Continuous-Flow Water Heating Control for Stable Outlet Temperature

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Solution Overview

Problem

Conventional water heating systems face challenges in maintaining precise domestic hot water target temperatures with variable heat requirements, leading to fluctuations and reduced service life due to cyclic operation of heat generators and pumps, which results in inefficient heat transfer and comfort issues.

Innovation Solution

The method involves modulating both the heat generator output and heating fluid volume flow to regulate the outlet water temperature, allowing for faster and more precise control of temperature deviations by utilizing different inertias and reaction times of these parameters, thereby maintaining a stable target temperature with extended cycle times and reduced mechanical stress on components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the heat generator and circulating pump operate cyclically to meet low heat requirements, then the system can provide heating when heat demand is below minimum output, but the outlet temperature fluctuates and component service life is reduced

Engineering Contradiction:
Improveheat requirement coverageVSAvoidtemperature stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies dynamics by making the heating fluid volume flow variable through pump modulation. Instead of fixed cyclic operation, the system dynamically adjusts the volume flow rate to match instantaneous heat requirements, enabling continuous adaptation to varying thermal demands while maintaining stable outlet temperatures and extending component service life through reduced mechanical stress from eliminated frequent cycling

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of heating fluid volume flow from fixed to variable. By modulating the pump to vary the volume flow rate of heating fluid through the heat exchanger, the system can precisely control heat transfer to match demand, eliminating the need for cyclic operation and its associated temperature fluctuations while improving temperature stability and component reliability

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the heat generator operates at minimum non-zero output, then low heat requirements can be met, but the outlet temperature cannot be maintained precisely and components experience increased wear from frequent cycling

Engineering Contradiction:
Improveheat output controlVSAvoidtemperature control precision
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent changes the controlled parameter from heat generator output to heating fluid volume flow. By modulating the pump to vary volume flow rate while maintaining continuous heat generator operation, the system achieves precise temperature control without the on/off cycling that causes wear and temperature instability. This parameter substitution enables fine-grained control precision while improving ease of operation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical on/off switching of the heat generator with a fluid-based control mechanism (variable volume flow pump). This substitution eliminates the mechanical stress of frequent start-stop cycles on the heat generator and its components, reducing wear while maintaining precise temperature control through continuous adjusted operation

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If the circulating pump speed is increased to meet higher heat demands, then heat transfer efficiency improves, but energy consumption increases and mechanical stress on components rises

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidpump energy consumption
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by implementing variable speed pump operation that adapts to instantaneous heat requirements. The pump speed is continuously modulated to provide only the necessary volume flow rate for current demand, avoiding the energy waste of maintaining high speed when low heat transfer is sufficient. This dynamic adjustment optimizes the balance between heat transfer efficiency and energy consumption while reducing mechanical stress from constant high-speed operation

Inventive Principle:
Principle #15Dynamics

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 enhances hot water convenience and service life by maintaining precise target temperatures with low and changing heat requirements, reducing fluctuations and improving efficiency by optimizing heat transfer and minimizing component wear.

Implementation Method 1

a heat generator (1) heats a heating fluid (3) conveyed in a circuit (3, 17) by a pump (4)

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

the heating fluid (3) heats drinking water (7) flowing through it via a heat exchanger (6)

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

a heat generator heats a heating fluid conveyed by a pump in a circuit

Methodology Applied
Scientific EffectPumping: Pump

Data Source

PatentEP2372259B1Method for heating water according to the circulation principle and water heating system
Publication Date: 2016.05.11 ROBERT BOSCH GMBH
  • EP2372259B1 patent drawingFigure 1~3
  • EP2372259B1 patent drawingFigure 4
  • EP2372259B1 patent drawingFigure 5

AI summary

The invention relates to a method for heating water with a variable volume flow according to the continuous flow principle and a water heating system in which a heat generator heats a heating fluid circulated by a pump in a circuit, the heating fluid heats water that is conducted in a continuous flow, and at least one sensor arranged in a water path measures an outlet temperature TW and/or a volume flow rate VW of the water. The object of the invention is to extend the cycle times with low heat requirements while largely retaining conventional components and to reduce the deviations from the target temperature with changing heat requirements and thus to offer a high level of hot water convenience and an improved mode of operation with regard to the service life of the components. The method according to the invention is characterized in that the modulation ranges of pump and heat generator as well as the different thermal and flow-mechanical inertias of the water heating system are specifically included in the temperature control method.