Multistage Compressor Injection Control for Stable Compression Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multistage compressors with injection circuits face efficiency and capacity reductions when the injection circuit is turned on/off due to changes in the compression ratio between the low and high stage compressing mechanisms, especially during varying operational conditions like mild-weather seasons.
Innovation Solution
A multistage compressor design incorporating a capacity control mechanism and an on/off mechanism for the injection circuit, allowing the capacity control mechanism to adjust the apparent displacement volume of the high stage compressing mechanism based on the injection status, maintaining an optimal compression ratio and ensuring high-efficiency operation regardless of injection circuit status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the injection circuit is turned on/off to adapt to varying operational conditions, then the compressor can operate efficiently across different loads, but the compression ratio between low stage and high stage changes, causing efficiency and capacity reduction
Solution Approach 1:
The patent applies dynamics by making the compression ratio adjustable through a variable displacement mechanism in the high-stage compressor. This allows the compression ratio to be dynamically changed based on operating conditions, resolving the contradiction between adaptability and efficiency. When the injection circuit is turned off, the high-stage compressor displacement is reduced to maintain the optimal compression ratio, preventing efficiency loss while adapting to varying loads.
Solution Approach 2:
The patent changes the physical parameter of compression ratio by adjusting the displacement volume of the high-stage compressor. This parameter change allows the system to maintain optimal compression ratio across different operating modes (with or without injection), thereby preserving efficiency and capacity while achieving adaptability to varying operational conditions.
2Productivity
If the compression ratio is optimized for injection mode, then efficiency is maximized during injection, but performance degrades when injection is turned off
Solution Approach 1:
The variable displacement mechanism enables dynamic adjustment of the high-stage compressor's compression ratio. When injection is active, the compressor operates at optimal compression ratio for injection mode. When injection is turned off, the displacement is automatically reduced to maintain optimal compression ratio, preventing performance degradation and achieving versatility across different injection states.
Solution Approach 2:
The system incorporates feedback control where the injection circuit status is detected and used to control the variable displacement mechanism. This feedback loop ensures that the compression ratio is automatically adjusted based on whether injection is on or off, maintaining optimal efficiency in both states and preventing performance degradation.
3Device complexity
If a fixed displacement high stage compressing mechanism is used, then the structure is simple, but the compression ratio cannot be adjusted when injection circuit status changes, leading to efficiency loss
Solution Approach 1:
The patent introduces a variable displacement mechanism that allows the high-stage compressor to dynamically adjust its compression ratio. While this increases device complexity compared to a fixed displacement design, it enables the system to maintain optimal efficiency across different injection circuit statuses by adjusting the compression ratio to match operating 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 design enables continuous high-efficiency and high-capacity operation by maintaining an optimal compression ratio and preventing performance degradation when the injection circuit is turned on/off, while also preventing liquid flowback and ensuring reliable startup and operation.
Implementation Method 1
a low stage side compressing mechanism compressing an intermediate pressure refrigerant gas
Implementation Method 2
a high stage side compressing mechanism suctioning the compressed intermediate pressure refrigerant gas to perform two-stage compression
Data Source
Figure 1
Figure 2
Figure 3
AI summary
To provide a multistage compressor including an injection circuit, which can continue high-efficiency and high-capacity operations even if the injection circuit is turned on/off in accordance with operating conditions. A multistage compressor (2) includes a high stage side compressing mechanism (5) suctioning the intermediate pressure refrigerant gas compressed with a low stage side compressing mechanism (4) to perform two-stage compression, and an injection circuit (15) for injecting an intermediate pressure refrigerant into the intermediate pressure refrigerant gas suctioned to the high stage side compressing mechanism (5), the high stage side compressing mechanism (5) including a capacity control mechanism (61) for bypassing a refrigerant gas that is being compressed to a suction side, the injection circuit (15) including an on/off mechanism (75) for performing on/off control of refrigerant injection, and the capacity control mechanism (61) and the on/off mechanism (75) being operated in conjunction with each other.