IJERD – International Journal of Environmental and Rural Development (2022) 13-1

Research article
erd

Design and Experimental Analysis of Atmospheric Water
Generator Based on the Climatic Conditions of Manolo
Fortich, Bukidnon
TAN JERICO D.*
Mindanao State University-Iligan Institute of Technology, Iligan City, Philippines
Email: jerico.tan@g.msuiit.edu.ph

ALBIENTO ELIZABETH EDAN M.
Mindanao State University-Iligan Institute of Technology, Iligan City, Philippines
Received 29 January 2022

Accepted 2 May 2022(*Corresponding Author)

Abstract Most Filipinos living in remote rural and island communities rely on unsafe
drinking water sources due to a lack of reliable water supply. With this, an atmosphericwater generator (AWG) can become an alternative water source by condensing andcollecting water vapour present in the air. However, previous research on the design of
AWG devices was conducted outside the Philippines and most studies did not design thelongitudinal profile of the fins and intake fan component of the device. This study designed
the longitudinal fin profile of the fins and intake fan speed based on the climatic conditionsof Manolo Fortich, Bukidnon and analysed the performance of the device by conducting afield experiment. The study designed the extended fins and varied the intake fan speed byconducting a parametric analysis using existing heat and mass transfer equations. The study
then conducted a field experiment of the AWG device by placing the device in a secure
open space. Results of the design showed that the 9 cm fin length was optimal for thedevice and that higher intake fan speed were more suitable for high relative humidity (RH)
and high air temperature conditions. Results from the field experiment showed that higher
water productivity was observed at higher RH level compared the lower RH levels. The
study concludes that a longer length of copper fins and greater magnitude of intake fanspeed does not necessarily translate to higher water productivity and that higher waterproduction rates were observed during high RH levels.
Keywords atmospheric water generator, Peltier effect, thermoelectric couple

INTRODUCTION
Potable water is a necessity for us humans to live. However, most of the river systems in thePhilippines face severe problems of pollution, which resulted in the higher cost of the supply of
potable water throughout the country (Rola et al., 2015). One way to obtain water cheaply andsustainably is to produce water out of air through condensation by using an atmospheric water
generator technology (AWG) with the use of thermoelectric couples (TEC).
AWGs are comprised of several components. The TEC is the main cooling unit which consistsof a cold surface on one side and a hot surface on the other side when an electric current is passed
thru the device. Copper fins are attached to the cold side to increase the surface area of the coldsurface. A fan is installed to suck in air into the device for air to come in contact with the cold
copper surface making the water vapor condense in these areas. Only around 1% of the carbon
dioxide (CO2) present in the air will dissolve in condensed water vapor to form carbonic acid
(H2CO3) making the water acidic with a pH as low as 5.5 (Bauer et al., 1980). With this, copper
pitting due to carbonic acid is less likely to occur at a lower PH of water (Taxen, 2002). The study
did not delve deeper in the extent of the effect of carbonic acid on the copper fins. The hot side isusually installed with an aluminum heat sink to dissipate the heat produced by the TEC. However,
little work has been done on the design of two major components of the AWG namely the cold sideⒸ ISERD152

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copper fins and the intake fan and most of the studies were designed outside the Philippines. In thisstudy, the length of copper fins was optimized and the intake fan speed was varied based on
Philippine climatic conditions and analyzed its performance in an actual field experiment.
OBJECTIVE
The main objective of this study is to optimize the design of an AWG device based on the climaticconditions of Manolo Fortich, Bukidnon. Specifically, the study will optimize the length of copper
fins, identify the appropriate intake air velocity considering a maximum air velocity, fabricate theAWG prototype, and analyze the field test results of the AWG device.
METHODOLOGY
Optimization of Length of Copper Fins
The study initially acquired climatic data for Manolo Fortich, Bukidnon. The average values of thelowest, median and highest temperature and relative humidity were computed and determined thedewpoint temperatures using these values. The study then considered four different lengths ofcopper fins namely 8 cm, 9 cm, 10 cm and 11 cm. To maximize the amount of water generated in
the device, all the surface area along the length of the copper fin should be less than the dewpointtemperature for maximum water condensation. Hence, the study performed a parametric analysis insolving the temperature distribution along the fins, using Equation 1, by using different fins lengths
and different climatic conditions. The temperature distribution equation was emulated from thestudy of Shourideh et al. (2018) and Kilic and Onat (1981). The lengths of fin 8 cm, 9 cm, 10 cm
and 11 cm that has a temperature distribution below the dewpoint at different climatic conditions
were chosen as the optimized length of copper fins.
(1)
Where m is fin parameter, T local fin temperature (K), Ta temperature of the surrounding air(K), hm mass transfer coefficient (m/s), hfg* modified latent heat of vaporization (J/kg), h convective
heat transfer (W/m2-K), Rv ideal gas constant (J/kg-K), Ta temperature of the surrounding air (K),
Pv,Ta partial pressure of water vapour in the surrounding air, and Pv,T partial pressure of watervapour in the fin surface.
Also, the boundary conditions for Equation 1 were shown in Equation 2 and Equation 3.
(2)(3)
Where Lf is length of fins (m) and T0 initial cold side temperature of TEC (K).
Variation of Intake Air Velocity
The study also conducted a parametric analysis to compute the theoretical water generation rate byusing different values of air velocity considering a maximum velocity of 4 m/s at different climaticconditions. The study utilized the equation shown in Equation 4 to compute the theoretical watergeneration rate. There were five cases of combinations of temperature and RH used in the analysis.
The intake air velocity that gave the maximum water generation rate was chosen as the appropriate
intake air velocity at that certain climatic condition.
(4)Ⓒ ISERD

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Where V is water generation rate (m3/s), ρl the density of water (kg/m3) and N number of finsattached to the TEC.
RESULTS AND DISCUSSION
Optimized Length of Copper Fins
Parametric analysis for the temperature distribution of the 8 cm, 9 cm, 10 cm and 11 cm lengths ofcopper fins for different climatic conditions were computed. Fig. 1 shows the results of thetemperature distribution of each of the copper fin lengths. It can be observed in Fig. 1 (b) that the10cm and 11cm fin lengths exceeded the dewpoint temperature at 80% percent of its length. This
meant that the surface temperature beyond this point was higher compared to the dewpointtemperature at that climatic condition. Hence, the water does not condense in these regions and thecopper fins can be considered as partially wet fins under these conditions since not all of its surface
area can condense water.

Fig. 1 Fin temperature distribution of different fin lengths at(a) Ta=23 C and RH =90%, (b) Ta=31.4 C and RH=70%
On the other hand, it can be seen in Fig. 2 that the 9 cm fin length did not reach the dewpointtemperature in all cases of climatic conditions. This meant that all the surface area of the 9 cm
length copper fins can condense water vapor. Hence, the optimum length of the copper fins that
was also incorporated in the design of the AWG was the 9cm length.
Variation of Intake Air Velocity
Table 1 presents the cases used in the analysis with different ambient air temperatures and variable
RH levels.
Table 1 Summary of cases of temperature and RH used in the analysis
Case No. Ta (oC) RH 1 (%) RH 2 (%) RH 3 (%) RH 4 (%)
1234

23.00
25.00
29.00
31.00

80.00
75.00
75.00
75.00

85.00
80.00
80.00
80.00

90.00
85.00
85.00
85.00

90.00
90.00
90.00

By applying these cases in the computation along with different variations of intake airvelocity considering a maximum velocity of 4 m/s, the theoretical water generation rate wasobtained and the results were shown in Fig. 2. It can be observed from the results that increasing
the air velocity generally increases the water generation rate for most of the cases presented.
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IJERD – International Journal of Environmental and Rural Development (2022) 13-1Fig. 2 Theoretical Water Generation Rate at different Air Velocitiesfor (a) Case 1, (b) Case 2, (c) Case 3, (d) Case 4, and (e) Case 5
For Case 1 and Case 2, there was low ambient air temperature paired with low RH levels. It
can be observed in Fig. 2 (a) and (b) that between RH of 75% to 80%, the water generation rateincreased initially when the air velocity was also increased but then decreased at higher magnitudesof air velocity. Hence, the air velocity of the fans can be adjusted at peak water generation rate
when the AWG device is subjected to low relative humidity such as in Case 1 and Case 2.
For Case 3 and Case 4, the increase in air velocity also increases the of water generation rate.
For this case, the increase in the value of the mass transfer coefficient resulting from the increase in
air velocity outweighed the decrease in the difference between the partial pressure of thesurrounding air and partial pressure at the fin surface.
Based from the results shown in Fig. 2, Table 2 summarizes the appropriate intake air velocity
at different climatic conditions. The values indicated in Table 2 were then incorporated into thedesign of the AWG in which the air velocity varied depending on the climatic conditions.
Table 2 Summary of appropriate air velocity at different climatic conditions
Relativehumidity
75%<80%80%<85%
85%<90%90% < 100%

23°C ≤ 24°C
0.00
0.60
2.00
4.00

Intake air velocity (m/s)
24°C ≤ 26°C
26°C ≤ 28°C
0.20
2.00
2.00
4.00
4.00
4.00
4.00
4.00

28°C ≤ Ta
4.00
4.00
4.00
4.00

Construction and Experimental Analysis of the Device
The study utilized the 9 cm copper fin length and the magnitudes of variable intake air velocity inthe design of the AWG device. Figure 3 shows the blow-up figure of the AWG prototype.
The AWG device was continuously operated for 30 days in a secure open space located atManolo Fortich, Bukidnon for the experimental analysis. The testing area for the field test waslocated in the backyard of a residential lot located in a rural community at Manolo Fortich,Bukidnon. The period of testing was between September to October 2021 and the experimentalⒸ ISERD

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setup is shown in Fig. 3b. The average hourly RH, and the ambient air temperature were shown inFig. 4 and the average hourly water collection was shown in Fig. 5.

Fig. 3 Blow-up picture of the AWG Device with its corresponding parts (a)and finished product and experimental setup (b)Fig. 4 Average hourly ambient air temperature and relative humidity

Fig. 5 Average hourly water collection for the AWG device
It can be seen in Fig. 5 that the highest water collection rate of the AWG was during nighttime
since there were high RH levels paired with low surrounding temperatures. Overall, the highest
recorded amount of water collected in a day was 526 mL. Table 3 shows the comparison between
the outputs of this study compared to past literature.
Table 3 Comparison of water collected per day to past literatures
Researcher
Joshi et al. (2017)
Liu et al. (2017)
Present work

Location
India
China
PhilippinesⒸ ISERD

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Water collected (mL/day)
480525526

IJERD – International Journal of Environmental and Rural Development (2022) 13-1

CONCLUSIONThe cold side fin length and air velocity are two important features of an AWG device that areneeded to be designed to improve the efficiency and water generation rate. The study observed thatwhile increasing the length of copper fins increases the cooling surface area, making the fin length
excessively longer does not positively impact the water generation rate of the AWG. Longer fin
lengths will develop dry regions along their length thus becoming inefficient.
Finally, the results of this study showed that there was an ideal air velocity at every climaticcondition to harness the maximum water generation rate for the AWG device. Low air velocities
were assigned to low surrounding temperature with low relative humidity conditions while high airvelocities were designated for high surrounding temperature and high relative humidity conditions.
The highest amount of water collected in a day was 526mL.
ACKNOWLEDGEMENTS
The author would like to acknowledge the Engineering Research and Development for Technology(ERDT) for funding this research and the Mindanao State University-Iligan Institute of Technologyfor supporting this research.
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