A method for switching compressor capacity
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Solution Overview
Problem
In vapor compression systems, efficiently distributing compressor capacity between high and medium pressure suction lines is challenging, leading to suboptimal utilization of available capacity and increased wear due to frequent compressor switching.
Innovation Solution
A method that defines options for distributing compressor capacity between high and medium pressure suction lines, predicts the impact on operating parameters, and selects the optimal option based on current demands, allowing for fast and efficient allocation without switching compressors off, using valve arrangements like two-way or three-way valves to connect compressors to either suction line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If one or more compressors are selectively connectable to the high pressure suction line or to the medium pressure suction line, then the total available compressor capacity can be utilized more efficiently, but it becomes necessary to control the connection of the compressor(s) in a suitable manner which fulfils various requirements for the operation of the vapour compression system
Solution Approach 1:
The system dynamically switches compressor connections between high pressure and medium pressure suction lines based on real-time operating conditions. The control method evaluates multiple options for distributing compressor capacity and selects the optimal configuration, allowing the system to adapt to varying demands while maintaining efficient capacity utilization without excessive complexity.
2Reliability
If a sufficiently high number of compressors are connected to each of the suction lines to meet peak demands, then sufficient compressor capacity is available to meet demand at any time, but this results in a high amount of unused compressor capacity
Solution Approach 1:
The control method enables dynamic allocation of compressor capacity by switching connections between high pressure and medium pressure suction lines based on actual cooling demands. This allows the system to meet peak demands when necessary while minimizing unused capacity during lower demand periods, optimizing the balance between reliability and energy efficiency.
3Use of energy by moving object
If the available compressor capacity is switched between high pressure and medium pressure suction lines, then the work required by the compressors is reduced when connected to high pressure suction line, but frequent switching increases wear on the compressors
Solution Approach 1:
The control method incorporates feedback mechanisms that monitor operating conditions and evaluate multiple distribution options before switching compressor connections. By base d on current operating demands and predicted impacts on operating parameters, the system makes informed switching decisions that reduce unnecessary wear while maintaining energy efficiency, rather than switching frequently in response to minor fluctuations.
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 approach ensures optimal distribution of compressor capacity, reduces wear, and allows the system to quickly adapt to changing demands while maintaining energy efficiency and meeting cooling requirements.
Implementation Method 1
a high pressure valve and/or an ejector is arranged in a refrigerant path, at a position downstream relative to a heat rejecting heat exchanger. Thereby refrigerant leaving the heat rejecting heat exchanger passes through the high pressure valve or the ejector, and the pressure of the refrigerant is thereby reduced.
Implementation Method 2
The refrigerant passing through the high pressure valve or the ejector is received in a receiver, where the refrigerant is separated into a liquid part and a gaseous part.
Data Source
Figure 1
AI summary
A method for operating a compressor unit (2) comprising one or more compressors (8, 9, 10) is disclosed, the compressor unit (2) being arranged in a vapour compression system (1). Two or more options for distributing the available compressor capacity of the compressor unit (2) between being connected to a high pressure suction line (11) and to a medium pressure suction line (13) are defined. For each option, an expected impact on one or more operating parameters of the vapour compression system (1), resulting from distributing the available compressor capacity according to the option, is predicted. An option is selected, based on the predicted expected impact for the options, and based on current operating demands of the vapour compression system (1), and the available compressor capacity is distributed according to the selected option, e.g. by means of settings of one or more valve arrangements (14, 15).