Ejector refrigeration circuit
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Solution Overview
Problem
Ejector refrigeration circuits face inefficiencies across a wide range of operational conditions due to the inability to effectively adjust refrigerant mass flow and optimize performance.
Innovation Solution
The implementation of an ejector refrigeration circuit with at least two variable ejectors, each equipped with a controllable motive nozzle and needle valve, allowing for modulation of flow through the nozzle and overall ejector operation, along with a control unit to adjust the operation based on ambient temperatures and refrigeration demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ejector with fixed opening is used, then the device complexity is reduced, but the efficiency across a wide range of operational conditions deteriorates
Solution Approach 1:
The ejector system is segmented into multiple independent ejectors (first ejector and second ejector) with different capacity ratings. This segmentation allows selective operation of individual ejectors based on ambient temperature conditions, enabling the system to maintain high efficiency across a wide range of operational conditions without requiring each ejector to be universally optimized for all conditions.
Solution Approach 2:
The system incorporates dynamic control through solenoid valves that can selectively open or close ejector pathways based on real-time ambient temperature sensing. This dynamic switching capability allows the system to adapt its configuration to match current operational conditions, thereby maintaining optimal efficiency without requiring complex variable geometry mechanisms in each ejector.
2Productivity
If multiple ejectors with different capacities are used, then the efficiency over a wide range of operational conditions is improved, but the device complexity increases
Solution Approach 1:
Multiple ejectors with different capacity ratings are integrated into a single refrigeration circuit, allowing the system to handle a universal range of cooling loads and ambient temperature conditions. The first ejector with higher capacity handles high-temperature conditions, while the second ejector with lower capacity handles low-temperature conditions, making the overall system universally applicable across diverse operational scenarios.
Solution Approach 2:
Solenoid valves act as intermediary control elements that selectively route refrigerant flow to appropriate ejectors based on ambient temperature conditions. These intermediary devices simplify the complexity by providing automated switching logic, eliminating the need for manual intervention or complex mechanical coupling between ejectors of different capacities.
3Device complexity
If the refrigerant mass flow is not adjusted, then the device complexity is reduced, but the efficiency according to actual conditions deteriorates
Solution Approach 1:
The system incorporates ambient temperature sensing that provides feedback to the control mechanism. Based on the sensed temperature conditions, the system automatically adjusts refrigerant mass flow distribution among ejectors, ensuring optimal efficiency for actual operating conditions without requiring complex manual adjustment mechanisms.
Solution Approach 2:
The refrigeration system performs self-adjustment of refrigerant flow distribution through automated solenoid valve control based on ambient temperature conditions. The system serves itself by automatically selecting the appropriate ejector configuration without external intervention, thereby maintaining high efficiency across varying conditions while keeping the control mechanism relatively simple.
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 configuration enables optimized efficiency by adjusting the mass flow of refrigerant according to actual conditions, ensuring high efficiency across a wide range of operational conditions.
Implementation Method 1
The efficiency of an ejector is a function of the high pressure mass flow rate which is given as a control input via the needed high pressure drop
Implementation Method 2
an ejector may be used as an expansion device additionally providing a so called ejector pump for compressing refrigerant from a low pressure level to a medium pressure level using energy that becomes available when expanding the refrigerant from a high pressure level to the medium pressure level
Data Source
Figure 1
Figure 2
AI summary
An ejector refrigeration circuit (1) comprises a high pressure ejector circuit (3) comprising in the direction of flow of a circulating refrigerant: a heat rejecting heat exchanger/gas cooler (4) having an inlet side (4a) and an outlet side (4b); at least two variable ejectors (6, 7) with different capacities connected in parallel, each of the variable ejectors (6, 7) comprising a primary high pressure input port (6a, 7a), a secondary low pressure input port (6b, 7b) and an output port (6c, 7c); wherein the primary high pressure input ports (6a, 7a) of the at least two variable ejectors (6, 7) are fluidly connected to the outlet side (4b) of the heat rejecting heat exchanger/gas cooler (4); a receiver (8), having an inlet (8a), a liquid outlet (8c), and a gas outlet (8b), wherein the inlet (8a) is fluidly connected to the output ports (6c, 7c) of the at least two variable ejectors (6, 7); at least one compressor (2a, 2b, 2c) having an inlet side (21a, 21 b, 21c) and an outlet side (22a, 22b, 22c), the inlet side (21a, 21 b, 21c) of the at least one compressor (2a, 2b, 2c) being fluidly connected to the gas outlet (8b) of the receiver (8), and the outlet side (22a, 22b, 22c) of the at least one compressor (2a, 2b, 2c) being fluidly connected to the inlet side (4a) of the heat rejecting heat exchanger/gas cooler (4). The ejector refrigeration circuit (1 ) further comprises a refrigerating evaporator flowpath (5) comprising in the direction of flow of the circulating refrigerant: at least one refrigeration expansion device (10) having an inlet side (10a), fluidly connected to the liquid outlet (8c) of the receiver (8), and an outlet side (7b); at least one refrigeration evaporator (12) fluidly connected between the outlet side (10b) of the at least one refrigeration expansion device (10) and the secondary low pressure input ports (6b, 7b) of the at least two variable ejectors (6, 7).