Latent Heat Energy Storage Material Research Articles

Exploring the potential of fly ash cenosphere—capric acid composite phase change material in concrete incorporating supplementary cementitious material

AbstractIncreasing demand for energy globally, with the building sector being a significant contributor to energy consumption, is a major issue. To address this, efforts are being made to make buildings more energy efficient, including lowering the demand for heating, ventilation, and air conditioning to decrease energy demand. Phase change material (PCM) functions as a latent heat energy storage material that absorbs heat energy while transforming its phase from solid to liquid and then releases the heat energy when it transforms from liquid to solid state. Integrating PCM into building materials can considerably enhance their energy storage density. In this study, the potential of using fly ash cenosphere—capric acid (CeCA) composite PCM in concrete is evaluated. The mechanical, durability and thermal properties of the CeCA blended concrete were investigated. Furthermore, the CeCA‐concrete is enhanced with auxiliary cementitious substance, namely ground granulated blast furnace slag (GGBS). The optimal proportion of CeCA was determined to ensure a balance of compressive strength and thermal conductivity. The results indicated that the compressive strength of the CeCA blended concrete lowered with an increase in the percentage of CeCA. The thermal conductivity of the concrete specimen was lowered by 33.14% at a 25% incorporation of CeCA, resulting in improved thermal performance. The incorporation of GGBS has enhanced the mechanical and durability performance of CeCA‐Concrete. The optimal concrete specimen was found to be 25% CeCA +40% GGBS, which had greater thermal efficiency than the control specimen with similar strength performance. The findings were validated by field emission scanning electron microscopy analysis of the concrete specimen.

Energy, Exergy, and Economic analysis of low thermal conductivity basin solar still integrated with Phase Change Material for energy storage

Latent heat energy storage material has been used by many researchers to achieve an enhancement in the yield of solar still. However, the poor thermal conductivity of Phase Change Materials (PCM) used in solar still led to slower charge/discharge of the energy stored in it. This led to the dissipation of most of the energy stored in the PCM as losses happening in the solar still instead of getting converted into useful work. In this study an attempt was made to improve the yield of the solar still incorporated with PCM by using a low thermal conductivity material to construct the basin of the still, thereby reducing the heat loss occurring along the bottom surface and sidewalls of the still. In the present study, the basin of the conventional solar still (CSS) used for experimentation was made of galvanized iron, which was used as a reference still. The other two stills were incorporated with PCM, whose phase change temperature ranges from 58.03 °C - 64.5 °C. Among the stills incorporated with PCM, the basin of one of the still was constructed using galvanized iron (GIBSS) while the basin of the other still was made using acrylic (ABSS). From the experimentation, it was inferred that the usage of acrylic as basin material helped to reduce the charging span of the PCM but also delayed the discharge time of the PCM, thereby enhancing the yield of the still. The yield of ABSS was 4.36 L/m2/day, which was 10.1% and 19.1% higher than GIBSS and CSS respectively. Meanwhile, the exergy efficiency of ABSS was 3.46% and that of CSS and GIBSS were 3.56% and 2.99% respectively. The cost per liter of water produced by CSS, GIBSS, and ABSS was found to be ₹0.67, ₹1.09, and ₹1.23 respectively.

A novel form stable PCM based bio composite material for solar thermal energy storage applications

• Development of PCM-water hyacinth biochar based form stable thermal energy storage material. • The thermophysical properties and thermal stability of the proposed composite material has been analysed and discussed. • Negligible leakage has been reported at 6:4 ratios (PCM: biochar). • The composite has good thermal conductivity and latent heat of fusion. • The developed material is suitable for solar energy applications. Phase change materials found to be a promising solution in the field of thermal energy storage. However, the low thermal conductivity and form stability over cycles of charging and discharging of PCM are challenges to address. In the proposed study, a novel and low cost biochar-PCM hybrid latent heat energy storage material have been developed and tested. The biochar is prepared from aquatic invasive weed plants by using a batch type pyrolyser. The characteristics and properties of the novel energy storage material have been evaluated using various experimental and analytical methods. The methods include Brunauer, Emmett and Teller (BET), Scanning electron microscope (SEM), X-ray powder diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT–IR) and thermal conductivity tester. The study also put forward the optimized proportion of biochar and PCM in hybrid thermal energy storage material. The new material shows superior thermal conductivity over pure PCM as well as better stability due to the high carbon content and porosity of the developed biochar. Simple Impregnation method has been used to prepare form stable composite material which has good thermal and structural stability. The best mixing ratio (PCM: biochar) is found to be 6:4 (wt/wt%) with minimum leakage of PCM from the composite. The sample prepared through this method yield all the desirable properties as compared to other developed samples. The chemical properties of the composite remain the same as the pure PCM, which confirms no chemical interaction between the PCM and biochar. The heat of fusion is calculated to be 179.4 J/g. The thermal conductivity of the PCM is enhanced up to 13.82 times with the addition of water hyacinth biochar as a supporting matrix. The addition of aluminum metal powder further increases the thermal conductivity by 17.27 times higher than that of PCM alone.

Performance of force circulation cross-matrix absorber solar heater integrated with latent heat energy storage material

The utilization of thermal energy storage in the thermal absorber applications has been increasingly important especially in the application where there is a mismatch between energy demand and energy supply. This technology implies that the heat is stored during charging or discharging process through melting and freezing of the thermal energy storage material so that it can be used in the future. This paper presents the outcome of the experimental investigation on the performance of cross-matrix absorber (CMA) utilizing paraffin as the thermal energy storage material. Experiments were carried out by exposing the CMA under different artificial solar radiation (300 W/m2, 500 W/m2, 700 W/m2 and 900 W/m2) for 30 minutes followed by 30 minutes of discharging process. Based on the observation, it was found that smaller mass flow rate value of 0.005 kg/s gave the highest temperature output regardless of the intensity of solar radiation as compared to the other after 30 minutes of charging process. In terms of heat gain by the thermal absorber, it was concluded that the highest mass flow rate of 0.01 kg/s passing through the absorber lead to the higher heat gain by the CMA, hence prolonged the cooling down / discharging period as shows by the result, where case with maximum mass flow rate (0.01 kg/s) consistently contributed to the higher heat gain by the absorber. This feature is very useful in the solar thermal collector related applications such as crop drying and domestic building heating. The heat gain by the absorber is also contributed by the intensity of the solar radiation.

Corrosive effect of lithium nitrate trihydrate on common heat exchanger materials

Lithium nitrate trihydate (LNH) is a promising latent heat energy storage material with one of the largest specific and volumetric enthalpies of fusion of all near‐room temperature melting phase change materials. However, the understanding of corrosion rates and mechanisms of common metals and polymers in LNH, which is an extremely high salt content solution (wH2O < 0.50), remains relatively limited. Here, we report corrosion rates and mechanisms resulting from 6 months immersion corrosion studies on 9 common polymeric materials and 12 metallic alloys in molten LNH along with likasite, a common nucleation agent. Copper alloys were observed to corrode in liquid LNH, experiencing both uniform surface corrosion and localized pitting corrosion. Aluminum alloys experienced localized corrosion in liquid LNH, which was more severe in cases with likasite present, in which cases Cu dissolved from likasite enhanced corrosion pitting rates. Thus, in the absence of effective corrosion inhibitors, aluminum, and copper are not viable as heat exchanger materials for LNH.

Studies on latent heat energy storage (LHES) materials for solar desalination application-focus on material properties, prioritization, selection and future research potential

In recent years latent heat energy storage (LHES) has received a worldwide focus in the area of solar still applications. Among various techniques available to improve the productivity of solar stills, heat storage is one of the proverbial areas in the present scenario. LHES surpasses sensible heat energy storage (SHES) in solar still applications owing to its properties like latent heat, thermal conductivity, etc. Focus has to be given in the selection of suitable LHES material since its properties are very significant during the performance and operation of solar stills. Though previous reviews on LHES in solar stills focus only on the productivity enhancement, this paper presents an up to date comprehensive review exclusively about LHES in solar stills focusing on its productivity, properties of LHES materials and the mechanisms behind the variation in properties of LHES materials. Further, in addition to this, a detailed analysis is also presented in this paper by employing analytical hierarchy process (AHP) which enable the researchers to prioritize the properties during the selection of LHES in solar still applications. Besides AHP analysis, we also evaluate the relative efficiency of the available LHES materials for solar still application by data envelopment analysis (DEA) to find the frontier LHES materials thereby suggesting the methods to augment the properties of the frontier material (identified through DEA analysis). Thus, this paper may be a reference guide in the near future for the academicians, researchers to get an overview about the various LHES materials used in solar stills and significance of their properties for improving the yield in solar still applications.

Cyclic thermal storage/discharge performances of a hypereutectic Cu-Si alloy under vacuum for solar thermochemical process

A copper-silicon alloy (Cu-Si alloy) was examined and evaluated as a phase-change material (PCM) for thermal energy storage applications such as load shaving and peak load shifting when coupled to a solar thermochemical reactor, reformer, or gasifier for the production of solar fuel. The Cu-Si alloy was selected as a high-temperature PCM thermal storage medium alternative to molten carbonate salts, and the compatibility of this alloy with a graphite-carbon encapsulation material was experimentally examined. The cyclic thermal storage/discharge properties of the Cu-Si alloy as a latent-heat energy storage material were studied with respect to thermal cycles. A thermal stability test was performed on Cu-20 wt% Si, Cu-25 wt% Si, and Cu-30 wt% Si alloys placed in a graphite container under vacuum. The performances of the Cu-Si alloys with increasing and decreasing temperature were measured during the thermal storage (heat-charge) and cooling (heat-discharge) modes, respectively. The elemental distribution of each Cu-Si alloy after the cyclic reaction was evaluated using an electron probe microanalyzer (EPMA). The heat storage capacities before and after the cyclic reaction were evaluated using differential scanning calorimetry (DSC) and were compared to the thermal storage properties of the molten carbonate salt.

Cyclic Properties of Thermal Storage/Discharge for Al-Si Alloy in Vacuum for Solar Thermochemical Fuel Production

Abstract Thermal energy storage using phase-change materials (PCM) can be utilizedfor load shaving or peak load shifting when coupled to a solar thermochemical reactor, reformer, or gasifier for the production of solar fuel. The PCM is embedded in packages or used in bulkin these storage systems, and therefore the compatibility of the encapsulation materials and the selection of the PCM arekey factorsfor ensuring the long operational life of the system. Variouskinds of molten fluoride, chloride and carbonate salts,andmixed moltensalt, which functionat high temperatures of over 500 °C, are known to cause corrosion or thermaldegradation. It is therefore worth studying newhigh-temperature PCM thermal storage alternatives to these molten salts foruse in solar thermochemical processes.In this study, the focus was on aluminum-silicon alloy (Al-Si alloy)as a high-temperature PCM thermal storage medium,and thecompatibility of this alloy with graphite-carbon encapsulation material wasexperimentally examined. The cyclic properties of thermal storage/discharge for Al-Si alloy as a latent-heat energy storage material was studied with respect to various thermal cycles. Athermal stability test was performed for the Al-20wt%Si, Al-25wt%Si, Al-30wt%Si, and Al-35wt%Si alloysplacedin the graphite container in vacuum. The temperatureincreasing and cooling performances of the Al-Si alloy weremeasured duringthe thermal storage (heat-charge) mode and during the cooling (heat-discharge) mode. Theoxidation levelof the Al-Si alloy after the cyclic reaction (20 cycles) was evaluated using an electron probe microanalyzer (EPMA).

Application Of Phase Change Materials (PCM’s) To Preserve The Freshness Of Seafood Products

The application of Phase Change Materials (PCMs) as one of latent heat energy storage materials in smart cold system has been investigated for preserving a freshness of seafood products. In this investigation, PCMs was installed on Expanded Polystyrene (EPS) box system as insulated container. The freshness of the seafood product was shown by the time of keeping temperature during storage or distribution. Keeping temperature time of smart cold system using PCMs was compared to conventional cold system using ice cubes. The result shows that EPS box system using PCMs can prolonged the keeping temperature time and reached colder temperature than the conventional one. Microbiology test of products was monitored to prove that products occured no changes in quality.

Thermal cycle test of binary mixtures of some fatty acids as phase change materials for building applications

This paper deals with the thermal cycle tests of the binary mixtures based on fatty acids, i.e. capric acid (CA), lauric acid (LA), myristic acid (MA), palmitic acid (PA) and stearic acid (SA). Overall, 13 binary mixtures, i.e. CA–LA (40/60wt.%, 50/50wt.%, 60/40wt.%, 70/30wt.% and 80/20wt.%), CA–MA (70/30wt.%, 80/20wt.% and 90/10wt.%), CA–PA (70/30wt.%, 80/20wt.% and 90/10wt.%) and CA–SA (60/40wt.% and 90/10wt.%) were developed as latent heat energy storage materials for the building applications. The Differential Scanning Calorimetry (DSC) technique was applied to the binary mixtures after 0, 50, 100, 150, 200, 250, 300, 600, 900, 1200 melt/freeze cycles to measure the melting temperatures and the latent heats of fusion. The DSC results showed that the changes in melting temperature were in between −1.69°C to 4.33°C, and the changes in the latent heat fusion was −35% to +25%. These results show that the melting temperatures and latent heat values of the PCMs are in the range of about 21–30°C and 100–170J/g which showed that these materials have good thermal stability up to 1200 thermal cycles and can be potentially applied for building applications.

Thermal reliability test of Al–34%Mg–6%Zn alloy as latent heat storage material and corrosion of metal with respect to thermal cycling

Abstract The purpose of this study is to determine the thermal reliability and corrosion of the Al–34%Mg–6%Zn alloy as a latent heat energy storage material with respect to various numbers of thermal cycles. The differential scanning calorimeter (DSC) analysis technique was applied to the alloy after 0, 50, 500 and 1000 melting/solidification cycles in order to measure the melting temperatures and the latent heats of fusion of the alloy. The containment materials were stainless steel (SS304L), carbon steel (steel C20) in the corrosion tests. The DSC results indicated that the change in melting temperature for the alloy was in the range of 3.06–5.3 K, and the latent heat of fusion decreased 10.98% after 1000 thermal cycles. The results show that the investigated Al–34%Mg–6%Zn alloy has a good thermal reliability as a latent heat energy storage material with respect to thermal cycling for thermal energy storage applications in the long term in view of the small changes in the latent heat of fusion and melting temperature. Gravimetric analysis as mass loss (mg/cm2), corrosion rate (mg/day) and a microscopic or metallographic investigation were performed for corrosion tests and showed that SS304L may be considered a more suitable alloy than C20 in long term thermal storage applications.

Thermal Energy Storage System Using a Technical Grade Paraffin Wax as Latent Heat Energy Storage Material

The objective of this study was to experimentally establish thermal energy storage (TES) performance using a technical grade paraffin wax as a phase change material (PCM) in a vertical concentric pipe-in-pipe latent heat storage system. The melting and solidification temperature range of the paraffin was found as 38°C–43°C and 36°C–42°C, respectively. These values were well in agreement with the values measured by differential scanning calorimetry (DSC) analysis. The inlet temperature and mass flow rate of the heat transfer fluid (HTF) were selected as experimental parameters. The radial and axial temperature distributions were determined during the heat charging and discharging processes of the PCM. The temporal temperature data showed that the relevant experimental parameters were more effective on the melting time than on the solidification time due to increased natural convection during the melting process. Furthermore, heat fraction during the charging and discharging processes of the PCM were established. Experimental results indicated that the heat charging fraction was affected by change in the relevant experimental parameters more during the heat charging than discharging processes of the PCM. Finally, it was concluded from the results that the investigated technical grade paraffin wax encapsulated in the annulus of the two vertical cylindrical pipes had good thermal energy storage performance and it is a suitable latent heat storage material for passive solar thermal energy storage applications.

Thermal properties and thermal reliability of eutectic mixtures of some fatty acids as latent heat storage materials

The present study deals with two subjects. The first one is to determine the thermal properties of lauric acid (LA)–stearic acid (SA), myristic acid (MA)–palmitic acid (PA) and palmitic acid (PA)–stearic acid (SA) eutectic mixtures as latent heat storage material. The properties were measured by the differential scanning calorimetry (DSC) analysis technique. The second one is to study the thermal reliability of these materials in view of the change in their melting temperatures and latent heats of fusion with respect to repeated thermal cycles. For this aim, the eutectic mixtures were subjected to 360 repeated melt/freeze cycles, and their thermal properties were measured after 0, 90,180 and 360 thermal cycles by the technique of DSC analysis. The DSC thermal analysis results show that the binary systems of LA–SA in the ratio of 75.5:24.5 wt.%, MA–PA in the ratio of 58:42 wt.% and PA–SA in the ratio of 64.2:35.8 wt.% form eutectic mixtures with melting temperatures of 37.0, 42.60 and 52.30 °C and with latent heats of fusion of 182.7, 169.7 and 181.7 J g −1, respectively. These thermal properties make them possible for heat storage in passive solar heating applications with respect to climate conditions. The accelerated thermal cycle tests indicate that the changes in the melting temperatures and latent heats of fusion of the studied eutectic mixtures are not regular with increasing number of thermal cycles. However, these materials, latent heat energy storage materials, have good thermal reliability in terms of the change in their thermal properties with respect to thermal cycling for about a one year utility period.

Thermal reliability test of some fatty acids as PCMs used for solar thermal latent heat storage applications

The purpose of this study is to determine the thermal reliability of stearic acid, palmitic acid, myristic acid and lauric acid as latent heat energy storage materials with respect to various numbers of thermal cycles. The fatty acids, as phase change materials (PCMs), of industrial grade (purity between 90% and 97%) were subjected to accelerated thermal cycle tests. The differential scanning calorimetry (DSC) analysis technique was applied to the PCMs after 0, 120, 560, 850 and 1200 melt/freeze cycles in order to measure the melting temperatures and the latent heats of fusion of the PCMs. The DSC results indicated that the change in melting temperature for the PCMs was in the range of 0.07–7.87 °C, and the change in latent heat of fusion was −1.0% to −27.7%, except for stearic acid between 560 and 1200 melt/freeze cycles. However, the decrease in the latent heats of fusion for all the PCMs was not regular with increasing thermal cycles. The experimental results also show that the investigated fatty acids as latent heat energy storage materials have a good thermal reliability in view of the latent heat of fusion and melting temperature with respect to thermal cycling for thermal energy storage applications in the long term.

Thermal energy storage system using stearic acid as a phase change material

The thermal performance and phase change stability of stearic acid as a latent heat energy storage material has been studied experimentally. The thermal performance and heat transfer characteristics of the stearic acid were tested and compared with other studies given in the literature. In the present study, parameters such as transition times, temperature range and propagation of the solid–liquid interface as well as the effect of the heat flow rate on the phase change stability of stearic acid as a phase change material (PCM) were studied. The experimental results showed that the melting stability of the PCM is better in the radial direction than in the axial direction. The variation in the melting and solidification parameters of the PCM with the change of inlet water temperature is also studied. We observed that while the heat exchanger tube is in the horizontal position, the PCM has more effective and steady phase change characteristics than in the vertical position. The heat storage capacity of the container (PCM tube) is not as good as we expected in this study and the average heat storage efficiency (or heat exchanger effectiveness) is 50.3%. This indicates that 49.7% of the heat is actually lost somewhere.

Thermal performance of myristic acid as a phase change material for energy storage application

Thermal performance and phase change stability of myristic acid as a latent heat energy storage material has been studied experimentally. In the experimental study, the thermal performance and heat transfer characteristics of the myristic acid were tested and compared with other studies given in the literature. In the present study is included some parameters such as transition times, temperature range, and propagation of the solid–liquid interface as well as heat flow rate effect on the phase change stability of myristic acid as a phase change material (PCM). The experimental results showed that the melting stability of the PCM is better in the radial direction than the axial direction. The variety of the melting and solidification parameters of the PCM with the change of inlet water temperature is also studied. The results show that the better stability of the myristic acid was accomplished at low inlet water temperature compared with the obtained results at high inlet water temperature. We also observed that while the heat exchanger tube is in the horizontal position, the PCM has more effective and steady phase change characteristics than in the vertical position. The heat storage capacity of the container (PCM tube) is not as good as we expected in this study and the average heat storage efficiency (or heat exchanger effectiveness) is 54%. It means that 46% of the heat acrually lost somewhere.

Thermal Energy Storage System Using Some Fatty Acids as Latent Heat Energy Storage Materials

Thermal performance and phase change stability of palmitic and stearic acids as a latent heat energy storage material has been study experimentally. In the experimental study, the thermal performance and heat transfer characteristics of the palmitic and stearic acid was tested and compared with other studies given in the literature. The present study included some parameters such as transition times, temperature range, and propagation of the solid-liquid interface as well as heat flow rate effect on the phase change stability of palmitic and stearic acid as phase change materials (PCMs). The results also show that better stability of the stearic and palmitic acids were accomplished at low inlet water temperature compared with the obtained results at high inlet water temperature. We also observed that while the heat exchanger tube is in the horizontal position, the PCMs have more effective and steady phase change characteristics than in the vertical position. Average heat storage efficiencies were found to be 50.3 and 53.3% for stearic and palmitic acids, respectively.

Heat Energy Release Characteristics of Shape-Stabilized Latent Heat Energy Storage Particles in a Fluidized Bed-Type Heat Storage Vessel.

This paper deals with heat energy release characteristics of shape-stabilized latent heat energy storage particles packed into a fluidized bed-type cylindrical heat energy storage vessel. This type of latent heat energy storage material consists of normal paraffin (pentacosane C25H52, latent heat : 164 kJ/kg, melting point of 327.2K) as a latent heat material, and polyethylene as a shape-stabilizing material. The effects of cold inlet air temperature and flow rate, and the amount of heat energy storage particles on the outlet air temperature from the heat storage vessel and the completion time of the heat energy release process were investigated. As a result, the non-dimensional correlations for the outlet air temperature from the heat storage vessel and the completion time of the heat energy release process were expressed in terms of non-dimensional pumping power, Stefan number and ratio of the packed particle layer height to the diameter of the cylindrical heat storage vessel.