Parallel Compressor and Reheater Refrigerant Flow Management for DOAS

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Solution Overview

Problem

Existing HVAC systems that condition solely outdoor air face challenges in managing refrigerant flow, which affects their efficiency and reliability in handling varying outdoor air temperatures and humidity levels.

Innovation Solution

A dedicated outdoor air system (DOAS) with a fluid management system that includes parallel compressors, condensers, and reheaters, along with a modulating valve and sensors to actively control refrigerant flow through multiple fluid loops, optimizing refrigerant distribution based on system parameters and operational modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a system uses only outdoor air for conditioning, then the demand for fresh air handling is met, but challenges arise in managing refrigerant flow efficiency

Engineering Contradiction:
Improveoutdoor air handling capabilityVSAvoidrefrigerant flow management
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The system segments the refrigerant flow path into multiple parallel loops, each with dedicated flow control. The refrigerant circuit is divided into first and second loops that can operate independently or in combination, allowing optimized refrigerant distribution to different heat exchangers based on outdoor air conditions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system employs dynamic flow control through electronic expansion valves and modulating valves that actively adjust refrigerant flow rates based on real-time temperature and humidity sensors. This dynamic adjustment optimizes refrigerant distribution across parallel compressors and heat exchangers varying outdoor conditions.

Inventive Principle:
Principle #15Dynamics

2Productivity

If multiple parallel compressors and heat exchangers are used, then system efficiency and adaptability improve, but device complexity increases

Engineering Contradiction:
Improvesystem efficiencyVSAvoidfluid flow management complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The parallel compressor arrangement and shared refrigerant loops create a universal system architecture where components can serve multiple functions. Compressors can operate individually or in combination, and heat exchangers can handle different refrigerant states, providing operational flexibility without requiring entirely separate systems.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

Temperature and humidity sensors provide continuous feedback to the control system, which automatically adjusts electronic expansion valves and modulating valves to optimize refrigerant flow. This closed-loop control simplifies the management of complex parallel configurations by using sensor data to automatically balance loads across components.

Inventive Principle:
Principle #23Feedback

3Device complexity

If refrigerant flow is not actively managed, then system simplicity is maintained, but efficiency and reliability under varying conditions deteriorate

Engineering Contradiction:
Improvesystem simplicityVSAvoidrefrigerant flow efficiency
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The system incorporates self-regulating features where electronic expansion valves and modulating valves automatically adjust refrigerant flow based on sensor feedback without requiring complex external control systems. The parallel compressor arrangement allows the system to self-balance loads by directing refrigerant flow to the most efficient operating path based on outdoor conditions.

Inventive Principle:
Principle #25Self-service

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 enhances the system's efficiency and reliability by optimizing refrigerant flow, reducing the need for multiple filter driers, and improving performance, maintenance, and cost-effectiveness while maintaining consistent air supply temperatures across varying outdoor conditions.

Implementation Method 1

a condenser, and a reheater arranged in fluid communication... the condenser and the reheater are arranged in parallel

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

an evaporator arranged in fluid communication

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

a plurality of compressors... arranged in parallel

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP4446670A1Refrigerant flow management for modulating reheat system
Publication Date: 2024.10.16 CARRIER CORP
  • EP4446670A1 patent drawingFigure 1
  • EP4446670A1 patent drawingFigure 2
  • EP4446670A1 patent drawingFigure 3

AI summary

A heating, ventilation, and air conditioning (HVAC) system includes a housing, a plurality of compressors, a condenser, a reheater, and an evaporator arranged in fluid communication. The condenser and the reheater are arranged in parallel and the plurality of compressors are arranged in parallel. A fluid management system is operable to actively manage a flow of a fluid within the HVAC system provided to the reheater.