Hello,
I have seen many research papers, in which few researchers report only melting curves of PCM (from DSC) while some report both melting and solidification curves obtained from DSC?
Is it necessary to report solidification curves?
Regards
Ravi
Dear Dr. Ravi Sharma,
I suggest you to have a look at the following, interesting open access papers:
-Thermal behaviour of materials in interrupted phase change
Zoltán Andrássy & Zoltán Szánthó
Journal of Thermal Analysis and Calorimetry Vol. 138, pp. 3915–3924 (2019)
Available at: https://link.springer.com/article/10.1007/s10973-019-08541-w
-Thermal characterization of bio-based phase changing materials in decorative wood-based panels for thermal energy storage
Damien Mathis, Pierre Blanchet, Véronic Landry, PhilippeLagière
Green Energy & Environment, Vol. 4, Issue 1, pp. 56-65 (2019)
Available at: https://www.sciencedirect.com/science/article/pii/S2468025718300189
-Phase Change Material Selection for Thermal Processes Working under Partial Load Operating Conditions in the Temperature Range between 120 and 200°C
Jaume Gasia, Marc Martin, Aran Solé, Camila Barreneche and Luisa F. Cabeza
Appl. Sci., 7, 722 (2017)
Available at: https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=2ahUKEwid2NXi3f7oAhVi16YKHWKFAMoQFjAEegQIBBAB&url=https%3A%2F%2Fwww.mdpi.com%2F2076-3417%2F7%2F7%2F722%2Fpdf&usg=AOvVaw2ZJErWA6X0ND88gECTbPfH
Enjoy reading and best regards, Pierluigi Traverso
Dear all, yes it is needed because of the hysteresis phenomenon, i.e., energy stored upon heating compared to that released upon cooling, to be realy classified as phase change material (PCM). Pleinty of literature is available on this topic. My Regards
Dear Ravi Sharma
The most properties of PCMs that is important for thermal energy storage system are melting point, freezing point, heat of fusion, heat of solidification (crystallization) and cyclic stability. Now, if one excludes the cyclic stability, the other properties can be tested and reported optionally by DSC according to the objective o any study, for example full melting-freezing cycle curve ,only melting curve or solidification curves of PCM, while for cyclic stability test a full melting and solidification curves required to report in order to be sure that PCM is stable under successive heating-freezing cycles.
Best regards
Dear all,
Many thanks for your valuable suggestions.
It helped me a lot.
Regards
Ravi
Yes, it is necessary because the enthalpies of PCMs may vary during melting and solidification. Therefore it is necessary to report both i.e. for energy storage and for energy recovery. e.g. see the following data sheet for paraffin RT 21.
Indeed, melting and solidification with time gives you an explanation of how the PCM (liquid or solid) develops. so you can control it by changing the dependant parameters.
Yes, absolutely.
And actually for two reasons:
1) The PCM can behave different
The PCM can supercool, it can have hindered crystallization (e.g. hysteresis in PE), it can go to a different crystal phase or an amorphous one, it can show phase separation ... and it could even happen that a material does not solidify at all (e.g. because of decomposition)
2) The hysteresis could also be from measurement (at least partly)
Due to temperature gradients in your calorimeter you could have artificial hysteresis in your results; if you just measure on heating once you might not become aware of it. Therefore you should do a heating rate test, including also cooling measurements.
For the last you can check for example my Presentation Calorimetric measurements on PCM
There is also a whole project with literature https://www.researchgate.net/project/Caloric-measurements-on-PCM-collection-of-key-publications-and-discussion
I concur with Harald Mehling : both curves are important. Also, also check in the melting/freezing energy is the same. I many papers they are not. This creates a non-conservation of energy in modelling and subsequent magic performance of the modelled device.
It's useful to obtain and report both melting and crystallization curve for PCMs. The reason is for the same cooling and heating rate, a pure PCM melting and crystallization profile can be different. The results from the article link below is one such instance that demonstrated this.
Article Phase behavior of monosulfones: Use of high polarity sulfony...
I fully agree, both curves are important. In addition: The impact of thermal hysteresis (different melting and solidification curves) on the heat transfer in a PCM can be studied by phenomenological numerical models. Different models have been proposed in literature: e.g. the curve track, curve switch and curve scale model. A comparison can be found here:
Article Phenomenological modelling of phase transitions with hystere...
The advantage of these models is that they are completely defined by the two curves (melting and solidification, which means they are data-driven. The disadvantage is that they are rate-indepedent, they have limitations regarding prediciton of kinetic behavior or delays due to supercooling.
And of course, these models should be used to mimic hysteresis of the material (1st reason mentioned by Harald Mehling above) and not hysteresis from measurment (2nd reason). (Hysteresis phenomena from measurement, stemming from temperature gradients, should be modelled by heat conduction or resistance.)
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