Introduction

Dr. Prasad Deodhar from Bhagirath Gramvikas Pratishthan contacted Vigyan Ashram regarding a problem a fisherwoman was facing in drying her leftover fish. The fisherwoman catches fish and sells it in a nearby market. Every day around 1-2 Kg of fish used to be leftover and to avoid financial loss she used to preserve the leftover fish by conventional salting and open sun drying. Dr. Deodhar wanted a better alternative to this conventional fish preservation method. The fisherwoman when contacted seemed to be fine with the conventional method and was reluctant to spend money on an alternate solution. Dr. Deodhar however asked Vigyan Asram to make a solar dryer anyway. After discussions in DIC, it was decided that since the customer doesn’t have any special requirements a simple low-cost flat solar dryer with a polycarbonate sheet should be made and sent.

PRODUCT DEVELOPMENT PROCESS:

DISCUSSION

3rd Jan 2022

The outcome of the discussion:

  1. Relative humidity of the air rises with respect to rise in its temperature, thus air will carry more moisture in it. This additional moisture will come from the fish present in the chamber.
  2. With all factors equal, moist air is less denser than the dry air because water has a lower molecular weight than nitrogen and oxygen. So the moist air will rise in the chamber and due to design of its roof (slant roof and an opening at top) it will leave the chamber.

6th Jan 2022

Data from the literature (internet):

  1. Water content in the raw fish – 80%
  2. Fish can be dried upto containing 15% moisture in it with the help of solar dryer.

Data from the customer:

  1. Weight of raw fish – 5kg
  2. Weight of dried fish by salting is 1.5kg

calculation:

The Outcome of the discussion: We need to remove 176g of water through the solar dryer from 1.5kg of dried fish. This 1.5kg of dried fish would be obtained from salting the 5kg of raw fish.

7th Jan 2022

Data from the literature (internet):

  1. Solar Irradiance (in general) = 1000W or 1000 Joule/sec.
  2. Polycarbonate sheet allows 70% light to pass through it.

Data from the design:

Area of the polycarbonate sheet = 1.656 sq. m.

Calculation:

The outcome of the discussion: 1159.2 Joul energy will be entered in the chamber per second due to solar radiation.

STEPS:

1: PROCESS FLOW DIAGRAM

2: MATERIAL FLOW DIAGRAM

3: DESIGN MODELLING

3A) Part List

3B) Market Survey

3C) Sketches

3D) Envelop dimensions

4: 3D MODELLING

4A) Part Modelling

4B) Assembly

4C) Draft

5: BILL OF MATERIAL (BOM)

6: PROCUREMENT

7: FABRICATION

PROCESS FLOW DIAGRAM

MATERIAL FLOW DIAGRAM

DESIGN MODELLING

Part List

Envelope Dimentions

3D MODELING

Part modeling and assembly files can be found in the below link

https://drive.google.com/drive/folders/1tk6Xp0DsoQFGA7lTk7QweTNGHF2hRLhn?usp=sharing

BILL OF MATERIAL

https://docs.google.com/spreadsheets/d/1DrYjfqcYUogBm0d75tt8rr4auiJancu0/edit?usp=sharing&ouid=100314879562853321735&rtpof=true&sd=true

PROCURMENT

S. No.MaterialVendorLocationContact No.
1L-angle barShree Bhairavnath Steel CentrePabal, Pune9890788455
2Nut, bolt, screwdriver,
spanners, paint, brush,
primer etc
Shree Super Market & HardwarePabal, Pune9922114809/9960005674
3PlywoodSaikrupa Plywood and Hardware Pabal, Pune9730409088/9730107043
4Polycarbonate sheetSanjay DistributorsBhavani Peth, Pune8087814339/9890015894

FABRICATION

Frame

Chamber

Final product

19th Jan 22

Trail

A mixture of sawdust and water is used to take the 1st trial. Details are mentioned in the below table:

Air
Inlet
slit
area
Air
outlet
slit
area
sample’s
exposed area
WaterSawdustInitial
temp.
Initial
relative
humidity
Maximum
temp.
DurationWater
remained
Drying
Open
Sun
1036 sq cm500gm500gm29 C28%31 C2pm-5pm337gm32.6%
Solar
dryer
60×2 sq c 120×1 sq c 1036 sq cm500gm500gm29 C 28% 64 C 2pm-5pm350gm30%

Result: As the drying capacity of the solar dryer is less (30%) than open Sun drying (32.6%) further ideation is needed.

Discussion

Factors that are affecting the drying capacity of the solar dryer:

  1. Height of the tray is heigher than the height of the sample mixture which is affecting the direct contact of inlet air to sample mixture.
  2. Area of the slits for inlet and outlet air is not adequet to provide enough air ventilation.

20th Jan 22

Trial

2nd trial is carried out with the following changes:

  1. Trays are not used to put the sample mixture. A plywood frame of 1 sq. foot is used to spread the sample mixture in 1 sq foot area. Then plywood frame is removed so that inlet air can contact directly to the sample mixture.
  2. Slit areas for air inlet and outlet are increased by 300%

Details are mentioned in the below table:

Air
Inlet
slit
area
Air
outlet
slit
area
sample’s exposed
area
WaterSawdustInitial
temp.
Initial
relative
humidity
Maximum
temp.
DurationWater
remained
Drying
Open
Sun
(30×30+ 30x2x4)=1140 sq. cm250gm 250gm27 C34%30 C12pm-4pm50gm80%
Solar
dryer

sample A
60×8 sq c 120×4 sq c 1140 sq. cm250gm 250gm27 C 34% 63.5 C 12pm-4pm17gm93.2%
Solar
dryer

sample B
60×8 sq c120×4 sq c 1140 sq. cm250gm250gm27 C34% 63.5 C 12pm-4pm13gm 94.8%

Conclusion

The solar fish dryer is around 13%-15% more effective than open Sun drying.

Delivery

The solar fish dryer has been safely delivered to Bhagirath Gramvikas Pratishthan.