DOAS Air Handling Layout for Humidity Control With Chilled Beams
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Solution Overview
Problem
Existing air conditioning systems face challenges in efficiently controlling temperature and humidity, particularly in buildings with chilled beams, due to limitations in dehumidification capacity and energy efficiency, as well as issues with condensation and airflow imbalances.
Innovation Solution
The system incorporates a recovery wheel, a dehumidification wheel, a primary cooling coil, a secondary direct-expansion refrigeration circuit, and multiple chilled beams, with a system controller to manage airflow and temperature, allowing for greater dehumidification efficiency and preventing condensation, while maintaining comfortable supply air temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a recovery wheel and dehumidification wheel are used to transfer heat and moisture between exhaust air and incoming outside air, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The patent combines the recovery wheel and dehumidification wheel into a single integrated assembly where both wheels share a common structure and operate simultaneously. The recovery wheel transfers sensible heat while the dehumidification wheel transfers moisture between the supply and exhaust airstreams, achieving dual functionality in one device rather than requiring separate components.
Solution Approach 2:
The integrated wheel assembly performs multiple functions: heat recovery, moisture recovery, and dehumidification all within a single component system. This multi-functional design reduces the overall number of components needed while maintaining energy efficiency benefits.
2Quantity of substance
If a secondary direct-expansion refrigeration circuit is added to provide additional cooling capacity, then dehumidification capacity is improved, but device complexity increases
Solution Approach 1:
The secondary direct-expansion refrigeration circuit is nested within the existing HVAC system architecture, with the secondary evaporator coil integrated into the air handling unit. The refrigeration circuit components are arranged concentrically and hierarchically to minimize space requirements and reduce overall system complexity despite adding functional capacity.
3Quantity of substance
If the supply airstream is cooled more to increase dehumidification, then dehumidification capacity is improved, but supply air temperature becomes too low affecting comfort
Solution Approach 1:
The cooling and dehumidification processes are segmented into separate functional stages: the primary cooling coil handles sensible cooling, the dehumidification wheel handles moisture removal, and the secondary evaporator coil provides additional dehumidification if needed. This segmentation allows independent control of temperature and humidity to achieve desired supply air conditions without over-cooling.
Solution Approach 2:
The dehumidification wheel acts as an intermediary component between the primary cooling coil and the secondary evaporator coil, using desiccant material to selectively remove moisture from the air stream. This intermediary mechanism enables dehumidification without proportionally reducing temperature, maintaining supply air comfort while achieving desired humidity levels.
4Productivity
If airflow rate is increased to improve cooling performance, then productivity is improved, but condensation risk increases
Solution Approach 1:
The system incorporates sensors and control mechanisms that monitor humidity levels, temperature, and airflow conditions in real-time. When conditions approach condensation thresholds, the control system automatically adjusts airflow rates, coil temperatures, or dehumidification wheel operation to prevent condensation while maintaining optimal cooling performance.
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 configuration enhances dehumidification capacity, improves energy efficiency, reduces condensation risks, and optimizes chilled beam performance by managing airflow and temperature, providing dryer supply air and better cooling performance.
Implementation Method 1
a recovery wheel... to transfer heat, moisture, or both, from outdoor air in a supply airstream to an exhaust airstream
Implementation Method 2
a dehumidification wheel... to transfer heat, moisture, or both, from outdoor air in a supply airstream to an exhaust airstream
Implementation Method 3
a cooling coil... to cool the supply airstream downstream of where the system transfers the first quantity of heat
Implementation Method 4
transfers a third quantity of heat from the supply airstream to the return air entering the exhaust airstream
Data Source
AI summary
Systems and methods for controlling temperature and humidity within a space in a building. Outdoor air and return air from the space are passed through particular equipment in a particular order. Equipment includes a secondary direct-expansion refrigeration circuit, a recovery wheel, a primary cooling coil, secondary circuit evaporator and condenser coils, and a dehumidification wheel. Various embodiments include multiple zones, chilled beams, and a dedicated outdoor air supply (DOAS) subsystem delivering dehumidified air to active chilled beams. In various embodiments, supply air passes first through the recovery wheel, then through the primary cooling coil, then through the dehumidification wheel, and then to the space. Further, in some embodiments, exhaust air passes through the dehumidification wheel and then through the recovery wheel. Pump modules may supply chilled beams and control their temperature to avoid condensation. A chiller may supply cooling water to both the primary cooling coil and the pump modules.