Heat Pump Compressor Pressure Control for Multi-Unit Temperature Demand

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Solution Overview

Problem

Heat pump systems operating with multiple usage units connected to a single heat source face challenges in supplying refrigerant optimally, as different units require varying outlet temperatures for different applications, leading to inefficient refrigerant distribution.

Innovation Solution

The system controls the compressor's operating capacity to set a target discharge pressure based on the highest required usage temperature across individual units, using equivalent target values for aqueous and air medium temperatures, and adjusts refrigerant flow rates and subcooling settings to ensure optimal refrigerant distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the heat pump system supplies refrigerant to multiple usage units with different temperature requirements, then the system can serve diverse applications, but the refrigerant distribution becomes inefficient and difficult to control

Engineering Contradiction:
Improveability to serve diverse applicationsVSAvoidrefrigerant distribution efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent applies local quality by determining individual equivalent target values for each usage unit based on their specific temperature requirements and characteristics. Each usage unit receives customized refrigerant control parameters (subcooling degrees) tailored to its local needs, allowing diverse applications to be served efficiently without compromising overall system performance

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts the compressor operating capacity and refrigerant flow distribution based on real-time conditions. The control method continuously calculates equivalent target values and modifies subcooling degrees for different usage units, enabling adaptive refrigerant distribution that responds to changing temperature requirements and load conditions

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the compressor discharge pressure is controlled to a single target value, then the system operation is simplified, but the refrigerant supply cannot be optimized for individual usage units with different temperature requirements

Engineering Contradiction:
Improvesystem control simplicityVSAvoidrefrigerant supply optimization
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent introduces an intermediary concept of 'equivalent target value' that bridges the gap between simple single-point control and complex multi-parameter optimization. By converting diverse temperature requirements into unified equivalent target values, the system maintains operational simplicity while achieving optimized refrigerant distribution through intermediate calculation steps

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the control parameter from direct temperature control to equivalent target value control. By transforming multiple temperature parameters into a single equivalent target value that reflects the highest requirement, the system simplifies the control variable while still optimizing refrigerant supply to meet all individual usage unit requirements

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the system uses individual temperature control for each usage unit, then each unit receives optimal refrigerant, but the overall system control complexity increases

Engineering Contradiction:
Improverefrigerant control precisionVSAvoidcontrol system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges individual usage unit control into a unified control framework by combining multiple temperature requirements into a single equivalent target value. This consolidation reduces control complexity while maintaining precision, as the equivalent target value encapsulates the cumulative effect of all individual requirements through a single control parameter

Inventive Principle:
Principle #5Merging (Combining)

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 allows for efficient refrigerant supply to all units, maintaining consistent subcooling in usage-side heat exchangers and preventing refrigerant accumulation, thereby optimizing performance across diverse applications.

Implementation Method 1

a heat source unit (2) having a compressor (21) for compressing a refrigerant

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

usage-side heat exchangers (41a, 41b) which function as radiators for the refrigerant

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

heating an aqueous medium through radiation by the refrigerant in a usage-side heat exchanger

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2402682B1Heat pump system
Publication Date: 2018.08.15 DAIKIN INDUSTRIES LTD
  • EP2402682B1 patent drawingFigure 1
  • EP2402682B1 patent drawingFigure 2
  • EP2402682B1 patent drawingFigure 3

AI summary

A heat pump system (1) is provided with a heat source unit (2) having a variable-capacity compressor (21) and a heat-source-side heat exchanger (24) that functions as an evaporator for a refrigerant, and with a plurality of usage units (4a, 4b) connected to the heat source unit (2) and having a usage-side heat exchanger (41a, 41b) that functions as a radiator for the refrigerant. The operating capacity of the compressor (21) is controlled to bring the discharge pressure of the compressor (21), or a state quantity equivalent thereto, to a first target value (A). The first target value (A) is determined on the basis of an equivalent target value (B) equivalent to a usage temperature required in individual usage units.