Ejector Refrigerant Cycle Capacity Switching for Low-Load COP
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Solution Overview
Problem
Ejector-type refrigerant cycle devices face challenges in maintaining high coefficient of performance (COP) due to reduced refrigerant discharge capacity, which affects the ability to sufficiently draw refrigerant from the suction side evaporator, especially when the required capacity is lower than standard, leading to reduced flow speed and kinetic energy recovery.
Innovation Solution
Incorporating a discharge capacity control mechanism that adjusts the compressor's refrigerant discharge capacity based on the required capacity, switching between high and low capacity operations to maintain optimal refrigerant circulation and suction, ensuring effective COP improvement regardless of the required capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the refrigerant discharge capacity of the compressor is reduced to match lower required capacity, then the refrigerant circulation amount is reduced, but the pressure difference across the ejector nozzle is reduced, lowering jet refrigerant flow speed and reducing the ejector's ability to draw refrigerant from the suction side evaporator
Solution Approach 1:
The patent applies dynamics by making the compressor discharge capacity adjustable rather than fixed. The discharge capacity control portion dynamically changes the compressor's refrigerant discharge capacity based on operating conditions, allowing the system to maintain optimal jet refrigerant flow speed even when the required capacity is low. This resolves the contradiction by enabling the system to adapt its performance characteristics to different operating requirements.
Solution Approach 2:
The patent changes the parameter of compressor discharge capacity to resolve the contradiction. By controlling the discharge capacity to be higher than the required capacity in certain operating conditions, the system maintains sufficient pressure difference across the ejector nozzle to ensure high jet refrigerant flow speed and effective refrigerant suction, while still matching the required capacity when conditions demand lower operation.
2Use of energy by moving object
If the refrigerant discharge capacity of the compressor is reduced, then energy consumption is reduced, but the coefficient of performance (COP) improvement from the ejector is reduced due to insufficient kinetic energy recovery
Solution Approach 1:
The patent changes the discharge capacity parameter to optimize the balance between energy consumption and kinetic energy recovery. By maintaining discharge capacity higher than required capacity in certain conditions, the system ensures sufficient pressure difference for high-speed jet refrigerant flow, which enables effective kinetic energy recovery in the diffuser portion and maintains high COP, while avoiding excessive energy consumption by not continuously operating at maximum capacity.
Solution Approach 2:
The discharge capacity control portion implements feedback control by continuously monitoring operating conditions and adjusting the compressor discharge capacity accordingly. This feedback mechanism ensures that the system maintains optimal performance by adjusting discharge capacity to preserve the pressure difference needed for effective ejector operation, thereby maintaining kinetic energy recovery and COP while adapting to varying load conditions.
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 effectively enhances the COP of the ejector-type refrigerant cycle device by ensuring sufficient refrigerant suction and kinetic energy recovery, even when the required capacity is lower than standard, by dynamically controlling the compressor's discharge capacity.
Implementation Method 1
refrigerant is decompressed and expanded in the nozzle portion of the ejector in iso-entropy
Implementation Method 2
the refrigerant downstream of the suction side evaporator is drawn into the ejector from the refrigerant suction port by the refrigerant suction action due to a high-speed refrigerant jetted from a jet port of the nozzle portion
Implementation Method 3
By converting the recovered kinetic energy to the pressure energy in the diffuser portion of the ejector, the pressure of the suction refrigerant of the compressor can be increased
Data Source
AI summary
An ejector-type refrigerant cycle device includes a compressor, a radiator, an ejector, a suction side evaporator disposed to evaporate refrigerant to be drawn into a refrigerant suction port of the ejector, and a discharge capacity control portion configured to control a refrigerant discharge capacity of the compressor. The discharge capacity control portion increases the refrigerant discharge capacity of the compressor in accordance with an increase of a requirement capacity required in a refrigerant cycle of a general operation, when the requirement capacity is larger than a standard value. In contrast, when the requirement capacity required in the refrigerant cycle is equal to or smaller than the standard value, the discharge capacity control portion controls the refrigerant discharge capacity of the compressor to be switched alternately between a high capacity operation and a low capacity operation. Thus, a refrigerant circulation amount in the refrigerant cycle can be suitably adjusted.