System and method for indirect evaporative cooling
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Solution Overview
Problem
Single-stage indirect evaporative cooling systems face challenges in achieving high wet bulb efficiency and large cooling capacity due to issues like high pressure build-up and airflow resistance, especially when scaling up to higher volumes of secondary air flows.
Innovation Solution
A multi-stage indirect evaporative cooling system is implemented with two separate exchangers arranged such that the primary blower pulls air through one exchanger and pushes it through the other, using a combination of blower motor configurations to manage pressure distribution and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single stage indirect evaporative cooling heat exchanger is used, then the system structure is simple, but the wet bulb efficiency is low and cooling capacity is limited
Solution Approach 1:
The cooling system is divided into multiple stages (first stage, second stage, etc.) with separate heat exchangers for each stage. This segmentation allows each stage to contribute progressively to the cooling process, achieving higher overall wet bulb efficiency while maintaining manageable structural complexity through modular design
2Productivity
If the cooling capacity is scaled up to handle higher volumes of secondary air flow, then the cooling capacity increases, but pressure build-up and airflow resistance increase
Solution Approach 1:
The system uses multiple stages with separate heat exchangers distributed throughout the system. Each stage handles a portion of the total cooling load and air flow, preventing excessive pressure build-up that would occur in a single large-stage system while maintaining high overall cooling capacity
Solution Approach 2:
The multi-stage arrangement extends the cooling process across multiple spatial dimensions and flow paths. By distributing heat exchangers across different stages and using multiple blowers positioned at different locations, the system manages high air volumes without creating excessive localized pressure
3Device complexity
If two indirect evaporative cooling exchangers are arranged adjacent to each other with a single blower, then the device complexity is reduced, but high resistance to air flow causes high positive or negative pressure
Solution Approach 1:
The system assigns different blowers to different stages and functional zones. The first blower handles the first stage with its associated primary and secondary air flows, while the second blower handles the second stage. This segmentation of air moving functions reduces the total resistance any single blower must overcome, improving ease of operation
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 achieves an efficiency of greater than 82% by reducing pressure build-up and improving airflow, allowing for higher wet bulb efficiency and effective cooling across multiple stages.
Implementation Method 1
indirect evaporative cooling achieves cooling by passing two streams of air through the non-communicating gaps separated by parallel heat exchange surfaces having alternate dry and wet passages... The second air stream absorbs the heat from the thin film of the evaporating liquid on the other side of the heat exchange surfaces, that is the wet passage side, drives the heat flow from the first air stream to the thin film of evaporating liquid
Implementation Method 2
The temperature difference between the first air stream and a thin film of the evaporating liquid on the other side of the heat exchange surfaces, that is the wet passage side, drives the heat flow from the first air stream to the thin film of evaporating liquid
Data Source
AI summary
A cooling system using indirect evaporative cooling (IEC) is disclosed. The implementation discloses use of two stages of IEC with two separate IEC exchangers. The two-stages of IEC exchangers are arranged in a manner such that the prime air mover (primary blower) pulls (sucks) air through one exchanger (1st stage) and then pushes air through the other exchanger (2nd stage).