Air conditioner
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Solution Overview
Problem
In air-conditioning apparatuses with variable refrigerant flow systems, excessive refrigerant in the circuit can lead to liquid backflow, potentially damaging the compressor and compromising the system's reliability.
Innovation Solution
A controller is used to regulate the refrigerant flow, preventing surplus refrigerant from accumulating in the accumulator, thereby maintaining a low liquid level and preventing excessive liquid backflow to the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a larger amount of refrigerant is added to the refrigerant circuit, then the heating capacity is improved, but the liquid level in the accumulator increases causing liquid backflow to the compressor
Solution Approach 1:
The injection expansion device controls the injection timing and amount of refrigerant into the compressor suction chamber before compression occurs. This preliminary action ensures that refrigerant is injected at the optimal moment to enhance heating capacity while preventing excessive liquid accumulation in the accumulator that would cause backflow to the compressor
Solution Approach 2:
The system changes the state parameters of the refrigerant by injecting it at specific pressure and temperature conditions into the suction chamber. The injection expansion device adjusts the refrigerant parameters (pressure, temperature, quality) to achieve improved heating capacity while maintaining safe operating levels in the accumulator
2Temperature
If refrigerant is injected into the compressor suction chamber, then the discharge temperature is reduced, but the liquid level in the accumulator increases
Solution Approach 1:
The injection expansion device implements partial injection of refrigerant into the suction chamber - enough to reduce discharge temperature to acceptable levels, but not so much that it causes excessive liquid accumulation in the accumulator. The device precisely controls the injection quantity to achieve the minimum necessary action for temperature control
3Productivity
If the opening degree of the injection expansion device is increased, then the refrigerant flow rate increases, but the liquid level in the accumulator rises causing overflow
Solution Approach 1:
The control device monitors the liquid level in the accumulator and the opening degree of the injection expansion device, adjusting the injection amount in real-time. This feedback mechanism ensures that the refrigerant flow rate is optimized for heating capacity while preventing the liquid level from rising to dangerous levels that would cause overflow and system failure
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 ensures the reliability of the air-conditioning apparatus by preventing compressor damage and maintaining system performance without deteriorating the air-conditioning performance.
Implementation Method 1
a controller 60 reduces the amount of refrigerant that flows into an accumulator to prevent surplus refrigerant from being accumulated therein
Implementation Method 2
the refrigerant transfers heat to air or removes heat from the air to heat or cool the air
Implementation Method 3
refrigerant is circulated. To be more specific, in the refrigerant circuit, the refrigerant transfers heat to air or removes heat from the air
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An air-conditioning apparatus includes a refrigerant circuit in which an outdoor unit, at least one load-side expansion device, and at least one load-side heat exchanger are connected by pipes to allow refrigerant to circulate. The outdoor unit includes a compressor including an injection port allowing the refrigerant to flow into a suction chamber, a heat-source-side heat exchanger for heat exchange for the refrigerant, and an accumulator. The load-side heat exchanger transfers heat between a load and the refrigerant. The outdoor unit includes: an injection pipe having one end connected between the heat-source-side heat exchanger and the load-side expansion device, and the other end connected to the injection port, in the refrigerant circuit; an outdoor-side expansion device located downstream from the one end of the injection pipe in the flow of the refrigerant from the load-side expansion device to the heat-source-side heat exchanger; and an injection expansion device that adjusts the amount of the refrigerant flowing through the injection pipe. Also, a controller is provided to control the opening degrees of the outdoor-side expansion device and the injection expansion device.