Hot Water Tank Temperature Sensing for Accurate Boiling Control

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Solution Overview

Problem

The existing water heater systems face challenges in accurately distinguishing between temperature distributions within the hot water tank, leading to potential inaccuracies in controlling the heating process.

Innovation Solution

The system incorporates both an upper part temperature sensor and a lower part temperature sensor within the hot water tank, allowing the controller to execute different boiling operations based on distinct temperature thresholds, thereby improving the accuracy of temperature distribution distinction and heating control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single thermistor is used to measure temperature in the hot water tank, then the device complexity is reduced, but the measurement precision of temperature distribution deteriorates

Engineering Contradiction:
Improvenumber of temperature sensorsVSAvoidtemperature distribution measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The hot water tank is divided into multiple measurement zones (upper part and lower part) with separate temperature sensors (first temperature sensor and second temperature sensor) positioned at different heights. This segmentation allows independent measurement of temperature distributions in different regions, enabling accurate distinction between heat dissipation-type and hot water withdrawal-type temperature distributions without requiring a single complex sensor system

Inventive Principle:
Principle #1Segmentation

2Reliability

If temperature distribution distinction accuracy is improved using multiple sensors, then the reliability of boiling operation control is improved, but the device complexity increases

Engineering Contradiction:
Improveaccuracy of temperature distribution distinctionVSAvoidsensor configuration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Temperature sensors are positioned at specific locations (upper part and lower part of the hot water tank) to capture locally characteristic temperature distributions. The first temperature sensor measures the upper region while the second temperature sensor measures the lower region, allowing the controller to distinguish between heat dissipation patterns and hot water withdrawal patterns based on local temperature differences, thereby improving control reliability with a simple sensor arrangement

Inventive Principle:
Principle #3Local quality

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 enables more precise control over the heating process, reducing the likelihood of unused hot water and minimizing power consumption by accurately determining when to initiate and terminate boiling operations based on temperature gradients within the tank.

Implementation Method 1

an upper part temperature sensor, provided in the hot water tank and provided higher than the lower part temperature sensor, that measures an upper part temperature of the heat medium stored in the hot water tank

Methodology Applied
Scientific EffectTemperature measurement: Thermistor

Implementation Method 2

a heating heat exchanger that heats the heat medium supplied to the hot water tank

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

a first pump that conveys the heat medium to the hot water tank

Methodology Applied
Scientific EffectPump: Pump

Data Source

PatentEP3657091B1Hot water supply device
Publication Date: 2021.10.27 MITSUBISHI ELECTRIC CORP
  • EP3657091B1 patent drawingFigure 1
  • EP3657091B1 patent drawingFigure 2
  • EP3657091B1 patent drawingFigure 3

AI summary

In a case in which an upper part temperature is lower than a first boiling temperature, a controller executes a first boiling operation in which a first pump is operated at a first pump rotation frequency. In a case in which the upper part temperature is lower than a second boiling temperature that is higher than the first boiling temperature and a lower part temperature is lower than a third boiling temperature that is lower than the first boiling temperature, the controller executes a second boiling operation in which the first pump is operated at a second pump rotation frequency that is lower than the first pump rotation frequency.