Compressor Lubrication Tank Cooling for Refrigeration Startup
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Solution Overview
Problem
The existing refrigeration apparatuses face challenges in ensuring proper lubrication of the compressor at startup or restart, particularly due to insufficient liquid refrigerant in the bypass flow passage, which can lead to compressor damage from refrigerant migration to other parts of the circuit.
Innovation Solution
A refrigeration apparatus with a lubrication refrigerant tank connected to the main refrigerant circuit between the condenser and expansion valve, storing liquid refrigerant and equipped with cooling means to ensure the refrigerant is in a liquid state at startup, using gravity-fed lubrication and thermoelectric cooling to attract refrigerant back to the tank, eliminating the need for pumps and additional fluid lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refrigeration apparatus uses a bypass flow passage to supply liquid refrigerant to the compressor for lubrication, then the compressor can be lubricated during operation, but insufficient liquid refrigerant is available in the bypass flow passage at startup or after standby periods due to gravity-induced migration to low parts of the circuit
Solution Approach 1:
The patent introduces a lubrication refrigerant tank that is pre-filled with liquid refrigerant and positioned at a high location. Before startup, the system ensures liquid refrigerant is available in the tank through preliminary cooling means, so that when the compressor needs lubrication at startup, liquid refrigerant is already in place and can be supplied immediately without relying on gravity-induced migration from other parts of the circuit.
Solution Approach 2:
The patent positions the lubrication refrigerant tank at a high location in the refrigeration apparatus, using gravity favorably to enable liquid refrigerant to flow down to the compressor under normal operation. This high-positioned tank counteracts the gravity-induced migration problem by being the highest point, ensuring refrigerant flows toward the compressor rather than away from it.
2Reliability
If additional components like pumps and fluid lines are added to ensure refrigerant availability at the compressor, then lubrication reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent employs a self-service mechanism where the lubrication refrigerant tank, positioned at a high location, uses gravity itself to supply liquid refrigerant to the compressor. The system leverages the existing gravity field rather than introducing additional active components like pumps, thereby maintaining reliability while avoiding increased complexity. The tank automatically supplies refrigerant when needed without external control mechanisms.
Solution Approach 2:
The lubrication refrigerant tank serves multiple functions: it stores liquid refrigerant for lubrication, acts as a gravity-fed supply reservoir, and eliminates the need for separate pump systems or complex fluid line configurations. By consolidating these functions into a single high-positioned tank, the system achieves reliable lubrication without adding overall device complexity.
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
Guarantees proper lubrication of the compressor at startup, preventing damage from refrigerant shortages and reducing system complexity and cost by self-induced refrigerant circulation and spontaneous migration, creating a cold point that attracts refrigerant back to the tank.
Implementation Method 1
refrigerant tank is placed in a top area of the refrigeration apparatus and feeds the compressor with lubrication refrigerant by gravity
Implementation Method 2
the cooling of the refrigerant in the tank produces a cold point that forms the coldest part of the refrigerant circuit. Gaseous refrigerant present in the tank is condensed, inducing a depression that spontaneously attracts liquid and gaseous refrigerant towards the tank
Data Source
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AI summary
This refrigeration apparatus (1) comprises a main refrigerant circuit (2) including a positive displacement compressor (4), a condenser (6), an expansion valve (8), and an evaporator (10), through which a refrigerant circulates successively in a closed loop circulation, and a lubrication refrigerant line (18) connected to the main refrigerant circuit (2) between the condenser (6) and the expansion valve (8) or to the condenser (6), in which circulates a portion of the refrigerant of the main refrigerant circuit (2) and connected to the compressor (4) for lubrication of said compressor (4) with the refrigerant. The refrigeration apparatus comprises a lubrication refrigerant tank (20) connected to the lubrication refrigerant line (18) upstream the compressor (4), the lubrication tank (20) being configured to store liquid refrigerant for lubrication of the compressor (4) and the lubrication refrigerant tank (20) comprises means (32, 34; 38, 40) to cool down the refrigerant stored in the lubrication refrigerant tank (20) prior to a starting operation of the refrigeration apparatus (1).