Refrigeration cycle device
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Solution Overview
Problem
When switching from a heating mode to a defrosting mode in a refrigeration cycle apparatus, the differential pressure between heat exchangers can cause a significant amount of refrigerant to move from the condenser to the evaporator, leading to a temperature decrease in the condenser, which may result in dew condensation or pipe damage due to solidification of the heat medium, destabilizing the refrigeration cycle.
Innovation Solution
The introduction of a pressure equalization mode, where a flow regulating valve is opened to reduce the differential pressure between the high and low pressure sides, allowing refrigerant to flow from the high pressure side to the low pressure side, thereby reducing the amount of refrigerant leaving the condenser and stabilizing the operation before transitioning to the defrosting mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the circulation direction of refrigerant is switched by a four-way valve to start a defrosting mode, then the defrosting operation can be initiated, but a large amount of refrigerant moves from the first heat exchanger to the second heat exchanger due to remaining differential pressure, causing temperature decrease in the first heat exchanger
Solution Approach 1:
The patent introduces a pressure equalization mode that is activated before the defrosting mode to equalize the pressure between the high-pressure side and low-pressure side. This preliminary pressure equalization prevents the sudden temperature drop that would occur if defrosting were initiated directly, as the differential pressure that drives excessive refrigerant movement is eliminated in advance.
Solution Approach 2:
The pressure equalization mode serves as an intermediary state between the heating mode and the defrosting mode. By introducing this intermediate step, the system transitions smoothly through a controlled pressure equalization process, preventing the harmful direct transition that causes temperature decrease in the first heat exchanger.
2Quantity of substance
If the amount of refrigerant in the first heat exchanger decreases, then the pressure and temperature in the first heat exchanger decrease, but this leads to dew condensation or pipe damage due to solidification of heat medium
Solution Approach 1:
The pressure equalization mode performs a preliminary action by equalizing pressure before the defrosting mode begins. This prevents the rapid refrigerant outflow that would cause the first heat exchanger temperature to drop below freezing, thereby preventing pipe damage and maintaining operational reliability.
Solution Approach 2:
The pressure equalization mode acts as a cushioning measure that prepares the system in advance for the defrosting operation. By equalizing pressure beforehand, it cushions against the harmful effects of sudden refrigerant movement and temperature drop, protecting the system from dew condensation and pipe damage.
3Power
If the differential pressure between high pressure side and low pressure side is large, then the compressor can operate efficiently, but a large amount of refrigerant flows from the first heat exchanger to the second heat exchanger when switching to defrosting mode
Solution Approach 1:
The pressure equalization mode performs a preliminary action by equalizing the differential pressure before the defrosting mode begins. This allows the compressor to maintain efficient operation during heating while preventing excessive refrigerant flow during the subsequent defrosting operation, as the pressure differential that drives harmful refrigerant movement is eliminated in advance.
Solution Approach 2:
The system dynamically adjusts the pressure differential by introducing a pressure equalization mode. During heating operation, a large differential pressure is maintained for efficient compressor operation. Before defrosting, the system transitions to a pressure equalization state where the differential pressure is reduced, thereby controlling refrigerant flow dynamics to prevent loss of refrigerant from the first heat exchanger.
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 approach effectively suppresses the temperature decrease in the condenser at the start of the defrosting mode, ensuring stable operation of the refrigeration cycle by reducing refrigerant flow and maintaining pressure balance, thus preventing potential damage and operational instability.
Implementation Method 1
refrigerant on the high pressure side flows through the flow regulating valve to the low voltage side
Data Source
Figure 1
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AI summary
A refrigeration cycle apparatus (1) according to the present invention includes an on-off valve (16) and a controller (17). The on-off valve (16) is connected in parallel with a compressor (11) between a discharge port and a suction port of the compressor (11). The controller (17) controls the on-off valve (16) to be opened and closed, and switches an operation mode. The operation mode includes a heating mode, a defrosting mode, and a pressure equalization mode. The on-off valve (16) is opened in the pressure equalization mode. In the pressure equalization mode, the on-off valve (16) that is opened is greater in flow path resistance than a four-way valve (15). The controller (17) switches the operation mode in order of the heating mode, the pressure equalization mode, and the defrosting mode.