Refrigeration system
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Solution Overview
Problem
Refrigeration systems with ejectors and multiple evaporator temperatures face challenges in maintaining energy efficiency across a wide range of ambient temperatures, as existing systems are not optimized to adapt efficiently to varying conditions.
Innovation Solution
A refrigeration system with an ejector circuit and two refrigeration paths, allowing operation in multiple modes (standard, economizer, first ejector, and second ejector modes) by selectively connecting components like compressors, expansion devices, and valves based on ambient temperature, enabling efficient energy use from below 10°C to above 35°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a refrigeration system uses a single operational mode with an ejector, then energy efficiency is improved under specific ambient temperatures, but performance deteriorates when ambient temperatures vary widely
Solution Approach 1:
The system implements dynamic operational mode switching between four distinct modes (standard cooling mode, ejector mode, heating mode, and defrosting mode) based on real-time ambient temperature conditions and system state. This dynamic adaptation allows the refrigeration system to maintain optimal energy efficiency across a wide range of ambient temperatures from below -10°C to above 35°C, resolving the contradiction between energy efficiency and adaptability
Solution Approach 2:
The system changes operational parameters by switching between different refrigerant flow paths and component configurations. The control unit adjusts which components are active (compressor, ejector, expansion valves, heat exchangers) based on ambient temperature thresholds, thereby changing the system's thermodynamic parameters to match environmental conditions and maintain energy efficiency
2Adaptability or versatility
If the system switches between multiple operational modes, then adaptability to different ambient temperatures is improved, but system complexity increases
Solution Approach 1:
The refrigeration system achieves multi-functionality by integrating four operational modes (standard cooling, ejector-enhanced cooling, heating, and defrosting) within a single system architecture. The same physical components (compressor, ejector, expansion valves, heat exchangers) serve multiple functions depending on their configuration and activation state, reducing the need for separate dedicated systems for each function while maintaining adaptability across temperature ranges
Solution Approach 2:
The control unit acts as an intermediary that manages the complexity of mode switching and component coordination. It processes temperature inputs and automatically selects appropriate operational modes, shielding the user from complexity while enabling adaptive behavior. The intermediary coordinates the activation and deactivation of components smoothly, managing the transitional states between modes
3Use of energy by moving object
If the ejector is continuously operated, then energy efficiency is improved, but reliability decreases due to increased wear and operational stress
Solution Approach 1:
The ejector operates periodically rather than continuously, being activated only during ejector mode when ambient temperatures fall within a specific range and cooling demand requires enhanced performance. This periodic operation reduces cumulative wear and thermal stress on the ejector components while maintaining energy efficiency during the periods when the ejector is actively engaged, thereby improving overall system reliability
Solution Approach 2:
The system applies partial action by using the ejector only when necessary for optimal performance rather than continuously. The ejector is engaged during specific operational conditions (ejector mode) where its energy recovery function provides the greatest benefit, and remains inactive during standard cooling mode or when ambient conditions make it unnecessary, thus reducing wear while maintaining efficiency where needed
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 system achieves high efficiency across a broad range of ambient temperatures by dynamically adjusting its operational modes, ensuring optimal performance regardless of temperature conditions.
Implementation Method 1
an ejector having a primary inlet fluidly connected to the outlet(s) of the heat rejecting heat exchanger/gas cooler; a secondary inlet; and an outlet
Implementation Method 2
a normal cooling temperature expansion device fluidly connected to a liquid outlet of the receiver; a freezing temperature expansion device fluidly connected to the liquid outlet of the receiver
Implementation Method 3
a normal cooling temperature evaporator; a freezing temperature evaporator
Implementation Method 4
a heat rejecting heat exchanger/gas cooler
Data Source
Figure 1
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Figure 3
AI summary
A refrigeration system (1) has A) an ejector circuit (3) comprising: Aa) a high pressure compressor unit (2) comprising at least one compressor (2a, 2b, 2c, 2d); Ab) a heat rejecting heat exchanger/gas cooler (4); Ac) an ejector (6); Ad) a receiver (8) having a gas outlet (8b) which is connected to an inlet of the high pressure compressor unit (2). B) a normal cooling temperature flowpath (5) comprising in the direction of flow of the refrigerant: Ba) a normal cooling temperature expansion device (10) fluidly connected to a liquid outlet (8c) of the receiver (8); Bb) a normal cooling temperature evaporator (12); Bc) an ejector secondary inlet line (68) with an ejector inlet valve (26) fluidly connecting an outlet (12b) of the normal cooling temperature evaporator (12) to a suction inlet (6b) of the ejector (6); and Bd) a normal cooling temperature flowpath valve unit (22) configured for fluidly connecting the inlet of the high pressure compressor unit (2) selectively either to the gas outlet (8b) of the receiver (8) or to the outlet (12b) of the normal cooling temperature evaporator (12); C) a freezing temperature flowpath (7) comprising in the direction of flow of the refrigerant: Ca) a freezing temperature expansion device (14) fluidly connected to the liquid outlet (8c) of the receiver (8); Cb) a freezing temperature evaporator (16); Cc) a freezing temperature compressor unit (18) comprising at least one freezing temperature compressor (18a, 18b); and Cd) a freezing temperature flowpath valve unit (20) configured for fluidly connecting the outlet of the freezing temperature compressor unit (18) selectively either to the inlet of the high pressure compressor unit (2) or to the ejector inlet valve (26).