Hot Water Heat Exchanger Flow Control for Overheating Prevention
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Solution Overview
Problem
Existing heating and hot water supply apparatuses face challenges in maintaining hot water discharge at set temperatures while protecting the heating device from overheating, as the heating capacity required often exceeds the device's maximum capacity, leading to potential damage and inefficient heat exchange.
Innovation Solution
The apparatus includes a heating device, a heating circulation path, a heat exchanger with primary and secondary paths, a bypass path, and a flow rate regulating valve, with a control unit that sets a reference limit flow rate based on the smaller of the maximum heating capacity and the capacity at which the output temperature reaches an upper limit, ensuring the hot water flow rate does not exceed this limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hot water flow rate is increased to meet demand, then hot water supply capacity is improved, but the heating device may overheat and be damaged
Solution Approach 1:
The control unit calculates and sets the reference limit flow rate before hot water supply operation begins, based on the heating device's maximum heating capacity and upper limit temperature. This preliminary determination prevents overloading the heating device during operation, ensuring both high hot water supply capacity and device safety.
2Reliability
If the heating capacity is reduced to protect the heating device, then device safety is improved, but hot water temperature drops below set temperature
Solution Approach 1:
The control unit continuously monitors the relationship between hot water flow rate and heating capacity, using the calculated reference limit flow rate as a feedback threshold. When the required heating capacity approaches the maximum capacity, the system adjusts the hot water flow rate to maintain the heating device output temperature at or below the upper limit, ensuring both device safety and adequate hot water temperature.
3Reliability
If the hot water flow rate is limited to prevent overheating, then heating device protection is improved, but hot water discharge volume is reduced
Solution Approach 1:
The system dynamically determines the reference limit flow rate based on changing parameters such as inlet water temperature, heating device capacity, and upper limit temperature. By adjusting this parameter according to real-time conditions, the system maximizes hot water discharge volume while ensuring the heating device operates within safe temperature limits, resolving the contradiction between protection and productivity.
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 configuration allows for the discharge of hot water at the set temperature while protecting the heating device by limiting the flow rate to prevent overheating and maintaining efficient heat exchange, ensuring reliable operation.
Implementation Method 1
a heat exchanger for hot water supply including a primary-side path and a secondary-side path for heat exchange between liquids
Data Source
AI summary
In a heating and hot water supply apparatus, a heat exchanger for hot water supply includes a primary-side path and a secondary-side path. A bypass path branches from a heating circulation path and is configured such that a heat transfer medium heated by a heating device flows through the primary-side path without passing through a heating terminal when hot water supply operation is performed and then joins the heating circulation path again. A control unit controls a flow rate regulating valve so that a hot water flow rate does not exceed a reference limit flow rate when hot water supply operation is performed. The reference limit flow rate is set on the basis of the smaller one between a maximum heating capacity of the heating device and a heating capacity of the heating device at which an output temperature of the heated heat transfer medium reaches an upper limit temperature.