Multiple Phase Change Materials Research Articles

Cascade Latent Heat Storage for Solar Cooking Applications

The present investigation explores the potential of multiple phase change material (PCM) based storage for real-time solar thermal applications. There are two types of storage configurations tested in this work for the simultaneous charging and discharging operation, i.e., single PCM-based NaNO3 storage and 2-stage cascade latent heat storage having NaNO3 and NaNO2 as the storage mediums in the consecutive stages. The storage is designed to achieve the end-use temperature condition of 513 K (the highest temperature required for cooking) with the latent thermal energy accumulation capacity of 1 MJ. The study envisages that instead of using a single PCM in the storage unit, 2-stage cascading of the PCMs can improve energy accumulation and retrieval in storage. After 8 hours of operation, none of the storage achieves the complete charging state. The energy accumulated in the NaNO3/NaNO2 cascade storage is found to be 2.6 times higher than the energy accumulated in the NaNO3 storage. NaNO3/NaNO2 storage achieves the desired constant outlet temperature of cold heat transfer fluid for chapati making (531 K) after 165 minutes of operation. At this moment, the latent energy accumulated in the NaNO3 and NaNO3/NaNO2 storage is observed as 35% and 14%, respectively

Phase transition of multiple encapsulated PCMs in a U-shaped channel under MHD with ternary nanofluid

Purpose Multiple encapsulated phase change materials (PCMs) are used in a wide range of applications, including convective drying, electronic cooling, waste heat recovery and air conditioning. Therefore, it is important to understand the performance of multiple PCMs in channels with flow separation and develop methods to increase their effectiveness. The aim of the study is to analyze the phase transition dynamics of multiple encapsulated PCMs mounted in a U-shaped tube under inclined magnetic field by using ternary nanofluid. Design/methodology/approach The PCMs used in the upper horizontal channel, vertical channel and lower horizontal channel are denoted by M1, M2 and M3. Magnetic field is uniform and inclined while finite element method is used as the solution technique. Triple encapsulated-PCM system study is carried out taking into account different values of Reynolds number (Re, ranges from 300 to 1,000), Hartmann number (Ha ranges from 0 and 60), magnetic field inclination (between 0 and 90) and solid volume fraction of ternary nanofluid (between 0 and 0.03). The dynamic response of the liquid fraction is estimated for each PCM with varying Re, Ha and t using an artificial neural network. Findings It is observed that for PCMs M2 and M3, the influence of Re on the phase transition is more effective. For M2 and M3, entire transition time (t-F) lowers by approximately 47% and 47.5% when Re is increased to its maximum value, whereas it only falls by 10% for M1. The dynamic characteristics of the phase transition are impacted by imposing MGF and varying its strength and inclination. When Ha is raised from Ha = 0 to Ha = 50, the t-F for PCM-M2 (PCM-M3) falls (increases) by around 30% (29%). For PCMs M1, M2 and M3, the phase transition process accelerates by around 20%, 30% and 28% when the solid volume fraction is increased to its maximum value. Originality/value Outcomes of this research is useful for understanding the phase change behavior of multiple PCMs in separated flow and using various methods such as nano-enhanced magnetic field to improve their effectiveness. Research outputs are beneficial for initial design and optimization of using multiple PCMs in diverse energy system technologies, including solar power, waste heat recovery, air conditioning, thermal management and drying.

Numerical analysis of the thermal behavior of a solar heat exchanger using multiple phase change materials

Currently, solar energy is the most abundant and cleanest source of renewable energy, making it a good substitute for increasing energy efficiency. Solar water heaters can significantly reduce the cost of electricity consumption in homes and help reduce greenhouse gas emissions. Most homes use water heaters to produce domestic hot water at a temperature between 50 °C and 60 °C. A latent heat phase change module is created to account for variations in energy supply to solve the inherent intermittency problem. The solar water/PCM heat exchanger, a phase change heat storage system, is designed in this work. A numerical analysis was conducted to examine the impact of various cooling temperatures on the solidification thermal cycle of the phase change material. As this temperature range is suitable for its melting. The phase change material (PCM) can be used to effectively control the temperature. Depending on the PCM and its storage capacity, the temperature of the produced water is controlled. Through the tubes, the water used for heat transfer from the solar collector transfers the heat from the sun’s rays to the PCM. During the discharge phase, the heat that has been stored in the PCMs is then transferred to the water and heats it up. In order to quantitatively evaluate the thermal performance of the water heat exchanger, a numerical simulation using the finite volume method was also analyzed.

Experimental and numerical investigation of a real-scale air to multiple PCM heat exchanger

Energy consumption by residential sectors has proliferated due to urbanization and lifestyle changes. Passive cooling and heating systems can reduce energy consumption and CO2 emissions in residential and commercial sectors. Phase change materials provide an efficient solution for passive energy storage, addressing a building's needs for free cooling and heating. These materials absorb and release heat energy, enhancing the overall efficiency of the energy management system. By employing energy storage devices, it becomes feasible to reduce and shift peak loads to off-peak hours. This study optimized the size and configuration of air-to-multiple PCM heat exchanger through the utilization of a 2D ANSYS (Fluent 19.2) model. This study employs multiple phase change materials (PCMs) with varying melting temperatures as a heat transfer technique to reduce the melting and solidifying times of the PCMs. Furthermore, it was observed that the arrangement of PCMs in series affected melting and solidification times, so two scenarios have been examined. The air-to-multiple PCM system has been investigated through numerical simulations and experimental analyses, focusing on the liquid fractions within the PCM and the outlet air temperatures across the air channels. The total time for entirely melting PCMs RT25HC and RT21HC is less than 4 h, but the solidification time for PCM-RT21HC needs more than 12 h. In both scenarios, PCM-RT21HC melted first, while PCM-RT25HC solidified first.

Energy assessment of a sliding window integrated with PV cell and multiple PCMs

Windows often serve as a thermal weak point between a room's interior and the outside world. As such, we are exploring a new design for a sliding window that integrates both multiple phase change materials (PCMs) and photovoltaic (PV) cells. During the day, the PV cells produce electricity, which can be used in the building during the night. The sliding mechanism introduces several innovative features: use the PV-PCM glass unit (as the external sliding layer) or a standard glass unit (the internal sliding component). The PV-PCM window also can be used as a sliding light shutter or curtain. The PV cell in the proposed design is operated in the closed and open case due to the sliding design. We compared the thermal performance of a single PCM type (either RT-35or RT-27) with a combination of multiple PCMs (RT-35-RT27). Further, we evaluated various thickness combinations of the multi-PCM configuration (RT-35-RT27), including 2.5mm–7.5mm, 5 mm–5 mm, and 7.5 mm–2.5 mm, to identify the best-performing setup. Over the course of a day, the multi-PCM setup (RT-35-RT27) maintains a consistently lower average interior wall temperature than using a single PCM. Among the configurations tested, the 5 mm–5 mm multi-PCM setup (RT-35-RT27) emerged as the most effective, displaying steadier results than the other variations. Compared to a standard single glass pane, the proposed PV-PCM window reduced the highest interior wall temperature by up to 46 % when employing multiple PCMs. As a result, we advocate for the adoption of this innovative sliding window in future building designs.

Melting process enhancement in double pipe storage with multiple latent heat storage materials and oriented fins

Combining more than one passive enhancement method can significantly improve the latent heat storage performance. This paper investigates the effect of multiple PCMs (phase change materials) used in the same storage unit as well as fins and their orientation for improving the performance of LHTES (latent heat thermal energy storage) in a double pipe storage configuration. A 2D mathematical model based on the enthalpy-porosity method is used for simulations along with finite volume techniques. Validation is conducted by comparing the numerical predictions with both numerical and experimental data available in the literature. Liquid fraction, temperature distribution, energy storage, and charging time are analyzed for the melting process considering the fin number, fin orientation, and dual-PCMs positions. Results show that adding two horizontal fins reduces the charging time by 16 %, while using dual PCM with fins reduces the charging time by 25 %. Furthermore, orientation of fins (inclination of 120°) leads to 46.5 % shorter melting time compared to the horizontally finned unit. These results help in designing of efficient and cost-effective thermal energy storage systems.

Investigation of multifactorial effects on the thermal performance of battery pack inserted with multi-layer phase change materials

The safe and efficient power battery thermal management system (BTMS) is a prerequisite for the effectiveness and long service life of electric vehicles. So, a BTMS with inserted multi-layer phase change materials (PCMs) is proposed to enhance the safety and working performance of battery pack. Effects of PCM settings and operating conditions on the thermal performance of battery pack are discussed and analyzed. The results reveal that PCM cooling plays a significant role in the thermal management of battery pack, where the maximum temperature value and temperature difference of BTMS with multi-layer PCM #C are respectively reduced by 13.61 °C and 2.54 °C compared to battery pack without PCM. Besides, the coupling effects of multiple factors, that is, PCM permutation, the thickness and height of PCMs, and ambient temperature, on the heat dissipation of battery pack are discussed via orthogonal results analysis. The optimized multi-layer PCMs are obtained for the BTMS, i.e., Ps = 121, h1 = 5 mm and L = 6 mm, which achieves the lowest values of Tmax = 43.02 °C and ΔT = 3.37 °C at Tamb = 20 °C. It provides insights for optimizing thermal control strategies for the advancement of thermal management in electric vehicles, ultimately enhancing safety, performance, and longevity.

Performance investigation and optimization of latent heat exchanger with pin fins based on non-uniform deployment strategy

Latent heat storage technology is an essential way of efficiently utilizing industrial residual heat, which helps to the objective of carbon neutrality in all countries. In this work, latent heat exchangers with pin fins are numerically investigated based on non-uniform deployment strategy and then optimized according to response surface method. The influences of rotation angle, non-uniform fin pitch, non-uniform fin length and combination of phase change materials with different melting temperatures on thermal storage performance are studied. Results show that the increment of rotation angle facilitates the reduction of complete melting time, and the optimal angle accelerates the melting speed by 10.3% compared to the 0° angle. The arrangements of gradually decreasing fin pitch and gradually increasing fin length along flow direction of heat transfer fluid improve the heat storage performance, which can reduce the complete melting time by 7.3% and 22.2% respectively, compared to the uniform arrangement. The multiple phase change materials latent heat exchanger with high melting temperature phase change material placed in high temperature region and low melting temperature phase change material in low temperature region can make better utilization of heat from heat transfer fluid, which can improve the melting speed by 16.8% compared with the single phase change material latent heat exchanger. The optimized latent heat exchanger based on response surface method reduces the complete melting time by 23.4% compared to the original model. In conclusion, the heat storage performance of latent heat exchanger with pin fins effectively improved by adopting the non-uniform deployment strategy.

Passive cooling of two phase change materials installed in series

Portable transport passive-type refrigeration systems keep products in specific temperature ranges for several days without electricity. Phase change material (PCM) is often combined with insulation panels to form an insulated box.This paper presents the effect of utilizing multiple PCMs with different melting temperatures and heat capacities on product storage and product temperature abuse. Two PCMs with different transition temperatures were thermally coupled, forming a cascade passive refrigeration system. The primary PCM (water) had the largest storage capacity. At the same time, the secondary PCM acted as a thermal buffer to prevent the temperature abuse, namely freezing, of the product carried inside the box.Modifications were made to an existing state-of-the-art refrigerated transport box to install PCM-based passive refrigeration systems that extended the refrigeration performance while maintaining the same envelope and interior volume. Experiments were conducted at ambient temperatures of 20 °C, 35 °C, and 42 °C while the temperature inside the container remained below 6 ℃ for several days. Effective thermal resistance values for the insulated refrigerated transport box and between the PCMs and the product inside the box were determined experimentally. A semiempirical numerical thermal model was developed to predict the duration, and the average error between the predicted duration and the data was 9.7 %. Correlations from the literature were also compared to estimate the transport box performance for various configurations, and the results indicated that such correlations estimated the storage duration satisfactorily only for simple configurations of the insulated box.

Thermal Management and Electrical Efficiency for Concentrator Photovoltaic Systems Using Multiple Phase Change Materials

The performance of solar panels in generating electrical energy is closely tied to the effectiveness of the employed cooling system. While the utilization of phase change materials (PCMs) as latent thermal units as a cooling system has been suggested for recovering solar panels’ heat, research focusing on a comprehensive comparison of various PCMs for this purpose has been lacking. To address this gap, our study aims to provide a thorough comparative analysis of three distinct PCMs: Gallium, Paraffin RT35HC and CaCl2.6H2O. The objective is to determine the most efficient PCM for cooling solar panels. Using Fluent-Ansys-based numerical simulations, our study investigates the transient (unsteady) thermal exchange between PCMs and a solar panel. The research examines various PCM types housed in a container behind the solar panel, while also assessing the impact of inclination angles (0° to 90°) on thermal and electrical efficiency. Our results highlight Gallium's superior cooling performance and sustained high electrical efficiency. Conversely, CaCl2.6H2O leads to decreased electrical efficiency (less cooling performance), while RT35HC shows potential at extreme angles with a slight efficiency decline (∼10.2%). By offering a comprehensive comparative assessment of diverse PCMs and considering the influence of inclination angles, our study contributes valuable insights to optimizing solar panel cooling systems and enhancing overall energy generation efficiency.

Numerical study on thermal resistance of PCMs incorporated in novel roof structures against energy loss

Incorporating Phase Change Materials (PCM) into building enclosures is one of the passive techniques to improve thermal comfort and reduce energy costs. The present study is dedicated to the assessment of various configurations of PCM incorporation in a roof structure in order to evaluate their impact on thermal resistance and consequent reduction in energy losses. Several arrangements of the PCM and brick are tested: small PCM blocks distributed through the structure, multiple long PCM blocks distributed horizontally or vertically, single PCM block occupying either the right half or the left half, and single PCM block occupying the top half or bottom half. The equations governing the flow and thermal transfer in the PCM, as well as heat transfer in the plaster and brick, are defined and derived in the non-dimensional form. The hydro-thermal behavior of the melting PCM is assessed in the different configurations and for two values of Rayleigh number. The results indicate that for low Ra, the highest thermal resistance is obtained when a single PCM block is located at the top of the cavity and separated from the hot source by brick. For high Ra, the maximum resistance is found when the PCM is placed in multiple vertical blocks. Putting the PCM in multiple horizontal blocks or in small blocks does not change the PCM melting when Ra is varied. In all cases, the fastest PCM melting is obtained when the PCM block is close to the hot source and is either in one single block or in multiple vertical blocks.

Adaptive machine learning based control of multi-temperature, multi-module latent thermal storage ensembles

Phase change material thermal energy storage systems can be used to alleviate disparities in renewable energy supply and demand. Performance of such systems can be enhanced using a cascade of multiple phase change materials but efficiency benefits currently rely on precise optimization of design parameters. Therefore, there is motivation to develop storage technologies which provide greater flexibility for applications with dynamic operating conditions. In this study, a novel system is proposed called a multi-temperature, multi-module ensemble which consists of multiple phase change materials combined in series and parallel configurations. The system is optimized and controlled by an artificial neural network trained using a multi-objective optimization scheme. The performance for the novel system is compared to two baseline systems: a single phase change material system and a cascaded system. Across a wide range of fixed operating conditions, the results show that the ensemble reduces the rate of exergy destruction by 60% compared to the single module system and achieves a 10 °C improvement in performance for matching target outlet temperature compared to the cascaded system. Over a dynamically changing load profile, the results show that the multi-temperature, multi-module ensemble with artificial neural network controller is the preferable design as it achieves the excellent exergy efficiency of a cascaded system while maintaining the flexibility needed to respond to dynamically changing operating conditions. Furthermore, this novel approach widens the potential applications of latent thermal energy storage by providing a means to standardize manufacturing to drive down system cost and allowing the system to adapt to unforeseen design parameters.

A novel liquid air energy storage system integrated with a cascaded latent heat cold thermal energy storage

Liquid air energy storage system (LAES) is a promising Carnot battery's configuration that includes thermal energy storage systems to thermally connect the charge and discharge phases. Among them, the high grade cold storage (HGCS) is of paramount importance due to the waste cold recovery of the liquid air regasification process. As of now, most of the literature studies on LAES designed to store the cryogenic energy using sensible heat material and only few works (including one recently carried out by the authors) proposed the implementation of phase change materials (PCMs) as alternative promising solution. This paper goes a step further numerically investigating a novel configuration of the HGCS system utilizing a cascade of multiple PCMs in place of the single PCM HGCS. By enhancing the thermal buffer effect typical of PCM media, the cascaded HGCS augments both the capacity ratio of the charge phase (0.87 vs 0.81) and the utilization factor of the discharge phase (0.87% vs 0.80%). As a result, the novel LAES system based on cascaded PCMs is capable to achieve a liquefaction specific consumption of 0.27 kWhe/kgLA, increasing thus the liquefaction performance of the single PCM HGCS by 6%.

Multi-level Reliability-Based Design Optimization (RBDO) study for electronic cooling: Application of heat sink based on multiple phase change materials enhanced with carbon nanoparticles

Phase change materials represent efficient performances in the thermal management field. However, the low thermal conductivity poses a serious restraint for electronic cooling applications. Recently, the use of multiple phase change materials and the dispersion of nanoparticles are the most recommended techniques to improve the performance of the heat sink. In this study, a developed heat sink filled with multiple phase change materials (PCMs) enhanced with carbon nanoparticles was proposed. First, a parametric study was carried out to determine the optimal pair of phase change materials and nanoparticles. Then, deterministic design optimization and various reliability-based design optimization methods are performed. The optimization and reliability problems are solved by coupling the MATLAB optimization toolbox and the ANSYS Finite Element Model. The optimization-reliability results prove the efficiency of the Robust Hybrid Method in proposing a reliable and optimal heat sink design filled with multiple nano-enhanced phase change materials. The temperature is reduced by 25 % (16,5 °C) and the discharge time is reduced by 8,69 % (14 min) compared to the baseline heat sink.

Comparative experimental analysis of potato slice drying using a multiple phase change material cascaded modified indirect solar dryer and conventional indirect solar dryer

In the present research, multiple phase change materials (M-PCMs) have been utilized to enhance the performance of conventional indirect solar dryer (ISD). The bheem paraffin and paraffin wax having phase change temperatures of 50–55 °C and 60–62 °C were cascaded in rectangular chambers at beneath of absorber plate at the inlet and outlet side up to nearly half the length of the absorber plate of the solar air heater (SAH), known as a modified ISD. The experiments were carried out on conventional and modified ISD simultaneously under the climate of Valsad (20.61° N, 72.91° E), Gujarat, India. An atmospheric air with a velocity of 15 m/s was flown through conventional and modified ISD. In the first batch, 0.5 kg of pre-processed potato slices were placed in the bottom and top trays of conventional and modified ISD whereas in the second batch, 0.3 kg was placed on each tray. A 2 h and 1 h faster drying of potato slices was achieved in the bottom and top trays for the first batch in modified ISD than in conventional ISD. In the second batch, nearly 92.11% and 54.35% drying of potato slices in the bottom and top trays was achieved in modified ISD, which was 269.92% and 227.41% higher than conventional ISD. During 12 h of the drying operation, a total of 1.13 kg of water evaporated from the potato slices in modified ISD compared to 0.87 kg in conventional ISD. Compared to conventional ISD, an enhancement of 22.29% and 7.92% in SAH efficiency without and with considering blower power, an enhancement of 29.69% in overall drying efficiency, and a reduction of 22.87% in specific energy consumption were achieved for modified ISD. The use of M-PCMs in conventional ISD significantly enhances the drying of potato slices during the sunshine as well as off-shine hours and enhances the performance of conventional ISD.

Improving the energy release of a latent heat storage with multiple phase change materials loading and partition shaping

This paper presents a theoretical study of the integration of two selected phase change materials (PCMs) into a vertical shell and tube latent-heat thermal energy storage unit. Various cell shapes and PCM arrangements are analyzed for their heat release characteristics and compared to a reference unit. Using the finite volume method with an enthalpy-porosity formulation, the study simulates conjugate heat transfer between an isothermal wall and PCMs. This approach examines the impact of both the delay of the phase transition and the layout of the PCM cavities on natural convection. The findings indicate that these factors have a significant influence on energy transport. Delaying the solidification process near the cold wall can lead to a substantial reduction in the phase transition time. Furthermore, triangular cross-section cells improve convection and increase the solidification and complete energy discharge times by 42.7% and 25.3%, respectively. The energy charging performance is also enhanced by 39.7%.

Thermal, exergy and economic analysis of a cascaded packed-bed tank with multiple phase change materials for district cooling system

In Singapore's industry, the required temperature of a district cooling system's outlet and return water are 5 °C and 12 °C, respectively. Thus far, few researches have been reported on the cascaded phase change material (PCM) tank focusing on this temperature duration. In this study, a cascaded packed-bed tank for a district cooling system is proposed to improve heat transfer efficiency and decrease tank cost with the same cold energy capacity. The cascaded PCM system, employing PCM-1 and PCM-2 (volume ratio 50%–50% and 30%–70% tetradecane-hexadecane mixtures), is designed, modeled, and validated through experimental data. Key results revealed that the PCM-1 tank performs poorly during its charging phase, while the PCM-2 tank performs poorly in discharging phase. However, the proposed cascaded packed-bed tank that simultaneously PCM-1 and PCM-2 can achieve high average exergy efficiencies during the charging and discharging phases. Additionally, the cascaded system incorporating 0.42 of PCM-1 and 0.18 of PCM-2 demonstrates higher exergy efficiency and tank volume but incurs higher construction costs than other tank designs. Comparatively, the same cold energy capacity tank with 0.18 of PCM-1 and 0.42 of PCM-2 reduces construction cost by 6.8%, with a depreciation of exergy efficiency by 14.1% during the discharging phase.

A novel attempt to enhance the heat transfer rate of thermal energy storage using multitemperature phase change materials through experimental and numerical modelling

This work aims to develop the numerical model for the three-stage phase transition of multi-level phase change materials (PCMs) and present the comparative performance analysis between single PCM and multi-temperature PCM thermal energy storage (TES) systems. The performance of the thermal energy storage system was conducted by the implementation of multiple phase change materials (PCMs) which are arranged following the temperature profile of the heat transfer fluid. The proposed TES system has two models; the first is fully packed with single PCM – Erythritol TES, and the second is packed with multi-temperature PCMs, namely acetanilide in the first half of the tank and 1-Naphthol in the second half of the tank. The experiments are conducted to validate the numerical model values and observed that the results are in close agreement with each other and the percentage variation is within 3–5%. The results show that using multi-temperature PCMs provides better performance than single-PCM systems. Based on the results, the performance of the TES system can be enhanced with multi-level PCMs rather than choosing high-conductivity materials in the system, which lead to considerable potential in saving energy loss and an economical way of designing the efficient TES system.

Multiple Phase Change Materials Integrated Into Power Module for Normal and High Current Reliability Enhancement

In many applications, power modules are subject to varying operating conditions and critical power cycles which cause the chip temperature to fluctuate. This will reduce the power module reliability due to thermal stresses. It can be beneficial to constrain the temperature variation through thermal management. This article proposes to integrate multiple phase change materials into the power module for such a purpose and verifies the concept by simulation of different operation scenarios. Experiment results on a power module containing two kinds of phase change materials show the superiority in reducing chip temperature at normal and high current conditions. The method can effectively reduce the chip temperature fluctuation of power modules with changing power or current level.

Dynamic modelling of a compressed heat energy storage (CHEST) system integrated with a cascaded phase change materials thermal energy storage

Carnot batteries represent an emerging thermo-mechanical energy storage technology based on the conversion of surplus electricity into medium–low temperature heat, and subsequent conversion of the heat into electricity. A promising Carnot battery’s configuration is the Compressed Heat Energy Storage (CHEST) that combines a high-temperature heat pump (charge phase), an Organic Rankine Cycle (discharge phase) and a thermal energy storage (TES) system. As of now, all the literature studies on CHEST were designed to store the thermal energy into a cascaded TES combining a pressurized water storage for the sensible section and latent heat material for the evaporation and condensation sections. The objective of the present work is to numerically investigate a novel configuration of the TES system utilizing a cascade of multiple phase change materials (PCMs) in place of the cascade of sensible heat and phase change materials presented in literature, aiming to enhance both the energy density and the round trip efficiency of the system. The comparative technical analysis has been carried out by developing for the first time a dynamic numerical model of the CHEST system. Indeed, while the current literature studies on CHEST are only focused on preliminary analyses to define the general thermodynamic potential and to identify the limits of the overall system, this paper overcomes this gap and presents a detailed dynamic analysis of the CHEST with focus on TES modelling. Notably, the authors developed a plant model in MATLAB that blends together algebraic and differential sub-models detailing the transient behaviour of the CHEST system. The results are of interest for academia and industry and contribute significantly to the development of a more efficient CHEST system. Indeed, by enhancing the thermal buffer effect typical of PCM media, the cascaded TES augments both the COP of the high-temperature heat pump (4.13 vs 3.79) and the electric efficiency of the ORC (11.69 % vs 11.31 %). As a result, the novel CHEST system based on cascaded PCMs is capable to achieve a round trip efficiency of 47.6 % and an energy density of 6.9 kWhe/m3, simultaneously increasing the respective values of the state-of-the-art solution by 13 % and 100 %, respectively.