Week 6: Continuing testing

This past week we conducted several tests outside of lab. The polystyrene box was tested and the fiberglass batt box was tested. Unfortunately there was a problem in our testing procedure; we did not allow the box’s temperature to become steady before taking data to calculate the cooling curve. Because of this we will be retesting and analyzing the data for these two boxes this next week. We will also be beginning the economic analysis.

The testing procedure follows: the box is sealed and a light bulb is turned on for an hour. The light bulb is then unplugged and the box begins to cool. The cadence of internal temperature data collection differs for each type of insulation, but it follows the form of: every half minute for twenty minutes, ever minute for forty minutes, ever two minutes for an hour, and every five minutes for an hour or two. The data is then analyzed with the equation γ=ln[(T_in(f) - T_out)/(T_initial,in – T_out)]. The data is then plotted t VS γ, and a linear trend-line is applied. The slope of the trend line is proportional to the thermal conductivity, which is the inverse of the resistance, or insulating ability of the material.