Air-conditioning apparatus
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Solution Overview
Problem
Air-conditioning apparatuses struggle to completely melt frost adhering to heat exchangers in extremely low-temperature environments, as existing defrosting methods are inadequate, leading to incomplete frost removal and subsequent accumulation, which complicates further defrosting and affects compressor operation.
Innovation Solution
An air-conditioning apparatus with a refrigerant circuit, pressure sensor, and controller that adjusts the defrosting operation time based on compressor suction pressure, ensuring the defrosting time is extended when pressure is above a threshold and shortened when below, to effectively melt frost while maintaining compressor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the frequency of the compressor is increased to increase the flow rate of high-temperature refrigerant, then the speed of frost melting is improved, but the low pressure of the compressor is lowered which may cause compressor failure
Solution Approach 1:
The patent applies dynamics by making the compressor frequency variable rather than fixed. The control device dynamically adjusts the compressor frequency based on real-time monitoring of low pressure values, allowing the system to optimize refrigerant flow rate while preventing compressor failure through adaptive frequency control.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the low pressure value during defrosting operation and using this information to adjust the compressor frequency. When the low pressure exceeds the threshold, the system increases frequency to enhance defrosting; when low pressure approaches the lower limit, the system reduces frequency to protect the compressor, creating a closed-loop control system.
2Reliability
If the defrosting operation time period is extended to completely melt frost, then the frost removal effectiveness is improved, but the compressor low pressure is lowered which limits the maximum frequency
Solution Approach 1:
The system dynamically adjusts compressor frequency during defrosting operation based on real-time low pressure monitoring. The frequency is varied within a controlled range to extend the effective defrosting time while maintaining compressor safety, transforming a static frequency setting into an adaptive control strategy.
Solution Approach 2:
The patent changes the operating parameters of the compressor by adjusting frequency based on low pressure thresholds. This parameter change allows the system to optimize the balance between defrosting effectiveness and compressor protection, enabling extended defrosting periods without causing harmful pressure drops.
3Device complexity
If a fixed defrosting time period is used, then the control simplicity is maintained, but incomplete frost removal occurs in extremely low-temperature environments
Solution Approach 1:
The patent replaces fixed-time control with feedback-based adaptive control. The control device monitors low pressure values during defrosting and adjusts the operation duration accordingly, allowing the system to adapt to varying environmental conditions while maintaining relatively simple control logic through threshold-based decision making.
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 ensures reliable frost removal by adjusting defrosting time according to compressor pressure, preventing frost accumulation and maintaining compressor performance, even in extreme cold conditions.
Implementation Method 1
a pressure sensor which is configured to detect a pressure on a suction side of the compressor
Implementation Method 2
a refrigerant circuit, in which a compressor, a refrigerant flow switching device, a heat source-side heat exchanger, an expansion device, and a use-side heat exchanger are connected via a refrigerant pipe to form a refrigeration cycle
Implementation Method 3
supply compressed refrigerant from the compressor to the heat source-side heat exchanger
Data Source
AI summary
An air-conditioning apparatus is configured to melt a large amount of adhering frost while maintaining an appropriate operation of a compressor by setting a defrosting operation time period depending on a low pressure of the compressor. The air-conditioning apparatus includes a refrigerant circuit including the compressor, a refrigerant flow switching device, a heat source-side heat exchanger, an expansion device, and a use-side heat exchanger, which are connected via a refrigerant pipe to form a refrigeration cycle, a pressure sensor configured to detect a pressure on a suction side of the compressor, and a controller configured to control, in a defrosting operation, the refrigerant flow switching device to supply compressed refrigerant from the compressor to the heat source-side heat exchanger, compare a value detected by the pressure sensor with a first threshold value, and change the defrosting operation time period based on a result of the comparison.