Tandem Compressor Cooling Stages With Pumped Refrigerant Economizer
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Solution Overview
Problem
Current data center cooling systems are inefficient, consuming at least half of the power used in a typical data center, with a focus on improving energy efficiency becoming increasingly important due to the high energy consumption by cooling and power conversion systems.
Innovation Solution
A high efficiency cooling system with staged cooling provided by multiple cooling circuits arranged serially, utilizing tandem digital scroll compressors and a pumped refrigerant economizer mode that bypasses the compressor when outdoor temperatures are low, allowing the liquid pump to circulate the refrigerant in its liquid phase, reducing energy consumption by minimizing the need for compressor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compressor operates continuously to provide cooling, then the cooling capacity is maintained, but the energy consumption increases significantly
Solution Approach 1:
The system dynamically switches between compressor operation and liquid pump operation based on outdoor temperature conditions. When outdoor temperature is low, the system uses the liquid pump to circulate refrigerant without compressing it, thereby maintaining cooling capacity while significantly reducing energy consumption. This dynamic adaptation resolves the contradiction between maintaining cooling capacity and reducing energy use.
Solution Approach 2:
The system changes the operating parameters of the refrigerant circulation by bypassing the compressor and using only the liquid pump when outdoor temperatures are favorable. This parameter change allows the system to maintain adequate refrigerant circulation and cooling capacity while operating at much lower energy consumption levels during certain conditions.
2Power
If the compressor is used to circulate refrigerant, then the refrigerant pressure and temperature are raised for effective cooling, but the system energy efficiency decreases
Solution Approach 1:
The invention extracts the essential function of refrigerant circulation from the compressor by introducing a separate liquid pump that can circulate refrigerant without compression. This allows the system to separate the circulation function from the compression function, enabling operation without the energy-intensive compressor when outdoor conditions permit, thereby improving overall system energy efficiency while maintaining necessary refrigerant flow.
3Temperature
If the system operates in traditional cooling mode, then cooling is provided, but the sensible coefficient of performance is lower compared to economizer mode
Solution Approach 1:
The system dynamically selects between traditional compressor-based cooling mode and liquid pump-based economizer mode based on outdoor temperature conditions. This dynamic operation allows the system to achieve higher sensible coefficient of performance during favorable outdoor conditions by using the economizer mode, while still providing adequate cooling when needed, thus resolving the contradiction between cooling effect and energy efficiency.
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 significantly reduces energy consumption by optimizing compressor operation and leveraging the liquid pump to circulate refrigerant at low outdoor temperatures, enhancing the system's sensible coefficient of performance and annual energy efficiency, particularly in colder climates.
Implementation Method 1
the liquid pump is on and pumps the refrigerant in a liquid phase and refrigerant is circulated around the cooling circuit by the liquid pump
Implementation Method 2
an evaporator disposed in the cabinet... air to be cooled passes over them in serial fashion
Implementation Method 3
a condenser... outdoor air temperature is low enough to provide sufficient heat rejection from the refrigerant flowing through the condenser to the outside air
Data Source
AI summary
A cooling system has a plurality of separate cooling stages including an upstream cooling stage having an upstream cooling circuit and a downstream cooling stage including a downstream cooling circuit, which are each a direct expansion cooling circuit including a tandem compressor. Each tandem compressor includes a fixed capacity compressor and a variable capacity compressor. A controller controls the fixed capacity compressor and variable capacity compressor of each tandem compressor based on a Call for Cooling, which of a plurality of ranges the Call for Cooling falls within, and whether the Call for Cooling is ramping up or ramping down.