Air conditioning system and control method thereof
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Solution Overview
Problem
Current carbon dioxide air conditioning systems with injectors face challenges in enhancing system performance and energy efficiency, particularly in large-scale commercial applications with varying temperature differences.
Innovation Solution
The air conditioning system incorporates a main circuit with a subcooling circuit, where a first subcooling circuit further cools the two-phase flow from the injector, increasing the liquid-phase refrigerant proportion entering the evaporator, and optional additional components like suction line heat exchangers and liquid pumps enhance energy efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a subcooling circuit is added to increase liquid-phase refrigerant proportion, then system performance and energy efficiency are improved, but device complexity increases
Solution Approach 1:
The subcooling circuit is nested within the existing refrigeration cycle system, with the subcooler integrated into the flow path between the compressor and evaporator. This allows the additional cooling function to be incorporated without requiring a completely separate system, thereby improving productivity while limiting the increase in device complexity.
Solution Approach 2:
The subcooling circuit serves multiple functions: it increases the liquid-phase refrigerant proportion to improve system performance, and simultaneously acts as a heat exchanger that can contribute to overall system efficiency. This multi-functionality helps justify the added complexity by delivering multiple benefits from a single integration.
2Loss of energy
If a subcooling circuit is added to increase liquid-phase refrigerant proportion, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The subcooling circuit is nested within the existing refrigeration cycle system, with the subcooler integrated into the flow path between the compressor and evaporator. This allows the additional cooling function to be incorporated without requiring a completely separate system, thereby improving energy efficiency while limiting the increase in device complexity.
Solution Approach 2:
The subcooling circuit utilizes the refrigerant's own expansion and phase change properties to provide subcooling without requiring external power input or additional active cooling components. The refrigerant naturally subcools as it passes through the throttling device and absorbs heat from the surrounding environment, achieving energy efficiency improvement with minimal additional energy consumption.
3Productivity
If multiple parallel injectors are used to improve partial-load regulation, then operating efficiency is improved, but device complexity increases
Solution Approach 1:
The refrigeration system is segmented into multiple parallel injector units, each capable of independent operation. This segmentation allows the system to adjust the number of active injectors based on load requirements, improving operating efficiency by matching capacity to demand while keeping the complexity increase manageable through modular design.
Solution Approach 2:
The parallel injector configuration enables dynamic adjustment of system capacity by selectively activating or deactivating individual injector units. This dynamic operation allows the system to optimize performance across varying load conditions, improving operating efficiency while maintaining a relatively simple control structure through on/off switching of modular units.
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 configuration effectively improves system performance and energy efficiency by increasing the liquid-phase refrigerant proportion for heat exchange, enhancing cooling capacity and reducing energy consumption.
Implementation Method 1
a first subcooling circuit further cools the two-phase flow from the injector, increasing the liquid-phase refrigerant proportion entering the evaporator
Implementation Method 2
a gas cooler connected between an exhaust port of the main compressor and a primary flow inlet of the injector
Implementation Method 3
a main throttling element and an evaporator connected between a liquid outlet of the gas-liquid separator and a secondary flow inlet of the injector
Data Source
AI summary
An air conditioning system and a control method thereof. The air conditioning system includes a main circuit and a first subcooling circuit, wherein the main circuit has: a main compressor and an injector; a gas cooler and a gas-liquid separator connected between the main compressor and the injector; and a main throttling element and an evaporator connected between the gas-liquid separator and the injector; and wherein the first subcooling circuit has: a first subcooling compressor, a first condenser, a first subcooling throttling element and a first subcooler connected in sequence; wherein the first subcooler is further disposed in a flow path between the outlet of the injector and the gas-liquid separator.