimize heat loss and accelerate heating. When the detected temperature approaches the preset temperature, the flow rate is restored to the pre-determined level to ensure sufficient hot water supply for normal operation.
Solution Approach 2:
The system continuously monitors the detected temperature and adjusts the water flow rate accordingly to maintain continuous and efficient heating action. The controller performs temperature control of discharged hot water throughout the operation, ensuring that the heating process remains optimized while transitioning from cold start to normal operation.
3Loss of time
If the water flow rate is reduced at the time of starting operation, then the time to reach preset temperature is shortened, but the operation complexity increases due to temperature monitoring and dynamic adjustment
Solution Approach 1:
The controller receives feedback from the temperature detection unit that detects the discharged hot water temperature. Based on this feedback, the controller determines whether to reduce or restore the water flow rate through the water flow rate control unit. This feedback mechanism enables automatic adjustment without requiring complex control algorithms.
Solution Approach 2:
The system performs self-adjustment of the water flow rate based on the detected temperature condition. The controller automatically reduces the flow rate when the detected temperature is low and restores it when the temperature approaches the preset value, eliminating the need for manual intervention or complex external control systems.
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 approach shortens the time to reach the preset temperature, saving water and gas during cold starts while maintaining sufficient flow rates for normal operation.
Implementation Method 1
a water supplying pipe and a hot-water discharging pipe are connected with a heat exchanger heated by a burner
Implementation Method 2
water is passed into the device... water passing through the heat exchanger... heated water is discharged
Implementation Method 3
a heat exchanger heated by a burner
Data Source
AI summary
At the time of starting a hot water discharge operation, a controller determines whether the first operation was made after the power source is switched on in S1, and the controller determines whether 5 minutes have passed after the previous operation in S2. When the first operation was not made or 5 minutes have lapsed after the last operation, the controller determines whether a difference between a detected temperature acquired by a thermistor and a preset temperature is more than 10° C. in S3. When a temperature difference is more than 10° C., a water flow rate servo is set at a position where a flow rate of flowing water is reduced from a determined flow rate by a predetermined amount in S4, and the controller performs a temperature control of discharged hot water in S8.