Water Heater Flow Pulsation to Limit Heat Exchanger Scale Return
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Solution Overview
Problem
Conventional water heaters with plate-type heat exchangers face issues with calcium carbonate scale deposition, which reduces heat-transfer performance and obstructs flow channels, as detached scale tends to re-adhere to the heat exchanger surfaces despite vibration-based cleaning methods.
Innovation Solution
A water heater design that incorporates a distribution control unit to pulsate the flow of heated liquid through the heating flow channel and limits the number of circulation times to prevent scale adhesion, using a tank, heater, and distribution control unit to manage flow rates and circulation within the heating flow channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge valve is opened/closed in a cycle to vibrate the plate-type heat exchanger, then scale can be detached from the heat exchanger, but the detached scale returns and re-adheres to the heat exchanger surfaces through the circulation circuit
Solution Approach 1:
The patent applies periodic pulsation to the to-be-heated liquid flow through the heating flow channel. The distribution control unit controls the flow rate to pulsate the liquid, creating periodic hydraulic shock that detaches scale from the heat transfer surfaces. This periodic action is designed to occur a predetermined number of times or less within a boiling time period, ensuring scale removal while preventing re-adhesion through controlled circulation timing
Solution Approach 2:
The patent changes the flow rate parameter of the to-be-heated liquid to achieve pulsation. By controlling the flow rate to vary over time rather than remaining constant, the system creates the necessary hydraulic shock for scale detachment. The distribution control unit specifically adjusts the flow rate parameter so that the entire volume of to-be-heated liquid passes through the heater a predetermined number of times or less within a boiling time, optimizing both scale removal and preventing re-adhesion
2Productivity
If the flow rate of to-be-heated liquid is increased to enhance heat transfer, then heat-transfer performance improves, but scale adhesion to the heating flow channel increases
Solution Approach 1:
The patent uses periodic pulsation of the flow rate rather than continuously high flow rate. The distribution control unit creates periodic variations in flow rate that generate hydraulic shock to detach scale, while the overall circulation is limited to a predetermined number of times or less within a boiling time. This approach maintains high heat transfer performance during pulsation periods while preventing excessive scale adhesion that would occur with continuous high flow
Solution Approach 2:
The patent ensures continuous heat transfer action by maintaining the heating process while controlling the pulsation frequency. The distribution control unit orchestrates the pulsation to occur during the heating process, ensuring that the to-be-heated liquid continuously receives heat while also experiencing the scale-detaching pulsation effects. The circulation is controlled to complete a predetermined number of passes within a boiling time, maintaining continuous useful heating action
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 effectively detaches and prevents the re-adhesion of scale on the heat-transfer surface, maintaining heat-transfer performance and preventing flow channel obstructions by controlling the flow rate and circulation frequency of the heated liquid.
Implementation Method 1
a heater disposed midway in a to-be-heated liquid piping to form a flow channel through which the to-be-heated liquid flown out from the tank flows into the tank again, the heater including a heating flow channel, the to-be-heated liquid flown out from the tank into the to-be-heated liquid piping flowing into the heating flow channel where a temperature of the to-be-heated liquid is increased
Implementation Method 2
the distribution control unit controlling a flow rate of the to-be-heated liquid which passes through the heating flow channel of the heater, thereby pulsating the to-be-heated liquid which passes through the heating flow channel of the heater
Data Source
AI summary
A water heater in which by applying pulsation of a liquid to be heated which circulates between a tank and a heat exchanger, scale that has been deposited on the inner wall (heat-transfer surface) of a to-be-heated liquid flow channel in a heat exchanger is detached, and the number of times of circulation of the liquid to be heated which circulates between the tank and the heat exchanger is controlled to be three times or less. The number of times of circulation is determined, based on the entire volume of the to-be-heated liquid stored in the tank, a boiling time to be taken for the entire volume of the to-be-heated liquid in the tank to reach a predetermined temperature, and the flow rate of the to-be-heated liquid which passes through the to-be-heated liquid flow channel.