Air conditioning systems and methods with cooling capacity modulation via fixed pump operation and variable condenser fan operation
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Solution Overview
Problem
Traditional cooling systems face inefficiencies in cooling capacity control, particularly in pumped refrigerant economizer mode, where cooling capacity is limited by outdoor ambient temperature and heat rejection capability, leading to energy wastage and potential freezing of liquid lines.
Innovation Solution
The system incorporates a control module that adjusts the speed of condenser fans and pumps based on a requested cooling percentage, operating in pumped refrigerant economizer or mixed modes to optimize cooling capacity and prevent freezing, while maintaining energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cooling capacity is increased to meet high cooling demands, then cooling performance is improved, but energy consumption increases and system stability deteriorates due to potential freezing of liquid lines
Solution Approach 1:
The system dynamically adjusts pump speed and condenser fan speed based on real-time cooling demands and outdoor ambient temperatures. The controller modulates pump speed to maintain optimal refrigerant flow while adjusting condenser fan speed to match heat rejection requirements, preventing both energy wastage and freezing conditions.
Solution Approach 2:
The system changes operating parameters (pump speed, condenser fan speed) based on outdoor ambient temperature conditions. When outdoor temperature is favorable, the system operates in pumped refrigerant economizer mode with reduced pump speeds to leverage ambient cooling. When cooling demand increases or ambient temperature rises, the system transitions to mixed mode or traditional cooling mode with adjusted parameters to maintain stability and prevent freezing.
2Loss of energy
If pump speed is reduced to save energy in pumped refrigerant economizer mode, then energy efficiency is improved, but cooling capacity is limited by heat rejection capability
Solution Approach 1:
The system dynamically switches between pumped refrigerant economizer mode and mixed mode based on cooling demand. In economizer mode, pump speed is reduced for energy efficiency when cooling demand is low and ambient conditions are favorable. When cooling demand increases beyond heat rejection capability, the system transitions to mixed mode with increased pump speed and compressor engagement to meet the higher cooling capacity requirement.
Solution Approach 2:
The system incorporates multiple cooling modes (pumped refrigerant economizer mode, mixed mode, traditional cooling mode) within a single HVAC system, allowing it to universally handle various cooling scenarios. The pump and condenser fan serve multiple functions: in economizer mode they provide primary cooling with reduced energy consumption, while in mixed mode they work alongside the compressor to provide enhanced cooling capacity when needed.
3Productivity
If cooling capacity is increased to meet high cooling demands, then cooling performance is improved, but system stability worsens due to potential freezing of liquid lines
Solution Approach 1:
The controller continuously monitors cooling demand, outdoor ambient temperature, and system operating conditions to adjust pump speed and condenser fan speed in real-time. This feedback mechanism ensures that cooling capacity is increased only when necessary and that system parameters remain within stable operating ranges, preventing freezing of liquid lines while meeting high cooling demands when required.
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 enhances energy efficiency by adjusting fan and pump speeds according to cooling demands, preventing energy wastage and ensuring stable operation by maintaining minimum pump speeds, thus improving overall cooling system performance.
Implementation Method 1
The first condenser fan module is configured to control a first condenser fan to transfer air across a first condenser of the first cooling circuit
Implementation Method 2
The first pump module is configured to control a first pump to pump a first cooling fluid through a first cooling circuit
Implementation Method 3
The condenser 60 may be a micro-channel condenser that cools the cooling fluid received from the compressor 58
Data Source
AI summary
A cooling system is provided and includes pump, condenser fan, and control modules. The pump module controls a pump to pump a cooling fluid through a cooling circuit. The condenser fan module controls a condenser fan to transfer air across a condenser of the cooling circuit. The control module, while operating in a pumped refrigerant economizer mode or a mixed mode, determines a requested CFC percentage. The pump module activates the pump if the requested CFC percentage is greater than or equal to a predetermined CFC percentage. The condenser fan module: if the requested CFC percentage is greater than or equal to the predetermined CFC percentage, activates the condenser fan or operates the condenser fan at least at a minimum speed; and based on the requested CFC percentage, adjusts a speed of the condenser fan between the minimum speed and a maximum permitted speed to provide the requested CFC percentage.