Parallel Ejector Refrigeration Circuit for Part-Load Efficiency
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Solution Overview
Problem
Ejector refrigeration circuits face inefficiencies in controlling high pressure mass flow and meeting varying refrigeration demands, particularly during part-load operations.
Innovation Solution
The use of at least two controllable ejectors connected in parallel, each with a controllable motive nozzle, primary high pressure input port, secondary low pressure input port, and medium pressure output port, operated by a control unit to adjust opening degrees and meet refrigeration demands efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ejector is used to control high pressure mass flow, then the device complexity is reduced, but the efficiency and ability to meet varying refrigeration demands deteriorates
Solution Approach 1:
The single ejector is divided into multiple parallel ejectors (first ejector, second ejector, etc.), each capable of independent operation. This segmentation allows the system to meet varying refrigeration demands by activating only the necessary number of ejectors, thereby maintaining efficiency while avoiding the complexity of a single oversized ejector operating in less efficient ranges.
2Productivity
If the ejector opening degree is increased to meet higher refrigeration demands, then the refrigeration capacity increases, but the efficiency of the ejector decreases
Solution Approach 1:
Instead of opening a single ejector to its maximum capacity (which reduces efficiency), the system segments the flow across multiple ejectors. Each ejector operates at or near its optimal opening degree, maintaining high efficiency while collectively meeting the total refrigeration demand through parallel operation.
Solution Approach 2:
The control unit dynamically adjusts the opening degree of each ejector based on actual refrigeration demands. This dynamic control ensures that ejectors operate in their efficient ranges while adapting to varying load conditions, preventing energy loss that would occur with fixed or suboptimal opening degrees.
3Productivity
If a single ejector operates at maximum capacity, then the refrigeration demand is met, but the ejector operates in less efficient ranges and lifespan is reduced
Solution Approach 1:
The refrigeration load is distributed across multiple ejectors rather than placing maximum demand on a single ejector. This segmentation prevents any single ejector from operating continuously at maximum capacity, reducing wear and tear while maintaining the required total refrigeration capacity through parallel operation of multiple ejectors at moderate loads.
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 ensures stable and efficient operation by avoiding less efficient ranges of operation, optimizing efficiency across a wide range of conditions and extending the lifespan of the controllable ejectors.
Implementation Method 1
An ejector additionally may operate as 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.
Implementation Method 2
a controllable motive nozzle, a controllable primary high pressure input port forming an inlet to the controllable motive nozzle
Data Source
Figure 1
Figure 2
AI summary
An ejector refrigeration circuit (1), which is configured for circulating a refrigerant, in particular carbon dioxide, comprises at least two controllable ejectors (6, 7), which are connected in parallel and respectively comprise a primary high pressure input port (6a, 7a), a secondary low pressure input port (6b, 7b) and an output port (6c, 7c); and a control unit (28), which is configured for operating the ejector refrigeration circuit (1) employing a method which comprises the steps of: a) operating a first ejector (6) of the at least two controllable ejectors (6, 7) by controlling the opening of its high pressure port (6a) until the maximum efficiency of said first ejector (6) has been reached or the actual refrigeration demands are met; b) operating at least one additional ejector (7) of the at least two controllable ejectors (6, 7) by opening its primary high pressure input port (7a) for increasing the refrigeration capacity of the ejector refrigeration circuit (1) in case the actual refrigeration demands are not met by operating the first ejector (6) alone.