Integrated Air Conditioning Control for Seamless Free-Cooling Switch
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Solution Overview
Problem
Integrated air conditioning systems face inefficiencies when operating in cooling mode at low ambient temperatures, as they continue to use compressors, which is less efficient than free-cooling mode, and switching between modes temporarily stops refrigeration, causing the working fluid to warm up.
Innovation Solution
An integrated air conditioning system with two units and a controller that allows seamless switching between cooling and free-cooling modes by using conduits to maintain fluid circulation, ensuring continuous conditioning through one unit while the other is transitioning, thereby avoiding interruptions in cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the air conditioning system operates in cooling mode at low ambient temperatures, then the compressor continues to provide cooling, but energy efficiency deteriorates
Solution Approach 1:
The system dynamically switches between cooling mode and free-cooling mode based on ambient temperature conditions. When ambient temperature is low, the system transitions to free-cooling mode where the compressor is bypassed and outdoor air directly cools the refrigerant through the condenser, significantly improving energy efficiency while maintaining cooling performance
Solution Approach 2:
The system changes operational parameters by switching the state of the compressor and flow control valves. In free-cooling mode, the compressor discharge pressure and refrigerant flow path are changed to allow direct heat exchange between outdoor air and refrigerant, optimizing system efficiency for low ambient temperature conditions
2Use of energy by moving object
If the system switches from cooling mode to free-cooling mode, then energy efficiency improves, but the refrigeration process is temporarily interrupted causing working fluid temperature to rise
Solution Approach 1:
The system performs preliminary action by pre-cooling the working fluid in the evaporator before the mode switch occurs. This ensures that when the transition to free-cooling mode begins, the working fluid is already at the desired temperature, preventing temperature rise during the transition period
Solution Approach 2:
The system maintains continuity of useful action by ensuring the refrigerant circulation and heat exchange processes continue uninterrupted during mode switching. The condenser and evaporator remain active throughout the transition, preventing any break in the cooling function and maintaining working fluid temperature stability
3Reliability
If the compressor is used for cooling at low ambient temperatures, then cooling function is maintained, but energy consumption increases
Solution Approach 1:
The system extracts the compressor from the active cooling cycle during free-cooling mode. By bypassing the compressor and using direct heat exchange between outdoor air and refrigerant through the condenser, the system eliminates the energy-consuming compression process while maintaining the cooling function through passive heat transfer
Solution Approach 2:
The system uses self-service by allowing outdoor air to directly cool the refrigerant without mechanical assistance from the compressor. The natural temperature difference between cool outdoor air and warmer refrigerant drives the heat exchange process, eliminating the need for external energy input while maintaining cooling functionality
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 enhances energy efficiency by utilizing free-cooling mode when ambient temperatures are low and prevents temperature fluctuations during mode switching by maintaining continuous fluid conditioning, ensuring consistent performance.
Implementation Method 1
the condenser heat exchanger is cooled by the working fluid in the second evaporator
Implementation Method 2
the first evaporator heat exchanger and the second evaporator heat exchanger are in heat exchange communication with each other
Data Source
Figure 1~2
Figure 3
AI summary
An integrated air conditioning system having a first air conditioning unit having a first evaporator with a first input and a first output; a second air conditioning unit having a second evaporator with a second input and a second output; a first conduit fluidly connecting the first input with the second output; a second conduit fluidly connecting the second input with the first output. The first and second conduits and the first and second evaporators form a working fluid circuit.