Two-Stage Evaporative Cooler with Pre-Cooling and Segmented Airflow
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Solution Overview
Problem
Conventional direct evaporative coolers are insufficient in cooling air to desired temperatures in habitable spaces when the wet bulb temperature is above the desired level, requiring additional energy-intensive air conditioning units and are not scalable due to inefficiencies in pre-cooling stages.
Innovation Solution
A compact evaporative cooling device with a central chamber surrounded by heat exchange units, featuring an air to water pre-cooler ahead of the evaporative cooling element and a water circuit for efficient irrigation and collection, allowing for focused delivery of cooled air and exhaust of humidified air, with individually controlled fans and a movable divider for adjustable airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a pre-cooling stage is added to the evaporative cooler, then the cooling temperature can be reduced below the wet bulb temperature, but the overall cooling efficiency decreases and the device requires a larger frontal area
Solution Approach 1:
The evaporative cooler is divided into two separate chambers: an upper chamber for evaporative cooling and a lower chamber for pre-cooling. This segmentation allows each chamber to perform its specific function optimally without interfering with the other, thereby maintaining high cooling efficiency while achieving temperatures below the wet bulb temperature.
Solution Approach 2:
The pre-cooling function is extracted from the main evaporative cooling body and placed in a separate lower chamber. This extraction allows the pre-cooling stage to operate independently using a portion of the cooled water from the evaporative stage, without compromising the overall cooling efficiency of the main chamber.
2Temperature
If the pre-cooling stage uses cooled water from the evaporative cooling stage, then lower wet bulb temperature can be achieved, but the coolest portion of air exiting the evaporative cooler is wasted and must be exhaust to ambient
Solution Approach 1:
The device segments the air flow into two separate streams: one stream is pre-cooled in the lower chamber and delivered to the habitable space, while another stream undergoes full evaporative cooling in the upper chamber and is exhausted. This segmentation prevents the waste of the coolest air while still achieving the desired temperature reduction.
Solution Approach 2:
The system uses a portion of the cooled water from the evaporative cooling stage to serve the pre-cooling function, creating a self-service cycle. The water that would otherwise be wasted is reused for pre-cooling, reducing energy loss while maintaining effective cooling performance.
3Temperature
If a conventional air conditioning unit is used instead of evaporative cooler, then the desired cooling temperature can be achieved, but significant energy is required to operate the compressor
Solution Approach 1:
The system changes the operating parameters by using evaporative cooling principles instead of mechanical compression. By utilizing the phase change of water and the psychrometric properties of air, the system achieves cooling without the high energy consumption associated with compressor operation, while still reaching desired temperatures through the two-stage process.
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 device achieves efficient cooling by delivering the coolest air downward for habitable spaces while exhausting humidified air upward, enhancing cooling efficiency and scalability, and can be used in both indoor and outdoor public areas with a compact and standardized design.
Implementation Method 1
direct evaporative coolers... When this takes place directly into the air stream, the temperature of the air may be lowered as far as the wet bulb temperature
Implementation Method 2
The pre-cooling stage may use cooled water from the evaporative cooling stage in an air-water cooling unit
Implementation Method 3
the water circuit is arranged to irrigate the cooling element and collect the irrigated water below the cooling element
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A two stage evaporative cooling device has a central chamber, divided into an upper chamber and a lower chamber by a divider, one or more heat exchange units surrounding the central chamber; an upper fan arranged above the upper chamber and a lower fan arranged below the lower chamber; and a water circuit; wherein each heat exchange unit comprises an evaporative cooling element and an air to water pre-cooler, the pre-cooler being placed ahead of a lower portion of the cooling element and the water circuit is arranged to irrigate the cooling element and collect the irrigated water below the cooling element for delivery to the pre-cooler whereby pre-cooled air may be drawn inwardly through the pre-cooler and the lower part of the cooling element by the lower fan and ambient air may be drawn inwardly through the upper part of the cooling element by the upper fan.