Freezing Unit Receiver Venting for Balanced Refrigerant Distribution

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing refrigeration apparatuses with multiple heat-source units experience unbalanced distribution of excess refrigerant, leading to overflow issues when refrigerant flow differences cause uneven accumulation in high-pressure receivers.

Innovation Solution

A refrigeration apparatus with a controller that adjusts the opening degrees of motor-operated valves in each heat-source unit's bypass channel to regulate the extraction of refrigerant, ensuring balanced distribution by controlling the ratio of liquid and gas refrigerant in high-pressure receivers and preventing liquid compression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If multiple heat-source units are connected in parallel to store excess refrigerant, then the refrigerant storage capacity is improved, but the refrigerant distribution balance deteriorates

Engineering Contradiction:
Improverefrigerant storage capacityVSAvoidrefrigerant distribution balance
Core Design Contradiction:
Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The control unit continuously monitors the refrigerant accumulation state in each high-pressure receiver and dynamically adjusts the opening degree of motor-operated valves in bypass channels. This feedback mechanism ensures that when one receiver accumulates excessive refrigerant, the system automatically redirects refrigerant flow to maintain balanced distribution across all receivers, thereby resolving the contradiction between increased storage capacity and distribution balance.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system employs dynamically adjustable motor-operated valves in each heat-source unit's bypass channel, allowing the refrigerant flow path to be flexibly controlled. By varying the opening degrees of these valves based on real-time receiver states, the system can adaptively balance refrigerant distribution while maintaining the benefits of multiple parallel receivers for excess refrigerant storage.

Inventive Principle:
Principle #15Dynamics

2Speed

If refrigerant flows readily in certain heat source units, then the refrigerant flow efficiency is improved, but the refrigerant accumulation balance deteriorates

Engineering Contradiction:
Improverefrigerant flow efficiencyVSAvoidrefrigerant accumulation balance
Core Design Contradiction:
SpeedVSStability of the object's composition

Solution Approach 1:

The system applies different control strategies to different heat-source units based on their individual refrigerant flow characteristics. By independently adjusting the opening degree of motor-operated valves in each unit's bypass channel according to its specific flow efficiency and accumulation state, the system maintains overall balance while allowing local variations in flow behavior.

Inventive Principle:
Principle #3Local quality

3Volume of stationary object

If the high-pressure receiver capacity is increased to store more excess refrigerant, then the refrigerant storage capability is improved, but the overflow risk increases

Engineering Contradiction:
Improvehigh-pressure receiver capacityVSAvoidoverflow prevention
Core Design Contradiction:
Volume of stationary objectVSReliability

Solution Approach 1:

The system proactively monitors refrigerant accumulation levels in each high-pressure receiver and takes preventive action by adjusting bypass valve opening degrees before the receivers reach their maximum capacity. This preliminary intervention prevents overflow conditions from developing, allowing the system to safely operate with larger receiver capacities while maintaining reliability.

Inventive Principle:
Principle #10Preliminary action

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 solution effectively suppresses drift between high-pressure receivers, prevents liquid compression, and enhances system reliability by maintaining a balanced refrigerant distribution, thereby preventing overflow and optimizing heat exchange efficiency.

Implementation Method 1

a first motor-operated valve provided to the first bypass channel... a second motor-operated valve provided to the second bypass channel... the opening degree of the first motor-operated valve is controlled so as to be greater than the opening degree of the second motor-operated valve

Methodology Applied
Scientific EffectFluid flow control through valve opening: Valve

Implementation Method 2

a first bypass channel to return refrigerant positioned at a top part in the first high-pressure receiver to an intake side of the first compressor

Methodology Applied
Scientific EffectRefrigerant circulation through bypass channel:

Implementation Method 3

first detecting means configured to detect whether the first high-pressure receiver is near flooding, second detecting means configured to detect whether the second high-pressure receiver is near flooding

Methodology Applied
Scientific EffectLiquid level detection:

Implementation Method 4

a first heat-source-side heat exchanger... a second heat-source-side heat exchanger

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 5

a first compressor... a second compressor

Methodology Applied
Scientific EffectGas compression: Gas Compressor

Data Source

PatentEP3101372B1Freezing unit
Publication Date: 2018.03.21 DAIKIN INDUSTRIES LTD
  • EP3101372B1 patent drawingFigure 1
  • EP3101372B1 patent drawingFigure 2
  • EP3101372B1 patent drawingFigure 3

AI summary

The present invention provides a refrigeration apparatus whereby a bias in the amount of excess refrigerant in high-pressure receivers can be suppressed even when a plurality of heat-source units having high-pressure receivers are connected. A first heat-source unit (2a) and a second heat-source unit (2b) each have a compressor (21 a, 21 b), heat-source-side heat exchangers (24a, 25a, 24b, 25b), a receiver (80a, 80b), a receiver liquid level detecting tube (43a, 43b) for detecting a state of near flooding, a receiver venting tube (41 a, 41 b), and an motor-operated valve (42a, 42b) provided to the receiver venting tube (41 a, 41 b). Heat-source-side controllers (20a, 20b) perform opening degree control so that the opening degree of the motor-operated valve corresponding to the receiver (80a, 80b) other than a receiver for which a nearly flooded state is detected is greater than the opening degree of the motor-operated valve corresponding to the receiver (80a, 80b) for which a nearly flooded state is detected.