Page History

...

We performed four different tests to evaluate the effects of water mass on cooking speed in the solar cooker.  We varied the test by adding an additional 3-lb of water filled pot to each successive test.  Figure 4 below shows the plots of temperature vs. time for the four parallel cooking tests. While the boiling time increased with water mass, the increase was not a direct relationship. The time to boil four pots of water (12 lbs) was far less than four times the amount of time to boil 1 pot of water (3 lbs).

Figure 4 - Boiling time (minutes) vs. average water temperature (°C) for parallel cooking tests.

...

To further examine the difference in temperature verses time, figure 5 shows the different temperatures after 60 minutes of cooking in the form of a bar graph.  The data shows that the difference between 1 and 2 pots of water is somewhat small---a difference of 3.3%.  However, the drop in temperature increases somewhat drastically from 2 pots to 3 pots, after 60 minutes of cooking. It is important to note that this drop, nevertheless, is not a decrease in time per unit thermal mass of water. The data shows conclusively that the greater the thermal mass of water heated in parallel the greater the efficiency.

Figure 5--The difference in temperature reached after 60 minutes of cooking during the parallel heating tests.

...

Another comparison we implemented was the difference in time it took each pot to reach 95°Celsius (figure 6).  Again, it is clear to see that the difference between 1 pot and 2 pots is relatively small, and then there is a jump between 2 and 3 pots. Also, the data collected for the 4 pot test, on average, never reached 95 degrees Celsius.

Wiki Markup
Figure 6 - The time (minutes) that it took the average temperature in the pots for each test to reach 95°C.  \[The average data collected for the 4 pot test never reached 95°C, hence it's absence in this bar graph.\]

...

This led us to re-examine the set up of the solar cooker. The pot in question was located at the front left-hand-side of the cooker as shown in figure 7 below.  Consulting our lighting set up, we noted that there are several lights that are burnt out on the left side of the cooker.  We also noted that this particular pot was near the door and the door eventually had to be fixed due to bowing of the wood.  Both of these issues could have influenced the lower temperature of the water in the front, left pot.

Figure 7. Visual depiction of weaker lighting zone

...

As shown in figure 8, the addition of the wood seal to the solar oven door did not have a significant impact on the overall temperature performance of the oven.

Figure 8 - Comparison of performance for the solar oven before and after the addition of the wood door seal.

...

The Solar Oven Group concluded that the performance improvement of the oven with the new door was small enough that the data collected for the 2 pot-3lbs, 3 pot-3lbs, and 4 pot-3lbs tests was accurate enough for the purposes of the group's analysis.

Figure 9 - Comparison of times required for solar oven to reach 95⁰C before and after the addition of the wood door seal.

...