1st Trial – 

I placed vegetables i.e. cauliflower and tomato in fridge and note down the temperature.

Day 1 :

Sr.no. Time Outside Temperature(°C) Inside Temperature(°C)
1. 12:30 PM 27.3 21.7
2. 01:30 PM 29.9 23.3
3. 02:30 PM 29.8 22.6
4. 03:30 PM 28.4 23.3
5. 04:30 PM 28.2 23.1
6. 05:30 PM 27.9 22.9

Day 2 :

Sr.no. Time Outside Temperature(°C) Inside Temperature(°C)
1. 10:00 AM 25.2 20.5
2. 11:00 AM 26.1 21.6
3. 12:00 PM 28.7 23.4
4. 01:00 PM 28.9 22.6
5. 02:00 PM 29.9 23.2
6. 03:00 PM 29.6 23.4
7. 04:00 PM 28.9 22.9
8. 05:00 PM 27.5 22.5

Weight Loss

Vegetables % weight loss
Evaporative fridge Outside
Tomato 16.65 17
Cauliflower 20 20

Problem – Here we get only 6°C temperature difference and very high weight loss in evaporative fridge which is nearly equal to outside.

Next Action – We will close the whole structure by using jute pads.

2nd Trial

Temperature- 

DAY 1:

Time Inside temp. Outside temp.
02:00 pm 24.8 32.9
03:00 pm 25.3 32.8
04:00 pm 23.2 32.6
05:00 pm 22.8 31

DAY 2:

Time Inside temp. Outside temp.
10:00 pm 22.4 30.4
11:00 pm 24.5 32.5
12:00 pm 27.3 35.2

Weight loss:

Table : % Weight loss in evaporative fridge, refrigerator and outside  

Vegetables % Weight loss
Evaporative fridge Refrigerator Outside
Tomato 0.6 0.35 0.95
Fenugreek 21.3 6.5 29

After 12 hrs:

Vegetables % Weight loss
Evaporative fridge Refrigerator Outside
Tomato 0.27 0.2 0.45
Fenugreek 6.6 2.56 19.58

After 36 hrs :

Vegetables % Weight loss
Evaporative fridge Refrigerator Outside
Tomato 0.53 0.12 1.13
Fenugreek 6.4 3.4 31.87

Problem – After covering whole model of fridge we get more temperature difference (i.e. 8 to 9°C temperature difference) between inside and outside of the fridge but vegetables requires more temperature difference (i.e cooling) for preservation. Weight loss of vegetables in evaporative fridge is less than outside and trial 1st also. But at this time weight loss in evaporative fridge is quite more than refrigerator.

Observation – I observed that the water which is falling on jute curtains, blockage the air which passing through the holes of jute curtains i.e decreases its porosity. Because of this, we get the temperature difference but we cannot maintain relative humidity that’s why cooling efficiency decreases and vegetables loses its weight.

Action –

  1. We decided to take cooling fans inside the evaporative fridge and take the readings of temperature.
    Inside temp. Outside Temp.
    20.9 26.8
    23.8 30.9

    Observation – here we get 5 to 7°C temperature difference. But I observed the cooling fans only circulates inside air.

  2. After this we decided to take readings by stopping water which falling on jute bags after 10 minutes.
    Inside Temperature Outside temperature
    18.4 31.6
    17.8 31.8
    22.5 31.5

Trial 3

I enclosed the whole fridge and remove cooling fans. Place the exhaust fan (29watt) on the upper side and cooling fan at (bottom) back side of the fridge. Connect timer or energy switch to motor which recirculates the water in fridge. By using timer, I turn on pump, exhaust fan for some duration and then timer goes off for some duration.

TIMER SETTINGS –

TIMER FOR TIME
ON OFF
Pump 12 sec. 1 min.
Exhaust fan 8 sec. 21 sec.

Temperature

OUTSIDE READING

Temperature Humidity
DB(dry bulb temperature) WB(wet bulb temperature)
34.5 18 18 %

INSIDE READING

Temperature Humidity
DB WB
26 19.5 57%

Weight loss

Vegetable % weight loss
Evaporative fridge Refrigerator
Fenugreek 2.3 4.8
Vegetable % weight loss
Evaporative fridge Refrigerator Outside
Fenugreek 2.88 3.2 21.42
Tomato 0.33 1.78 1.54