Container Refrigeration Reheat Control for Stronger Dehumidification

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Solution Overview

Problem

Container refrigeration devices face insufficient dehumidification performance, particularly when handling precision machines or fresh foods, as the existing reheat heat exchanger dehumidification method is inadequate.

Innovation Solution

The implementation of multiple dehumidification control strategies, including varying refrigerant pressure, superheat degree, and compressor revolution speed, along with the use of a reheat heat exchanger and a flow regulating valve, to enhance dehumidification and cooling performance within a predetermined temperature range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the reheat heat exchanger is used for dehumidification, then the temperature inside the container is maintained, but the dehumidification performance is insufficient

Engineering Contradiction:
Improvedehumidification performanceVSAvoidtemperature maintenance
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent implements dynamic control of refrigerant pressure and flow rate to the reheat heat exchanger based on dehumidification load conditions. The system switches between multiple dehumidification control modes (first, second, and third controls) that adjust refrigerant parameters dynamically, transforming the static reheat operation into a dynamic adaptive process that optimizes both dehumidification effectiveness and temperature maintenance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes physical parameters of the refrigerant system including pressure, flow rate, and superheat degree to enhance dehumidification performance. By increasing refrigerant pressure discharged to the reheat heat exchanger and adjusting the flow rate, the system modifies thermal exchange parameters to achieve better dehumidification while maintaining temperature control.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the refrigerant flow rate is increased to improve cooling performance, then the cooling performance increases, but the dehumidification performance decreases

Engineering Contradiction:
Improvecooling performanceVSAvoiddehumidification performance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent segments the refrigerant flow into two separate paths: one path through the evaporator for cooling and another path directly to the reheat heat exchanger for dehumidification. This segmentation allows independent control of cooling and dehumidification functions, enabling the system to optimize refrigerant flow rate for cooling while simultaneously directing additional refrigerant to the reheat heat exchanger for enhanced dehumidification performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The reheat heat exchanger acts as an intermediary component that receives refrigerant directly from the compressor and uses it to dehumidify air that has been cooled by the evaporator. This intermediary mechanism allows the system to decouple the cooling and dehumidification processes, enabling independent optimization of refrigerant flow rates for each function.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

These controls increase dehumidification performance by boosting the heating and cooling capabilities of the reheat heat exchanger and evaporator, effectively maintaining the desired temperature and humidity levels inside the container.

Implementation Method 1

In the evaporator (33), the refrigerant is cooled by exchanging heat with the air sucked from the inside of the container (C)

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

condensation occurs, thereby dehumidifying the inside of the container (C)

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 3

the discharged refrigerant exchanges heat with the air having been subjected to cooling dehumidification in the evaporator (33), and the air having been subjected to cooling dehumidification is heated

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 4

the pressure of the refrigerant discharged from the compressor (30) is caused to be higher than the pressure of the refrigerant discharged from the compressor (30) under the first dehumidification control

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP2881684B1Container refrigeration device
Publication Date: 2019.05.01 DAIKIN INDUSTRIES LTD
  • EP2881684B1 patent drawingFigure 1
  • EP2881684B1 patent drawingFigure 2
  • EP2881684B1 patent drawingFigure 3

AI summary

A container refrigeration device aims to improve dehumidification performance of the container refrigeration device. The container refrigeration device is configured to perform, in accordance with a dehumidification load, first dehumidification control under which air having passed through an evaporator is heated by exchanging heat with a refrigerant in a reheat heat exchanger, and blown into an inside of a container, and second dehumidification control under which a pressure of the refrigerant discharged from a compressor and flowing into the reheat heat exchanger is caused to be higher than a pressure of the refrigerant discharged from the compressor under the first dehumidification control, and a flow rate of the refrigerant discharged from the compressor is regulated such that a temperature inside the container is within a predetermined temperature range.