Intercooler Bypass Control in CO2 Refrigeration Defrosting
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Solution Overview
Problem
Conventional air-conditioning apparatuses using carbon dioxide as a refrigerant face inefficiencies due to high pressure and temperature differences, leading to heat radiation losses and reduced defrosting capacity, especially when operating in supercritical ranges.
Innovation Solution
The refrigeration apparatus incorporates an intercooler and intercooler bypass tube to manage refrigerant flow, allowing the intercooler to function as a cooler during cooling operations and bypassing it during heating operations, minimizing heat radiation and maintaining defrosting efficiency by ensuring refrigerant does not flow to the intercooler after defrosting is complete.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the refrigerant is cooled in the outdoor heat exchanger, then the refrigerant temperature is reduced, but heat radiation losses increase due to large temperature difference
Solution Approach 1:
The patent divides the compression process into two stages with an intercooler between them. The intercooler is segmented from the outdoor heat exchanger, allowing intermediate cooling of the refrigerant without requiring the outdoor heat exchanger to perform the full cooling function, thereby reducing heat radiation losses.
Solution Approach 2:
The intercooler acts as an intermediary heat exchanger between the compression stages. It provides a dedicated cooling function for the intermediate refrigerant without relying on the outdoor heat exchanger, reducing the thermal load and heat radiation losses on the outdoor unit.
2Temperature
If the intercooler is used during heating operation, then refrigerant cooling is provided, but defrosting capacity is reduced
Solution Approach 1:
The patent implements dynamic control of the intercooler bypass tube through a switching mechanism that adjusts refrigerant flow based on operational mode. During heating operation, the bypass tube is activated to divert refrigerant away from the intercooler, preserving defrosting capacity while allowing intercooler usage during cooling operations.
Solution Approach 2:
The bypass tube provides a localized alternative flow path that selectively excludes the intercooler from the refrigerant circuit during heating operation. This local modification allows the system to maintain defrosting capacity in the outdoor heat exchanger while preserving the option to use the intercooler during cooling operations.
3Use of energy by moving object
If multi-stage compression is implemented, then compression efficiency is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple compression stages and the intercooler into a single integrated compressor unit. This merging of functions reduces overall system complexity compared to having separate compressors and heat exchangers, while still achieving the efficiency benefits of multi-stage compression.
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 enhances operating efficiency by reducing heat radiation losses and maintaining defrosting capacity, allowing for faster and more effective defrosting operations.
Implementation Method 1
The intercooler is a heat exchanger integrated with the heat source-side heat exchanger and having air as a heat source, and 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 heat source-side heat exchanger is caused to function as a refrigerant cooler whereby a defrosting operation for defrosting the heat source-side heat exchanger is performed
Data Source
AI summary
A refrigeration apparatus uses a refrigerant that operates in a supercritical range. The refrigeration apparatus includes a compression mechanism, a heat source-side heat exchanger, an expansion mechanism, a usage-side heat exchanger, a switching mechanism, an intercooler which functions as a cooler of refrigerant discharged from a first-stage compression element of the compression mechanism and drawn into a second-stage compression element of the compression mechanism, and an intercooler bypass tube. The switching mechanism is configured to switch between cooling and heating operation states in which refrigerant is circulated differently. When a defrosting operation for defrosting the heat source-side heat exchanger is performed, refrigerant flows to the heat source-side heat exchanger and the intercooler. After defrosting of the intercooler is detected as being complete, the intercooler bypass tube is used to ensure that the refrigerant does not flow to the intercooler.