Air-conditioning apparatus
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Solution Overview
Problem
In air-conditioning apparatuses, frequent thermo-off operations can lead to repetitive starting and stopping of the compressor before the oil concentration reaches a sufficient level, risking wear or burning of the motor shaft due to low lubrication levels.
Innovation Solution
An air-conditioning apparatus with a controller that estimates the oil concentration based on the temperature and pressure of discharged gas refrigerant and continues compressor operation when the concentration is low, ensuring the oil concentration remains sufficient by maintaining the compressor's heating and evaporating the refrigerant mixed with oil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the compressor is stopped frequently under thermo-off conditions, then energy consumption is reduced, but oil concentration drops below sufficient levels causing inadequate lubrication
Solution Approach 1:
The controller performs preliminary action by detecting oil concentration before stopping the compressor and predicting future concentration levels. This allows the system to anticipate when oil concentration will drop below sufficient levels and adjust stopping decisions accordingly, preventing inadequate lubrication before it occurs.
Solution Approach 2:
The system implements feedback by continuously detecting oil concentration levels and using this information to adjust compressor operation decisions. The controller monitors oil concentration trends and uses this feedback to determine whether to maintain compression operation or allow stopping, ensuring lubrication reliability is maintained while optimizing energy consumption.
2Reliability
If the compressor operation is continued to maintain oil concentration, then lubrication reliability is improved, but energy consumption increases
Solution Approach 1:
The controller applies partial action by continuing compressor operation only when necessary to maintain oil concentration above sufficient levels. Rather than continuous operation, the system applies compression action selectively based on oil concentration predictions, maintaining adequate lubrication while minimizing unnecessary energy consumption.
Solution Approach 2:
The system changes the operational parameter from fixed continuous operation to variable operation based on oil concentration levels. The controller adjusts compressor operation dynamically according to detected oil concentration and predicted concentration trends, optimizing the balance between lubrication reliability and energy consumption.
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 prevents repetitive low-lubricity operations, maintaining a sufficient oil concentration and enhancing compressor reliability by ensuring continuous operation during thermo-off conditions, thereby reducing the risk of wear or failure.
Implementation Method 1
estimate an oil concentration inside the compressor based on a temperature of gas refrigerant discharged from the compressor and a pressure of the gas refrigerant discharged from the compressor
Implementation Method 2
estimate an oil concentration inside the compressor based on a temperature of gas refrigerant discharged from the compressor and a pressure of the gas refrigerant discharged from the compressor
Implementation Method 3
the compressor is heated, and thus the refrigerant mixed with the refrigerating machine oil evaporates
Data Source
AI summary
An air-conditioning apparatus includes: a refrigerant circuit including a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger that are connected by a refrigerant pipe so that refrigerant circulates through the refrigerant circuit; and a controller configured to control an operation state of the compressor, in which the controller is configured to estimate an oil concentration inside the compressor based on a temperature of gas refrigerant discharged from the compressor and a pressure of the gas refrigerant discharged from the compressor, and when the oil concentration is less than an oil concentration reference value, continue an operation of the compressor even under a state in which the thermo-off condition is satisfied.