Closed-Cycle Air Refrigeration Pressure Balancing at Compressor Inlet
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Solution Overview
Problem
Closed-cycle air refrigeration systems face challenges in maintaining consistent refrigerant pressure at the compressor inlet, leading to potential drops in cooling performance and requiring separate machine designs for open- and closed-cycle operations, resulting in increased costs.
Innovation Solution
A closed-cycle gas refrigeration system that uses a sealed refrigerant gas supply/discharge system with an expansion tank to adjust refrigerant gas pressure via pressure difference, utilizing valves and a pressure sensor for precise control, allowing the system to operate within a preset range without external gas release, thus enabling equivalent design specifications for both closed- and open-cycle systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a closed-cycle air refrigeration system operates at atmospheric pressure, then the system is simple in design, but the refrigerant pressure on the compressor inlet side drops to negative levels causing compression performance to deteriorate
Solution Approach 1:
A pressure adjustment mechanism is introduced as an intermediary device between the compressor inlet and the refrigerant circulation system. This mechanism actively regulates the refrigerant pressure on the compressor inlet side, preventing it from dropping to negative levels while maintaining the closed-cycle configuration. The pressure adjustment mechanism acts as a mediator that balances the system's simplicity with the need for reliable compression performance.
2Reliability
If separate machines are designed for open-cycle and closed-cycle systems, then each machine is optimized for its specific operation mode, but the cost increases
Solution Approach 1:
The refrigeration system is designed with multi-functionality, incorporating a pressure adjustment mechanism that enables a single machine to operate effectively in both closed-cycle and open-cycle modes. The pressure adjustment mechanism can be configured to maintain atmospheric pressure levels when operating in open-cycle mode, allowing the same hardware platform to serve multiple purposes. This universal design approach eliminates the need for separate optimized machines for each operation mode, thereby reducing manufacturing costs while maintaining operational reliability.
3Adaptability or versatility
If the refrigerant pressure on the compressor inlet side is made adjustable, then a single machine can serve both closed- and open-cycle systems, but the device complexity increases
Solution Approach 1:
The pressure adjustment mechanism is designed with dynamic characteristics, allowing it to adapt its operation based on the system's mode (closed-cycle or open-cycle). The mechanism can dynamically adjust the refrigerant pressure on the compressor inlet side according to real-time operating conditions, enabling seamless transition between different operation modes. This dynamic approach provides dual-cycle capability while keeping the added complexity manageable through intelligent control rather than rigid mechanical structures.
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 solution allows for reliable pressure adjustment within the compressor inlet-side passage, preventing performance drops and enabling a single machine to function as both closed- and open-cycle systems, reducing costs while maintaining refrigerant integrity and eliminating the need for dehumidification systems.
Implementation Method 1
air is compressed to high pressure and high temperature by a compressor
Implementation Method 2
cooled by a cooler that uses a cooling water
Implementation Method 3
the air is expanded to low pressure and low temperature by an expander
Implementation Method 4
heat is exchanged between low-temperature air on the outlet side of an expander and brine
Data Source
Figure 1
Figure 2
AI summary
Provided is a closed-cycle air refrigeration system 10A in which high-temperature, high-pressure air refrigerant compressed by a compressor 22 is cooled by a water cooled heat exchanger 16 and a heat recovery heat exchanger 18, then expanded by an expander 26 to obtain very low-temperature and low-pressure air refrigerant. This low-temperature, low-pressure air refrigerant is supplied to a brine cooler 20. The system includes a sealed air refrigerant supply/discharge system 50 formed by an expansion tank 51, a compressor inlet-side connecting passage 52, and a compressor outlet-side connecting passage 54. A pressure sensor 62 detects a pressure of the air refrigerant in a compressor inlet-side air refrigerant passage 12a, and air refrigerant is supplied or discharged between the expansion tank 51, and the compressor inlet-side air refrigerant passage 12a or a compressor outlet-side air refrigerant passage 12b such that the air refrigerant pressure stays within a preset range.