Staged Cooling Circuits for Lower-Energy Data Center Cooling
Find Innovative SolutionsGenerate Solutions
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 is introduced, featuring staged cooling with multiple cooling circuits arranged in series, 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 without compression, and an electronic expansion valve for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional cooling system with compressor is used, then cooling capacity is sufficient, but energy consumption is high (at least half of total data center power)
Solution Approach 1:
The cooling system is divided into multiple independent cooling circuits operating in series, each capable of functioning autonomously. This segmentation allows the system to operate with reduced compressor capacity in each stage, lowering overall energy consumption while maintaining total cooling capacity through the series arrangement of multiple circuits.
Solution Approach 2:
The system dynamically switches between compressor-based cooling and pump-based economizer mode depending on outdoor conditions. When outdoor temperatures are favorable, the system transitions to pump-only operation for the refrigerant loop, eliminating compressor energy consumption during economizer operation while maintaining cooling capacity through heat exchange with outdoor air.
2Loss of energy
If compressor operates continuously, then cooling demand is met, but pressure differences across evaporators and condensers increase energy loss
Solution Approach 1:
Multiple cooling circuits operate in series with staggered compression stages. The first circuit handles the initial temperature reduction with its compressor, while subsequent circuits operate at lower pressure differences. This segmentation of the compression workload across multiple stages reduces the pressure differential each compressor must overcome, minimizing energy loss while collectively meeting the total cooling demand.
3Loss of energy
If dehumidification is performed aggressively, then humidity control is improved, but waste energy increases due to over-cooling
Solution Approach 1:
Different cooling circuits are assigned different functions based on local conditions. The first cooling circuit primarily handles sensible cooling and dehumidification when needed, while subsequent circuits provide fine-tuned temperature control. This local differentiation of cooling functions allows precise humidity control without excessive energy waste from uniform aggressive cooling across all circuits.
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 reduces energy consumption by optimizing compressor operation, lowering pressure differences across evaporators and condensers, and increasing the sensible heat ratio, thereby enhancing energy efficiency and reducing waste energy in dehumidification processes.
Implementation Method 1
the compressor is on and compresses a refrigerant in a vapor phase to raise its pressure and thus its condensing temperature
Implementation Method 2
an evaporator disposed in the cabinet... refrigerant is circulated around the cooling circuit by the compressor
Implementation Method 3
a condenser... Heat rejection device 124 that transfers heat from the return fluid from CRACs 116 to a cooler medium, such as outside ambient air
Data Source
AI summary
A cooling system has a cabinet and a plurality of separate cooling stages including an upstream cooling stage and a downstream cooling stage. At least the upstream cooling state is a variable capacity cooling stage. Each cooling stage has a cooling circuit. Evaporators of the cooling circuits are arranged in the cabinet so that air passes over them in serial fashion. A controller when a Call for Cooling first reaches a point where cooling is needed, operating the upstream cooling circuit to provide cooling and not the downstream cooling circuit. When the Call for Cooling has increased to a second point, the controller additionally operates the downstream cooling circuit to provide cooling. The cooling capacity at which the upstream cooling circuit is being operated is less than its full capacity when the Call for Cooling reaches the second point.