Systems and methods for computer room air conditioning
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Solution Overview
Problem
Current computer room air conditioner (CRAC) units in data centers are inefficient in terms of energy consumption, relying heavily on external water or air for cooling, which can be costly and unsustainable.
Innovation Solution
A refrigeration economizer system is introduced, comprising a condenser, two cooling circuits, and control valves to optimize refrigerant flow and pressure, allowing the CRAC unit to operate in multiple modes based on ambient temperature, using a combination of direct expansion and economizer circuits to enhance efficiency without external water or air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If external water or air cooling is used to cool CRAC units, then cooling effectiveness is improved, but energy consumption and operational costs increase
Solution Approach 1:
The system changes the operating parameters of the refrigeration cycle by using an economizer circuit to subcool liquid refrigerant below its condensing temperature. This subcooling increases the refrigeration effect per unit of refrigerant, allowing the system to achieve the same cooling effect with less refrigerant circulation and lower compressor energy consumption
Solution Approach 2:
The economizer circuit utilizes the phase transition of refrigerant from liquid to vapor at lower temperatures through flash gas formation. This phase transition occurs in the economizer evaporator where a portion of liquid refrigerant flashes into vapor, absorbing heat and subcooling the remaining liquid refrigerant before it enters the main evaporator
2Device complexity
If a single cooling circuit is used in CRAC units, then device complexity is reduced, but energy efficiency is insufficient
Solution Approach 1:
The refrigeration system is segmented into two independent circuits: a high-side circuit with the compressor and condenser, and a low-side circuit with the economizer evaporator and main evaporator. This segmentation allows the system to operate in different modes (single circuit or dual circuit) depending on ambient conditions, optimizing energy efficiency without requiring a completely complex multi-circuit design
3Device complexity
If fixed refrigerant flow is used in cooling circuits, then device complexity is reduced, but adaptability to varying ambient temperatures is poor
Solution Approach 1:
The system employs dynamic control of refrigerant flow through electronic expansion valves (EEV) in both the economizer circuit and main circuit. These EEVs can dynamically adjust their opening degrees based on real-time ambient temperature conditions and cooling load requirements, allowing the system to adapt efficiently to varying operating conditions
Solution Approach 2:
The refrigeration system incorporates feedback control through temperature sensors that monitor ambient conditions and evaporator temperatures. This feedback information is used by the control system to adjust the EEV openings and compressor speed, optimizing refrigerant flow distribution between the economizer and main circuits based on actual operating conditions
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 increases the energy efficiency of CRAC units by optimizing refrigerant flow and pressure, reducing energy consumption and operational costs, while maintaining reliable cooling performance across varying ambient temperatures.
Implementation Method 1
a condenser configured to condense refrigerant to a liquid
Implementation Method 2
a direct expansion valve coupled to the condenser... configured to regulate the first portion of liquid refrigerant
Implementation Method 3
a first evaporator coil coupled to the direct expansion valve... output first refrigerant vapor
Implementation Method 4
a compressor coupled to the first evaporator coil... configured to receive the first refrigerant vapor and output a compressor refrigerant output
Implementation Method 5
an economizer valve coupled to the pump and second evaporator coil... configured to divert a selected portion of the liquid refrigerant
Implementation Method 6
a second evaporator coil coupled to the economizer valve... output a second vapor refrigerant
Implementation Method 7
a pump coupled to the condenser... configured to pump the liquid refrigerant from the condenser
Data Source
AI summary
A cooling system includes a condenser and first and second cooling circuits. The condenser is configured to condense refrigerant to a liquid. The first cooling circuit includes a direct expansion valve coupled to the condenser, a first evaporator coil coupled to the direct expansion valve, and a compressor coupled to the first evaporator coil. The first cooling circuit receives at least a first portion of the liquid refrigerant and output first refrigerant vapor, and the compressor receives the first refrigerant vapor and output a compressor refrigerant output to the condenser. The second cooling circuit includes a pump coupled to the condenser, an economizer valve coupled to the pump, and a second evaporator coil coupled to the economizer valve. The second cooling circuit receives at least a second portion of the liquid refrigerant and output a second vapor refrigerant to the condenser.