Multi-Split HVAC Refrigerant Zoning With Heat Recovery Backup
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Solution Overview
Problem
Current HVAC systems face limitations in efficiently providing both heating and cooling, especially in low ambient environments and in ductless configurations where backup heat is lacking and air distribution is inadequate, leading to energy inefficiencies and compliance issues.
Innovation Solution
A multi-split HVAC system with variable refrigerant flow, modulating compressors, and electronically controlled expansion valves, along with a system controller for bidirectional communication and zone control, allows for flexible operation in both heating and cooling modes, and includes additional refrigeration connections for heat recovery, enhancing energy efficiency and air distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a multi-split HVAC system operates in ductless configurations, then installation flexibility is improved, but backup heat capability deteriorates
Solution Approach 1:
The outdoor unit is designed to perform multiple functions: primary cooling/heating, backup heat provision, and heat recovery. The system can operate in different modes (cooling mode, heating mode, heat recovery mode) using the same outdoor unit, eliminating the need for separate backup heating equipment in ductless configurations.
Solution Approach 2:
The system recovers heat that would otherwise be wasted during cooling operations. The outdoor unit captures waste heat and redirects it for backup heating purposes, transforming a discarded resource into a useful function that addresses the backup heat capability issue.
2Adaptability or versatility
If refrigerant flow is selectively routed to multiple indoor units, then zone control flexibility is improved, but system complexity deteriorates
Solution Approach 1:
The system divides the HVAC control into independent zones, with each indoor unit capable of independent operation. The outdoor unit segments refrigerant distribution through multiple refrigerant lines, allowing selective routing to different indoor units based on zone requirements.
Solution Approach 2:
The outdoor unit acts as an intermediary that manages refrigerant distribution to multiple indoor units. The electronic expansion valves serve as intermediaries that precisely control refrigerant flow to each zone, simplifying the overall control architecture despite the multi-zone capability.
3Use of energy by moving object
If heat recovery connections are added, then energy efficiency is improved, but device complexity deteriorates
Solution Approach 1:
The heat recovery function is merged into the existing outdoor unit rather than being implemented as a separate system. The outdoor unit combines primary heating/cooling functions with heat recovery capabilities, using shared components like the compressor, condenser, and refrigerant circulation system.
Solution Approach 2:
The outdoor unit is designed as a multi-functional device that performs cooling, heating, backup heat provision, and heat recovery operations. This universal design consolidates multiple functions into a single device, reducing overall system complexity despite the added energy efficiency capabilities.
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
The system improves energy efficiency, addresses backup heat limitations, and enhances air distribution, qualifying for energy ratings and incentives, while extending HVAC system applications to broader markets, including large homes and light commercial buildings.
Implementation Method 1
a compressor configured to selectively compress refrigerant
Implementation Method 2
a heat exchanger configured to selectively transfer heat between refrigerant and air
Implementation Method 3
an electronic expansion valve configured to selectively meter refrigerant flow and reduce refrigerant pressure
Data Source
AI summary
A heating, ventilation, and/or air conditioning (HVAC) system has a first variable refrigerant flow outdoor unit, a first ducted variable speed indoor unit configured to selectively exchange refrigerant with the first variable refrigerant flow outdoor unit, and a second indoor unit configured to selectively exchange refrigerant with the first variable refrigerant flow outdoor unit.