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The Use of Phase Change Materials to Improve the External Walls' Thermal Parameters of Heated Buildings

Kaczmarek Anna, Nakielska Magdalena

Civil and Environmental Engineering Reports

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2023

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Vol. 33, no. 4

63--72

EN

Currently, it is estimated that the construction sector consumes over 40% of the energy produced and about 50% of the mass of processed materials. As a consequence, there is a challenge to look for alternative material solutions allowing for the storage and conversion of energy. Phase change materials give us such opportunities. Their introduction leads to additional benefits related to thermal parameters. The work presents a short overview of PCMs along with the possibility of their application. Then, as part of the research, the selected phase change material was applied to the internal plaster layer of an external wall to check its activity. The obtained results were compared to the values of reference samples (without PCM). The proposed solution leads to the improvement of the analyzed partitions' thermal parameters.

2

Multi-objective optimization of PCM-fin structure for staggered Li-ion battery packs

Qiu Chenghui, Wu Chongtian, Yuan Xiaolu, Wu Linxu, Yang Jiaming, Shi Hong

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 4

art. no. e145677

EN

Endurance capability is a key indicator to evaluate the performance of electric vehicles. Improving the energy density of battery packs in a limited space while ensuring the safety of the vehicle is one of the currently used technological solutions. Accordingly, a small space and high energy density battery arrangement scheme is proposed in this paper. The comprehensive performance of two battery packs based on the same volume and different space arrangements is compared. Further, based on the same thermal management system (PCM-fin system), the thermal performance of staggered battery packs with high energy density is numerically simulated with different fin structures, and the optimal fin structure parameters for staggered battery packs at a 3C discharge rate are determined using the entropy weight-TOPSIS method. The result reveals that increasing the contact thickness between the fin and the battery (X) can reduce the maximum temperature, but weaken temperature homogeneity. Moreover, the change of fin width (A) has no significant effect on the heat dissipation performance of the battery pack. Entropy weight-TOPSIS method objectively assigns weights to both maximum temperature (Tmax) and temperature difference (DT) and determines the optimal solution for the cooling system fin parameters. It is found that when X = 0:67 mm, A = 0:6 mm, the staggered battery pack holds the best comprehensive performance.

3

Water-paraffin dispersion systems: manufacturing and application

Yovchenko Alla, Bespalko Sergii, Tryhub Oksana, Poliakov Sviatoslav, Baret Guy, Munoz Miranda Alberto

Acta Innovations

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2020

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no. 36

31--47

EN

The paper presents the study results of the stability and heat storage capacity of paraffin-in-water phase change suspensions (PCSs) obtained by the homogenization of paraffin and water in the developed rotary hydrodynamic homogenizer. The optimal concentration of components for obtaining stable paraffin-in-water suspensions is found. It is shown that the stable PCSs in the form of pastes, gels, and liquids can be obtained depending on the concentration of water, paraffin, and the surface active agent (SAA) as well as its type. In addition, the scheme of the solar heating system with the heat storage tank where the PCS functions both as the heat transfer fluid and the heat storage media is presented. It is shown that the use of PCS in the domestic solar heating system allowed the heat storage capacity of the storage tank to be increased by 25% as a result of the high fusion heat of paraffin and the high value of the water specific heat capacity. The estimation of the saving rate from applying fluid PCS as a heat storage medium is also presented and discussed.

4

Application of Nanoparticles in the Process of Phase Change Paraffin in a Chamber

Alizadeh As’ad

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 3

113--119

EN

In this study, melting of a phase changing material enriched with nanoparticles in a circular ring-rectangular enclosure was investigated and the results were analyzed. At the beginning of the melting process in the absence of a natural displacement, the mechanism of conduction heat transfer around the hot cylinder is the dominant mechanism. Over time, natural displacement gradually appears and deforms the melting boundary above the cylinder. Over time, when the thickness of the liquid phase grows, the thermal resistance increases, this can be verified by reviewing the Nusselt chart. So this phenomenon reduces the rate of melting and temperature changes. The results show that increasing the nanoparticle volume fraction due to increased conductivity and decreasing latent heat causes an increase in the melting rate and the amount of energy absorbed. From the study of various volume fractions, it can be concluded that the use of a higher volume fraction of 3% is more appropriate both in terms of energy and in terms of the melting rate. However, it should be taken into account that if the melting rate exceeds this value, it may cause agglomeration and deposition of nanoparticles and reducing system efficiency.

5

Experimental Study of the Thermoregulating Properties of Nonwovens Treated with Microencapsulated PCM

Bendkowska W., Wrzosek H.

Fibres & Textiles in Eastern Europe

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2009

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Vol. 17, no. 5 (76)

87--91

EN

This paper reports a study on the thermoregulation properties of PCM nonwovens. Microencapsulated n-alkanes (n-octadecane and n-eicosane) dispersed in a polymer binder (acrylic-butadiene copolymer) were applied to needled and hydroentangled nonwovens by the pad-mangle or screen printing method. The surface morphology and cross section of PCM nonwovens were observed by means of scanning electron microscopy (SEM). The thermal storage/release properties of the nonwoven samples treated with microPCMs were analysed by DSC, and the thermal resistance of the nonwovens under steady state conditions was determined by means of a sweating guarded hotplate instrument. The transient thermal performance of the nonwoven samples containing microPCMs was examined using novel apparatus with a dynamic heat source. The temperature regulating factor (TRF), defined by Hittle, was determined for selected cycle times of heat flux changes (t), the results of which are shown in diagrams presenting the relation TRF = f(t). The results obtained show that the main factor determining the TRF value is the amount of latent heat in a unit area of nonwoven fabric. Thermoregulating properties of the printed nonwoven sample with microPCMs are identified as being dependent on the position of the microPCMs layer. This work shows the possibility of achieving a significant thermoregulation effect even with moderate amounts of microPCMs incorporated at a proper location in the nonwoven system.

PL

Mikrokapsułki PCM (oktadekan i eikosan), zdyspergowane w środku wiążącym (kopolimer butadienowo-akrylowy), były aplikowane na włókniny igłowane techniką napawania i techniką druku sitowego. Następnie, posługując się stanowiskiem pomiarowym umożliwiającym badanie właściwości termicznych tekstyliów w warunkach dynamicznych, wyznaczano współczynnik termoregulacji termicznej (TRF) przygotowanych próbek włóknin. Współczynnik TRF, zdefiniowany przez Hittle’a był wyznaczany dla dla 6 wybranych okresów (t) zmian strumienia ciepła. Wyniki tych pomiarów przedstawiono w postaci krzywych obrazujących zależność TRF = f(t). Stwierdzono, że zasadniczym czynnikiem determinującym wartość współczynnika TRF jest ilość utajonego ciepła przemiany fazowej, zakumulowana przez jednostkę powierzchni materiału tekstylnego. W przypadku włóknin drukowanych, wartość TRF w znacznym stopniu zależy od położenia warstwy PCM względem źródła ciepła. Umieszczenie warstwy PCM w bezpośrednim sąsiedztwie źródła ciepła powoduje pogorszenie właściwości termoregulacyjnych układu. Uzyskane rezultaty wskazują na możliwość uzyskania znacznego efektu termoregulacyjnego, nawet przy umiarkowanych ilościach mikrokapsułek umieszczonych w odpowiednim położeniu w strukturze włóknistej.