CO2 Refrigeration Intercooler Layout for Heat Loss and Icing Control
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Solution Overview
Problem
Refrigeration apparatuses using carbon dioxide as a refrigerant in a supercritical range face inefficiencies due to high heat radiation loss and icing-up phenomena, particularly when operating in air-cooling mode, as the temperature difference between the refrigerant and air source is large, leading to reduced heat transfer performance and equipment reliability.
Innovation Solution
The refrigeration apparatus incorporates an intercooler integrated with the heat source-side heat exchanger, positioned above to enhance air flow and reduce heat radiation loss, and configures heat transfer channels to optimize temperature differences, ensuring improved heat transfer performance and preventing icing-up by directing airflow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the outdoor heat exchanger functions as a refrigerant cooler using air as heat source, then the refrigerant can be cooled during air-cooling operation, but the large temperature difference between refrigerant and air causes high heat radiation loss and reduced operating efficiency
Solution Approach 1:
The outdoor heat exchanger is divided into two functional sections: an upper intercooler section for cooling intermediate-pressure refrigerant and a lower gas cooler section for cooling high-pressure refrigerant. This segmentation allows each section to operate at optimized temperature differences with the air heat source, reducing overall heat radiation loss while maintaining high operating efficiency.
2Loss of energy
If the intercooler is integrated with the heat source-side heat exchanger and disposed in the upper part, then air flow is enhanced and heat radiation loss is reduced, but the structural complexity increases
Solution Approach 1:
The intercooler and gas cooler are merged into a single integrated outdoor heat exchanger assembly with a unified air flow path. The intercooler is positioned in the upper part and the gas cooler in the lower part, sharing common structural components and air flow channels, which reduces overall device complexity while maintaining the benefits of reduced heat radiation loss.
3Productivity
If the refrigerant operates in supercritical range with large temperature difference, then cooling capacity is achieved, but icing-up phenomena occur and equipment reliability decreases
Solution Approach 1:
Different temperature control strategies are applied to different sections of the system. The intercooler section uses intermediate-pressure refrigerant at lower temperatures appropriate for its cooling function, while the gas cooler section handles high-pressure supercritical refrigerant at higher temperatures. This local quality differentiation prevents icing-up in the intercooler section while maintaining cooling capacity in the gas cooler section, thereby improving equipment reliability.
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 configuration minimizes heat radiation loss, enhances heat transfer performance, and improves equipment reliability by maintaining optimal temperature differences and preventing icing issues, thus achieving more efficient operation during both cooling and heating cycles.
Implementation Method 1
an intercooler having air as a heat source, the intercooler being provided to an intermediate refrigerant tube for drawing the refrigerant discharged from the first-stage compression element into the second-stage compression element, and the intercooler functioning as a cooler of the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element
Implementation Method 2
a heat source-side heat exchanger that uses air as a heat source
Implementation Method 3
an indoor heat exchanger
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An air-conditioning apparatus (1) uses carbon dioxide as a refrigerant, and comprises a two-stage-compression-type compression mechanism (2), a heat source-side heat exchanger (4), an expansion mechanism (5), a usage-side heat exchanger (6), and an intercooler (7) which is provided to an intermediate refrigerant tube (8) for drawing the refrigerant discharged from a first-stage compression element (2c) into a second-stage compression element (2d), and which functions as a cooler of the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element. The intercooler (7) constitutes a heat exchanger integrated with the heat source-side heat exchanger (4), and the intercooler is disposed in the upper part of the heat exchanger.