What is fogger ?
Foggers and misters are watering devices that focus primarily on reducing temperature and controlling humidity level. They produce higher pressure on water which creates a mist or fog effect. In fogging system water is applied in the form of very fine spray in order to create humidity in air at low level. This system reduces indoor temperature in greenhouse and polyhouse.
Need of Project –
Polyhouse requires a maintained temperature for whole day for proper growth of plants. In Vigyan Ashram, a fan pad cooling system is installed for maintaining the inside temperature of the polyhouse. But from last few months , the pads which are mounted on west side of sidewall of the polyhouse are not working. Which resulted in increased in temperature of polyhouse in that specific area. It also affected the growth of plants and humidity inside polyhouse. So to maintain the humidity and temperature of the polyhouse, we are going to design and install fogger system in the polyhouse.
Objectives –
- To get desired pressure of 3.5 kg/sq. cm for the application of foggers.
- To design fogging system for the polyhouse.
- To get desired temperature about 5° C less than outside temperature and humidity between 70 to 80% .
Estimated bill of material –
| Sr. No. | Material | Quantity | Base Price | Total Cost |
| 1. | 4-way fogger | 10 | Rs.139 | Rs.1390 |
| 2. | 20 mm lateral | 56 m | Rs.12 per m | Rs.672 |
| 3. | 20 mm L-joiner | 2 | Rs.8 | Rs.16 |
| 4. | 20 mm T-joiner | 2 | Rs.8 | Rs.16 |
| 5. | 20 mm grommet nipple | 3 | Rs.12 | Rs.36 |
| 6. | 20 mm grommet starter | 3 | Rs.8 | Rs.24 |
| 7. | 2” PVC pipe | 30 ft. | Rs.315 per 10 ft. | Rs.945 |
| 8. | 2” elbow | 4 | Rs.40 | Rs.160 |
| 9. | 2” T-joiner | 1 | Rs.145 | Rs.145 |
| 10. | 1 HP submersible motor | 1 | Rs.8500 | Rs.8500 |
| 11. | Metal wire | 3 kg | Rs.60 per kg | Rs.180 |
| Total | Rs.12,084 |
Actual Bill of Material –
| Sr. No. | Material | Quantity | Base Price | Total Cost |
| 1. | 4-way fogger | 10 | Rs.139 | Available |
| 2. | 20 mm lateral | 56 m | Rs.12 per m | Rs.672 |
| 3. | 20 mm L-joiner | 2 | Rs.8 | Rs.16 |
| 4. | 20 mm T-joiner | 2 | Rs.8 | Rs.16 |
| 5. | 20 mm grommet nipple | 3 | Rs.12 | Rs.36 |
| 6. | 20 mm grommet starter | 3 | Rs.8 | Rs.24 |
| 7. | 2” PVC pipe | 30 ft. | Rs.315 per 10 ft. | Rs.945 |
| 8. | 2” elbow | 4 | Rs.40 | Available |
| 9. | 2” T-joiner | 1 | Rs.145 | Available |
| 10. | 1 HP submersible motor | 1 | Rs.8500 | Rs.8500 |
| 11. | Metal wire | 3 kg | Rs.60 per kg | Rs.180 |
| Total | Rs.10,389 |
Process flow chart –
Study pipeline system of polyhouse
Calculate pressure of water at the inlet of sand filter and at the outlet of screen filter
Measure dimensions of polyhouse
Draw rough structure of fogging system
Design calculations
Draw fair layout of fogging system
Make a list of required material
Collect some quotations of required material from market
Buy required material from market
Installation of fogging system
Observation and maintenance
On going work –
16/08/2022 to 24/08/2022
There are three types of foggers :
- Single or one way fogger
- Two way fogger
- 4-way fogger
Single Way Fogger –
Operating pressure – 1.5 to 2.5 kg/ sq. cm
Coverage area – 1.5 sq. m
Flow rate – 7.5 LPH
Droplet size – 75 to 100 micron
Two way fogger –
Operating pressure – 2 to 4 kg/ sq. cm
Coverage area – 1.5 sq. m
Flow rate – 15 LPH
Droplet size – 70 micron
4-way fogger –
Operating pressure – 3 to 5 kg/ sq. cm
Coverage area – 5.5 sq. m
Flow rate – 30 LPH
Droplet size – 70 to 90 micron
As 4-way fogger have higher flow rate and coverage area than other two types of foggers. So we decided to use 4-way foggers for fogging system.
Firstly, we measured the incoming pressure of water at the inlet of sand filter. It was about 2.3 kg/sq.cm. We had to measured the pressure of water at the outlet of screen filter, so we purchased a new saddle piece to attach a pressure gauge to it. Then we measured the pressure of water and it was about 2 kg/sq.cm.
As we needed a water pressure of 3 kg/sq.cm to operate foggers, se we made a new water pipeline connection to reduce the pressure drop and velocity drop of water inside pipeline. Again, we measured the water pressure and it was 2.8 kg/sq.cm. As we didn’t get the desired water pressure, we decided to use a water tank as water source with a separate submersible water pump.
To refill the water tank of the fogging system we should make pipeline connections as per following figure.
Designing of fogging system –
14/09/2022 to 28/09/2022
Measured dimensions of polyhouse for designing rough layout of fogging system.
Drawn rough layout of fogging system for polyhouse.
In the rough layout, there were 4 foggers on the second lateral. But the first fogger of that lateral was near to the exhaust fan. So we had to remove it and we added it on the third lateral.
Then we drawn a fair layout of fogging system with these corrections.
Calculations –
Flow rate of water in 2″ pipe i.e. flow rate submersible motor
Q = 7200 LPH = 0.002 m3/s
Cross-sectional area of 2″ pipe
d = 0.0508 m
r = 0.0254 m
A = πr²
= 3.14*(0.0254)²
= 0.00203 m²
Velocity of water in 2” pipe
Q = AV
∴ V = Q/A
= 0.002/0.00203
= 0.9852 m/s
Cross-sectional area of 20 mm lateral
d = 0.02 m
r = 0.01 m
A = πr²
= 3.14*(0.01)²
= 0.000314 m²
Velocity of water in 20 mm lateral ( 3 laterals )
Q = AV
∴ V = Q/A
= 0.002/0.000314
= 6.369 m/s
Therefore, velocity of water in each lateral
V1 = V2 = V3 = V/3
= 6.369/3
= 2.123 m/s
Flow rate of water in each lateral
Q = AV
= 0.000314*2.123
= 0.0006666 m3/s
Discharge of one 4-way fogger
Q = 30 LPH
Discharge at first fogger
Q1 = Q – 30 LPH
= 2400 – 30
= 2370 LPH
= 0.0006583 m3/s
Discharge at second fogger
Q2 = Q1 – 30 LPH
= 2370 – 30
= 2340 LPH
= 0.0006500 m3/s
Discharge at third fogger
Q3 = Q2 – 30 LPH
= 2340 – 30
= 2310 LPH
= 0.0006417 m3/s
Discharge at fourth fogger
Q4 = Q3 – 30 LPH
= 2310 – 30
= 2280 LPH
= 0.0006333 m3/s
Pressure drop in 20 mm lateral
For first lateral :
ΔP = f*L/D*ρ/2*V²
where,
ΔP – pressure drop in lateral,
f – friction factor,
L – length of lateral,
D – diameter of lateral,
ρ – fluid density,
V – velocity
∴ ΔP = 0.02167*(21.5/20*10-3)*1/2*(2.123)²
= 2.0998/0.04
= 52.49 KPa
= 0.5352 kg/cm²
For second lateral :
ΔP = f*L/D*ρ/2*V²
∴ ΔP = 0.02167*(19/16*10-3)*1/2*(2.123)²
= 1.8557/0.04
= 46.39 KPa
= 0.4730 kg/cm²
For third lateral :
ΔP = f*L/D*ρ/2*V²
∴ ΔP = 0.02167*(16.5/16*10-3)*1/2*(2.123)²
= 1.6115/0.04
= 40.28 KPa
= 0.4108 kg/cm²
Velocity drop in lateral when foggers are on –
V1 = A/Q1
= 0.000314/0.0006583
= 0.4770 m/s
V2 = A/Q2
= 0.000314/0.0006500
= 0.4831 m/s
V3 = A/Q3
= 0.000314/0.0006417
= 0.4893 m/s
V4 = A/Q4
= 0.000314/0.0006333
= 0.4958 m/s
Total velocity drop = V1 + V2 + V3 +V4
= 0.4770 + 0.4831 + 0.4893 + 0.4958
= 1.9452 m/s
Installation of fogger system –
29/09/2022 to 14/10/2022
Cleaned a water tank and placed it inside the polyhouse. Made some connections of pipeline to supply water from the filtration system to the water tank.
Brought out the required material for installation of fogging system from market and collected some remaining material from scrap.
First , we cut the lateral into designed length and marked out the points on 20 mm lateral where we had to attached foggers. Then drilled 20 mm holes in mainline for the laterals and then drilled holes in lateral to attach fogger. Lastly we connected laterals to the mainline and mainline to the water pump.
Lastly we attached a screen filter to the mainline to purify the water and hence to avoid blockage of fogger nozzles.
Observations –
Discharge of the outlet of the mainline : 1800 LPH
Discharge of one fogger : 29.4 LPH
Observation table –
| Date : 19/10/2022 | ||||||||
| Time : | 11.00 AM | 12.15 PM | For 15 min. | 14.45 PM | 17.00 PM | |||
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | Beforer Fogging | After Fogging | |
| Dry Bulb Temp : | 30° C | _ | 35° C | 28° C | 28° C | _ | 28° C | _ |
| Wet Bulb Temp : | 21° C | _ | 23° C | 18° C | 17° C | _ | 18° C | _ |
| Humidity : | 45.00% | _ | 40.00% | _ | 40.00% | _ | ||
| Date : 20/10/2022 | ||||||||
| Time : | 11.00 AM | For 5 min. | 14.30 PM | For 15 min. | 17.00 PM | |||
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | |||
| Dry Bulb Temp : | 30° C | 28° C | 30° C | 28° C | 24° C | _ | ||
| Wet Bulb Temp : | 17° C | 19° C | 20° C | 19° C | 11° C | _ | ||
| Humidity : | 44.00% | 41.00% | 44.00% | _ | ||||
| Date : 21/10/2022 | ||||||||
| Time : | 10.15 AM | 12.45 PM | 17.15 PM | |||||
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | |||
| Dry Bulb Temp : | 26° C | _ | 26° C | _ | 26° C | _ | ||
| Wet Bulb Temp : | 16° C | _ | 17° C | _ | 16° C | _ | ||
| Humidity : | 39.00% | _ | 43.00% | _ | 39.00% | _ | ||
| Date : 28/10/2022 | ||||||||
| Time : | 10.00 AM | For 5 min. | 12.10 PM | For 15 min. | 14.30 PM | For 15 min. | 17.05 PM | |
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | Beforer Fogging | After Fogging | |
| Dry Bulb Temp : | 25° C | 25° C | 35° C | 27° C | 30° C | 26° C | 27° C | _ |
| Wet Bulb Temp : | 14° C | 14° C | 25° C | 18° C | 15° C | 14° C | 18° C | _ |
| Humidity : | 44.00% | 43.00% | 43.00% | _ | ||||
| Date : 29/10/2022 | ||||||||
| Time : | 10.35 AM | 10 min. | 12.15 PM | 15 min. | 14.30 PM | 20 min. | 16.45 PM | |
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | Beforer Fogging | After Fogging | |
| Dry Bulb Temp : | 24° C | 22° C | 30° C | 24° C | 34° C | 25° C | 24° C | _ |
| Wet Bulb Temp : | 14° C | 12° C | 17° C | 13° C | 24° C | 13° C | 14° C | _ |
| Humidity : | 38.00% | 36.00% | 36.00% | 44.00% | 38.00% | _ | ||
| Date : 31/10/2022 | ||||||||
| Time : | 10.20 AM | For 10 min. | 12.45 PM | For 15 min. | 14.35 PM | For 15 min. | ||
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | |||
| Dry Bulb Temp : | 30° C | 25° C | 35° | 27° C | 35° C | 25° C | ||
| Wet Bulb Temp : | 20° C | 15° C | 25° C | 17° C | 24° C | 15° C | ||
| Humidity : | 41.00% | 38.00% | 44.00% | 40.00% | 38.00% | |||
| Date : 1/11/2022 | ||||||||
| Time : | 10.05 AM | 10 min. | 12.15 PM | 15 min. | 14.45 PM | 15 min. | 17.15 PM | |
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | Beforer Fogging | After Fogging | |
| Dry Bulb Temp : | 30° C | 27° C | 32° C | 28° C | 28° C | 24° C | 23° C | _ |
| Wet Bulb Temp : | 23° C | 22° C | 22° C | 23° C | 24° C | 21° C | 21° C | _ |
| Humidity : | 53.00% | 62.00% | 42.00% | 63.00% | 69.00% | 74.00% | 81.00% | _ |
| Date : 2/11/2022 | ||||||||
| Time : | 10.10 AM | 12.20 PM | 10 min. | 14.40 PM | 20 min. | 17.00 PM | ||
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | Beforer Fogging | After Fogging | |
| Dry Bulb Temp : | 25° C | _ | 30° C | 28° C | 32° C | 28° C | 26° C | _ |
| Wet Bulb Temp : | 22° C | _ | 25° C | 26° C | 25° C | 25° C | 23° C | _ |
| Humidity : | 74.00% | _ | 64.00% | 83.00% | 54.00% | 75.00% | 75.00% | _ |
| Date : 3/11/2022 | ||||||||
| Time : | 11.00 AM | 10 min. | 12.35 PM | 15 min. | 14.45 PM | 15 min. | 17.15 PM | |
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | Beforer Fogging | After Fogging | |
| Dry Bulb Temp : | 28° C | 26° C | 29° C | 26° C | 29° C | 26° C | 23° C | _ |
| Wet Bulb Temp : | 23° C | 24° C | 23° C | 23° C | 25° C | 23° C | 21° C | _ |
| Humidity : | 63.00% | 82.00% | 58.00% | 75.00% | 69.00% | 75.00% | 81.00% | _ |
| Date : 4/11/2022 | ||||||||
| Time : | ||||||||
| Before Fogging | After Fogging | Before Fogging | After Fogging | Before Fogging | After Fogging | Beforer Fogging | After Fogging | |
| Dry Bulb Temp : | 26° C | _ | 29° C | _ | 32° C | 27° C | 25° C | _ |
| Wet Bulb Temp : | 22° C | _ | 24° C | _ | 24° C | 24° C | 22° C | _ |
| Humidity : | 68.00% | _ | 69.00% | _ | 50.00% | 75.00% | 74.00% | _ |
| Date : 11/11/2022 | ||||||
| Place : | Outside | Centre from working pads | Centre from 1st fan | Centre from non-working pads | Centre from 2nd fan | Centre of polyhouse |
| Time : 10.30 AM | ||||||
| Temp. above foggers : | 30° C | 32° C | 30° C | 32° C | 31° C | 32° C |
| Temp. below foggers : | _ | 26° C | 26° C | 28° C | 28° C | 29° C |
| Time : 11.30 AM | ||||||
| Temp. above foggers : | 35° C | 33° C | 31° C | 34° C | 34° C | 37° C |
| Temp. below foggers : | _ | 25° C | 25° C | 27° C | 27° C | 30° C |
| Time : 12.30 PM | ||||||
| Temp. above foggers : | 37° C | 34° C | 35° C | 36° C | 35° C | 38° C |
| Temp. below foggers : | _ | 27° C | 27° C | 29° C | 29° C | 30° C |
| Time : 14.30 PM | ||||||
| Temp. above foggers : | 32° C | 33° C | 30° C | 33° C | 31° C | 35° C |
| Temp. below foggers : | _ | 26° C | 26° C | 26° C | 26° C | 28° C |
| Date : 12/11/2022 | ||||||
| Place : | Outside | Centre from working pads | Centre from 1st fan | Centre from non-working pads | Centre from 2nd fan | Centre of polyhouse |
| Time : 10.00 AM | ||||||
| Temp. above foggers : | 31° C | 31° C | 29° C | 30° C | 29° C | 33° C |
| Temp. below foggers : | _ | 28° C | 28° C | 30° C | 29° C | 32° C |
| Time : 12.30 PM | ||||||
| Temp. above foggers : | 34° C | 32° C | 31° C | 35° C | 34° C | 37° C |
| Temp. below foggers : | _ | 26° C | 26C | 27° C | 27° C | 29° C |
| Time : 14.30 PM | ||||||
| Temp. above foggers : | 32° | 32° C | 31° C | 33° C | 32° C | 34° C |
| Temp. below foggers : | _ | 27° C | 27° C | 27° C | 27° C | 29° C |
Conclusion –
- Foggers are very useful for maintaining temperature and humidity.
- After taking some observations, we observed that 10 foggers reduced 5 to 7° C temperature if it operates for 30 minutes.
- As per specifications of 4-way fogger, it should cover 5.5 sq. m area but after observation it covered only 4.5 sq. m area due to pressure drop.
