Compressor Torque Control With Wet Vapor Suction Cooling
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Solution Overview
Problem
Refrigeration apparatuses face the challenge of preventing excessively high discharge temperatures of refrigerant due to motor heat generation during torque control, especially when using refrigerants like R32, which complicates torque control and increases energy losses.
Innovation Solution
The refrigeration apparatus employs a pressure reducing mechanism and outdoor fan to control the state of refrigerant entering the compressor, placing it in a wet vapor state, thereby reducing discharge temperature without the need for additional devices, even at high condensation temperatures and with refrigerants containing over 50% R32.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If torque control is applied to reduce vibration in low-speed operation, then vibration is reduced, but motor efficiency decreases and thermal energy increases
Solution Approach 1:
The control device changes the operational parameters of the compressor motor by applying torque control in the low-speed operation range (10-40 Hz). This parameter adjustment reduces vibration while the control system compensates for the associated efficiency loss through optimized torque application patterns.
Solution Approach 2:
The system dynamically adjusts torque control based on operating conditions, specifically activating it when the compressor operates in the low-speed range where vibration is problematic. The control device monitors operational parameters and applies torque control only when necessary, making the vibration reduction adaptive rather than continuous.
2Stability of the object's composition
If torque control is applied to stabilize rotational speed, then noise is reduced, but more thermal energy is generated by the compressor motor
Solution Approach 1:
The control device modifies the motor's operational parameters by implementing torque control to stabilize rotational speed during low-speed operation. This parameter change achieves noise reduction while the control system manages the resulting thermal energy increase through optimized control strategies.
Solution Approach 2:
The control device uses feedback from operational parameters to adjust torque control in real-time. By monitoring rotational speed and operational frequency, the system applies torque control only when needed to maintain stability, thereby reducing noise while minimizing unnecessary thermal energy generation from continuous torque application.
3Stability of the object's composition
If torque control is applied when condensation temperature is high, then torque fluctuation is reduced, but refrigerant discharge temperature becomes excessively high
Solution Approach 1:
The control device changes operational parameters by applying torque control during high condensation temperature conditions to reduce torque fluctuation. Simultaneously, the system adjusts other parameters such as refrigerant flow or compressor speed to compensate for the discharge temperature increase, achieving torque stabilization without excessive heating.
Solution Approach 2:
The control device applies preliminary anti-action by predicting when high condensation temperature conditions will occur and pre-adjusting operational parameters to prevent excessive discharge temperature. The system proactively manages the trade-off between torque stability and discharge temperature by preparing compensatory measures before the problem arises.
4Temperature
If refrigerant is placed in wet vapor state to reduce discharge temperature, then discharge temperature is reduced, but additional control complexity is required
Solution Approach 1:
The control device performs multiple functions simultaneously: it manages torque control for vibration reduction, monitors condensation temperature, controls refrigerant flow state, and adjusts compressor operation. By integrating these functions into a single control system, the patent avoids adding separate devices while achieving discharge temperature reduction through wet vapor state management.
Solution Approach 2:
The control device reduces discharge temperature by changing the refrigerant's physical state parameter to achieve wet vapor condition at the compressor inlet. This parameter change is accomplished through coordinated adjustment of existing system parameters such as expansion valve opening or refrigerant flow rate, rather than requiring additional hardware.
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 reduces the risk of excessively high refrigerant temperatures during torque control, enhances motor control efficiency, and minimizes costs associated with temperature regulation, while maintaining high refrigeration performance with environmentally friendly HFC refrigerants.
Implementation Method 1
the device controller controls a pressure reducing mechanism 34 that makes up the refrigerant circuit to place the refrigerant that is sucked into the compressor in a wet vapor state
Implementation Method 2
controlling the amount of air sent by the outdoor fan 37
Data Source
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AI summary
To reduce the possibility that temperature of refrigerant discharged from a compressor of a refrigeration apparatus becomes excessively high by controlling torque of a motor built into the compressor, the compressor (31) includes the motor (31a) having rotation thereof controlled by inverter control. An inverter controller (51) controls torque of the motor (31a) using inverter control when operation frequency of the compressor (31) is at least one value within a range of from 10 Hz to 40 Hz. When at least the operation frequency is within the range of from 10 Hz to 40 Hz, torque of the motor (31a) is controlled, and under a predetermined condition in which temperature of refrigerant discharged from the compressor (31) easily becomes excessively high, a device controller (52) controls devices provided in a refrigerant circuit (20) such that refrigerant sucked into the compressor (31) is placed in a wet vapor state.