Background
A primary objective for the rapidly urbanizing regions of Southeast Asia (SEA) is achieving widespread access to energy and fresh water. Despite recent advances within these communities, water security is a luxury many regions do not have. The quest for these resources is further complicated by decreased natural capital and the unpredictability resulting from the climate crisis. Modern solutions to urbanization require consideration for low-energy alternatives not just for the purpose of preserving our remaining resources, but also because the alternative will only perpetuate climate issues further. Unfortunately, the countries least responsible for climate change are the first to experience the most detrimental effects of a rapidly changing environment which includes many parts of SEA. SEA’s tropical climate and adequate rainfall during the wet season does not shield it from impacts of climate change. Impacts include rising temperatures, thermal alterations, additional pollution, decrease in biodiversity and changes to rainfall patterns have contributed to water scarcity throughout the region. Because of this, passive and noninvasive methods of water harvesting are becoming increasingly attractive solutions for meeting modern water demands.
Maximizing water yields from passive collection methods is a promising way to provide water for agricultural, domestic, and reforestation purposes while reducing the strain on traditional freshwater sources reserved for potable use. Atmospheric water harvesting through fog collection is a versatile solution for increasing access to freshwater. These devices have successfully been used in both humid and temperate climates and can be easily customized to meet a region's specific/changing needs. Fog collectors are particularly advantageous for developing or rural communities due to their simple design which can be constructed using indigenous natural materials and implemented without dependence on alternative energy sources.
Studies have identified the contact angle of the liquid collected on the surface of the mesh as one of the most influential factors for estimating collection efficiency (Jarimi et al., 2020). The goal of the following research on this topic was to further quantify how a fog collector’s interception efficiency is impacted by the contact angle of its mesh. Completing the literature review for this topic led to the hypothesis that a contact angle of 60 degrees would produce the highest water yield. It was assumed that this angle would provide a satisfactory balance of creating enough adhesion force to allow for the collection of larger fog droplets while maintaining limited surface tension to prevent clogging.
Research Question(s):
1. How does the contact angle impact the interception efficiency of a fog collection system?
Hypothesis:
It is assumed that a contact angle of approximately 60 degrees will produce the highest water yield and that a vertical net will increase the interception efficiency.
Maximizing water yields from passive collection methods is a promising way to provide water for agricultural, domestic, and reforestation purposes while reducing the strain on traditional freshwater sources reserved for potable use. Atmospheric water harvesting through fog collection is a versatile solution for increasing access to freshwater. These devices have successfully been used in both humid and temperate climates and can be easily customized to meet a region's specific/changing needs. Fog collectors are particularly advantageous for developing or rural communities due to their simple design which can be constructed using indigenous natural materials and implemented without dependence on alternative energy sources.
Studies have identified the contact angle of the liquid collected on the surface of the mesh as one of the most influential factors for estimating collection efficiency (Jarimi et al., 2020). The goal of the following research on this topic was to further quantify how a fog collector’s interception efficiency is impacted by the contact angle of its mesh. Completing the literature review for this topic led to the hypothesis that a contact angle of 60 degrees would produce the highest water yield. It was assumed that this angle would provide a satisfactory balance of creating enough adhesion force to allow for the collection of larger fog droplets while maintaining limited surface tension to prevent clogging.
Research Question(s):
1. How does the contact angle impact the interception efficiency of a fog collection system?
Hypothesis:
It is assumed that a contact angle of approximately 60 degrees will produce the highest water yield and that a vertical net will increase the interception efficiency.
Materials
Table 1. Material Selection and Price Breakdown
(NPN = No Purchase Needed)
(NPN = No Purchase Needed)
Materials |
Quantity |
Cost |
Humidifier |
2 |
NPN |
Analytical Balance |
1 |
NPN |
Container for water collection |
1 |
NPN |
Threaded Rod |
4 |
$10 |
28 gauge wire |
100 ft |
$6 |
Wood |
2 |
$10 |
Polycarbonate |
11 sqft |
Value |
Humidity Sensor |
1 |
NPN |
2" diameter plastic tubing |
1ft |
$5 |
TOTAL |
$21 |
Materials:
Humidifier x2
Analytical Balance (scale)
Container for water collection
Humidity Sensor
28 Gauge Wire
Threaded Metal Rods x4
Polycarbonate
2" Plastic Tubing
Wood for frame
Method:
A simple support frame will be constructed using scrap wood. The support frame will be connected to the mesh through a pivot joint so the contact angle can be adjusted. An analytical balance and collection container will be placed underneath the mesh frame to measure the amount of water collected from the humidifier's fog flow. After determining the ideal contact angle, other accessible mesh materials will be tested to identify potential alternative materials.
Humidifier x2
Analytical Balance (scale)
Container for water collection
Humidity Sensor
28 Gauge Wire
Threaded Metal Rods x4
Polycarbonate
2" Plastic Tubing
Wood for frame
Method:
A simple support frame will be constructed using scrap wood. The support frame will be connected to the mesh through a pivot joint so the contact angle can be adjusted. An analytical balance and collection container will be placed underneath the mesh frame to measure the amount of water collected from the humidifier's fog flow. After determining the ideal contact angle, other accessible mesh materials will be tested to identify potential alternative materials.
Schedule for Testing
Tasks |
Timeline |
Mockup Creation |
2/22/22 |
Prototype Creation |
3/1/22-3/8/22 |
Prototype Improvement |
3/8/22-3/22/22 |
Design Electronic Controls |
3/15/22-3/22/22 |
Prototype Due |
3/22/22 |
Design Alterations/More Testing |
3/22/22-4/19/22 |
Progress Update (in-class pinup) |
4/19/22 |
Alterations to Design |
4/19/22-5/3/22 |
Innovations of Design Concept |
5/3/22-5/10/22 |
Final Presentation of Data |
5/10/22 |
Mockup
A mockup was constructed using cardboard and a mesh net obtained from fruit packaging. The mock up design went in a different direction from the original proposal depicted in Figure 1. Instead of a mesh net attached to a support structure via a pivot joint, the frame would tilt by inserting its base into a support structure with pre-cut slits meant to induce angle changes for the experiments.
Loosely structured tests were conducted on the mockup by directing a fog stream at the device. The purpose of these tests was to determine how the fog stream would interact with the frame. Based on these tests, the following changes were planned for the design of the prototype:
- Alter the frame so it only supports the net on its y-axis to prevent condensation from collecting above net and interfering with results.
- Construct frame using metal wire woven through the threads of bolts to produce a sturdier product.
- Use vertical orientation for net instead of crossing mesh pattern to avoid "clogs" on horizontal sections of mesh.
Prototype
Figures 6-8 represent the design used to test for the first three trials. This initial design of the environmental chamber was ineffective due to inadequate ventilation and the frame was not sturdy enough to produce constant results. Based on trials 1-3 the following changes were planned for the updated prototype:
- Increase size of ventilation holes to prevent excess pressure buildup.
- Construct sturdier frame capable of producing more accurate angles.
The prototype redesign seen in Figure 9-11 represent the set of changes made to increase collection efficiency of device. The redesign replaced the angled slits on the base for a more secure and accurate dowel-based system and the ventilation holes were widened to 7/8".