Insulated box testing

Setup
Two boxes were constructed with three layers of 1/2" extruded polystyrene foam board and hot glue. The larger box was made with an inner volume of 4"x4"x7". The smaller box had and inner volume of 2"x2"5". The boxes were wrapped in aluminum foil so that the tape used to seal the lid would not damage the foam when removed.

Cold packs (ammonium nitrate reacting with water in a plastic bag) were placed in the boxes. Five packs went in the larger box around 20mL of water and the temperature probe. One pack was wrapped around the temperature probe in the smaller box. It should be noted that the lid of the smaller box would not quite sit properly as the cold pack was slightly larger than the inner box volume. For control data, a cold pack was wrapped around another temperature probe but not placed in an insulating box. Another probe took the ambient temperature.

Results
Data was taken with the Vernier software package, LoggerPro, over a fifteen hour period, sampling every five minutes. Future tests may want to have a finer resolution at the test's beginning to better view the cooling effects. The LoggerPro file may be downloaded in the attachments tab. The plot is shown in the figure to the right. The colored traces are as follows:

• ch1: large box, five cold packs (red)
• ch2: small box, one cold pack (green)
• ch3: cold pack, no insulation (blue)
• ch4: ambient (orange)

Conclusions
The large insulated box remained below 10degC for a little less than five hours, the small box a little less than three. It's clear from comparison to the uninsulated cold pack that the foam board is working. It may be worth trying to improve the insulation on the boxes via better seams, more layers of foam, and glue that keeps the foam boards held tightly together. Future tests should also examine the effects of high ambient temperatures and also consider an increased humidity.