Demand ventilation HVAC system comprising independently variable refrigerant flow (VRF) and variable air flow (VAF)
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current HVAC systems are not as energy-efficient as they could be, leading to unnecessary energy usage and inefficiencies in providing thermal comfort and indoor air quality.
Innovation Solution
The implementation of dedicated outdoor air systems (DOAS) with independently addressable evaporator coils and variable refrigerant and air flow control, allowing for precise adjustment of cooling capacity and air flow based on demand, CO2 levels, and humidity, using a directional air flow exposure valve and variable refrigerant flow to optimize energy usage and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional HVAC systems are used to provide ventilation and thermal comfort, then indoor air quality and temperature control are maintained, but energy consumption is excessive and efficiency is poor
Solution Approach 1:
The evaporator coil is divided into multiple independently controlled sections, each with its own refrigerant flow control valve. This segmentation allows the system to activate only the cooling sections needed for the current load, rather than running the entire coil at full capacity, thereby reducing energy consumption while maintaining adequate cooling delivery.
Solution Approach 2:
The system dynamically adjusts refrigerant flow to each evaporator section based on real-time cooling demands detected by temperature and humidity sensors. This dynamic control enables the system to optimize energy usage by matching cooling capacity delivery to actual needs, preventing energy waste from over-cooling while ensuring sufficient cooling when required.
2Loss of energy
If fixed cooling capacity is provided to all zones, then simple system design is maintained, but energy waste occurs due to inability to meet varying zone-specific cooling demands
Solution Approach 1:
The evaporator coil is segmented into multiple independently controlled sections, each serving different cooling zones or demands. This segmentation enables zone-specific cooling control, allowing the system to deliver appropriate cooling capacity to each area based on its unique requirements, thereby eliminating energy waste from uniform over-cooling while maintaining manageable system complexity through modular design.
Solution Approach 2:
Each evaporator section has independent refrigerant flow control and is equipped with local temperature and humidity sensors. This local quality control allows the system to respond to specific cooling demands in different zones, providing tailored cooling capacity where needed while avoiding energy waste in areas with lower cooling requirements, all within a unified system architecture.
3Productivity
If full refrigerant flow is maintained in evaporator coils, then maximum cooling capacity is available, but energy consumption increases unnecessarily during partial load conditions
Solution Approach 1:
The system continuously monitors temperature and humidity conditions and dynamically adjusts refrigerant flow to each evaporator section accordingly. During partial load conditions, the system reduces refrigerant flow to only the necessary sections, maintaining adequate cooling capacity while significantly reducing compressor and fan energy consumption compared to maintaining full refrigerant flow throughout.
Solution Approach 2:
The system changes operational parameters by selectively controlling refrigerant flow rates to different evaporator sections based on real-time cooling demands. This parameter adjustment allows the system to maintain sufficient cooling capacity during partial load conditions while optimizing energy consumption by reducing refrigerant flow to levels matching actual cooling needs rather than operating at maximum capacity continuously.
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 approach enables significant energy savings and improved comfort by adjusting cooling capacity and air flow dynamically, reducing fan and compressor energy usage, and maintaining a constant dew point, thereby enhancing the efficiency of HVAC systems.
Implementation Method 1
a heat exchanger that receives a stream of air to be cooled and dehumidified and a refrigerant and that transfers heat between the stream of air and the refrigerant
Implementation Method 2
The compressor system directs a variable flow rate of refrigerant toward the evaporator coil
Data Source
AI summary
A dedicated outside air system comprising a combined variable refrigerant flow and variable air flow that provides ventilation in an energy efficient way or otherwise as desired.