Refrigeration system and the control method thereof
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Solution Overview
Problem
Refrigeration systems with Enhanced Vapor Injection (EVI) compressors face efficiency reduction at extremely low ambient temperatures or significant temperature differences, struggling to maintain performance below -25°C and above 40°C temperature gaps.
Innovation Solution
A refrigeration system incorporating a compressor, condenser, first and second throttling devices, an ejector, and a controller that adjusts the opening of the first throttling device based on pressure difference or dryness of the gas-liquid two-phase refrigerant to optimize the operation of the ejector loop, ensuring efficient gas-liquid phase conversion and improved system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an EVI compressor is used to improve heating capacity at low temperatures, then system efficiency is improved at -15°C, but the system becomes difficult to cope with when ambient temperature is below -25°C or temperature difference exceeds 40°C
Solution Approach 1:
The system divides the refrigerant flow into multiple paths: a first path through the ejector for low-temperature refrigeration effect, and a second path bypassing the ejector for direct heating. This segmentation allows the system to adapt to different temperature conditions by adjusting the proportion of refrigerant in each path, resolving the contradiction between heating capacity and adaptability to extreme temperatures.
Solution Approach 2:
The system dynamically adjusts the opening degree of the first throttling device based on the pressure difference between the ejector outlet and suction inlet, which changes the refrigerant flow parameters. This parameter adjustment optimizes the ejector's performance across different ambient temperatures, enabling the system to maintain efficiency from -15°C to below -25°C while preserving adaptability.
2Productivity
If the ejector operates with high pressure difference to improve refrigeration effect, then the ejector efficiency is improved, but the throttling device cannot ensure appropriate dryness of two-phase refrigerant
Solution Approach 1:
The controller receives feedback from pressure sensors measuring the pressure difference between the ejector outlet and suction inlet. Based on this feedback, the controller dynamically adjusts the opening degree of the first throttling device to maintain appropriate dryness (0.05-0.5) of the two-phase refrigerant. This feedback mechanism ensures both high refrigeration effect through optimized pressure difference and precise dryness control, resolving the contradiction between refrigeration effect and dryness control precision.
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
The solution enables the EVI compressor system to operate efficiently at ambient temperatures ranging from -25°C to -30°C, improving efficiency by 5% to 10% and extending the operating temperature range, effectively addressing the limitations of EVI technology in extreme conditions.
Implementation Method 1
an ejector having a high-pressure fluid inlet, a fluid suction inlet and a fluid outlet, wherein the high-pressure fluid inlet of the ejector is connected to the first throttling device to receive the gas-liquid two-phase refrigerant
Implementation Method 2
a first throttling device for throttling liquid refrigerant from the condenser to produce gas-liquid two-phase refrigerant
Implementation Method 3
the fluid outlet of the ejector is connected to a flash tank, the gas-phase outlet of the flash tank is connected to the compressor inlet, the liquid-phase outlet of the flash tank is connected to an evaporator
Data Source
AI summary
A refrigeration system and a control method thereof. The refrigeration system includes a compressor and a condenser, and further includes a first throttling device for receiving liquid refrigerant from the condenser; an ejector having a high-pressure fluid inlet, a fluid suction inlet and a fluid outlet, the high-pressure fluid inlet of the ejector is connected to the first throttling device, the fluid outlet of the ejector is connected to a flash tank, a gas-phase outlet of the flash tank is connected to a compressor inlet, a liquid-phase outlet of the flash tank is connected to an evaporator via a second throttling device, and the evaporator is connected to the fluid suction inlet of the ejector; and a controller configured to control an opening of the first throttling device based on a pressure difference between the fluid outlet and the fluid suction inlet of the ejector.