Gas-replenishing and enthalpy-increasing control method, device and apparatus for two-stage compressor
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Solution Overview
Problem
Current two-stage compression systems with two-way valves face reliability issues and inefficient gas replenishment due to sudden load increases and inability to accurately control enthalpy injection, especially in low-temperature environments, leading to degraded heating capacity and compressor reliability.
Innovation Solution
A gas-replenishing and enthalpy-increasing control method using a gas-replenishing electronic expansion valve that gradually increases its opening degree in a time sequence, adjusts based on detected superheat degrees, and controls the gaseous refrigerant replenishment to avoid sudden load changes and ensure efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-way valve is used to control enhanced vapor injection, then the switching function is simple and reliable, but the suction volume of high-pressure cylinder increases suddenly and compressor load increases greatly when the valve opens at high speed
Solution Approach 1:
An electronic expansion valve is introduced as an intermediary device between the control system and the refrigerant flow. This intermediary provides gradual, proportional control of the injection amount rather than abrupt on/off switching, thereby preventing sudden suction volume increases and load spikes that compromise compressor reliability.
Solution Approach 2:
The control system transitions from static two-way valve switching to dynamic proportional control using an electronic expansion valve. The valve opening degree can be continuously adjusted based on real-time compressor operating conditions, enabling adaptive control that prevents sudden load changes while maintaining reliability.
2Device complexity
If a two-way valve is used for gas replenishment control, then the control structure is simple, but the replenishment amount cannot be accurately controlled during intermediate enthalpy increase
Solution Approach 1:
The control system incorporates feedback from temperature and pressure sensors that monitor the gas replenishment process. Based on this feedback, the electronic expansion valve adjusts the opening degree to achieve precise control of the replenishment amount, ensuring accurate enthalpy increase while maintaining a relatively simple overall control structure.
3Speed
If the gas-replenishing electronic expansion valve opens suddenly, then the gas replenishment response is fast, but the compressor load increases suddenly reducing reliability
Solution Approach 1:
The electronic expansion valve opens in a controlled sequential manner rather than all at once. The control system divides the opening process into stages or time intervals, gradually increasing the opening degree to allow the system to adapt progressively, thereby maintaining fast response while preventing sudden load increases that would harm reliability.
4Productivity
If enhanced vapor injection is implemented to increase heating capacity, then the heating capacity and energy efficiency are improved, but the suction efficiency and compression efficiency may be affected by improper gas replenishment control
Solution Approach 1:
The control system dynamically adjusts key parameters including the electronic expansion valve opening degree, injection timing, and injection amount based on real-time monitoring of temperature, pressure, and compressor operating conditions. This parameter optimization ensures that enhanced vapor injection increases heating capacity while maintaining compression efficiency and system reliability.
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 method enhances the reliability and stability of the two-stage compressor by gradually increasing the compressor load, improving heating capacity and efficiency, and accurately controlling enthalpy injection, thereby ensuring continuous and efficient operation across a wider temperature range.
Implementation Method 1
a gas-replenishing electronic expansion valve, disposed between a medium-pressure liquid storage tank and the two-stage compressor
Implementation Method 2
The injected gaseous refrigerant will be mixed with a refrigerant discharged after being compressed by the low-pressure cylinder and then enter the high-pressure cylinder for compression
Implementation Method 3
a low-pressure cylinder is used for a first-stage compressor, and a high-pressure cylinder is used for a second-stage compressor
Data Source
AI summary
Provided are a gas-replenishing and enthalpy-increasing control method, device and apparatus for a two-stage compressor. The method includes: when a gas-replenishing electronic expansion valve needs to be opened, gradually increasing, by a controller, an opening degree of the gas-replenishing electronic expansion valve in a time sequence; after the gas-replenishing electronic expansion valve is opened, acquiring a detected gas-replenishing superheat degree of a two-stage compressor; and adjusting, based on the gas-replenishing superheat degree of the two-stage compressor, the opening degree of the gas-replenishing electronic expansion valve, wherein the gas-replenishing electronic expansion valve is disposed between a medium-pressure liquid storage tank and the two-stage compressor, and when the opening degree of the gas-replenishing electronic expansion valve is not zero, a gaseous refrigerant in the medium-pressure liquid storage tank replenishes gas and increases enthalpy for the two-stage compressor.