In this section the plots with the temperature profiles of the sample will be shown only for the case of For the rest of the conductivities considered similar phenomena take place and the results have been omitted for the reader’s convenience. The decision of showing the results for the lower conductivity of the sample has been made because the gradients obtained in the sample are higher and the results are more visual. In the next chapter, however, the results obtained for the whole range of conductivities will be studied as a summary.
Next, as stated before, the comparative charts for the temperature profiles of the sample will be shown for each of the operating ranges of the heating cylinder, in ascending order. The temperature profiles obtained with the original support are shown in blue, whereas in red the temperature profiles obtained with the modified support are shown.
It can be noticed that the use of the modified support has a positive effect on the thermal behaviour of the sample. On the one side, it is noticed that the temperature gradient of the sample gets noticeably reduced, specifically, the gradient obtained is 16.6ºC lower. Thus, the desired result is achieved. On the other hand, the sample mean temperature obtained is considerably higher with the new support, confirming the enhancement of the ensemble energy efficiency.
A temperature gradient reduction of 52.75% is obtained in the sample with respect to the original value, being the net reduction in absolute value very close to the one obtained in the previous case (16.3ºC).
The temperature profile obtained with the new support gets flatter and flatter each time compared to the original support. In this case a gradient reduction of 60.5% is achieved.
The result obtained with the new support keeps being outstanding. In this case a gradient reduction of 68.42% is achieved.
This is the most interesting case and the one that deserves a closer look. As it is noticed, with the new thinner support the temperature profile reached in the sample is symmetrical horizontally, with practically the same temperature in both ends. If it is compared with the original profile, it is seen that the temperature in the upper end is almost the same in both cases, however, as thermal symmetry is reached in the sample by using the new support, a gradient reduction of 70% is achieved. This is the point where the greatest enhancement is attained.
At this stage the situation drastically changes due to the inversion of the sample temperature profile achieved with the new support. As it can be seen in the image, with the modified support the maximum temperature is reached at the bottom of the sample instead of the top of it. This temperature inversion causes a slight rise in temperature gradient -of 2ºC-, thus, the result achieved with the new support is not desirable. However, although the gradient gets increased, this is a minor increment and it has an easy solution, if needed, since the original support may be used instead.
In this case the temperature profiles obtained are ver similar in shape. Both are inverted but a higher mean temperature (also a bigger temperature gradient) is reached with the new support. As the case above: the desired solution is not achieved but, in case it may be necessary, at high temperatures it can be used the original support instead. Nevertheless, despite the gradient increases with the new support at high temperatures, it is to be noticed that the gradients are yet small compared to the ones obtained at low temperatures. For this reason, although the sample thermal behaviour gets worse with the new support at high temperatures, it is likely that this worsening does not have any negative impact over the most of the experiments carried out.