Horizontal Heat Exchanger Layout for Hot Water Tank Stratification

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Solution Overview

Problem

Conventional hot water supply apparatuses experience reduced usable hot water due to thermal stratification and inefficient heat exchange, leading to decreased heating efficiency and increased energy consumption.

Innovation Solution

A hot water supply apparatus with a heat exchanger pipe disposed horizontally in the hot water tank to minimize downward water flow and mixing, using a spirally wound design that connects to both the upper and lower portions of the tank, and employing a supercritical refrigerant heat pump cycle for enhanced energy efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a pipe heat exchanger is disposed vertically in the hot water tank, then heat exchange function is provided, but downward stream of water is generated and mixed layer increases reducing usable hot water

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidusable hot water amount
Core Design Contradiction:
Loss of energyVSQuantity of substance

Solution Approach 1:

The patent changes the orientation of the heat exchanger pipe from vertical to horizontal arrangement in the hot water tank. This dimensional change prevents the formation of downward water streams that occur with vertical pipes, thereby reducing mixed layer formation while maintaining heat exchange functionality through the horizontal pipe configuration

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Temperature

If water temperature in the hot water tank is increased for next heating cycle, then heating capacity is improved, but heat pump operation efficiency is deteriorated

Engineering Contradiction:
Improvewater temperatureVSAvoidheat pump operation efficiency
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent changes the physical parameter of water temperature distribution in the hot water tank by suppressing mixed layer formation through horizontal pipe arrangement. This maintains higher average water temperature in the tank while preventing excessive temperature increases that would deteriorate heat pump efficiency, optimizing the balance between heating capacity and energy consumption

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If the mixed layer becomes large due to downward stream, then heat distribution is improved, but temperature of stored hot water is lowered and heating efficiency is reduced

Engineering Contradiction:
Improvethermal stratificationVSAvoidheating efficiency
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent applies horizontal arrangement of heat exchanger pipes instead of vertical arrangement, which changes the flow pattern dimension and prevents downward streams that cause excessive mixing. This maintains thermal stratification stability while avoiding energy losses from excessive mixed layer formation

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 suppresses the formation of a mixed layer, maximizing usable hot water and improving heating efficiency while reducing energy consumption.

Implementation Method 1

a heat exchanger which is formed with a pipe in the hot water tank and exchanges between heat of hot water in the hot water tank and heat of water flowing through the pipe

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

employing a supercritical refrigerant heat pump cycle for enhanced energy efficiency

Methodology Applied
Scientific EffectHeat pump cycle:

Data Source

PatentEP2325569B1Hot water supply apparatus
Publication Date: 2020.02.12 PANASONIC HOLDINGS CORP
  • EP2325569B1 patent drawingFigure 1
  • EP2325569B1 patent drawingFigure 2
  • EP2325569B1 patent drawingFigure 3

AI summary

A hot water supply apparatus comprising a hot water tank 1, a pipe disposed in the hot water tank 1, and a heat exchanger 9 for exchanging between heat of hot water in the hot water tank 1 and heat of water flowing through the pipe, wherein the pipe is disposed in the hot water tank 1 substantially in a form of a horizontal plane, and heating efficiency of the hot water tank 1 is enhanced.