CO2 Refrigeration Intercooler Bypass for Faster Defrosting
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Solution Overview
Problem
Conventional air-conditioning apparatuses using carbon dioxide as a refrigerant face inefficiencies due to high temperature differences between the refrigerant and water or air in heat exchangers, leading to increased heat radiation loss and reduced operating efficiency, especially during defrosting operations where frost deposits form and affect the intercooler's defrosting capacity.
Innovation Solution
The refrigeration apparatus incorporates an intercooler bypass tube to minimize refrigerant flow through the intercooler during heating operations, preventing frost buildup and maintaining efficient defrosting by ensuring the intercooler does not function as a cooler after defrosting is complete, thus reducing heat radiation and preserving defrosting capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If refrigerant flows through the intercooler during heating operations, then heat exchange can occur, but frost deposits form on the intercooler surface reducing defrosting capacity
Solution Approach 1:
The refrigerant flow path is segmented into separate channels: one for heating operation and another for defrosting operation. The intercooler is divided into regions that can be selectively activated, allowing independent control of heat exchange and defrosting functions.
Solution Approach 2:
The system dynamically switches the intercooler's function based on operational mode. During heating, the intercooler bypass is closed to enable heat exchange. During defrosting, the bypass opens to redirect refrigerant flow for defrosting while preventing frost accumulation on the intercooler surface.
2Loss of energy
If the intercooler functions as a cooler during heating operations, then heat radiation loss increases, but stopping refrigerant flow reduces heat exchange efficiency
Solution Approach 1:
The intercooler undergoes periodic functional switching between heat exchange mode and defrosting mode. During heating operations, it performs heat exchange; during defrosting operations, it is bypassed to allow the heat source-side heat exchanger to perform defrosting without heat radiation losses.
3Reliability
If refrigerant flow continues through the intercooler after defrosting is complete, then defrosting capacity is maintained, but heat radiation loss increases and energy consumption rises
Solution Approach 1:
The system uses temperature sensors to detect the defrosting status of the heat source-side heat exchanger. When defrosting is detected as complete, the control mechanism closes the intercooler bypass, stopping refrigerant flow through the intercooler and eliminating unnecessary heat radiation losses while maintaining defrosting capacity.
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 minimizing heat radiation loss and maintaining defrosting capacity, allowing for faster and more effective defrosting of the intercooler and heat source-side heat exchanger, thereby reducing overall energy consumption and improving system performance.
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
Implementation Method 2
The heat source-side heat exchanger is a heat exchanger having air as a heat source... and functions as a heater or cooler of refrigerant
Implementation Method 3
an expansion mechanism for depressurizing the refrigerant
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An air-conditioning apparatus (1) uses carbon dioxide as a refrigerant, and has 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), a switching mechanism (3), an intercooler (7) which functions as a cooler of refrigerant discharged from a first-stage compression element and drawn into a second-stage compression element, and an intercooler bypass tube (9). When the air-conditioning apparatus (1) performs a defrosting operation for defrosting the heat source-side heat exchanger (4), refrigerant flows to the heat source-side heat exchanger (4) and the intercooler (7), and after defrosting of the intercooler (7) is detected as being complete, the intercooler bypass tube (9) is used so as to ensure that the refrigerant does not flow to the intercooler (7).