Free-Cooling Refrigeration Loop for High-Ambient Mode Switching
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Solution Overview
Problem
Refrigeration systems face efficiency decreases at high ambient air temperatures, as free-cooling systems struggle to maintain performance and efficiency when ambient temperatures exceed 110°F, and existing systems lack the ability to seamlessly transition between free-cooling and mechanical cooling modes without loss of efficiency.
Innovation Solution
A refrigeration system with a first and second refrigerant circuit, along with a free-cooling loop, controlled by a device to operate in free-cooling-only, free-cooling-plus-mechanical-cooling, and full mechanical cooling modes, allowing the free-cooling loop to interact with both the liquid cooling fluid loop and the second refrigerant circuit to maintain efficiency across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If free-cooling systems are used at high ambient air temperatures (greater than 110°F), then the system can operate without additional energy input from compressors or thermoelectric devices, but the performance and efficiency of the condenser and HVAC&R system decrease due to higher condensing temperatures and pressures
Solution Approach 1:
The free-cooling loop is designed to serve multiple functions: it acts as the primary cooling source during free-cooling mode, serves as a heat rejection path for the second refrigerant circuit during mechanical cooling mode, and can operate independently or in combination with the first refrigerant circuit. This multi-functionality allows the system to maintain efficiency across varying ambient temperatures by adapting the operational mode based on conditions.
Solution Approach 2:
The control device dynamically switches between different operational modes (free-cooling-only, free-cooling-plus-mechanical-cooling, and full mechanical cooling) based on ambient temperature conditions and cooling requirements. This dynamic operation allows the system to optimize performance by engaging the appropriate cooling path, preventing efficiency degradation at high ambient temperatures while maintaining the ability to reject heat from the second refrigerant circuit when needed.
2Use of energy by moving object
If a separate heat exchanger or coil portion is used for free-cooling mode, then the system can exploit low ambient temperatures to provide cooling without additional energy input, but the system lacks the ability to seamlessly transition between free-cooling and mechanical cooling modes without loss of efficiency
Solution Approach 1:
The free-cooling loop is merged with both the liquid cooling fluid loop and the second refrigerant circuit, creating an integrated system where the same loop can serve multiple purposes. The control device manages the integration by directing the free-cooling liquid to different heat exchangers based on operational mode, enabling seamless transitions between free-cooling-only, hybrid, and full mechanical cooling modes without efficiency loss.
Solution Approach 2:
The control device acts as an intermediary that manages the interaction between the free-cooling loop, the first refrigerant circuit, and the second refrigerant circuit. It coordinates the operation of these subsystems, determining when to engage each cooling path and how to route the free-cooling liquid, thereby enabling smooth transitions between different cooling modes while maintaining optimal system efficiency.
3Device complexity
If the free-cooling loop is used as the unique source of cooling in free-cooling-only mode, then the system can operate without mechanical cooling components, but the system cannot reject heat from the second refrigerant circuit when mechanical cooling is required
Solution Approach 1:
The free-cooling loop is designed with universal functionality to serve as both the primary cooling source during free-cooling mode and the heat rejection path for the second refrigerant circuit during mechanical cooling mode. This design allows the system to operate efficiently in free-cooling-only mode with simplified operation while maintaining the capability to reject heat from the second refrigerant circuit when mechanical cooling requirements arise, all within a single integrated loop.
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 system maintains efficiency and capacity at high ambient air temperatures, allowing operation in mechanical cooling mode without loss of efficiency and utilizing the free-cooling loop as a unique cooling source, with no need for new heat exchangers or changes in system footprint.
Implementation Method 1
The free-cooling loop may be used to cool the liquid cooling fluid when the ambient air temperature is low
Implementation Method 2
circulating air is used for heat exchange in an air-cooled condenser
Implementation Method 3
The fluid flowing within the closed loop is generally formulated to undergo phase changes within the normal operating temperatures and pressures of the system so that considerable quantities of heat can be exchanged by virtue of the latent heat of condensation and vaporization of the fluid
Implementation Method 4
considerable quantities of heat can be exchanged by virtue of the latent heat of condensation and vaporization of the fluid
Implementation Method 5
In an air-cooled condenser, the refrigerant flowing through the condenser can exchange heat with circulating air generated by an air moving device such as a fan or blower
Data Source
AI summary
A system for cooling air for use with a liquid cooling fluid loop. The system includes a first refrigerant circuit with an air-cooled condenser, a second refrigerant circuit with a liquid-cooled condenser, and a free-cooling loop. A control device is provided for controlling the operation of the system between a first mode, a second mode, and a third mode. When operating in the first mode, only the free-cooling loop cooperates directly with liquid cooling fluid in the liquid cooling fluid loop to cool the liquid cooling fluid, when operating in the second mode, the second refrigerant circuit is not engaged, and when operating in the third mode, the free-cooling loop interacts with the second refrigerant circuit to reject heat of the second refrigerant circuit through the free-cooling loop.