Refrigerating circuit and method for controlling the oil distribution within the same
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Solution Overview
Problem
In conventional multi-compressor refrigerating circuits, maintaining a consistent oil level across compressors is challenging, leading to potential damage from oil loss or accumulation, which reduces efficiency and requires shutting down compressors for oil redistribution, affecting operational efficiency.
Innovation Solution
A refrigerating circuit with a solenoid valve-controlled oil balance line between compressors, allowing oil flow adjustment based on pressure differences and rotational speed thresholds, ensuring balanced oil distribution without shutting down compressors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oil distribution methods are used in multi-compressor units, then compressors can operate independently, but oil levels become unbalanced causing compressor damage or inefficiency
Solution Approach 1:
An oil balance line is introduced as an intermediary component connecting the oil sumps of multiple compressors. This allows oil to flow freely between compressors based on level differences, automatically balancing oil distribution without requiring complex control systems or shutdown procedures.
Solution Approach 2:
The oil balance line connects oil sumps at substantially the same positions of height, creating an equipotential system where oil naturally flows to equalize levels across all compressors. This gravitational equilibrium eliminates the need for active control mechanisms while ensuring reliable oil distribution.
2Reliability
If compressors are shut down to redistribute oil, then acceptable oil levels are restored, but operational efficiency significantly decreases
Solution Approach 1:
The oil balance line enables continuous oil redistribution while all compressors remain operational. Oil flows continuously through the balance line during normal operation, eliminating the need to shut down compressors for oil level correction and maintaining continuous productive action.
Solution Approach 2:
The oil balance line is pre-established between compressors before operation begins. This preliminary infrastructure allows immediate oil balancing whenever level differences occur, preventing oil level issues from developing to critical points that would require shutdowns.
3Reliability
If additional oil separators are added to control oil distribution, then oil levels can be maintained, but device complexity and costs increase
Solution Approach 1:
The oil balance line creates a self-regulating system where oil automatically flows from compressors with higher oil levels to those with lower levels. This passive, self-service mechanism eliminates the need for external control devices, sensors, or additional components to monitor and adjust oil distribution.
Solution Approach 2:
The invention extracts the essential oil balancing function from complex control systems and reduces it to a simple gravitational flow mechanism through the balance line. By removing unnecessary sensors and control components, the system achieves reliable oil level maintenance with minimal complexity.
4Adaptability or versatility
If compressors operate at different rotational speeds, then system flexibility increases, but oil distribution becomes more unstable
Solution Approach 1:
The oil balance line acts as a mediator that decouples the oil distribution stability from compressor speed variations. By providing a direct gravitational flow path between oil sumps, it ensures that oil levels remain stable and balanced regardless of changes in compressor operational speeds or loads.
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 maintains acceptable oil levels across compressors, enhancing the refrigerating circuit's efficiency by preventing compressor shutdowns and eliminating the need for additional oil separators, while minimizing sensor equipment and costs.
Implementation Method 1
a pressure difference sensor is provided which senses a pressure difference between the compressors
Implementation Method 2
a solenoid valve allowing oil flow in either direction is arranged in the oil balance line between the first compressor and the at least one further compressor for controlling the oil distribution
Implementation Method 3
an oil balance line is provided between the oil sumps of the compressors, said oil balance line connecting the oil sumps of the compressors at substantially the same positions of height
Implementation Method 4
allowing an oil flow between the oil sumps of the compressors
Data Source
Figure 1
AI summary
A refrigerating circuit according to the invention comprises - in flow direction - a multi-compressor unit (4, 6, 8), a condenser/gas cooler (12), a receiver (14), at least one evaporator (18, 22, 26) having a respective expansion device (16, 20, 24) arranged before it, and conduits circulating a refrigerant containing oil therethrough, wherein the multi-compressor unit (4, 6, 8) comprises a first compressor (4) the rotational speed of which can be controlled and at least one further compressor (6, 8) running at a constant rotational speed, wherein the suction sides and the pressure sides of the compressors (4, 6, 8) are connected in parallel, wherein an oil balance line (30) is provided between the oil sumps of the compressors (4, 6, 8), said oil balance line (30) connecting the oil sumps of the compressors (4, 6, 8) at substantially the same positions of height, and wherein a solenoid valve (32) allowing oil flow in either direction is arranged in the oil balance line (30) between the first compressor (4) and the at least one further compressor (6, 8) for controlling the oil distribution between the oil sumps of the compressors (4, 6, 8) during operation of the compressors (4, 6, 8) of the multi-compressor unit (4, 6, 8).