Stratified Hydrant Boiler Buffering for Low-Loss Heat Storage

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Solution Overview

Problem

Current energy storage solutions for balancing fluctuating renewable energy production and consumption are inefficient and costly, particularly for electricity and district heating, due to limitations in existing hot water boilers and the need for large, expensive infrastructure.

Innovation Solution

A system comprising a hydrant boiler housed in an insulated hut, connected to a solar energy collector and an online energy source, with a controller that forecasts energy consumption and adjusts charging and discharging based on weather and energy availability, allowing for efficient stratification and heat transfer between layers to maximize energy storage capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the upper temperature limit of boilers is increased to improve energy storage capacity, then the energy storage capacity is improved, but heat losses increase in the fourth power of temperature

Engineering Contradiction:
Improveenergy storage capacityVSAvoidheat losses
Core Design Contradiction:
Quantity of substanceVSLoss of energy

Solution Approach 1:

The boiler is divided into multiple stratified layers with different temperature zones. The water volume is segmented into upper, middle, and lower sections, each maintaining different temperatures. This allows the system to store more thermal energy by creating temperature gradients without uniformly increasing the temperature of the entire water volume, thereby reducing overall heat losses while maintaining increased energy storage capacity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the boiler are assigned different temperature characteristics. The upper layers maintain higher temperatures for maximum energy density, while lower layers maintain lower temperatures to reduce heat loss to the environment. This local differentiation of temperature quality allows the system to optimize both energy storage capacity and heat loss reduction simultaneously.

Inventive Principle:
Principle #3Local quality

2Quantity of substance

If larger boilers are used to increase energy storage capacity, then the energy storage capacity is improved, but the insulation effectiveness decreases due to reduced exterior space relative to water content

Engineering Contradiction:
Improveenergy storage capacityVSAvoidinsulation effectiveness
Core Design Contradiction:
Quantity of substanceVSLoss of energy

Solution Approach 1:

The boiler interior is segmented into multiple stratified zones with different temperature levels. This segmentation allows for more efficient use of the water volume, creating temperature gradients that maximize energy storage while maintaining effective insulation throughout the structure. The segmented approach allows better utilization of the boiler's exterior space for insulation purposes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the temperature parameters throughout the boiler volume by creating stratified layers. Instead of uniform high temperature, the system maintains a gradient from hot upper layers to cooler lower layers. This parameter change allows the boiler to store more energy in the upper regions while the lower regions maintain temperatures that reduce heat loss, thereby improving overall insulation effectiveness.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If hot water boilers are dimensioned small to meet domestic hot water needs, then the ease of operation is improved, but the energy supply buffering capacity becomes marginal

Engineering Contradiction:
Improveease of operationVSAvoidenergy supply buffering capacity
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The boiler is segmented into functional zones: upper layers dedicated to domestic hot water supply and lower layers dedicated to energy buffering and storage. This segmentation allows the single boiler to simultaneously provide both domestic hot water needs and large-scale energy buffering capacity, resolving the contradiction between ease of operation and buffering capacity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The boiler is designed to perform multiple functions simultaneously: it serves as both a domestic hot water generator and a large-capacity energy buffer. The stratified structure enables the upper portions to fulfill domestic hot water demands while the lower portions provide substantial energy storage and buffering capacity, making the system universally applicable to both needs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Loss of energy

If thick insulation is applied to boilers, then the heat loss is reduced, but the exterior space is reduced making thick insulation impractical

Engineering Contradiction:
Improveheat lossVSAvoidexterior space
Core Design Contradiction:
Loss of energyVSArea of stationary object

Solution Approach 1:

The system changes the temperature parameters within the boiler by creating stratified layers. The lower layers maintain lower temperatures which reduces the temperature differential between the boiler interior and exterior environment. This parameter change reduces the driving force for heat loss, allowing effective heat loss reduction without requiring excessively thick insulation layers.

Inventive Principle:
Principle #35Parameter changes

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

The system effectively stores and releases heat energy, reducing material and construction costs while minimizing heat losses, enabling efficient balancing of energy supply and demand with a larger energy storage capacity at a lower cost compared to traditional solutions.

Implementation Method 1

a solar energy collector to the hydrant boiler

Methodology Applied
Scientific EffectSolar energy collection: Solar Energy

Implementation Method 2

connecting a solar energy collector to the hydrant boiler

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 3

the hut is separated by insulation from the building

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 4

efficient stratification and heat transfer between layers

Methodology Applied
Scientific EffectHeat transfer: Convection

Implementation Method 5

heat transfer between layers

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2873940A1Renewable energy storing
Publication Date: 2015.05.20 SOLIXI OY
  • EP2873940A1 patent drawingFigure 1
  • EP2873940A1 patent drawingFigure 2
  • EP2873940A1 patent drawingFigure 3~4

AI summary

A heat buffering system that has a hydrant boiler (100) for storing energy and a hut (101) for housing the hydrant boiler outside a building (102) being heated using the energy stored in the hydrant boiler. The hut is insulated. The system has a heat source coupling (140,141) for connecting a local solar energy collector to the hydrant boiler. Heat is stored in the hydrant boiler in separately controllable layers. Heat is transferred from one of the layers to at least one other layer. A controller (180) is configured to control charging and discharging of the hydrant boiler (100). Buffered energy can be used for heating the building (102) or for selling to others via district heating.