Refrigeration cycle device
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Solution Overview
Problem
In refrigeration cycle apparatuses, the accumulation of refrigerant in the oil reservoir portion leads to a decrease in the amount of refrigerating machine oil, causing insufficient lubrication in the compressor and an increase in the refrigerant amount, which can strain the system's capacity.
Innovation Solution
A refrigeration cycle apparatus design that includes a flow control device and a specific configuration of oil return pipes and reservoirs to manage the flow of refrigerating machine oil and refrigerant, ensuring adequate lubrication and reducing refrigerant accumulation, thereby maintaining system efficiency and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oil reservoir portion is used to store refrigerating machine oil during continuous operation, then the oil can be returned to the compressor during start to prevent poor lubrication, but refrigerant accumulates in the oil reservoir portion causing a decrease in oil amount and potential insufficiency of lubricating oil
Solution Approach 1:
The oil return path is segmented into two separate paths: a first oil return path that operates during continuous operation and a second oil return path that operates during start. This segmentation allows each path to be optimized for its specific operating condition, preventing refrigerant accumulation during continuous operation while ensuring adequate oil return during start.
Solution Approach 2:
The system dynamically switches between different oil return paths based on operating conditions. During continuous operation, the first oil return path is used with the opening/closing device closed to prevent refrigerant accumulation. During start, the second oil return path is used with the opening/closing device open to maximize oil return to the compressor.
2Loss of substance
If the opening and closing device is kept closed during continuous operation to prevent refrigerant accumulation, then refrigerant loss is reduced, but the oil reservoir portion cannot store sufficient oil for start-up lubrication
Solution Approach 1:
During continuous operation, the first oil return path is used to preliminarily accumulate refrigerating machine oil in the oil reservoir portion. The opening/closing device remains closed during this phase to prevent refrigerant accumulation, and oil is stored in advance for use during the subsequent start phase.
Solution Approach 2:
The system employs periodic action by alternating between two operational phases: during continuous operation, oil is accumulated in the reservoir through the first path with the device closed; during start, the accumulated oil is utilized through the second path with the device open. This periodic switching optimizes both refrigerant conservation and oil availability.
3Reliability
If the oil reservoir portion is made larger to ensure sufficient oil supply during start, then lubrication is improved, but the system capacity is strained and refrigerant amount increases
Solution Approach 1:
The oil return system is segmented into two paths with different functions. The first path handles continuous operation with restricted flow to prevent refrigerant accumulation, while the second path handles start-up with unrestricted flow to maximize oil return. This segmentation eliminates the need for an oversized reservoir.
Solution Approach 2:
The system changes the flow parameters dynamically by switching between two oil return paths. During continuous operation, flow is restricted through the first path to prevent refrigerant accumulation. During start, flow is maximized through the second path to ensure adequate oil supply, eliminating the need to increase reservoir size.
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
The design effectively prevents refrigerant accumulation in the oil reservoir, ensuring a consistent supply of refrigerating machine oil to the compressor, reducing the risk of poor lubrication and minimizing the increase in refrigerant amount, thus maintaining system performance and capacity.
Implementation Method 1
part of the high-temperature refrigerating machine oil separated by the oil separator accumulates in the oil reservoir portion
Implementation Method 2
heat moves from the oil reservoir portion to low-temperature outdoor air via a pipe and a container of the oil reservoir portion
Implementation Method 3
heat moves from the oil reservoir portion to low-temperature outdoor air via a pipe and a container of the oil reservoir portion
Implementation Method 4
a flow control device and a specific configuration of oil return pipes and reservoirs to manage the flow of refrigerating machine oil
Data Source
Figure 1A~1B(c)
Figure 1C~1C(c)
Figure 1D
AI summary
A refrigeration cycle apparatus includes: a refrigerant circuit including a compressor, a condenser, an expansion device, and an evaporator; an oil separator provided at a refrigerant discharge side of the compressor and configured to separate refrigerant and a refrigerating machine oil; a first oil return path connecting the oil separator to a refrigerant suction side of the compressor; a flow control device provided on the first oil return path and configured to reduce pressure of the refrigerant and the refrigerating machine oil; an oil reservoir provided so as to branch from the first oil return path between the flow control device and the refrigerant suction side of the compressor and configured to store the refrigerating machine oil; a second oil return path on which the oil reservoir is provided and through which the oil accumulated in the oil reservoir flows when being returned to the compressor; a first opening and closing device provided on the first oil return path or the second oil return path and configured to control flow of the refrigerant and the refrigerating machine oil; and a controller configured to control the first opening and closing device to return the refrigerating machine oil via the second oil return path to the refrigerant suction side of the compressor.