The data include two laboratory tests performed in both test platform A and B. The test data record the air temperature distribution of the cooling tank unit, CO2and O2 concentration level of the refrigerated container unit and the temperature inside the vaccine package. The details of each test are described as follows,
The first test was performed in test platform A (fig. 1). The thermocouples have been installed inside the cooling tank unit to monitor the temperature distribution. The location of these thermocouples is shown in FIG. 3. 20 Styrofoam boxes (b1 to b20) were placed inside the cooling container unit in two rows along both side walls, while an additional box (b0) was placed outside the environment for comparison purposes. The location of the boxes can be seen in Fig. 4. The dry ice is delivered and filled in these 21 boxes (b0 to b20) with approximately 50 lbs of dry ice in each of them. A thermocouple is installed inside each of these 21 boxes (fig. 5), but the placement of thermocouples inside these boxes is not the same for all boxes, which will lead to the different characteristics of the temperature profiles of the boxes in test 1.
To evaluate the dry ice sublimation, one of the boxes (b11 in fig. 4) on the inside of the container was placed on a mechanical scale with a closed caption television camera pointed at the scale. This was also repeated on the outside with the box b0 that was in the environment for comparison purposes.
A set O2 and CO2 sensors were used using a diaphragm pump located on the back of the device. It was connected by means of plastic hose to pump the air from the inside of the cooling tank to the sensor through a hole that went through the drain holes of the cooling tank.
To monitor the pressure difference from inside and outside the cooling tank, an Omega 5 V differential pressure monitor was installed on the back of the unit with a tube running through the cooling unit frame and extending to the pressure monitor.
The test starts when the unit reaches the set temperature -34.5 ° C and 100% open fresh air valve (FAV), and all temperatures are recorded with a 10 second test time. Although CO2 was kept low concentration level, but it is not able to maintain the set point. FAV was closed after approx. 24 hours. Approximately 100 hours after the test stare, the FAV was opened for CO discharge2 while still trying to maintain the set point inside the cooling container. FAV was left open for the rest of the test. The mechanical scale reading of boxes (b11 and b0) is recorded through closed caption television camera at 3-hour intervals.
The second test was performed in test platform B (fig. 2). Thermocouples have been installed inside the cooling container unit to monitor the temperature distribution, as shown in fig. 6. 20 Styrofoam boxes (B1 to B20) were placed inside the refrigerated container unit in two rows and two layers along both side walls, while two boxes were placed inside the laboratory for comparison purposes. The location of the boxes can be seen in Fig. 7. An empty small payload box was placed inside each package with dry ice around it, as shown in fig. 8. A thermocouple was placed in the center of each payload box to represent the vaccine temperature.
Corresponding to test 1, a set O2 and CO2 sensors were used using a diaphragm pump located on the back of the device. It was connected by means of plastic hose to pump the air from the inside of the cooling tank to the sensor through a hole that went through the drain holes of the cooling tank.
The test starts with the unit reaching the set temperature -30 ° C and closed FAV. FAV was left closed throughout the test. All temperatures are recorded at 1 minute intervals. Approximately 66 hours and 210 hours after the test stare, the rear door of the refrigeration unit was open to examine the changes in CO2/ISLAND2 concentration levels inside the refrigerated container unit during the open period of the door. The door was closed after CO2/ISLAND2 concentration levels reach safe values.
According to the test data, the temperatures for each payload box follow similar temperature profiles, a generic temperature profile for a vaccine payload box can be defined as shown in fig. 9. The temperature profile can be divided into two areas: a temperature tolerable zone and a temperature intolerable zone. If the amount of dry ice left in the vaccine package cannot keep the payload box temperature within the required temperature range between -80 ° C and -60 ° C, it is at the temperature that cannot be tolerated. Otherwise, it is in the temperature tolerant zone, which can be further divided into two phases: a stable period and an unstable period. During the stable period, the dry ice can hold the payload box at the dry ice boiling point (sublimation point) temperature of -78.5 ° C. When the payload box temperature starts to rise but is still within the required temperature range, it is during the unstable period in the temperature tolerable zone.