Hot Water Preheating Circulation for Low-Flow Temperature Control
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Solution Overview
Problem
Conventional hot water supply systems cannot control the temperature of hot water effectively at low-flow rates, often failing to ignite the burner or accurately measure flow rates below the operational threshold, resulting in inadequate temperature control for users, especially during low-water usage scenarios like showering or shaving.
Innovation Solution
The method involves activating a preheating circulation mode using a pump to circulate water through an internal path, allowing temperature control by setting specific preheating temperatures and operating the heating device accordingly, even at low flow rates or low water pressure, ensuring hot water is supplied at the user's desired temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the flow sensor is designed to detect flow rates at the operational threshold (2-3 l/min), then the water heater can control temperature at normal usage, but the measurement accuracy deteriorates at very low flow rates (below 2-3 l/min)
Solution Approach 1:
The system performs preliminary heating by circulating water through the heat exchanger before actual water usage. This preheating action raises the baseline temperature of water in the system, enabling effective temperature control even at very low flow rates where the flow sensor would otherwise fail to detect sufficient flow for burner ignition.
2Temperature
If the burner is ignited to control temperature at set-temperature, then hot water can be supplied at desired temperature, but the burner cannot be ignited when flow rate is below operational threshold
Solution Approach 1:
The system performs preliminary heating by circulating water through the heat exchanger before actual water usage. This preheating action raises the baseline temperature of water in the system, enabling effective temperature control even at very low flow rates where the flow sensor would otherwise fail to detect sufficient flow for burner ignition.
Solution Approach 2:
The system uses the water flow itself to activate the preheating circulation mode. When the flow sensor detects flow rate at or below the operational threshold, it automatically triggers the preheating circulation, eliminating the need for manual intervention or complex control logic.
3Use of energy by moving object
If the water heater operates only at minimum heating power, then energy consumption is reduced, but hot water at higher temperature than set-temperature is supplied when inflow water temperature is slightly high
Solution Approach 1:
The system continuously monitors the temperature of water circulating through the heat exchanger using a temperature sensor. Based on this feedback, the controller adjusts the burner operation - igniting the burner when temperature falls below the preheating circulation-on temperature and stopping combustion when temperature reaches the preheating circulation-off temperature, thereby maintaining precise temperature control at low flow rates.
4Adaptability or versatility
If preheating circulation is activated at low flow rates, then temperature control is enabled, but additional energy consumption occurs
Solution Approach 1:
The system uses the water flow itself to activate the preheating circulation mode. When the flow sensor detects flow rate at or below the operational threshold, it automatically triggers the preheating circulation, eliminating the need for manual intervention or complex control logic.
Solution Approach 2:
The system changes the operational parameters of the water heater based on detected flow rate conditions. By switching to preheating circulation mode at low flow rates, the system adapts its heating strategy to maintain temperature control capability across different operating conditions, accepting increased energy consumption as necessary for functionality.
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 enables consistent temperature control of hot water at low-flow rates, preventing pipe freezing and ensuring hot water is available at the user's set temperature, even when the flow rate is below the operational threshold, thus addressing the limitations of conventional systems.
Implementation Method 1
transferring the heat of the burner to the water flowing into the water heater using a heat exchanger
Implementation Method 2
a pump that is disposed in a pipe line connecting a first diverging point formed at a pipe line for an outlet and a second diverging point formed at a pipe line for an inlet
Data Source
Figure 1~2
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Figure 5
AI summary
The present invention relates to a method of controlling the temperature of hot water for using hot water at a low-flow rate in a hot water supply system. The hot water supply system includes: a flow sensor; a heat exchanger; a water tank, a temperature sensor; a controller having an input unit; and a pump that is disposed in a pipe line connecting a first diverging point formed at a pipe line for an outlet and a second diverging point formed at a pipe line for an inlet. The method includes: measuring the flow rate of water flowing into the hot water supply system, using the flow sensor; preheating-circulating the water in the hot water supply system through an internal circulation path connecting the first diverging point, the second diverging point, and the heat exchanger, using the pump, after the controller stops the combustion of the heating device when the measured flow rate is an operation flow rate of the water supply system or less; measuring the temperature of the water circulating, using the temperature sensor; and setting predetermined temperature above user set-temperature as preheating circulation-off temperature and predetermined temperature below the set temperature as preheating circulation-on temperature, and then starting operation of the heating device when the temperature measured by the temperature sensor is preheating circulation-on temperature or less and stopping the operation of the heating device when the measured temperature is the preheating circulation-off temperature or more, using the controller.