Two-Stage Refrigeration Cycle With Intercooler Bypass Startup Control
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Solution Overview
Problem
Conventional refrigeration apparatuses with multistage compression cycles face inefficiencies due to high heat radiation loss in outdoor heat exchangers and reliability issues caused by liquid refrigerant accumulation in intercoolers, leading to reduced operating efficiency and compressor reliability.
Innovation Solution
The refrigeration apparatus incorporates an intercooler bypass tube and an intake return tube to bypass the intercooler during startup, reducing pressure and preventing liquid refrigerant accumulation, and includes a switching mechanism for switching between cooling and heating operations to manage refrigerant flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the refrigerant discharged from the first-stage compression element is drawn into the second-stage compression element through the intercooler, then the temperature of the refrigerant is reduced and heat radiation loss is minimized, but liquid refrigerant may accumulate in the intercooler and be drawn into the second-stage compression element causing liquid compression
Solution Approach 1:
The patent introduces an intake return tube as an intermediary component that connects the intercooler to the intake side of the compression mechanism. This intermediary pathway allows liquid refrigerant accumulated in the intercooler to be returned to the intake side before being drawn into the second-stage compression element, thereby preventing liquid compression while maintaining the cooling function of the intercooler
Solution Approach 2:
The patent implements preliminary action by returning liquid refrigerant from the intercooler to the intake side before the compression cycle begins or before liquid compression could occur. This preliminary removal of liquid refrigerant ensures that only vapor refrigerant enters the second-stage compression element, preventing reliability issues while maintaining energy efficiency
2Productivity
If the refrigerant is cooled in the intercooler before entering the second-stage compression element, then the temperature difference in the outdoor heat exchanger is reduced improving efficiency, but the device complexity increases due to additional tubes and switching mechanisms
Solution Approach 1:
The intercooler is designed to serve multiple functions: it cools the refrigerant during normal operation to improve operating efficiency, and simultaneously serves as a reservoir whose contents can be returned to the intake side during startup or shutdown phases. The intake return tube and bypass tube work together to provide multiple flow path configurations, allowing the system to maintain high operating efficiency while managing the complexity through integrated multi-functionality
3Adaptability or versatility
If the refrigerant flow is switched between cooling and heating operations, then the adaptability of the system is improved, but the difficulty of controlling refrigerant flow increases
Solution Approach 1:
The patent implements dynamic control by providing switching mechanisms that can change the refrigerant flow configuration based on operational requirements. The system dynamically switches between cooling operation (where refrigerant flows through the intercooler) and heating operation (where refrigerant bypasses the intercooler via the bypass tube), allowing adaptability to different seasonal and operational conditions while managing control complexity through well-defined switching states
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 reduces heat radiation loss, prevents liquid compression in the second-stage compression element, and enhances the reliability of the compressor by ensuring that liquid refrigerant is not drawn into the second-stage compression element, thereby improving overall operating efficiency and reliability.
Implementation Method 1
The intercooler is provided to an intermediate refrigerant tube for drawing refrigerant discharged from the first-stage compression element into the second-stage compression element, and the intercooler functions as a cooler of the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element
Implementation Method 2
the refrigerant flowing through the heat source-side heat exchanger is a two-phase refrigerant that has undergone phase change from liquid to vapor in an evaporator
Implementation Method 3
the compression mechanism has a plurality of compression elements and is configured so that the refrigerant discharged from a first-stage compression element, which is one of the plurality of compression elements, is sequentially compressed by a second-stage compression element
Data Source
Figure 1
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AI summary
An air-conditioning apparatus (1) is provided with a two-stage-compression-type compression mechanism (2), a heat source-side heat exchanger (4), a usage-side heat exchanger (6), an intercooler (7), an intercooler bypass tube (9), and an intake return tube (92). The intercooler (7) is provided to an intermediate refrigerant tube (8) for drawing refrigerant discharged from the first-stage compression element (2c) into the second-stage compression element (2d), and the intercooler functions as a cooler of the refrigerant discharged from the first-stage compression element (2c) and drawn into the second-stage compression element (2d). The intercooler bypass tube (9) is connected to the intermediate refrigerant tube (8) so as to bypass the intercooler (7). The intake return tube (92) is a refrigerant tube for connecting the intercooler (7) and the intake side of the compression mechanism (2).