Intercooler Bypass Control to Prevent Wet Compression
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Solution Overview
Problem
Conventional air-conditioning apparatuses with multistage compression refrigeration cycles face challenges in achieving high operating efficiency due to excessive cooling of refrigerant during low heat source temperatures, leading to refrigerant wetness and compressor reliability issues.
Innovation Solution
The refrigeration apparatus incorporates an intercooler bypass tube to prevent refrigerant flow to the intercooler when the heat source temperature is equal to or less than the saturation temperature, and controls the flow rate of water through the intercooler to maintain the refrigerant above saturation temperature, preventing wetness and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the intercooler is used to cool the refrigerant discharged from the first-stage compression element, then the temperature of the refrigerant drawn into the second-stage compression element is reduced and heat radiation loss in the outdoor heat exchanger is decreased, but the refrigerant is excessively cooled under low heat source temperature conditions causing wetness and compromising compressor reliability
Solution Approach 1:
The patent implements dynamic control of the intercooler by switching between two operational modes: normal cooling mode and bypass mode. The control unit dynamically adjusts the refrigerant flow path based on real-time temperature conditions, opening or closing the intercooler bypass tube to prevent excessive cooling and wetness while maintaining efficient heat exchange when conditions are favorable.
Solution Approach 2:
The patent changes the operational parameters of the intercooler system by introducing a bypass path that alters the refrigerant flow characteristics. By controlling the bypass tube, the system can adjust the degree of cooling applied to the refrigerant, effectively managing the temperature parameter to avoid saturation and wetness while still achieving heat radiation loss reduction when appropriate.
2Productivity
If the refrigerant is cooled in the intercooler to reduce the temperature difference with the heat source, then the operating efficiency is improved, but the refrigerant temperature drops to or below saturation temperature causing wetness
Solution Approach 1:
The patent implements a feedback control mechanism where the control unit continuously monitors the temperature of the refrigerant and the heat source, and adjusts the intercooler operation accordingly. When the refrigerant temperature approaches or reaches saturation temperature, the control unit activates the bypass tube to prevent further cooling, thereby maintaining optimal operating efficiency while preventing wetness and ensuring compressor reliability.
3Reliability
If the intercooler bypass tube is used to prevent refrigerant flow to the intercooler when heat source temperature is low, then wetness is prevented and compressor reliability is enhanced, but the refrigerant temperature cannot be reduced and heat radiation loss increases
Solution Approach 1:
The patent employs dynamic switching between two operational states: when the heat source temperature is low, the bypass tube is opened to prioritize compressor reliability by preventing wetness; when the heat source temperature is favorable, the bypass tube is closed to enable efficient cooling and reduce heat radiation loss. This dynamic adaptation allows the system to optimize performance based on real-time conditions.
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 solution effectively prevents refrigerant wetness and reduces heat radiation loss, enhancing compressor reliability and operating efficiency by maintaining the refrigerant temperature and power consumption.
Implementation Method 1
an intercooler (7) 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), the intercooler (7) functioning as a cooler of the refrigerant discharged from the first-stage compression element (2c) and drawn into the second-stage compression element (2d)
Implementation Method 2
the temperature of water to be fed to the intercooler is increased by a predetermined temperature or more
Data Source
Figure 1
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AI summary
In a refrigeration apparatus that carries out a multistage compression refrigeration cycle, it is possible to prevent refrigerant drawn into a second-stage compression element from becoming wet, even under operation conditions in which the temperature of a heat source of the intercooler is low. An air-conditioning apparatus (1) has a two-stage compression mechanism (2); a heat source-side heat exchanger (4); a usage-side heat exchanger (6); an intercooler (7) which is provided to an intermediate refrigerant tube (8) for drawing refrigerant discharged from a first-stage compression element (2c) into a second-stage compression element (2d); and an intercooler bypass tube (9) connected to the intermediate refrigerant tube (8) so as to bypass the intercooler (7). In the air-conditioning apparatus (1), a wet prevention control is performed using the intercooler bypass tube (9) so that refrigerant does not flow to the intercooler (7) when the heat source temperature of the intercooler (7) or the outlet refrigerant temperature of the intercooler (7) is equal to or less than the saturation temperature of the refrigerant fed from the first-stage compression element (2c) to the second-stage compression element (2d).