Introduction/Need of Project:
There is difficulty of cooking brown rice in pressure cooker or traditional method of cooking rice. It is usually cooked by using Sarai cooker which uses coal as fuel. Nowadays people are not comfortable with this method therefore there is a need of elimination of using coal as a fuel. Instead of coal it can be used with any other means to avoid the mess.
Objectives:
- To eliminate use of coal in sarai cooker.
- To define procedure for cooking brown rice
Procedure to be followed:
- To know procedure of brown rice cooking by using Sarai Cooker.
- Data collection of temperatures while cooking rice.
WORK DONE STATUS
1st Trial of Readings on Sarai Cooker:
I have Taken 110 gm of coal
Brown rice taken in 3 containers: 80 gm, 90 gm, 80 gm respectively.
water taken in 3 containers: 200 ml, 170 ml, 170 ml respectively. 225 ml of water taken in outer container.
Cooking started at 11:05 am
Readings taken at 11:25 am, 11:50 am and 12:15 pm
After this trial, it was observed that rice was not cooked properly. This trial was failed due to disturbance while cooking, steam lost due to opening whole setup at each 20 mins interval. Therefore the temperature readings I have got are of no use.
2nd Trial:
This time I have decided to take readings from outer container only.
Readings were taken by using thermometer and infrared thermometer.
Cooking started:6:15 pm
Boiling of water starts at: 6:25 pm
| Time | Temperature by thermometer | Temp by IR thermometer |
| 6:25 pm | 82°C | 84.3°C |
| 6:40 pm | 101°C | 103°C |
| 6:55 pm | 100°C | 84.3°C |
| 7:10 pm | 98°C | 73°C |
From these temperatures I got to know that IR Thermometer readings were very fluctuating and not correct. And in thermometer, if water in outer container was boiling then it was obvious that temperature would be around 100°C.
3rd trial of readings on Electric Rice Cooker:
I have taken 3rd trial on electric rice cooker.
Rice taken: 80gm
water in rice: 150 ml
water in outer container: 250 ml
Start time: 6:15 pm (Red light ON)
Yellow light ON at 6:30 pm (Keep warm mode on)
At the end, it was observed that rice was not cooked properly.
4th trial on electric rice cooker:
water in rice: 250 ml
water in outer container: 325 ml
rice taken: 60 gm
start time: 6:25 pm (Red light ON)
Yellow light ON at 7:05 pm (Keep warm mode ON)
Since, water added in outer container was more. It was observed that after 40 mins. keep warm mode was ON. Still brown rice was not cooked properly.
5th Trial:
Collected temperature data of sarai cooker from inner 3 containers after water starts boiling in a outer container. Data collected is as follow:
| Temp. | After 5 min | 10 min | 15 min | 20 min | 35 min | 50 min |
| T 1 | 60˚C | 78˚C | 80˚C | 81˚C | 84˚C | 84˚C |
| T 2 | 75˚C | 80˚C | 85˚C | 84˚C | 86˚C | 86˚C |
| T 3 | 81˚C | 83˚C | 85˚C | 87˚C | 85˚C | 87˚C |
6th Trial:
Collected temperature data of Electric Rice cooker from inner 3 containers after water starts boiling in a outer container. Data collected is as follow:
| Temp | After 5 min | 10 min | 15 min | 20 min | 25 min | 35 min | 45 min |
| T 1 | 64 ˚C | 81˚C | 82˚C | 63˚C | 70˚C | 79˚C | 72˚C |
| T 2 | 64˚C | 81˚C | 84˚C | 66˚C | 73˚C | 81˚C | 77˚C |
| T 3 | 78˚C | 83˚C | 84˚C | 69˚C | 75˚C | 79˚C | 78˚C |
Initial temperatures from starting were recorded after each 2 minutes up to boiling of water:
| Time | Temperature |
| 4:04 pm(start) | 28˚C |
| 4:06 pm | 38˚C |
| 4:08 pm | 44˚C |
| 4:10 pm | 52˚C |
| 4:12 pm | 59˚C |
| 4:14 pm | 66˚C |
| 4:16 pm | 73˚C |
| 4:18 pm | 81˚C |
| 4:20 pm | 89˚C |
| 4:22 pm (water starts boiling) | 94˚C |
#Work done on pressure cooker weight (whistle):
I brought pressure cooker whistle of about 5 to 6 litres volume from market.
Now, I wanted to reduce the weight of the whistle upto 50 gm, 25gm and 13 gm
1st whistle:
Reduced weight of the whistle by machining it on lathe
Initial weight: 57.484 gm
Final weight: 50.91gm
2nd whistle:
Damaged while machining on lathe.
3rd whistle:
Damaged ring while machining on lathe.
4th whistle:
Initial weight:55.56 gm
weight of the whistle after machining on lathe:31 gm
I want to reduce the weight upto 25 gm. then I have decided to reduce weight by filing.
final weight of the whistle after filing: 25 gm
CALCULATIONS
# Pressure calculation in an ordinary pressure cooker:
Internal diameter of steam vent (id): 2.94 mm
Therefore, internal radius(ir): 1.47 mm
Area of valve =πr² = π*(1.47)² = 6.78 mm² = 0.0678 cm²
Now, Pressure = Force/Area
Force = Pressure cooker weight (whistle) = 79.270 gm = .07927 kg
Therefore, P = F/A = .07927/0.0678 = 1.169 kg/cm² = 16.627 psi = 0.1146 MPa
Now, Total Pressure = Gauge Pressure + Atmospheric Pressure
= 0.1146 + 0.1013
= 0.2159 MPa
i.e., Temperature range is 120 to 125˚C …………………….from steam table
# For Brown rice cooker I want to maintain temperature about 105˚C
Then, at 105˚C
Total pressure = 0.1208 MPa
now, total pressure – atmospheric pressure = gauge pressure
0.1208 – .1013 = 0.01952 MPa
= 0.1990 kg/cm²
therefore, P = F/A
0.1990 = F/0.0678
= 0.0134 kg
= 13.4 gm
# Verification of pressure from another cooker:
id = 2.75 mm
ir = 1.375 mm
A = πr² = π (1.375)² = 5.939 mm² =0.05939 cm²
F = 66.09 gm = 0.06609 kg
P = F/A = 0.06609/0.05939 = 1.11280kg/cm²
= 0.1091 MPa
Now, Total Pressure = Gauge Pressure + Atmospheric Pressure
= 0.1091 + 0.1013
= 0.2104 MPa
i.e., the temperature range is 120 to 125˚C ………………………from the steam table
TRIALS
Trials with the whistles:
I want to check if temperature in the cooker is similar to sarai cooker or not. For this purpose I have only added water in three cookpots. I have taken 250 ml of water in each cookpot and 350 ml of water in cooker.
Temperature readings after 40 minutes with 50 gm whistle:
| Cookpot | Temperature |
| 1 | 82˚C |
| 2 | 85˚C |
| 3 | 84˚C |
Remaining water in cooker = 230 ml
Temperature readings after 40 minutes with 25 gm whistle:
| Cookpots | Temperature |
| 1 | 86˚C |
| 2 | 85˚C |
| 3 | 82˚C |
Remaining water in cooker = 200 ml
Temperature readings recorded with both 50 gm and 25 gm whistle are having resemblance with sarai cooker temperature data i.e., in the range of 80˚C to 90˚C. From this it may be concluded that both whistles are suitable for the brown rice cooking.
Now, from both the whistles it was necessary to choose efficient one for the cooker. Efficiency of the whistle was decided with the help of water left in the cooker. Amount of water left in the cooker was 230 ml and 200 ml for 50 gm and 25 gm whistle respectively. From this it can be said that 50 gm whistle is more efficient since energy losses for the particular whistle are less.
So, selected 50 gm whistle for brown rice cooker.
Trials on brown rice:
Trial 1:
Now, I have taken trial on brown rice with 50 gm whistle.
Cooking started at 3:20 pm
Cooking ceased at 4:20 pm
Cooker was put on the gas on low flame for complete one hour.
After one hour rice was cooked completely with pressure cooker.
Trial 2:
| Rice in a cookpot | 60 gm |
| Water in a cookpot | 310 ml |
| Water in a cooker | 450 ml |
Cooking started at 6:07 pm
Cooking ceased at 7:07 pm
Cooker was put on the gas on low flame for complete one hour.
After one hour rice was cooked completely with pressure cooker.
Now I have decided to take trial with the combination of both whistles i.e, 50 gm and 80 gm and by adjusting flame low to high. I have decided 3 combinations of time, weight of whistles and flame control. It is given as follow:
| 1 | 20 minutes – 50 gm whistle – at low flame10 minutes – 80 gm whistle – at high flame for two whistles and then low. |
| 2 | 30 minutes – 50 gm whistle – at low flame10 minutes – 80 gm whistle – at high flame for two whistles and then low. |
| 3 | 20 minutes – 50 gm whistle – at low flame20 minutes – 80 gm whistle – at high flame for two whistles and then low. |
From trials of these combination 2nd one was better than the other two.
Ingredients taken in particular trial were as follow:
Cooking started at 3:20 pm
Cooking ceased at 4:20 pm
At the end, brown rice was cooked completely.
