Cooling Unit Transition to Economizer Mode

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Solution Overview

Problem

Existing data center cooling systems face inefficiencies when abruptly switching from mechanical mode to economizer mode, leading to undesirable humidity changes that can necessitate a return to mechanical mode, reducing the efficiency of economizer mode usage.

Innovation Solution

A system that controls the transition from mechanical mode to economizer mode by waiting for the humidifier media to saturate, then gradually increasing outdoor air usage while decreasing recirculated air over a defined interval, monitored by humidity sensors to maintain desired humidity levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the cooling unit abruptly switches from mechanical mode to economizer mode, then energy efficiency is improved, but humidity levels drop below acceptable ranges

Engineering Contradiction:

Improveenergy efficiencyVSAvoidhumidity level stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system performs preliminary action by pre-saturating the humidifier media with water before transitioning to economizer mode. This ensures that when the transition occurs, the humidifier is already prepared to add moisture to the air, preventing the harmful drop in humidity levels that would otherwise occur during the mode switch.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies beforehand cushioning by introducing moisture into the air stream during the transition period. The humidifier runs in advance to condition the air, creating a buffer that cushions against the harmful effect of humidity drop when outdoor air (which may be drier) is introduced during economizer mode.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If the cooling unit waits for humidifier media to saturate before transitioning to economizer mode, then humidity control is improved, but transition time is increased

Engineering Contradiction:

Improvehumidity controlVSAvoidtransition time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system applies partial action by transitioning to economizer mode after the humidifier media becomes sufficiently saturated, rather than waiting for complete saturation. This provides the necessary humidity control while avoiding excessive wait time, achieving an optimal balance between reliability and time efficiency.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If the cooling unit uses progressive transition with increasing outdoor air, then humidity stability is improved, but cooling capacity is reduced during transition

Engineering Contradiction:

Improvehumidity stabilityVSAvoidcooling capacity

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The system applies dynamics by implementing a progressive transition strategy where the ratio of outdoor air to recirculated air is gradually adjusted over time. The outdoor air percentage increases incrementally during the transition period rather than changing abruptly, allowing the system to dynamically balance humidity stability requirements with cooling capacity needs.

Inventive Principle:

Principle #15Dynamics

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 allows for efficient and cost-effective use of economizer mode while maintaining necessary humidity levels, preventing abrupt humidity drops and optimizing energy usage.

Implementation Method 1

waits for a wait interval to allow humidifier media of the cooling unit to become sufficiently saturated

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

the cooling unit receives return air, cools the return air, and releases the cooled return air as supply air

Methodology Applied

Scientific EffectHeat removal: Cooling

Data Source

PatentUS10888027B1Cooling unit control

Publication Date: 2021.01.05 EQUINIX INC

AI summary

A method includes, at a start time, controlling a cooling unit to start the cooling unit in a mechanical mode and controlling the cooling unit to transition, after waiting a waiting interval from the start time and over a transition interval, the cooling unit from the mechanical mode to an economizer mode. In the mechanical mode, the cooling unit receives return air, cools the return air, and releases the cooled return air as supply air. The supply air is air supplied to a cooled volume. In the economizer mode, the cooling unit receives outdoor air and releases the outdoor air as at least a portion of the supply air. Transitioning the cooling unit from the mechanical mode to the economizer mode includes transitioning, over the transition interval, from receiving only the return air to receiving progressively less of the return air and progressively more of the outdoor air.