Cooling system with oil return to oil reservoir
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Solution Overview
Problem
Cooling systems using certain primary refrigerants like carbon dioxide face issues where oil gets stuck in low side heat exchangers, leading to compressor failure and reduced efficiency due to the inability to cycle the oil back effectively.
Innovation Solution
The cooling system operates in three modes: normal, oil drain, and oil return modes, where oil from low side heat exchangers is drained into vessels and then pushed back to the compressor using compressed refrigerant, allowing for the efficient return of oil and maintenance of heat exchanger efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If certain primary refrigerants (e.g., carbon dioxide) are used in the cooling system, then the cooling system can effectively cool various spaces, but the oil gets stuck in the low side heat exchanger leading to compressor failure
Solution Approach 1:
The patent extracts the oil from the low side heat exchanger by providing a separate oil return line that allows oil to be drained from the heat exchanger and returned to the compressor. This separation of oil and refrigerant flow paths resolves the issue of oil accumulation in the heat exchanger while maintaining the effectiveness of the refrigerant cooling cycle.
Solution Approach 2:
The patent introduces an intermediary oil return line and control valve system that mediates between the low side heat exchanger and the compressor. This intermediary pathway allows oil to be selectively removed and returned to the compressor without disrupting the primary refrigerant cooling function, thus protecting the compressor while maintaining cooling effectiveness.
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 prevents compressor failure and maintains the efficiency of low side heat exchangers by ensuring oil is returned to the compressor, thereby extending the lifespan and improving performance.
Implementation Method 1
the first low side heat exchanger uses primary refrigerant from the flash tank to cool a secondary refrigerant
Implementation Method 2
compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor
Implementation Method 3
the first compressor compresses primary refrigerant from the accumulator, and the second compressor compresses primary refrigerant from the first compressor
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A cooling system (200) drains oil from low side heat exchangers (206A, 206B) to vessels (222A, 222B) and then uses compressed refrigerant to push the oil in the vessels back towards a compressor (210). Generally, the cooling system operates in three different modes of operation: a normal mode, an oil drain mode, and an oil return mode. During the normal mode, a primary refrigerant is cycled to cool one or more secondary refrigerants. As the primary refrigerant is cycled, oil from a compressor may mix with the primary refrigerant and become stuck in a low side heat exchanger. During the oil drain mode, the oil in the low side heat exchanger is allowed to drain into a vessel. During the oil return mode, compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor.