Two-Stage Compressor Cooling Capacity Modulation

Solution Overview

Problem

Cooling systems for small IT spaces, such as server rooms, face challenges in efficiently modulating cooling capacity without noisy or costly digital and variable speed compressors, particularly in part-load conditions.

Innovation Solution

A method utilizing a two-stage compressor and a variable speed fan, controlled by a controller, to continuously adjust cooling capacity by switching between loaded and unloaded states and varying fan speeds, allowing for precise temperature control and efficient operation from maximum to minimum capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If digital or variable speed compressors are used to achieve variable capacity cooling, then cooling capacity modulation is improved, but noise level and cost increase

Engineering Contradiction:

Improvecooling capacity modulationVSAvoidnoise level

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The compressor is divided into two distinct stages: a first stage compressor and a second stage compressor. The first stage operates at full capacity while the second stage operates at reduced capacity. By selectively engaging only the second stage during part-load conditions, the system achieves variable capacity cooling without requiring digital or variable speed compressors, thereby avoiding increased noise and cost.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between different compressor configurations based on cooling demand. During full-load conditions, both stages operate together. During part-load conditions, only the first stage operates. This dynamic switching enables continuous variable capacity modulation while maintaining quiet and cost-effective operation without noisy variable speed mechanisms.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If digital or variable speed compressors are used to achieve variable capacity cooling, then cooling capacity modulation is improved, but ownership cost increases

Engineering Contradiction:

Improvecooling capacity modulationVSAvoidownership cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The compressor is divided into two distinct stages: a first stage compressor and a second stage compressor. The first stage operates at full capacity while the second stage operates at reduced capacity. By selectively engaging only the second stage during part-load conditions, the system achieves variable capacity cooling without requiring digital or variable speed compressors, thereby avoiding increased noise and cost.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of investing in expensive digital or variable speed compressors with complex control mechanisms, the system uses a simpler two-stage compressor design where the second stage can be engaged or disengaged based on load conditions. This approach provides cost-effective variable capacity cooling without the high ownership costs associated with advanced compressor technologies.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If maximum cooling capacity is provided continuously, then temperature control reliability is improved, but energy efficiency deteriorates in part-load conditions

Engineering Contradiction:

Improvetemperature controlVSAvoidenergy efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically switches between different compressor configurations based on cooling demand. During full-load conditions, both stages operate together. During part-load conditions, only the first stage operates. This dynamic switching enables continuous variable capacity modulation while maintaining quiet and cost-effective operation without noisy variable speed mechanisms.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters by selectively engaging or disengaging the second stage compressor based on cooling load conditions. During part-load conditions, the second stage is disengaged, reducing the overall cooling capacity to match the lower demand. This parameter change enables energy-efficient operation during part-load conditions while maintaining reliable temperature control, avoiding the energy waste of continuous maximum capacity operation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11925006B2Cooling system with continuously variable capacity

Publication Date: 2024.03.05 VERTIV CORP

AI summary

A cooling system can include a two-stage compressor, a variable speed fan and a controller for continuously modulating cooling capacity of the system. The compressor can run in a loaded state and the fan can run at a first speed when a call for cooling calls for maximum system cooling capacity. The compressor can run in the loaded state and the fan speed can decrease to a second fan speed as the called for cooling capacity decreases. The compressor can run in an unloaded state and the fan speed can be increased. The compressor can run in the unloaded state and the fan speed can decrease to a third fan speed as the called for cooling capacity decreases.