Direct Expansion (DX) Refrigerant Evaporator with Liquid Ejector
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Solution Overview
Problem
Direct expansion evaporators in refrigeration systems face a reduction in cooling capacity due to reduced liquid refrigerant flow, which is necessary to achieve superheat and prevent liquid carryover.
Innovation Solution
The solution involves increasing the liquid refrigerant flow through local recirculation from the coil outlet to the coil inlet using a liquid-powered ejector, which pumps unevaporated refrigerant from lower to higher pressure, thereby enhancing heat absorption capacity while maintaining superheat and preventing liquid carryover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid refrigerant flow is increased through the coil, then heat absorption capacity is improved, but liquid carryover occurs at the coil outlet
Solution Approach 1:
The invention extracts and removes liquid refrigerant from the outlet header before it can be carried over to the compressor. The ejector actively pulls out unevaporated liquid from the low-pressure outlet environment and returns it to the high-pressure inlet side, separating the liquid removal function from the normal evaporator operation.
Solution Approach 2:
The ejector acts as an intermediary device between the outlet header and the inlet distributor. It mediates the liquid refrigerant flow by capturing liquid at the outlet, pressurizing it through its internal geometry, and returning it to the inlet, thereby preventing liquid carryover while maintaining high liquid flow through the coil.
2Object-generated harmful factors
If liquid refrigerant flow is reduced to achieve superheat, then liquid carryover is prevented, but cooling capacity decreases
Solution Approach 1:
The ejector creates a feedback loop where liquid refrigerant that exits the evaporator coil is continuously monitored and actively returned to the inlet. This feedback mechanism ensures that liquid is removed from the system at the outlet while simultaneously being fed back to maintain high flow through the coil, decoupling the traditional trade-off between superheat and capacity.
Solution Approach 2:
The invention discards liquid refrigerant from the outlet header (where it would cause carryover) and recovers it by returning to the inlet distributor. This allows the system to operate with high liquid flow for maximum heat absorption while the ejector continuously discards and recycles any liquid that reaches the outlet, preventing carryover without sacrificing capacity.
3Productivity
If a liquid-powered ejector is added to recirculate liquid refrigerant, then cooling capacity is boosted, but device complexity increases
Solution Approach 1:
The ejector is self-powered by the liquid refrigerant flow itself. The liquid entering the ejector provides the motive force needed to drive the recirculation process, eliminating the need for external power sources, motors, or complex control systems. The device uses the system's own operating fluids and pressure differentials to perform the liquid removal and recirculation function.
Solution Approach 2:
The ejector utilizes hydraulic principles to recirculate liquid refrigerant. By leveraging the kinetic energy and pressure of the incoming liquid flow, the ejector creates a suction effect that draws liquid from the outlet header and uses the flow's own momentum to pressurize and deliver it back to the inlet,实现ing liquid recirculation through pure hydraulic action without mechanical moving parts.
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 approach significantly boosts the cooling capacity of the evaporator coil by up to 38% while maintaining a low superheat and preventing liquid carryover, thus improving the overall performance of direct expansion refrigeration systems.
Implementation Method 1
The liquid refrigerant flow is increased through local recirculation of liquid from coil outlet to coil inlet through an ejector which pumps the unevaporated liquid refrigerant from a lower pressure (suction pressure) to a higher pressure
Implementation Method 2
heat absorbing capacity is increased by increasing coil liquid refrigerant flow
Data Source
AI summary
A system and method for increasing the refrigeration capacity of a direct expansion refrigeration system having an inlet separator and a liquid ejector in which heat absorbing capacity is increased by increasing coil liquid refrigerant flow but retaining liquid free evaporator outlet flow and also retaining few degrees of superheat. The liquid refrigerant flow is increased through local recirculation of liquid from coil outlet to coil inlet through an ejector which pumps the unevaporated liquid refrigerant from a lower pressure (suction pressure) to a higher pressure. The ejector is powered by either saturated or subcooled liquid after the expansion valve.