More testings were done on the repaired V1. However following serious observations could be made:
- Auto-thermal operation has not yet been achieved. The flames occur as interpreted by significant rise in flue gas temperatures even when the heater is switched off by the PID control. However the flames do not sustain and the heater is required to be fired up. This process occurs every 1000 seconds of operation.
- Due to operation through natural draft, significant amount of heat is lost in the pre-pyrolysis stages due to continuous air convection.
- Due to the straight and simple geometry, the flames of pyrolysis gases and vapors do not reside for a long time in the system, not enough to transfer sufficient heat to the waste chamber. This again calls for firing the heater.
- Pyrolysis and consequently the flames arise only when the heater is on for sufficiently long time. Even when the temperatures at the exit are the required > 270C, there are seldom smoke signs of flaming.
- When i tested with child diapers that have a lot of water content, 1 hour is simply not sufficient for 2 diapers. Infact its been observed that a sufficient drying stage is mandatory or else the following case occurs: The drying of top regions is not complete and continues while the pyrolysis of bottom content produces pysolysis fumes. The net gas outflow is not fuel rich and since it has H2O content its too hard to reach and sustain a flame at the gas exit due to the heat capacity of moisture. Thus, the highly toxic white smoke.
- There is no way to know as of the current model as to when the contents of the waste chamber have been completely charred. A pre-fixed time of process works only for a known number of sanitary pads, for example 1 hour of process from start to finish is good for 5-7 pads at max, ½ hour is good for 2-3 pads and so on. Chamber capacity being 15 pads this can not be predetermined. An algorithm or technique to determine when pyrolysis is no longer occuring even when temperatures are alright is being developed.
- Even with all the above observations taken into account, im not able to set a proper PID loop that can work efficiently. I have significant overshoots and undershoots resulting in bad operation : white smoke, black smoke when overheated, wastage of time, no definition of whats actually going on.