Latent Heat Storage Material Research Articles

Fundamental study on development of latent heat storage material for waste heat recovery of biomass gasification

Recently, latent heat thermal energy storage system (LHTES) has gained attention in order to utilize middle temperature (373~573 K) waste heat from biomass gasification. This paper has investigated thermo- physical properties of erythritol [CH₂OHCHOH CHOHCH₂OH], mannitol [CH₂OH (CHOH)₄CH₂OH] and their compounds as phase change materials (PCMs). The differential scanning calorimetry (DSC) was applied to measure the melting point and latent heat of these PCMs. Also the melting and solidification characteristics of these PCMs were observed in a glass tube with a digital camera. In the DSC measurement, when the amount of mannitol content was more than 40 mass%, the melting point of these compounds show two melting points. The experimental results showed that the velocity of melting and solidification were different for every mixture ratio of compounds. These compounds had the super-cooling phenomenon during the solidification process.

A review of research and development work on solar dryers with heat storage

Drying of agricultural food products is one of the most attractive and cost-effective applications of solar energy. The solar dryer is less reliable due to the intermittent nature of solar energy. This shortcoming can be overcome to some extent by storing solar energy. Information on sensible and latent heat storage materials and systems is spread widely in the literature. In this paper, we try to gather information about the previous and current research works in the field of thermal energy storage technology for solar air heater and dryer. The relative studies are classified on the basis of the type of storage material used in solar dryers, i.e. phase change material (PCM), rock, water, etc. Several designs of solar dryers with different heat storage materials were proposed by researchers. Recent studies focused on PCMs such as Paraffin and salt hydrate, due to their high heat storage capacity per unit volume.

Electrospun heat management polymeric materials of interest in food refrigeration and packaging

ABSTRACTThe use of latent heat storage materials using phase change materials (PCMs) is an effective way of buffering thermal fluctuations and has the advantages of high‐energy storage density and the isothermal nature of the storage process. The aim of this work was to develop slabs with energy storage capacity for their application in refrigerated foods. To this end, polycaprolactone (PCL) and polystyrene (PS) were used as encapsulating matrices of a PCM, specifically RT5 (a paraffin which has a transition temperature at 5°C), by using electrohydrodynamic processing. The effect of storage temperature (4°C and 25°C) and time on the morphology and thermal characteristics of the PCL/RT5 and PS/RT5 slabs was evaluated. Results showed that RT5 can be properly encapsulated inside both polymers, although PCL provided better encapsulation efficiency. Encapsulation efficiency was affected not only by the polymer matrix but also by storage time at 25°C. The greatest encapsulation efficiency (98.6%) and optimum heat management performance was achieved for PCL/PCM slabs stored at 4°C, corresponding to materials composed of ∼44 wt % of PCM (core material) and ∼56 wt % of the PCL shell material. These temperature buffering materials can be of great interest to preserve the quality of packaged foods and to increase efficiency and reduce energy consumption in refrigeration equipment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40661.

Application of Phase Change Materials to Reduce the Risk of Overheating of Building Interior

People in the developed world require comfortable indoor climatic conditions. In the summer time there is often risk of the overheating of buildings, especially buildings with lightweight envelope. Requirements for interior temperature are not summarized in one piece of legislation, but parameters of indoor environment are set according to the type of using of internal space by various laws, regulations, standards and other regulations. Passive cooling can maintain a state of indoor environment in the required temperature range in accordance with legislative framework. Presented system uses phase change materials as a latent heat storage medium for better absorption of heat. The tested system combines the latent heat storage material in the form of micro pellets, which are dispersed in the gypsum plaster, and capillary cooling for their activation so that the secondary effect is possibility of a direct radiant cooling of the room.

Study on the Mechanism of Coagulation and Cooling of Phase-Change Latent Heat Storage Material Sodium Acetate Trihydrate in a Horizontal Rectangular Container

Study on the Mechanism of Coagulation and Cooling of Phase-Change Latent Heat Storage Material Sodium Acetate Trihydrate in a Horizontal Rectangular Container

2種類の潜熱蓄熱物質による混合材料の融解特性

本研究では，工場から出る100℃〜250℃の中間温度域の廃熱を利用するため，潜熱蓄熱システムで利用可能な相変化物質としてエリスリトールとマンニトール，およびこれらの混合物の基礎的融解特性に関する実験を行った．エリスリトールとマンニトールの融点，混合物の融解ピーク温度および潜熱量をDSCで測定し，さらに試験管に入れた試料の融解挙動をデジタルカメラで観察した．その結果1)混合物のマンニトール含有量が10〜40mass%と50〜65mass%，および70〜90mass%の時にそれぞれ1ヶ所，3ヶ所，2ヶ所の融解ピーク温度が現れることを確認した．2)混合物の基礎的融解挙動観察では，凝固融解の繰り返しによって挙動が変化しないこと，固相と液相の密度差が融解挙動に影響を与えることを確認した．

Mechanical Properties and Melting Heat Transfer Characteristics of Shape-Stabilized Paraffin Slurry

This article is presented in the framework of the increasing interest for the use of latent heat transfer slurries for cooling processes. Paraffin serves as a latent heat storage material, and a polymer network acts as the supporting material. The phase change material melts around 7°C with a latent heat of fusion of 115 kJ/kg. Differential scanning calorimetry and indentation analysis were employed to investigate the thermal properties and mechanical stability of the material under freezing–thawing cycles. Results indicated that the form-stable phase change material with the advantages of no liquid leakage constitutes a potential material in the field of low-temperature thermal energy storage. Experimental investigation is made to study the melting process of a single slurry in an agitated bath. Analysis of data permits the development of a phenomenological correlation adapted to the millimetric dimension of the particle, leading to an estimation of the melting phase change time duration as a function of the main parameters of the problem.

Systematic investigation on shape stability of high-efficiency SEBS/paraffin form-stable phase change materials

In this work, form-stable phase change materials (FSPCMs) comprising paraffin as latent heat storage material and styrene-b-(ethylene-co-butylene)-b-styrene triblock copolymer (SEBS) as supporting material were prepared, and their shape stability was studied systematically by rheological analysis for a deep understanding of shape stability mechanism. The mass percentage of paraffin can reach 90wt% without any obvious leakage of paraffin above its melting point, suggesting excellent energy storage capacity. The results of rheological measurement reveal that the shape stability of these composites derives from the formation of SEBS–paraffin reversible physical gel, which can prevent the free flowage of melted paraffin, while the failure to keep their apparent shapes stable at a further higher temperature may be ascribed to hard gel–soft gel and gel–fluid transitions. In addition, thermal properties and thermal stability of the composites were also investigated. This study proposed a universal method to detect the variation of materials with temperature and deeply understand the physical mechanism of shape stability, which not only accelerates the pace for practical application of existing FSPCMs, but also provides foundational insight for the design of new FSPCMs. Considering the proposed analysis method is applicable for most FSPCMs, this work may build up bridges for both comprehensive academic research and industrial application of FSPCMs.

Difunctional olefin block copolymer/paraffin form-stable phase change materials with simultaneous shape memory property

In this work, a novel sort of form-stable phase change materials (FSPCMs) which possesses simultaneously the shape memory function was designed and prepared. The FSPCMs consist of paraffin with melting point of approximately 53°C as a latent heat storage material and olefin block copolymer (OBC) as a supporting material. With mass percentage of paraffin up to 40wt%, the FSPCMs exhibit good shape stability until temperature approaches 90°C as shown by visual photographs, and this result is confirmed by dynamic mechanical analysis. At the same time, composites with 40wt% paraffin also maintain the excellent mechanical property of OBC and exhibit large elongation at break as well as similar tensile stress, insuring excellent tenacity and deformation ability. The results of shape memory testing demonstrate that the composites possess good shape memory property, with nearly complete shape fixing and recovery. Compared with other reported FSPCMs, this material can be both temperature-controlled and temperature-sensitive, and may show advantages in some advanced applications such as intelligent textile. The diversity of paraffin endows the composites with flexibility of design for applications with wide range of temperatures. Considering the inexpensive sources and easy processing, this work may open up opportunities to produce difunctional FSPCMs in the industrial field.

Thermal conductivity enhancement of form-stable phase-change composites by milling of expanded graphite, micro-capsules and polyethylene

Structured form-stable phase change composites were prepared by wet milling and hot-compaction of microencapsulated phase change material (MPCM), expanded graphite (EG) and high density polyethylene (HDPE). In the composites, MPCM serves as a latent heat storage material, EG as a heat transfer promoting agent and HDPE as a matrix. Scanning electron microscope (SEM) characterization reveals that MPCM particles kept undamaged with a uniform dispersion in the composites. Thermal conductivity of the composites with 20 wt% EG loaded could be enhanced by 22 times compared to HDPE/MPCM composites without EG. And thermal conductivity of the composite could be increased by 10 times at a loading of 10 wt% EG.

Preparation and Properties of Polyacrylonitrile Fiber/Binary of Fatty Acids Composites as Phase Change Materials

A new kind of form-stable polyacrylonitrile fiber/binary of fatty acids composites as phase change materials was prepared by a solution blending process. In this material, the binary system between stearic acid and lauric acid with different components was served as latent heat storage material and polyacrylonitrile as the supporting material, N,N-dimethylformamide as solvent. Phase change temperature and latent heat and the thermal stability of the polyacrylonitrile/binary of fatty acids composites were characterized using differential scanning calorimetry. The structure, crystalline morphology, surface morphology, and thermal insulation properties of the polyacrylonitrile/binary of fatty acids composites were investigated using Fourier transformation infrared spectroscope, polarizing optical microscopy, scanning electron microscope, and temperature-recording instrument. The Fourier transformation infrared results showed that polyacrylonitrile and binary of fatty acids were combined by intermolecular forces. The differential scanning calorimetry results indicated that polyacrylonitrile/binary of fatty acids composites had high latent heat storage capacity of more than 135.8 J/g, the phase transition temperature was about 25°C. The photograph of polarizing optical microscopy and scanning electron microscope suggested that stearic acid and lauric acid were homogeneous distribution in the polyacrylonitrile matrix; Cooling curve of polyacrylonitrile/binary of fatty acids composites showed that its soaking time was continued for about 17.7 minutes, and the thermal insulation properties remain unchanged after more than once cycling. The best process condition was obtained by the soaking time and orthogonal experiment.

Phase Change Characteristics of a Nanoemulsion as a Latent Heat Storage Material

The primary objective of this study was to investigate the fundamental phase change characteristics of a nanoemulsion using differential scanning calorimetry (DSC). Tetradecane, which has a slightly higher melting point than water, was utilized as the phase change material for the nanoemulsion. The melting point of the nanoemulsion, the melting peak temperature, and latent heat were examined in detail. Regarding the fundamental phase change characteristics of the nanoemulsion, it was found that its phase change characteristics were strongly affected by the temperature-scanning rate of the DSC. Moreover, it was confirmed that the phase change behavior does not change with repeated solidification and melting.

Experimental study on latent heat storage characteristics of W/O emulsion -Supercooling rate of dispersed water drops by direct contact heat exchange-

Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand-concentration on day-time of summer by the air conditioning. The flowable latent heat storage material, Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enable to transport the latent heat in a pipe. The flowable latent heat storage material can realize the pipe size reduction and system efficiency improvement. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase brings the obstruction of latent heat storage. The latent heat storage rates of dispersed water drops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The water drops in emulsion has the diameter within 3 ~ 25μm, the averaged water drop diameter is 7.3μm and the standard deviation is 2.9μm. The direct contact heat exchange method is chosen as the phase change rate evaluation of water drops in W/O emulsion. The supercooled temperature and the cooling rate are set as parameters of this study. The evaluation is performed by comparison between the results of this study and the past research. The obtained experimental result is shown that the 35K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It was clarified that the supercooling rate of dispersed water particles in emulsion shows the larger value than that of the bulk water.

Experimental Study on Latent Heat Storage Characteristics of W/O Emulsion by Ultrasonic Wave Impression

The flowable latent heat storage material like Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enabled to transport the latent heat in a pipe. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase is obstructed by a latent heat storage. The latent heat storage rates of dispersed waterdrops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The waterdrops in emulsion have the diameter within 3 - 25 μm, the averaged diameter of waterdrops is 7.3 μm and the standard deviation is 2.9 μm. Supercooling release of waterdrops in emulsion is examined by short time impressing of the ultrasonic. The direct contact heat exchange method is chosen as the phase change rate evaluation of waterdrops in W/O emulsion. The supercooled temperature is set as parameters of this study. The previous obtained experimental result, as the condition without impressing ultrasonic wave, showed that the 35 K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It is clarified that it is possible to reduce 20 K of supercooling degree by impressing the ultrasonic.

G061042 直接接触潜熱蓄熱槽におけるエリスリトールの凝固・融解挙動([G061-04]熱工学部門,一般セッション(4) : 固液相変化)

The purpose of this study is to develop the latent heat storage system using erythritol as a latent heat storage material. In this study, the direct contact melting and solidification behaviors of erythritol were visualized in order to investigate the characteristics of direct contact heat storage and release between oil and erythritol. In this direct contact method, if the packed height of erythritol increases, erythritol may be flowed out from a vessel with oil. So to control the packed erythritol height, the effect of a perforated aluminum lattice in the vessel was investigated. The experimental results show that the increase of erythritol bubbles was inhibited by the perforated aluminum lattice. And it is found that the amount of heat release is influenced by the form of perforated aluminum lattices.

Direct Contact Latent Heat Storage System Using Erythritol as a Latent Heat Storage Material

Direct Contact Latent Heat Storage System Using Erythritol as a Latent Heat Storage Material

D143 潜熱蓄熱材と熱媒体オイルの直接接触凝固挙動(OS-11:凝固・融解を伴う伝熱現象とその応用(3))

The present study is investigated the direct contact solidification behavior between latent heat storage material and heat transfer oil. Purpose of this study is development of a latent heat storage system which is suggested using waste heat of temperature region (100〜200℃) as heat source from factories. Mixture of mannitol and erythritol was adopted as phase change material (PCM). To examine detailed heat exchange behavior, test section was constituted glass tube and the number of nozzle hole for injecting heat transfer oil is one. By this study, the following matters became clear. Size of injected oil droplets rise with the increasing flow of oil. Flow path is different depending on the height direction.

Thermal Conductivity and Specific Heat of Phase Change Latent Heat Storage Material Sodium Acetate Trihydrate and Heat Transfer of Natural Convection in a Horizontal Enclosed Rectangular Container

Thermal Conductivity and Specific Heat of Phase Change Latent Heat Storage Material Sodium Acetate Trihydrate and Heat Transfer of Natural Convection in a Horizontal Enclosed Rectangular Container

Development of a Wall Collector Unit and Phase Change Material (PCM), Air Heat Exchanger for Heating Application in Greenhouses

Greenhouse heating is essential in the northern region of China during winter season in order to maximize crop production in terms of quality and quantity and thus increase their overall efficiency. But the use of heating systems faces the problem of high running cost and noxious gases emission for heating systems based on fossil fuel and there is also a risk of frost cropping for electrical heating systems due to electrical power failure during heavy weather conditions. In this paper the performance of flat plate collector and a PCM serpentine heat exchange is investigated. An eutectic mixture CH3COONa·3H2O-HCONH3 was used as a latent heat storage material, this material possess a melting temperature of 40.5°C, relatively higher compared to commonly used phase change materials for heating applications. The energy capacity of the PCM during charge and discharge phase has been determined based upon the measurement results made in the heating process during February 2012, one of the coldest winter months in Beijing, China. It was observed that the average net energy efficiencies was 45%, therefore the PCM in study, was founded to be suitable for solar thermal storage applications.

Experimental Investigation of PCM-LWA Composite for Building Wallboard

In this paper, a experimental investigation of application of room wallboard containing Phase-Change-Material / Lightweight-Aggregate composite (PCM-LWA) was carried out. A PCM-LWA composite thermal energy storage material was prepared by absorbing the paraffin. In such a composite, the paraffin serves as a latent heat storage material and the porous lightweight aggregate acts as the supporting material. Mixture of cement paste and epoxy were used to seal the PCM-LWA surface. Through comparing temperature curves of a general room model and the model using wallboards containing PCM-LWA, it can be known that the highest temperature of the room model using the wallboards containing PCM can be controlled in a narrow range. Therefore, room model assembled with the walls containing phase change material can effectively reduce the highest indoor temperature and the range of reduced temperature is about 2~4°C.