Phase Change Material Material Research Articles

Thermal performance of phase change material embedded in building Wall- a numerical analysis

Due to the energy demand the Phase Change Material (PCM) is used in the building envelope to reduce the inner room temperature. The PCM plays an important role in Thermal Energy Storage (TES). So, the PCM is used in the construction for energy conservation. Mostly device, by using a comparatively high storing density, constant phase change temperature and latent heat property. PCM is potentially appropriate as construction material as it is possible to combine into the building covering used for energy management. The main objective of using PCM is to enhancing the thermal performance of building to maintain a human thermal comfort. Ansys Transient thermal is the selected software to simulate the PCM in the building envelope. In this article a detail discusses about the numerical analysis of building thermal features with PCM materials on the wall for climatical situations in Chennai. The n- Octadecane (C18H38), Calcium chloride hexahydrate (CaCl2·6H2O) and Sodium carbonate decahydrate (Na2 CO3·10H2O) PCM are used in this analysis. The numerical test results show that nearly 4 to 5℃ fewer temperatures throughout the diurnal in the PCM filled building model, related by the without PCM packed model. From the simulation result can concluded that the usage of PCM in the building wall will also decrease the energy consumption for cooling that chamber.

Phase change materials influence on temperature variatio buildings

For the design of sustainable buildings, it is crucial with accurate methods to evaluate how alternative constructions will influence thermal comfort, as well as energy efficiency. This study introduces a model to investigate how the use of phase change materials (PCM)in building envelopes can influence the temperature stratification, which also influences the indoor thermal comfort. PCM is characterized by large latent heat in the melting/solidifying process during phase transition. Applications with PCM have been recognized as possible alternatives in building envelopes to improve thermal comfort as well as energy efficiency. The selection of the properties of the PCM, as well as how and where the PCM was installed in the building envelope, are crucial factors to be considered before application in practice. In this study, a simplified experimental set-up including a hot-box was used. The PCM material Climsel28 with different layers thicknesses was installed in the sidewall of a hot-box. Extruded polystyrene (XPS) foam boards were used as wall insulation material in the study. XPS was installed as a reference case and in different layer combinations with the PCM. The sequence of the XPS and PCM was varied. Temperature and heat flux were measured in different positions of the hot-box and on the tested walls. A 3D COMSOL model was developed to study the thermal performance of the system. The model was validated in the study using the collected experimental data. The results indicated that the developed COMSOL model can reasonably predict the performance of the system, both with and without the incorporation of PCM. Additionally, the measured temperature stratification were theoretically validated by the COMSOL model. The study gives indicative guidance of how PCMs can be installed in building constructions elements to reduce temperature peak loads and thus also contributing to an improvement of the indoor thermal comfort.

Phase change materials for thermal energy storage: A perspective on linking phonon physics to performance

Thermal energy storage is being actively investigated for grid, industrial, and building applications for realizing an all-renewable energy world. Phase change materials (PCMs), which are commonly used in thermal energy storage applications, are difficult to design because they require excellent energy density and thermal transport, both of which are difficult to predict from simple physics-based models. In this Perspective, we describe recent advances in the understanding of the equilibrium and transport properties of PCM materials that can help accelerate technology development. We then emphasize how the microscopic phonon picture of both liquids and solids enables a better understanding of novel PCM systems and their predictive power. We then show how this microscopic picture can be used to understand kinetic processes, such as supercooling, and how it can impact the thermal power output in thermal energy storage systems.

Experimental and Simulation of Solar Drying Cabinet with PCM and SiO2 Materials

Solar energy is a potential renewable source in Indonesia, especially for the drying process. The process needs a drying cabinet as a support component to store the drying product. A high-quality drying cabinet to store heat for a long time is needed. This research aims to compare the thermal performance of the drying cabinet without PCM (phase change material) and SiO2 materials or DC I (drying cabinet I) with the drying cabinet that uses PCM and SiO2 materials or DC II (drying cabinet II). The research was carried out by experimental and simulation to investigate thermal performance and fluid flow characteristics. The experiment was carried out inside the laboratory to set uniform initial parameters and the simulation using computational fluid dynamics software. The drying cabinet was modeled in 3D. The experiment result showed DC II had a higher air temperature and lowered relative air humidity for two hours than DC I. The simulation result showed air temperature differences and backflow in the air streamline in the DC II.

Polyester Fibres Enhanced with Phase Change Material (PCM) to Maintain Thermal Stability

Polyester is one of the textile materials that are widely used, with different forms as textile or yarns or fibres. This depends on the properties of the polyester polymer and the final application that is used in it. Staple and crimps polyester fibres (poly-fil®) have also been used for comfort applications in addition to the durability property. The general use of crimps polyester fibres as alternatives of fillings for pillows and mattresses. This research is aiming to enhance the staple and crimpy polyester fibres with Phase Change Material (PCM) to give the ability to change their thermal state in a large range to use it as a filling or compressed sheet for thermal protection of different purposes, regardless of ambient temperatures. So, short and crimps polyester fibres treated in a simple way using Octadecane as (PCM material) loaded on Pectin/Stearic acid and Alginate/Stearic acid to form PCM composite treatment materials. The properties of the fibres were evaluated after treatment with Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), in addition to the Physico-mechanical properties. It can conclude that; the polyester fibres can be covered with PCM composites and the covered one has a preferable result over its uncovered. Also, after the evaluation of blank/uncovered and covered polyester fibres properties, it was these treatments enhanced the mechanical and physical properties of fibres, and they kept and maintain the fibres crimps shape to achieve the air changing. Additionally, acquisition of the required thermal properties to reach the state of thermal stability.

Experimental study of the thermal performance of a PCM in heat sinks

Phase change materials (PCMs) can be great solutions as heat sink for energy storage in microgravity conditions. To guarantee the reliability of the systems, the thermal behavior of the PCMs and their degradation should be understood. Two different configurations of heat sink devices, a cylindrical and a finned hollow parallelepiped based on phase change material (PCM), were investigated. The hydrated salt sodium phosphate dibasic dodecahydrate (Na2HPO4·12H2O) was used as the PCM material, in three different volumes. Were also investigated the effect of copper sponges in the effective thermal conductivity, and the thermal property degradation in the finned heat sink by the sequential heat cycles. The PCM was replaced in each experiment and two power supply heat flux levels were studied. In the second heat sink configuration, consisting of finned heat sink hollow block provided with internal fins, the PCM was not replaced, to observe its property degradation. Power supplied in finned devices varied from 75W to 100W. Experimental results showed a reduction of approximately 50% in the maximum temperature of the heat sink when the copper sponge is inserted. Gaps in hydrated salt decrease the thermal conductance of the heat sink. The PCM thermo-physical properties degradation is negligible for a few numbers of continuous heating cycles. In the case of finned block device, it was observed a variation of 6% in latent heat storage at the first cycles when the same test was realized several times. Contact area loss increased up 15% at the end of the experiments.

Review of Solutions for the Use of Phase Change Materials in Geopolymers.

The paper deals with the possibility of using Phase Change Materials (PCM) in concretes and geopolymer composites. The article presents the most important properties of PCM materials, their types, and their characteristics. A review of the latest research results related to their use in geopolymer materials is presented. The benefits of using PCM in building materials include the improvement of thermal comfort inside the building, and also the fact that the additive in the form of PCM reduces thermal gradients and unifies the temperature inside the concrete mix, which can reduce the risk of cracking. The paper also presents a critical analysis related to the feasibility of mass scale implementations of such composites. It was found that the use of PCM in sustainable construction is necessary and inevitable, and will bring a number of benefits, but it still requires large financial resources and time for more comprehensive research. Despite the fact that PCM materials have been known for many years, it is necessary to refine their form to very stable phases that can be used in general construction as well as to develop them in a cost-effective form. The selection of these materials should also be based on the knowledge of the matrix material.

Experimental investigation of the charging and discharging of latent heat in phase change material (PCM) based aluminium tube heat exchanger

Nowadays, given the increasing importance of energy sources, the possibility of energy storage in the heat exchangers through the Phase Change Materials (PCM) and releasing it when needed has been extremely essential. This study seeks to develop a model as that of the domestic water heating system in which the phase change material is used for storing that heat energy as latent heat and it can be discharged during cooling. The behaviour of a PCM material is studied and the performance is tried to improve by using aluminium as the inner tubes instead of copper. In this experimental study, the thermal characteristics of PCM is studied by passing hot fluid and cold fluid through the tubes. Further the heat-storing capacity and the temperature distribution of wax along the tube was studied at different fluid temperatures. Also, the type of flow created by the fluid for different temperatures and the corresponding behaviour of the PCM during that particular temperature is also studied. A commercial grade Paraffin wax as PCM material with specific heat capacity of 2 kJ/kg-K is used and arrived at effectiveness around 0.48 for 40-50 °C and 0.59 for 50-60 °C. Logarithmic average of the temperature difference between 40°C-50 °C hot cycle is 10.654°C and during the cold cycle it is: 2.495°C, In the same way for 50°C -60 °C, during Hot cycle 11.56°C and for cold cycle 3.77°C. Finally, it is observed that based on the experimental study on the charging and discharging of latent heat storage, due to the low thermal conductivity of Phase change material, the rate of heat transfer during discharging is very low and the time required for discharging of latent heat storage is longer compared to the time required for charging of latent heat storage due to low heat transfer rate between PCM and hot Temperature fluid (Water).

Analysis of Heat Transfer and Natural Convective of a Phase Change Material

A phase-change material (PCM) is a substance with a high latent heat storage capacity which on melting and solidifying at a certain temperature, is capable of storing and releasing large amounts of energy. Various PCM like Paraffin wax, stearic acid are considered which are used to absorb heat from the coolant water from the engine. The conduction and convection criterion of heat transfer enable the PCM to store this heat as latent heat. The amount of convection and temperature change brought about due to the heat flux has been simulated and studied in detail using FLUENT. The thermal energy storage device (TESD) works on the effect of absorption and rejection of heat during the solid-liquid phase change of heat storage material. The overall function of the TESS is dominated by the PCM. The PCM material should be selected considering the application and the working conditions. Depending on the applications, the PCMs should first be selected based on their melting temperature for heat recovery system.

Effects of flow separation and shape factor of nanoparticles in heat transfer fluid for convection thorough phase change material (PCM) installed cylinder for energy technology applications

In this study, flow separation effects on the performance of PCM embedded thermo-fluid system is numerically analyzed by using the finite element method. In the heat transfer fluid, shape effects of nanoparticles are considered. Spherical, blade, brick and cylindrical shaped alumina nanoparticles are used in water. The numerical work is performed for different values of Reynolds number (between 100 and 300), expansion ratio of the channel (0.35 and 1), nanoparticle volume fraction (between 0 and 2%) and different shape of particles. The PCM material is paraffin wax with spherical shaped capsules of 20 mm in diameter. There is significant impact of channel expansion and flow separation zone on the performance of the system. When the area expansion is introduced in the straight channel, the configuration with the highest Reynolds number resulted in performance degradation due to flow recirculation extended in the PCM region. The charging time for a straight channel is reduced by about 84% when comparison is made with the channel having an expansion ratio of 0.35. The shape factor of the alumina nanoparticles significantly affects the flow recirculations and thermal exchange between the PCM and heat transfer fluid. Among various particles, cylindrical shaped one performs best while 23.8% reduction in charging time is obtained at the highest solid volume fraction when comparison is made with pure water as heat transfer fluid.

Structure effect of the envelope coupled with heat reflective coating and phase change material in lowering indoor temperature

The building envelopes that integrate heat reflective coatings (HRCs) and phase change materials (PCMs) can block solar radiation from outdoors and have a high thermal inertia, which helps lower the indoor temperature and save the cooling energy costs. However, an inappropriate combination of the two materials could lead to a worse cooling performance. This paper studies the cooling performance of a wall which is coated with the HRC, coupled with a cavity filling the PCM and insulation materials. This work intends to find out the optimal way of integrating the HRC and PCM together to improve the passive cooling performance of the envelope. The effects of the relative positions of HRC and PCM boards on the indoor temperature are studied by comparing 15 combinations of HRCs and PCMs. The results show that the HRC coated on the exterior surface of the wall can block the radiation heat more efficiently than that on the interior surface. An insulation layer between the HRC and PCM is essential to improve the thermal regulation performance of the wall. The insulation layer avoids the fast heat conduction through the PCM and decouples the roles of the HRC as a radiation reflector and the PCM as a thermal storage medium. The thermal conductivity of PCMs, the thickness of PCM layers as well as insulation air gap are also changed to investigate their influence on temperature fluctuations. The RT31/SiO2 (0.09 W/m K) can effectively reduce the indoor temperature by up to 3.6°C compared with the RT31/expanded graphite (EG) (1.25 W/m K). The optimum thickness of both PCM cavity and air cavity are no more than 8 mm. The work provide an insight into the optimal combination of the PCM and HRC in the building envelope for passive cooling.

Numerical modeling of the thermal performance of soil containing microencapsulated PCM

Phase change material (PCM) can be used with soil as an alternative type of thermal regulation of the subgrade, since it has an ability to accumulate and generate heat during the phase change. This paper evaluates the position of PCM microcapsules in the soil by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. The SEM image processing method includes an integrated approach to transferring a color pixel image into a numerical matrix, followed by noise removal and precise determination of the position and size of microcapsules. Based on these data, a macroscale model of the soil volumetric unit with the inclusion of the microencapsulated phase change material (mPCM) was created, which made it possible to estimate the temperature of the mixture at a changing external temperature, as well as the nature of the effect of mPCM on the soil temperature regime. Through the analysis of many points in the model, the following results were obtained: 1) mPCM not only reduces the peak temperatures of its own volume, but it also softens the peak temperatures of the surrounding soil, 2) with a decrease in the external temperature, there is a tendency to a decrease in the temperature change rate as the model temperature approaches the phase change temperature range, 3) in the second cycle of changing the outside temperature, the effect of mPCM on peak temperatures is greater than in the first cycle due to the cumulative effect of decreasing the temperature change from cycle to cycle. PCM materials release/absorb a large amount of latent heat during hardening/melting, which can be useful in solving problems associated with seasonal freezing and thawing of pavements.

Supercooling in a new two-stage thermoelectric cooler design with phase change material and Thomson effect

A novel physical model of a two-stage thermoelectric cooler (TEC) is developed, based on geometry factor (γ) analysis between stages under pulsed current conditions and with phase change material (PCM), to improve performance. A detailed investigation of a two-stage Peltier cooler based on a general thermodynamic formulation considering the Thomson effect is presented. The minimum cold side temperature, coefficient of performance (COP), and further the thermoelement’s characteristic temperature profiles are discussed. The numerical analysis was carried out considering square pulse current, hot side heat transfer, metal strips, ceramic plates, and a PCM material volume in the heat sink. The investigation results proved that the geometry relation between both stages and the Thomson effect directly impacts supercooling, and a higher reduction in the cold side temperature can be achieved compared with conventional thermoelectric coolers. A reduction of 25.2 K in a two-stage over a single-stage TEC with PCM is achieved considering a large cross-sectional area in the first stage. It has been found that the holding time and the characteristic temperature profiles during and after pulse operation depends strongly on Thomson heat and geometry. A shorter holding time and maximum temperature drop are found for γ>1 values due to the PCM’s melting temperature and the higher pulse current. The characteristic cooling length reveals the part of the semiconductor element that is cooled during pulse operation. Results will guide the design or selection of a heat sink crucial to a solid-state cooling device’s overall performance.

Experimental investigation of novel hybrid phase change materials

The novel potential of hybrid phase change materials (PCM) as a mix of animal fat, specifically pork fat (lard), with edible and waste oil from the food processing industry was investigated in this paper. Lard is a relatively accessible phase change material of organic origin, with a significantly lower unit price when compared to conventional PCM materials (wholesale price of lard can be less than 0.50 €/kg). On an annual basis, a large amount of lard is thrown away because it has become inedible from a nutritional point of view. Experimental results directed that the addition of oils can improve the thermal constants of lard such as thermal conductivity, volumetric heat capacity, with the thermal diffusivity being reduced. The best result was achieved for a hybrid PCM as a combination of pork fat and waste burnt oil as the thermal conductivity was improved by 1.4% and the volumetric heat capacity by 11% with respect to the base PCM, i.e., pork fat (lard). The novel proposed hybrid PCMs are more economically viable, enabling the utilization of waste resources, and securing less environmental impact when compared to conventional PCMs as organic materials. The possible application of lard should be further investigated for specific engineering applications, such as thermal energy storage.

Li4(OH)3Br-Based Shape Stabilized Composites for High-Temperature TES Applications: Selection of the Most Convenient Supporting Material.

Peritectic compound Li4(OH)3Br has been recently proposed as phase change material (PCM) for thermal energy storage (TES) applications at approx. 300 °C Compared to competitor PCM materials (e.g., sodium nitrate), the main assets of this compound are high volumetric latent heat storage capacity (>140 kWh/m3) and very low volume changes (<3%) during peritectic reaction and melting. The objective of the present work was to find proper supporting materials able to shape stabilize Li4(OH)3Br during the formation of the melt and after its complete melting, avoiding any leakage and thus obtaining a composite apparently always in the solid state during the charge and discharge of the TES material. Micro-nanoparticles of MgO, Fe2O3, CuO, SiO2 and Al2O3 have been considered as candidate supporting materials combined with the cold-compression route for shape-stabilized composites preparation. The work carried out allowed for the identification of the most promising composite based on MgO nanoparticles through a deep experimental analysis and characterization, including chemical compatibility tests, anti-leakage performance evaluation, structural and thermodynamic properties analysis and preliminary cycling stability study.

Numerical Simulations of a PV Module with Phase Change Material (PV-PCM) under Variable Weather Conditions

The electrical efficiency of photovoltaic (PV) modules can be improved through the cooling of the PV. Among the passive cooling strategy, one of the most promising concerns the use of phase change materials (PCMs) to decrease the operative temperature of a PV panel. This paper investigates the performances of a conventional PV panel in which two organic PCMs are added (PV-PCM) to reduce the temperature rise of PV cells and consequently to increase the electrical performances. With this aim, unsteady numerical simulations have been carried with Ansys Fluent software using a two-dimensional simplified geometry for the PV modules with the PCM is incorporated (PV-PCM), as well as for the benchmark PV module. The numerical simulations have allowed evaluating the PV cell temperatures, the power production, as well the PCM thermal behavior. As regards this latter aspect the dynamic analysis has evidenced the need to extend the time of simulation at least for two days in such way to take into account of the degree of solidification achieved during the night by the PCM materials. PCM with low melting temperature cannot complete solidifying during the night and so the heat stored during the day will be lesser than the theoretical one. The results of this study pointed out that the PV-PCM units allow achieving higher performances in comparison with a conventional PV module, especially during the hottest months. An increase in the peak power of 10% and of 3.5% of the energy produced all year round is attained.

A novel and effective passive cooling strategy for photovoltaic panel

This paper reports experimental work related to passively cooled free-standing silicon photovoltaic panels (PV) in different cooling configurations with a considered utilization of phase change materials (PCM). The PV panels (20Wp) were examined in typical Mediterranean climate conditions during several months of field monitoring. The focus of the research was to reconsider the usually conventional applied passive cooling approach for PVs in cases when the PV panel is cooled with phase-change materials (PV-PCM cooling systems). The conventional approach usually assumes one solid container filled with a PCM that is fixed into the backside surface of the PV panel to regulate the operating temperature of the PV panel. In the herein considered novel approach, instead of one PCM filled container, several smaller containers filled with PCM materials were used and experimentally tested to determine the performance benefit. The gained experimental results of the two different PV-PCM cooling configurations were compared with a referent PV panel. Based on the experimental results, it was found that the performance of the PV system (overall power yield), for the assumed measurement period, was improved for about 2.5% in the case of the concept with a full PCM container when compared to the referent PV panel. The proposed novel PV-PCM passive cooling approach, with several independent PCM containers, reached a performance improvement of 10.7%, which is considerably higher with respect to the usually applied concept with a full PCM container. The quantity of utilized PCM materials and aluminum, in several container configurations, was 47% (PCM) and 36% (aluminum) less, when compared with the passive cooling configuration with solid a PCM container. The revealed results indicated the potential of the novel proposed PV-PCM passive cooling approach regarding performance improvements and resource utilization, which would affect both economic and environmental aspects.

Cold thermal energy storage by encapsulated phase change materials system using hybrid nanofluids as the heat transfer fluid

The comprehensive study of the cascaded latent heat thermal energy storage (LHTES) systems and usage of phase change materials (PCM) are of great interest in the literature. Experimental and numerical measurements have been performed to analyze the performance of LHTES systems employing different PCMs. Overcharging is a known obstacle in the way of deploying a cascaded energy storage system that reduces the stored energy quality and amount. Furthermore, the complicated character of the phase transition of materials conjures up the importance of an accurate model. In the current study, the effects of overcharging a three-stage cascaded cold LHTES through a concentric dispersion model had been analyzed. Three nanoparticles, Al2O3, CuO, and Fe3O4, in the ethylene glycol and water (EG/W) mixture selected as the heat transfer fluid. Also, three eutectic and hydrated salt solutions were chosen as three PCM materials, encapsulated in spherical high density polyethylene shells, and arranged in three stages, namely, PCM-1, PCM-2, and PCM-3, storing high grade, medium grade, and low grade thermal energy, respectively. To overcome the overcharging issue of the system, two different scenarios were introduced. Results indicate that Al2O3, CuO, and Fe3O4 nanoparticles in the EG/W mixture reach their highest charging efficiency at 74.8%, 69.1%, and 75.1%, respectively. Results also revealed that to reach a shorter overcharging time utilizing Al2O3 and CuO nanoparticles, the optimized ratio of the PCM-2 to PCM-1 and PCM-3 to PCM-1 capacity were both 0.55. The optimized ratio of the PCM-2 to PCM-1 and PCM-3 to PCM-1 capacity utilizing Fe3O4 nanoparticles were 0.68 and 0.61, respectively. To maintain the highest charging thermal efficiency, the optimized ratio of the PCM-2 to PCM-1 and PCM-3 to PCM-1 heat capacity was 0.55 for all the three nanofluids.

Experimental and Numerical Investigation of the Thermal Performance of a Hybrid Battery Thermal Management System for an Electric Van

The temperature and the temperature gradient within the battery pack of an electric vehicle have a strong effect on the life time of the battery cells. In the case of automotive applications, a battery thermal management (BTM) system is required to maintain the temperature of the cells within a prescribed and safe range, and to prevent excessively high thermal gradients within the battery pack. This work documents the assessment of a thermal management system for a battery pack for an electric van, which adopts a combination of active/passive solutions: the battery cells are arranged in a matrix or composite made of expanded graphite and a phase change material (PCM), which can be actively cooled by forced air convection. The thermal dissipation of the cells was predicted based on an equivalent circuit model of the cells (LG Chem MJ1) that was empirically calibrated in a previous study. It resulted that, in order to keep the temperature of the battery pack at or below 40 °C during certain charge/discharge cycles, a purely passive BTM would require a considerable amount of PCM material that would unacceptably increase the battery pack weight. Therefore, the passive solution was combined with an air cooling system that could be activated when necessary. To assess the resulting hybrid BTM concept, CFD simulations were performed and an experimental test setup was built to validate the simulations. In particular, PCM melting and solidification times, the thermal discrepancy among the cells and the melting/solidification temperatures were examined. The melting time experimentally observed was higher than that predicted by the CFD model, but this discrepancy was not observed during the solidification of the PCM. This deviation between the CFD model results and the experimental data during PCM melting can be attributed to the thermal losses occurring through the mock-up casing as the heating elements are in direct contact with the external walls of the casing. Moreover, the temperature range over which the PCM solidifies was 6 °C lower than that estimated in the numerical simulations. This occurs because the simple thermodynamic model cannot predict the metastable state of the liquid phase which occurs before the onset of PCM solidification. The mockup was also used to emulate the heat dissipation of the cells during a highway driving cycle of the eVan and the thermal management solution as designed. Results showed that for this mission of the vehicle and starting from an initial temperature of the cells of 40 °C, the battery pack temperature could be maintained below 40 °C over the entire mission by a cooling air flow at 2.5 m/s and at a temperature of 30 °C.

Peningkatan konduktivitas termal lemak sapi sebagai bahan PCM dengan menambahkan arang sekam padi

Phase change material (PCM) is a material that can absorb and store energy and can release it based on the principle of latent heat energy storage. Beef tallow is one of the materials that can be used as PCM but its low thermal conductivity is around 0.181 W/mK. Hence, thermal conductivity is considered an important factor in the conduction heat transfer. This further affects kinetic absorption and heat release. However it is possible to increase the values by adding another material that has a high thermal conductivity. The purpose of this study is to elevate the thermal conductivity of beef tallow by adding rice husk char. This research involves direct incorporation method, where beef tallow is thawed and mixed with the rice husk char then stirred with a rotation of 100 rpm until the mixture becomes solid. Addition of rice husk char with weight fractions of 5 and 10% and grain size of 0.045 mm. Subsequently, thermal conductivity test was performed using the TQ Heat Transfer Experiment Base Unit.The results show that with the addition of rice husk can increase the thermal conductivity of PCM beef tallow. The increase obtained in the addition of 10% rice husk char is 37 times compared to the pure sample. Based on this result it is concluded that carbon-based materials such as rice husk char can be used to increase the thermal conductivity of PCM materials.