Heat Pump Startup Control for Compressor Pressure and Lubrication
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Solution Overview
Problem
Air conditioning apparatuses face issues with refrigerant dissolution in the compressor oil during startup in low temperatures, leading to potential oil shortages and poor lubrication due to increased compressor internal pressure when driven at a given rotation number.
Innovation Solution
The air conditioning apparatus employs flow passage switching devices and outdoor expansion valves, controlled by a controller, to manage the operation of outdoor heat exchangers as either evaporators or condensers, and adjusts compressor rotation numbers based on outdoor temperature to prevent increased internal pressure and refrigerant dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor is driven at a given rotation number to eliminate refrigerant dissolution, then the refrigerant dissolution is reduced, but the compressor internal pressure increases causing refrigerant dissolution
Solution Approach 1:
The patent dynamically adjusts the compressor rotation number based on outdoor temperature conditions. During startup in low temperature conditions, the compressor rotation number is controlled to increase gradually rather than maintaining a fixed high value, thereby preventing excessive internal pressure buildup while still eliminating refrigerant dissolution over time
Solution Approach 2:
The patent changes the operational parameters of the compressor by adjusting the rotation number according to outdoor temperature. When outdoor temperature is below a predetermined threshold, the rotation number is controlled to increase gradually from a lower initial value, preventing the internal pressure from rising too quickly and causing refrigerant dissolution
2Temperature
If the compressor is driven at a given rotation number to warm the compressor, then the compressor temperature increases eliminating refrigerant dissolution, but the internal pressure increases causing oil shortage
Solution Approach 1:
The patent dynamically controls the compressor rotation number to increase gradually during startup in low temperature conditions, rather than maintaining a fixed high rotation number. This gradual increase allows the compressor temperature to rise slowly enough to eliminate refrigerant dissolution while preventing excessive internal pressure that would cause oil to be carried away
Solution Approach 2:
The patent implements preliminary control measures by detecting outdoor temperature before startup and pre-setting the rotation number increase schedule. When low temperature is detected, the system prepares to increase rotation number gradually from a lower initial value, preventing both refrigerant dissolution and oil shortage before they occur
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 effectively prevents refrigerant dissolution and maintains proper lubrication by controlling the operation of outdoor heat exchangers and compressor rotation, ensuring efficient startup and operation even in low temperatures.
Implementation Method 1
at least two outdoor heat exchangers, flow passage switching devices connected to one end of each of the outdoor heat exchangers for switching the connection of the outdoor heat exchangers to the refrigerant discharge opening or refrigerant suction opening of the one or more compressors
Implementation Method 2
outdoor expansion valves each connected to the other end of each of the outdoor heat exchangers for adjusting the refrigerant flow amount of the outdoor heat exchangers, and controller for executing the switching control of the flow passage switching devices and the valve opening rate control of the outdoor expansion valves
Implementation Method 3
drives the one or more compressors at a predetermined rotation number
Implementation Method 4
the flow passage switching devices corresponding to the one or more outdoor heat exchangers to allow it or them to function as an evaporator or evaporators, controls the flow passage switching devices corresponding to at least one of the other outdoor heat exchangers than one functioning as an evaporator to allow it or them to function as a condenser or condensers
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An air conditioning apparatus 1 includes first start control and second start control as its start control. In the first start control, first outdoor heat exchangers 24a, 24b are controlled to function as evaporators and second outdoor heat exchangers 25a, 25b are controlled to function as condensers. Thus, even when the compressors 21a, 21b are driven on at a given rotation number, the discharge pressures thereof can be prevented from increasing, thereby being able to prevent the internal pressures of the compressors 21a, 21b from increasing. Also, after end of the first start control, the first outdoor heat exchangers 24a, 24b and second outdoor heat exchangers 25a, 25b are all controlled to function as evaporators, and the compressors 21a, 21b are driven on at a given rotation number. This can shorten the rising time of the heating capacity in the start of the normal heating operation.