Dual-Loop Hot Water Heating With Tank Buffer and Heat Pump Control

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Solution Overview

Problem

Conventional hot water circulation heating systems, especially those using heat pumps, face inefficiencies in thermal performance and energy conservation, particularly when employed in indoor settings, leading to reduced benefits compared to systems using boilers or electric heaters.

Innovation Solution

A hot water circulation heating system incorporating a tank, room radiators, and a vapor compression heat pump with a second circulation pump to efficiently circulate and reheat hot water, optimizing thermal efficiency by controlling the heat pump's operation based on room and water temperature settings, and using inverter control for the compressor to conserve energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a heat pump is employed as a heat source in an air conditioning system that causes hot water to circulate indoors, then thermal efficiency can be improved, but the degree of improvement becomes smaller when the cold water/hot water supplying means are installed outdoors compared to when installed indoors

Engineering Contradiction:
Improvethermal efficiencyVSAvoidsystem configuration complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The system is divided into two independent circulation loops: a first loop for heating rooms via radiators and a second loop for heating water in the tank via heat pump. This segmentation allows the heat pump to efficiently heat water while the radiators distribute heat to rooms, resolving the contradiction by optimizing each loop's function separately.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A tank serving as a heat storage device is introduced as an intermediary between the heat pump and the radiators. The heat pump heats water in the tank, which then serves as a thermal buffer and distribution medium for the radiators, enabling efficient heat transfer and system operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Area of stationary object

If the cold water/hot water supplying means are installed outdoors, then space utilization is improved, but the thermal efficiency improvement from using a heat pump becomes smaller due to heat loss in the tank

Engineering Contradiction:
Improveindoor space utilizationVSAvoidheat loss in tank
Core Design Contradiction:
Area of stationary objectVSLoss of energy

Solution Approach 1:

The system converts the potential harm of heat loss in the outdoor tank into a benefit by using the tank as a thermal buffer. The large volume of water in the tank stores heat efficiently, and the two-loop configuration ensures continuous circulation and heat distribution, turning the tank's thermal mass into an advantage for system stability and efficiency.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Temperature

If hot water temperature is maintained at high levels, then heating performance is improved, but energy consumption increases

Engineering Contradiction:
Improvehot water temperatureVSAvoidenergy consumption
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The system uses periodic circulation of hot water through the radiators and tank, combined with inverter control of the compressor, to maintain optimal temperatures only when needed. The circulation pumps operate periodically to distribute heat, reducing continuous energy consumption while maintaining effective heating performance.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The inverter-controlled compressor dynamically adjusts its operation based on system needs, varying speed and power consumption to match heating demands. This dynamic control optimizes the balance between maintaining high hot water temperature for effective heating and reducing energy consumption during lower demand periods.

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

The system achieves high thermal efficiency and energy conservation by maintaining optimal hot water temperatures and reducing energy consumption, especially in buildings with high heat storage capacity, such as those with brick or stone outer walls.

Implementation Method 1

The heat pump includes a compressor, a radiator, an expansion mechanism and an evaporator and heats the hot water that flows out from the tank by heat emitted from the radiator

Methodology Applied
Scientific EffectHeat pump heating: Heat Exchanger

Implementation Method 2

The room radiator is disposed in a room of the building and causes heat that the hot water has to radiate into room air of the room

Methodology Applied
Scientific EffectHeat radiation: Thermal Radiation

Implementation Method 3

The heat pump includes a compressor, a radiator, an expansion mechanism and an evaporator

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP2056025B1Hot water circulation heating system for heating building by hot water circulation
Publication Date: 2018.05.23 DAIKIN INDUSTRIES LTD
  • EP2056025B1 patent drawingFigure 1
  • EP2056025B1 patent drawingFigure 2
  • EP2056025B1 patent drawingFigure 3

AI summary

A hot water circulation heating system performs heating by causing hot water to circulate and comprises: a tank (40) that stores the hot water; a room radiator; an indoor heating-use circulation pump (51) that causes the hot water to flow from the tank (40) to the room radiator and returns the hot water back to the tank (40); a heat pump (10) that heats the hot water; and a hot water heating-use circulation pump (25). The hot water heating-use circulation pump (25) causes the hot water to flow from the tank (40) to the heat pump (10) and returns the hot water back to the tank (40). The heat pump (10) includes a compressor (11), a radiator (12), an expansion valve (13) and an evaporator (14) and heats the hot water by heat emitted from the radiator (12).