Cooling Tower Bypass for Plume Abatement
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Solution Overview
Problem
Cooling towers face challenges in plume abatement and water conservation, with existing solutions requiring complex and costly wet and dry air heat transfer mechanisms, increasing operational costs when not in plume abatement mode, and affecting thermal performance, while also concentrating contaminants that can diminish cooling efficiency.
Innovation Solution
A cooling tower design with vertically oriented heat exchange modules that include separate paths for dry and wet air streams, allowing for efficient heat transfer and plume abatement by adjusting the position and orientation of heat exchange modules to optimize airflow and reduce pressure drop, and incorporating dampers to control air flow and maintain thermal performance across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a separate heat exchanger is used to partially cool hot water before it enters the cooling tower, then plume is reduced, but the efficiency of the cooling tower is reduced and operational costs increase
Solution Approach 1:
The cooling tower is divided into separate functional sections: a dry cooling section with heat exchange fins for plume abatement, and a wet cooling section with fill pack for primary cooling. This segmentation allows each section to perform its specific function optimally without interfering with the overall efficiency of the system.
Solution Approach 2:
The cooling tower is designed to perform multiple functions simultaneously: it provides primary cooling through evaporative cooling in the wet section, plume abatement through dry cooling in the dry section, and can operate in different modes (plume abatement mode, non-plume mode, water conservation mode) depending on environmental conditions. This multi-functionality resolves the contradiction by making the plume abatement capability an integrated part of the normal cooling operation rather than a separate efficiency-reducing system.
2Object-generated harmful factors
If air is forced through heat exchange packs for plume abatement, then plume is reduced, but more fan energy is expended causing operational costs to significantly increase
Solution Approach 1:
The cooling tower incorporates adjustable dampers that can dynamically control the airflow paths through the dry and wet sections based on environmental conditions and operational requirements. This dynamic control allows the system to optimize fan energy usage by adjusting airflow resistance and directing air through the most efficient path for the current operational mode, thereby reducing unnecessary energy consumption while maintaining plume abatement effectiveness when needed.
3Loss of substance
If water is conserved by reducing evaporative cooling, then water consumption is reduced, but thermal performance is affected
Solution Approach 1:
The dry cooling section with heat exchange fins acts as an intermediary mechanism that transfers heat from the hot water without requiring evaporative cooling. Ambient air passes through the heat exchange fins, absorbing heat from the water condensate or process water, thereby providing a water-conserving heat rejection path that maintains thermal performance while significantly reducing water consumption, especially in water conservation mode.
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
Enables efficient plume abatement and water conservation without significant cost increase, maintaining thermal performance and reducing contaminant concentration, by optimizing airflow and heat transfer through adjustable heat exchange modules and dampers, allowing operation in both plume abatement and non-abatement modes effectively.
Implementation Method 1
The thin sheet walls separating the passages act as heat exchange surfaces, thereby condensing moisture from the warm effluent air stream
Implementation Method 2
heat is transmitted from the water to the air by both sensible and evaporative heat transfer
Implementation Method 3
heat is transmitted from the water to the air by both sensible and evaporative heat transfer
Data Source
Figure 1
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AI summary
A cooling tower having an evaporative media along with a liquid distribution system that distributes hot liquid over the evaporative media. The cooling tower includes a pair of heat exchanger modules that each have a first set of passageways in fluid communication with a first flow duct and a second set of passageways in fluid communication with a second flow duct. The heat exchanger module transfers heat from a first air stream into a second air stream. The cooling tower further includes a first bypass flow path that extends between the first heat exchanger module and the second heat exchanger module whereby a bypass door regulates airflow there through.