Air replenishment and enthalpy increase control method and apparatus for two-stage compressor and equipment
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Solution Overview
Problem
Current two-stage compression systems face instability and reliability issues due to sudden changes in compressor load and inability to accurately control gas replenishment and enthalpy increase, primarily caused by the switching function of two-way valves used in gas-replenishing systems.
Innovation Solution
A gas-replenishing and enthalpy-increasing control method and device that employs a gas-replenishing electronic expansion valve, gradually increasing its opening degree in a time sequence, and adjusts based on detected superheat degrees to ensure controlled gas replenishment and enthalpy increase, avoiding sudden load changes and improving compressor stability.
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:
The patent replaces the mechanical two-way valve with an electronic expansion valve that can be precisely controlled by an electronic controller. This substitution allows for gradual opening of the valve and accurate control of the replenishment amount, eliminating the sudden load changes and stability issues caused by mechanical valve switching.
Solution Approach 2:
The electronic expansion valve provides dynamic control capability, allowing the opening degree to be adjusted continuously based on operating conditions. The controller can gradually increase the opening degree and adjust the replenishment amount in real-time, transforming the static on/off control of mechanical valves into dynamic proportional control.
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 patent replaces the two-way valve with an electronic expansion valve that accepts electronic control signals. This allows the controller to precisely regulate the valve opening degree and thereby accurately control the replenishment amount, overcoming the limitation of mechanical valves that can only provide on/off control.
Solution Approach 2:
The system implements feedback control where the controller monitors operating conditions and adjusts the electronic expansion valve opening degree accordingly. This closed-loop control enables accurate regulation of the replenishment amount during intermediate enthalpy increase, ensuring optimal system performance.
3Speed
If the two-way valve opens suddenly at high compressor speed, then the switching response is fast, but the compressor load increases suddenly and component operating life is affected
Solution Approach 1:
The electronic expansion valve enables dynamic control where the opening degree can be gradually increased rather than suddenly switched. The controller can ramp up the opening over time even at high compressor speeds, avoiding sudden load changes that would stress components and reduce their operating life.
Solution Approach 2:
The system prepares for potential sudden load changes by using gradual valve opening control. The electronic controller can preemptively adjust the opening degree in small increments, cushioning the impact on compressor load and protecting components from sudden stress spikes.
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 stabilizes compressor operation by gradually increasing load and accurately controlling gas replenishment, enhancing the reliability and efficiency of two-stage compression systems, particularly in low-temperature environments, and ensuring continuous operation across a wider temperature range.
Implementation Method 1
a controller gradually increases an opening degree of the gas-replenishing electronic expansion valve in a time sequence
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
Figure 1
Figure 2
Figure 3~4
AI summary
Provided are a gas-replenishing and enthalpy-increasing control method, device and apparatus for a two-stage compressor (10). The gas-replenishing and enthalpy-increasing control method includes: when a gas-replenishing electronic expansion valve (20) needs to be opened, gradually increasing, by a controller (40), an opening degree of the gas-replenishing electronic expansion valve (20) in a time sequence; after the gas-replenishing electronic expansion valve (20) is opened, acquiring a detected gas-replenishing superheat degree of a two-stage compressor (10); and adjusting, based on the gas-replenishing superheat degree of the two-stage compressor (10), the opening degree of the gas-replenishing electronic expansion valve (20), wherein the gas-replenishing electronic expansion valve (20) is disposed between a medium-pressure liquid storage tank (30) and the two-stage compressor (10), and when the opening degree of the gas-replenishing electronic expansion valve (20) is not zero, a gaseous refrigerant in the medium-pressure liquid storage tank (30) replenishes gas and increases enthalpy for the two-stage compressor (10), thereby solving the problem in the related art of unsatisfying operating stability of a two-stage compressor.