Issue link: https://cp.revolio.com/i/932105
Contrary to what has been observed on the ocean, the amplitude of temperatures during a 24 hour period is known to be larger on the ground. Figure 4 shows there is almost no exposure of the product to high amplitudes of temperature in the center of the pallets. In fact, the middle of the pallet is surrounded by product that plays the role of thermal buffer. (Leinberger, 2006) made the same observation between temperatures measured in containers on the ocean with up to 20°C difference of temperatures between bottom container sensors and top container sensors for an outside air temperature of 19°C. Also, temperature measured in the empty volume of a partially filled container was less moderate than the filled volume. Understanding the described differences between inside and outside pallet temperature profiles, this study focused on analyzing in detail the worst cases for the product. Indeed, external layers of a pallet are exposed to higher temperatures and higher minimum/maximum ranges of temperature. The difference between minimum and maximum temperature was measured up to 13°C between the night and the day, and up to 7°C higher than outside temperature during the day (Figure 5: Temperature profile at the top of a pallet compared to outside air temperature during transportation). In the next paragraph of this article, we will describe in detail how measurements have been analyzed and cross checked with the literature to build a predictive temperature model of the "worst case" scenario during transportation. 17 ista views • December 2017/January 2018 • www.ista.org > MORE ON PAGE 18 10 e 80 90 95 e 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 le d Mid alle P p o T t e ll Pa t le Dat Dat 1 - 09 - 03 1 - 09 - 03 1 - 09 - 03 1 - 09 - 04 1 - 09 - 04 1 - 09 - 04 1 - 09 - 05 1 - 09 - 05 1 - 09 - 06 1 - 09 - 06 1 - 09 - 06 1 - 09 - 07 1 - 09 - 07 1 - 09 - 07 1 - 09 - 08 1 - 09 - 08 1 - 09 - 09 1 - 09 - 09 1 09 09 1 - 09 - 09 1 - 09 - 10 1 - 09 - 10 1 - 09 - 10 1 - 09 - 11 Figure 4 – Recorded temperatures (°C) from sensors in a pallet (top and middle of a pallet). Observations show the sensors on the top of the pallet follow the 24h outside temperature cycles while there is almost no variation for the center of the pallet during 9 days. 67 72 77 82 87 92 97 102 107 112 12:21:28 AM 1:21:28 AM 2:21:28 AM 3:21:28 AM 4:21:28 AM 5:21:28 AM 6:21:28 AM 7:21:28 AM 8:21:28 AM 9:21:28 AM 10:21:28 AM 11:21:28 AM 12:21:28 PM 1:21:28 PM 2:21:28 PM 3:21:28 PM 4:21:28 PM 5:21:28 PM 6:21:28 PM 7:21:28 PM 8:21:28 PM 9:21:28 PM 10:21:28 PM 11:21:28 PM FW Top Pallet FW Oustide trailer Inside truck Outside air temperature 19.4 °C 25.0 °C 36.1 °C 30.6 °C 41.7 °C Figure 5 – Temperature profile at the top of a pallet compared to outside air temperature during transportation during one warm day in Arizona.