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The Concept of a Novel Cold Storage Device Utilizing the Magnetocaloric Effect

Katana Katarzyna, Grzebielec Andrzej

Modern Engineering

2023

nr 4

38--49

Cold storage poses many more problems than heat storage. This is due to the fact that the temperature range is smaller than in the case of heat storage facilities. The simplest example is that cold water chillers operate in the temperature range of 12/7 C and the heating system operates in the temperature range of 90/70 C. This means that at the start the volume in sensible heat is almost three times greater. For this reason, cold is rarely stored in the form of sensible heat. Phase change solutions (PCM) or physical reactions (adsorption) or chemical reactions (absorption) are much more frequently used. A completely different idea for improving the operation of cold stores is the use of magnetocaloric materials. These are materials that change temperature under the influence of a magnetic field. The article presents the concept of a cold store that cooperates with a heat exchanger made of magnetocaloric materials (pure Gadolinium). As a result of the preliminary analysis, it was determined that this combination of vapour compressor system and magnetocaloric heat exchanger allows for a reduction in energy consumption for storage purposes at the level of 58,6% in comparison to regular vapour compressor system.

Wettability, reactivity and interfaces in the Gd/TiO2 system

Turalska P., Homa M., Nowak R., Bruzda G., Sobczak N., Kaban I., Mattern N., Eckert J.

Prace Instytutu Odlewnictwa

2017

Vol. 57, no. 4

303--308

High-temperature interaction of liquid Gd in contact with dense, polycrystalline TiO2 substrate, was investigated. Wettability and reactivity tests were carried out at two different temperatures (1362°C and 1412°C) in flowing gas (Ar, 850−900 hPa) using the sessile drop method and classical contact heating of the examined couple of materials. The procedure was combined with a drop pushing procedure. During high temperature studies, images of the Gd/TiO2 couple were continuously recorded by a high-resolution CCD camera. The results of wettability tests of liquid gadolinium on titanium dioxide substrate show that the Gd/TiO2 system is non-wettable at both test temperatures (in either case the final contact angle was 100°). The results of structure examinations on the cross-sectioned samples show the dissolution of the TiO2 substrate in liquid Gd and the presence of two sublayers at the drop/substrate interface: Gd2TiO5 (from the drop side) and Gd2Ti2O7 (from the substrate side).

Zwilżalność i reaktywność ciekłego Gd w kontakcie z ceramiką Al2O3

Turalska P., Sobczak N., Polkowska A., Bruzda G., Kudyba A., Kaban I., Mattern N., Eckert J.

Inżynieria Powierzchni

2017

nr 4

41--48

W niniejszej pracy przeprowadzono badania wysokotemperaturowego oddziaływania ciekłego gadolinu w kontakcie ze zwartym podłożem z tlenku glinu.. Badania zwilżalności i reaktywności wykonano w obojętnym gazie przepływowym (Ar, 850–900 hPa) metodą kropli leżącej z zastosowaniem klasycznej procedury wspólnego nagrzewania badanej pary materiałów w dwóch temperaturach: 1362°C i 1412°C. Podczas testów w badanym układzie Gd/Al2O3 odnotowano cykliczne występowanie zjawiska zwilżalności (kąt zwilżania  < 90°) w obydwu temperaturach, przy czym w temperaturze 1362°C wartości kąta zwilżania zmieniały się w zakresie od 89° do 137° natomiast w temperaturze 1412°C – od 77° do 107°. Badania strukturalne próbki po testach zwilżalności przeprowadzono przy użyciu mikroskopu optycznego i skaningowego mikroskopu elektronowego z emisją polową wspomaganą termicznie. Wykazały one, że ciekły Gd reaguje z podłożem z tlenku glinu, a na granicy rozdziału kropla/podłoże powstaje nowy produkt reakcji – potrójny tlenek GdAlO3.

The paper describes the study on the high temperature interaction of liquid gadolinium in contact with a dense aluminium oxide substrate. Wettability and reactivity tests were performed in inert flow gas (Ar, 850-900 hPa) by the sessile drop method using a classic procedure of contact heating of the tested pair of materials at two temperatures: 1362 °C and 1412 °C. During the tests, in the tested Gd/Al2O3 system the occurrence of the phenomenon of wettability was observed (contact angle < 90°) at both temperatures; at 1362°C the contact angle values varied from 89° to 137° whereas at 1412°C from 77° to 107°. The structural tests of the sample after the wettability tests have been carried out using an optical microscope and a scanning electron microscope equipped with a thermally assisted field emission. They have shown that liquid Gd reacts with Al2O3 substrate and a new reaction product is formed at the interface between the drop/substrate - which was identified as the triple oxide GdAlO3.