Oil separator and return for ejector-based direct expansion (DX) evaporator
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Solution Overview
Problem
In direct expansion evaporator refrigeration systems without hot gas defrost, refrigerant oil can accumulate in the evaporator coil tubes due to recirculation of liquid refrigerant, leading to potential operational issues.
Innovation Solution
An oil separator/collector is integrated downstream of the ejector, which separates and collects refrigerant oil from the refrigerant mixture and intermittently returns it to the suction connection, preventing oil accumulation in the evaporator coil tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid refrigerant is recirculated from the suction header back to the distributor to boost cooling capacity, then cooling capacity increases by up to 38%, but refrigerant oil accumulates in the evaporator coil tubes
Solution Approach 1:
The patent extracts the harmful component (refrigerant oil) from the recirculated refrigerant stream by installing an oil separator downstream of the ejector. The oil separator removes oil from the liquid refrigerant before it returns to the distributor, preventing oil accumulation in the evaporator coil tubes while maintaining the beneficial recirculation of refrigerant for enhanced cooling capacity.
Solution Approach 2:
The oil separator acts as an intermediary device between the ejector and the distributor. It mediates the recirculation process by separating oil from the refrigerant stream, allowing clean refrigerant to be recirculated while isolating and removing the harmful oil component. This intermediary function enables the system to maintain high cooling capacity without the detrimental effects of oil buildup.
2Reliability
If an oil separator is added downstream of the ejector to remove refrigerant oil, then oil accumulation is prevented, but device complexity increases
Solution Approach 1:
The patent merges the oil separator function into the existing recirculation line downstream of the ejector, utilizing the same refrigerant stream for both cooling enhancement and oil removal. The oil separator is integrated into the flow path without requiring separate parallel systems, thereby reducing overall complexity while maintaining reliable oil return to the compressor.
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 solution effectively separates and manages refrigerant oil, ensuring it is returned to the compressor, thereby maintaining system efficiency and preventing oil-related operational issues in Ejector DX evaporators without hot gas defrost.
Implementation Method 1
separates and collects refrigerant oil from the refrigerant mixture
Implementation Method 2
separates and collects refrigerant oil from the refrigerant mixture
Implementation Method 3
recirculating liquid refrigerant from the suction header back to the distributor with an ejector
Data Source
AI summary
A system and method for increasing the refrigeration capacity of a direct expansion refrigeration system having a vapor separator and a vapor ejector. After the throttling process at the expansion device, the mixture of liquid and vapor enters the inlet separator. The vapor separator generates vapor to power the ejector through flashing of warm refrigerant liquid from a higher temperature and pressure to a lower pressure. The cooler refrigerant liquid then goes to the evaporator coil inlet. The vapor goes to the ejector as well as refrigerant vapor from the outlet of the evaporator. The ejector sends oil and vapor and liquid refrigerant to an oil separator which returns oil to the compressor and sends the liquid and vapor refrigerant to the evaporator.