Variable air variable refrigerant flow (VAVRF)
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Solution Overview
Problem
Existing HVAC systems, such as VAV and VRF, face inefficiencies in managing varying cooling and heating demands across different zones in a building, with VAV systems relying on airflow modulation and VRF systems on refrigerant flow, leading to energy inefficiencies and inadequate control over individual room temperatures.
Innovation Solution
A VAVRF system that combines airflow and refrigerant flow modulation, using a centralized controller to manage both simultaneously, incorporating sensors and valves to adjust airflow and refrigerant flow based on zone-specific demands, and a packaged outdoor unit for efficient energy management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If VAV systems modulate airflow to match space cooling load, then zone air temperature can be maintained at set temperature, but energy efficiency is lower compared to VRF systems
Solution Approach 1:
The patent combines VAV airflow modulation with VRF refrigerant flow modulation in a single integrated system. The indoor unit includes both a damper for airflow control and an electronic expansion valve for refrigerant flow control, allowing simultaneous optimization of both air volume and refrigerant quantity to match space cooling load, thereby achieving higher energy efficiency while maintaining temperature control.
Solution Approach 2:
The indoor unit is designed to perform multiple functions: it acts as both a VAV terminal with damper-controlled airflow and a VRF evaporator with EEV-controlled refrigerant flow. This multi-functional design allows the system to adapt to varying cooling loads more efficiently than traditional single-function systems.
2Use of energy by moving object
If VRF systems vary refrigerant amount and temperature to cool the room, then energy efficiency is improved by 25%-50% over VAV, but there is still room for further efficiency improvement
Solution Approach 1:
The system merges the advantages of both VAV and VRF by integrating airflow modulation (from VAV) with refrigerant flow modulation (from VRF) in each indoor unit. This combination allows the system to achieve even higher energy efficiency by simultaneously optimizing both air volume and refrigerant quantity based on real-time space cooling demands.
3Temperature
If traditional VAV systems use dampers to regulate supply air volume, then zone temperature can be controlled, but energy efficiency is limited compared to VRF systems
Solution Approach 1:
The patent integrates damper-controlled airflow regulation with EEV-controlled refrigerant flow regulation in the same indoor unit. This merging allows the system to achieve temperature control through both air volume modulation and refrigerant quantity modulation, reducing energy loss and improving overall energy efficiency compared to traditional VAV systems that rely solely on airflow modulation.
4Ease of operation
If VRF systems use constant speed internal fan to provide constant airflow, then system operation is simplified, but energy efficiency is reduced compared to variable airflow systems
Solution Approach 1:
The system combines the operational simplicity of VRF with the energy efficiency of VAV by integrating a damper-controlled airflow path into the VRF indoor unit. The controller coordinates both the damper position and EEV opening to match space cooling load, achieving variable airflow operation that reduces energy consumption while maintaining the simplicity of centralized refrigerant distribution.
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 VAVRF system achieves enhanced energy efficiency and precise temperature control across zones by integrating airflow and refrigerant flow control, reducing energy consumption and improving comfort by adapting to varying heating and cooling needs.
Implementation Method 1
an air handling unit having a supply fan that is configured to generate the airflow that is received by the plurality of indoor units
Implementation Method 2
The VRF system operates on the direct expansion (DX) principle. That is, the heat is transferred to or from the space directly by circulating refrigerant to an indoor evaporator located within the conditioned space
Implementation Method 3
an outdoor unit comprising a condensing unit and a compressor
Data Source
AI summary
The present disclosure describes various embodiments of a new HVAC system and apparatuses (and related methods) that combine the efficiencies of VRF and VAV systems. An exemplary system comprises a plurality of indoor units located in different zones of a building, each comprising a damper operable to modulate airflow through the indoor unit into a building space and a valve operable to modulate a flow of refrigerant through the indoor unit; an air handling unit having a supply fan that is configured to generate the airflow that is received by the plurality of indoor units; and a controller unit operable to control the damper and the valve simultaneously for each of the plurality of indoor units, wherein the controller unit is operable to control the supply fan and an amount of airflow generated by the supply fan.