Tandem Compressor Pressure Control for HVAC System Reliability

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Solution Overview

Problem

HVAC systems with tandem compressors face challenges in maintaining refrigerant pressure within normal operating ranges, leading to potential malfunctions and component damage due to abnormal pressure conditions.

Innovation Solution

A control system that detects high pressure in the high pressure side of the HVAC system and operates the first compressor while shutting off the second compressor, adjusting the flow rate of air or other heat transfer media to lower pressure and extend the cooling period, thereby preventing damage and maintaining system functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the control system shuts down the HVAC system in response to abnormal pressure conditions, then damage to compressors and other components is prevented, but the cooling function is interrupted and system productivity is reduced

Engineering Contradiction:

Improvecomponent protectionVSAvoidcooling function continuity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system segments the compressor operation by selectively shutting down only the second compressor while maintaining operation of the first compressor during abnormal pressure conditions. This partial segmentation allows the cooling function to continue at reduced capacity rather than complete shutdown, balancing component protection with productivity maintenance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of completely shutting down the HVAC system, the control system applies partial action by maintaining operation of the first compressor. This partial operation provides sufficient cooling to prevent complete system failure while reducing the load to protect against abnormal pressure conditions.

Inventive Principle:

Principle #16Partial or excessive action

2Productivity

If both compressors operate simultaneously, then the cooling capacity is maximized, but the risk of abnormal pressure conditions and component damage increases

Engineering Contradiction:

Improvecooling capacityVSAvoidabnormal pressure conditions

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts compressor operation based on real-time pressure monitoring. The control system transitions between two-compressor and one-compressor operation modes, optimizing the balance between cooling capacity and pressure management according to system conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control system continuously monitors pressure conditions and uses this feedback to determine when to switch from dual-compressor to single-compressor operation. This feedback mechanism prevents abnormal pressure buildup while maintaining adequate cooling capacity through intelligent compressor management.

Inventive Principle:

Principle #23Feedback

3Productivity

If the first compressor operates alone during abnormal pressure conditions, then the cooling period is extended and productivity is maintained, but the pressure management complexity increases

Engineering Contradiction:

Improvecooling period extensionVSAvoidcompressor control logic

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The control system changes the operational parameters by switching from dual-compressor to single-compressor mode based on pressure thresholds. This parameter change simplifies the control logic to a clear conditional rule while extending the cooling period through sustained first compressor operation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9759468B2System for controlling operation of an HVAC system having tandem compressors

Publication Date: 2017.09.12 LENNOX IND INC

AI summary

The present invention provides for a control system for operating a heating, ventilation, and air conditioning (HVAC) system. A controller operates compressors in tandem. In response to detection of a high pressure condition in refrigerant flowing through a high pressure side of the HVAC system, the controller operates the HVAC system with a first compressor on and a second compressor off.