Phase Change Material Module Research Articles

Improving the performance of the finned absorber inclined rooftop solar chimney combined with composite PCM and PV module

Solar Chimney (SC) can play a significant role in energy consumption reduction of ventilation applications. The primary purpose of this study is to ameliorate the performance of an inclined rooftop SC integrated with the Phase Change Material (PCM) and Photovoltaic (PV) module, called the SC-PCM-PV system. To this aim, the effects of using finned absorbers and composite PCMs on the performance of the SC-PCM-PV system are investigated for the first time. A 3D-CFD model is developed via the finite volume method to examine the impact of various design parameters, including fin number, fin thickness, PCM type, and PCM mass on natural ventilation duration, ventilation capacity, and power output. The results indicate that increasing the PCM mass decreases the ventilation capacity for the finless cases and does not significantly enhance ventilation duration. However, increasing the PCM mass enhances the ventilation capacity, ventilation duration, and power generation for the finned cases. Ventilation capacity and duration are improved by 7.7% and 17.6% when a finned absorber is used. It is revealed that copper-foam-based composite PCMs extend the ventilation duration of the SC-PCM-PV system. Furthermore, employing Sodium Acetate Trihydrate/Copper Foam (SAT/CF) as the PCM enhances ventilation capacity up to 19.8% compared to an SC combined with a PV module called the SC-PV system. Also, using paraffin/copper foam (Pa/CF) as the PCM provides the highest power output (5.54 kWh) and ventilation duration (22 h and 30 min), approximately 16% and 101 % more than those of the SC-PV system. Conducting a case study for Shanghai city, it is demonstrated that the SAT/CF and Pa/CF are decent candidates to provide natural ventilation for commercial (77.9% of ventilation capacity) and residential buildings (83.1% of ventilation capacity), respectively.

Experimental study on the thermal management performance of phase change material module for the large format prismatic lithium-ion battery

Phase change material (PCM) technology is an interesting method for battery thermal management, while the cooling behavior and cooling efficiency of PCM on prismatic lithium-ion batteries are unclear. In this work, a series of experiments are conducted to systematically investigate the cooling efficiency of PCM and the several detailed factors on the thermal management performance, such as the structure, phase change temperature and thickness of PCM. The results show that the PCM structure (sides of the battery surround by PCM) has an excellent heat dissipation efficiency at high discharge rate of 2C. Decreasing the phase change temperature is beneficial to enhance the cooling performance. Moreover, increasing the thickness of PCM enhances the cool performance, but the heat dissipation efficiency will decrease once the thickness exceeds the value of 25 mm, hence the selection of the PCM thickness is variable based on the heat dissipation capability and cooling efficiency. Furthermore, by investigating the cooling behavior of PCM during the cycle test, it is found that the PCM structure with 25 mm thickness can keep the maximum temperature of the battery under 55 °C in dynamic cycling. This work can provide experimental references for the thermal management system of prismatic batteries.

Mitigation effects on thermal runaway propagation of structure-enhanced phase change material modules with flame retardant additives

Majority existing organic composite phase change materials (CPCMs) are flammable that result in thermal hazards such as fire and explosions in battery modules. Furthermore, the performance of PCM-based battery modules in extreme conditions like thermal runaway has not been studied adequately. In this study, a tubular CPCM-cell structure is designed using physically flame-retardant-modified CPCMs, and a series of experiments on the CPCMs with/without real cells is conducted with calorimeter tests and SEM analysis on morphology structure. First, the calorimeter tests and comparison on the heat release rate (HRR) are conducted on the CPCMs with and without flame retardant additives. Results show that the addition of Al(OH)3 reduced the HRR from 242.5 to 204.4 kW/m2 with 15 wt% additives. Besides, the analysis of the mitigating performances of structure-enhanced tubular module and traditional cuboid module with real batteries is conducted. A factor of safety (FOS) parameter is defined to evaluate the safety degree of thermal runaway domino with energy density. The FOS of blank, CPCM–0C, and CPCM–15C modules are 0, 3.59, and 16.67, respectively, while that of CPCM-15T reaches 21.01, indicating a significant improvement on mitigating effects by structure enhancement compared to adding flame retardant additives. This study brings novelty in the design of PCM-based battery modules, particularly from the thermal safety prospect.

Operation strategy of multiple stage independent phase change material modules integrated with thermal storage

This paper presents a study on a new technique for the packed bed Thermal Energy Storage (TES) system that consists of having multiple stages of Phase Change Materials (PCMs) modules placed independently. The TES model is integrated with the domestic water heating application and consists of a cylindrical storage tank with spherical PCMs inside the tank. Water is used to transfer heat from the hot water to the PCMs during daytime. The system operates according to a well-defined control strategy that ensures an appropriate distribution of the heat transfer fluid toward the various modules. A parametric study is conducted to evaluate the thermal behavior of the PCMs and the storage performance of the system for complete charge and discharge modes. The paper evaluates the multiple stage independent PCM modules advantageous side compared to the conventional TES system and indicates that the usage temperature and useful energy are significantly enhanced through the use of the proposed technique. In addition to that, the charging and discharging processes analysis are conducted in order to examine the thermal behavior of the independent PCM modules with the variation of different operation parameters.

Phase change material based ventilation module - Numerical study and experimental validation of serial design

There is an increasing demand for innovative, efficient, and environmentally friendly cooling technologies as alternatives to the conventional vapor compression-based technologies. In this study, a theoretical and experimental investigation of a Phase Change Material (PCM)-based module for a ventilation system is presented. An in-situ application employing the considered PCM module is investigated. A one-dimensional numerical model is developed to predict the dynamic performance of the PCM-driven ventilation system. In addition, the model is validated with data collected from the experimental application and the PCM hysteresis behavior is calibrated. The developed model predicts the system well, with an average deviation of less than 6% and less than 4% for the PCM and air temperatures, respectively. Parametric analysis is conducted to assess the impact of design and operational parameters on the performance. This includes, volume flow rate, PCM mass and PCM phase change temperature interval. Larger PCM mass is found to decrease efficiency of the PCM module but increase the peak heat transfer. An optimal PCM melting temperature of 20 °C is found to increase the cooling provided per kg of PCM and peak cooling capacity as compared to the reference melting temperature of 22.32 °C by 38.4% and 71.1%, respectively.

Experimental study of a novel strategy to construct the battery thermal management module by using tubular phase change material units

For the thermal management of cylindrical power battery module, the classical cuboid-like phase change material (PCM) module still remains problematic, because the bulky structure remarkably decreases the energy density and secondary heat-dissipation capability of the battery module. Here a novel strategy to construct the PCM module was proposed by substituting the bulky cuboid PCM module with tubular PCM units. Compared to the classical cuboid module, the assembled tubular PCM module confers numerous naturally-formed channels for air flow, an enlarged outer surface area for secondary heat dissipation, and a greatly reduced module weight. As a result, the tubular PCM module demonstrates a superior heat-dissipation performance for cylindrical power batteries. For example, with forced air convection, the temperature and temperature difference can be controlled below 47.2 and 1.0 °C respectively under an extreme working environment, i.e., 10 charge and discharge cycles at a high environment temperature of 40 °C. More importantly, this novel strategy also benefits the flexible assembling and maintenance of the modules, and saves 54% of the PCM amount, thus increasing the energy density of the battery module from 75.5 to 94.4 Wh kg−1.

Experimental Evaluation of a Latent Heat Storage Module with a Heat Spreader for Thermal Management of a Tablet Computer

The objective of this work was to experimentally determine the feasibility of using a phase change material (PCM)-based temperature control module, in conjunction with a heat spreader and thermal interface material, to improve the thermal management of a tablet computer. An experimental apparatus was designed to be representative of a tablet computer. This mock tablet was used to perform a series of transient heating and cooling experiments to compare the impact of the PCM module on the thermal response of the system. The PCM module consisted of n-eicosane encapsulated with heat-sealable laminated film forming a 2 mm thick sheet of encapsulated PCM. A full comparison, including the use of a heat spreader and a thermal interface material (TIM), was conducted at heat generation rates of 4.5 and 7 W. The temperature control module was able to reduce the mean and peak temperatures of the internal components and at a heat generation rate of 7 W it extended its operating time by 30% before it reached a critical threshold temperature.

Thermoeconomic analysis of solar water heaters integrating phase change material modules and mounted in football pitches in Tunisia

The dynamic behavior of solar energy leads to a discontinuity in the electricity generation, which affects the performance of systems. In the present work, an experimental analysis of a closed-loop model of a thermosyphon solar water heater (TSWH) integrated with phase change material (PCM) to heat football pitches in Tunisia is conducted. The PCMs are introduced as horizontal modules encapsulated into the storage tank side surface. The thermodynamic and mathematical models of the system are developed and solved by TRNSYS and EES Software. An economic feasibility study of the proposed system is also introduced. A comparison study is made for the cases of TSWH with and without PCM and for heating systems with and without solar water heaters. It is found that the variation of the water temperature with the PCMs module keeps a difference of about 10°C in comparison to the case without the PCMs module. The energy stored in the PCM modules will play its full role in the operation of the system during the night on all days of the year. Another advantage is that thermal energy is stored in the encapsulated PCM and can be used during the absence of sunshine. The maximum thermal energy efficiency of the system is found to be 26% and 32% in winter and summer operations, respectively. The electrical backup contribution in the system is found to be 54%, and the solar share is 46%. The share of solar energy can be increased for areas with higher climate temperatures and achieve up to 80% savings. The gross payback period of the system is found to be 3.57 years.

Numerical analysis of different fin structures in phase change material module for battery thermal management system and its optimization

A cooling technology like phase change material has been recognised as a promising approach due to its sustainable life span and high latent heat without any need of pumping power like in the air or liquid cooling. It can be made in passive or semi-passive mode, owing to which it is compact, lightweight, efficient and safe. However, it usually suffers from heat accumulation in PCM due to its low heat conduction, for this insertion of fin structure in the PCM module could be an alternative. In this study, the thermal performance of the battery module has been numerically investigated by adopting a phase change cooling technique. Firstly, the performance of the battery module is tested with and without PCM using three different current rates, 1C, 2C and 3C. Then the application fin structure in the PCM module is tested using various fin shapes (likes rectangular, triangular, trapezoidal, I-shape and T-shape) and increasing fin number for heat transfer enhancement. Additionally, convection effects at the outer shell of the PCM module is also been explored. Finally, an optimized PCM module is proposed based on above, and compared with the PCM module. Results demonstrate that optimized PCM module show superior performance over the PCM module. This optimized module not only improves conduction heat transfer in PCM but also convection heat transfer at the outer shell. It is found that battery temperature is reduced by 2.38% and 9.28% at 2C and 3C current rates respectively.

Defrosting Performance Improvement of Air-Source Heat Pump Combined Refrigerant Direct-Condensation Radiant Floor Heating System with Phase Change Material

Traditional defrosting methods applied to solve frosting problems of air-source heat pumps operating in cold periods may reduce heat capacity of the system and decrease indoor thermal comfort. In order to improve the performance of air-source heat pump (ASHP) and maintain indoor temperature in defrosting conditions, an air-source heat pump combined with a refrigerant direct-condensation radiant floor heating system with phase change material is proposed and evaluated in this study. Two radiant floor heating terminals with and without composite phase change material modules were compared through experiments. A composite phase change material based on dodecanoic acid-tetradecanol-hexadecanol mixture and expanded graphite was investigated for this application. Experimental results indicate that both heat fluxes of two comparing terminals are higher than 70 W/m2 in heating condition. At the same time, the floor surface temperature, indoor air temperature, and heating capacity of the terminal with composite phase change material modules are higher than those without composite phase change material modules in defrosting condition. This suggests that the proposed system with composite phase change material modules can improve indoor thermal comfort in defrosting condition as well as satisfy the heating requirement in heating condition.

Durability of phase-change-material module and its relieving effect on battery deterioration during long-term cycles

Phase change material cooling is now a hotspot in the field of battery thermal management. However, for promoting the practical application, the long-term durability of the phase change material module requires further evaluation, and thus, its relieving effect on the performance-deterioration of the battery module can be analyzed to further optimize the cooling structure of the actual battery packs. In this study, we investigate the thermo-electrochemical performance of a battery module with phase change material cooling for 200 cycles. The results show that after coupling with phase change material cooling, the temperature and temperature gradient of the module can be reduced to a large extent, for example, an obvious decrease of the maximum temperature from 51.7 to 47.5 °C at the 200th cycle. Thus, the cycle life can be prolonged by 65.3% compared with that of the module without phase change material. After systematically analyzing the internal resistance, impedance and micro/crystal structure of the electrodes in the cell, the relieving effect of the phase change material cooling on the performance deterioration can be attributed to the alleviation of the cell inconsistency and the cathode destruction during the long-term cycles.

EXPERIMENTAL STUDY ON GRAPHENE/TRANSITION METAL CHALCOGENIDE BASED ENERGY STORAGE AND CONVERSION

The ever-increasing energy demand and the shortage of fossil fuels force the researchers to do research on utilization and conversion of renewable energy sources. In Recent years, the graphene and Transition Metal Chalcogenide (TMC) based Phase Change material (PCM) have been reviewed towards the future energy storage and energy conversion. This PCM is considered as a promising pathway to alleviate the energy crisis. The TMC material is considered as an emerging material due to their optoelectronic behavior and stability of the material. Moreover, the integration of TMC with graphene, significantly improve the performance of the system. The storage of solar energy in the form of sensible and latent heat has become an important aspect of energy management. To improve the performance of domestic solar water heater system, the vertical spiral and cylindrical heat exchanger is designed. The spiral module and cylindrical modules filled with and without PCM are analyzed and the obtained results are compared with each other. The results show that the spiral and cylindrical heat exchanger filled with PCM store and release the thermal energy efficiently and it performs the desired functions than the without PCM module.

A novel thermal management structure using serpentine phase change material coupled with forced air convection for cylindrical battery modules

The temperature control technology based on phase change material (PCM) demonstrates excellent performance in the field of battery thermal management. However, the compact and bulky structure of the traditional composite PCM (CPCM) module reduces the energy density of the battery pack greatly, and is unfavorable to the secondary heat dissipation. In this work, we develop a novel PCM cooling structure by substituting the common block-shaped CPCM (B-CPCM) module with serpentine CPCM (S-CPCM) plates. The S-CPCM plates with high shape stability provide a much larger surface area and many air flow channels in comparison to the B-CPCM module, thus endowing the module with outstanding secondary heat dissipation capability. For example, under the same fan power of forced air convection (5.2 W), the S-CPCM module delivers a much lower maximum temperature than the B-CPCM module (51.9 vs. 54.2 °C) during the repeated charge-discharge process. As highlighted here, on the basis of guaranteeing the cooling performance, the S-CPCM cooling structure also saves ~70% of the CPCM amount, and thereby the energy density of the battery module is increased by 13.8 Wh kg−1.

Cooling performance of a thermal energy storage-based portable box for cold chain applications

Cooling performance of a portable box integrating with phase change material (PCM)-based cold thermal energy storage (TES) modules was studied and reported in this paper. The effects of locations of the PCM modules, melting point of the PCM, and insulation materials on the cooling duration of the box were numerically investigated with an experimentally validated model. Five configurations of PCM modules inside the box were examined: Case 1 - 100 % of the PCM located at the top; Case 2 - 20 % at the top and 20 % on each of side walls; Case 3 - 25 % on each of the side walls; Case 4 - 20 % on each of the side walls and 20 % at the bottom; and Case 5 - 100 % at the bottom. Five different PCMs with melting points at 2 °C, 3 °C, 4 °C, 5 °C and 8 °C were considered. A comparison was made between two different insulation materials (polyurethane, vacuum insulated panels) on the cooling performance. It was found that the configuration of PCM modules, the PCM melting point, and the type of insulation material all affected the cooling durations. The configuration of PCM with 20 % located at the top and 20 % on each of the side walls, with the melting point at 2 °C and the vacuum insulated panel (VIP) gave the longest duration time. The maximum cooling time was up to 46.5 h with the maximum discharging efficiency at 90.7 % and the highest discharging depth at 99.4 %, offering a great potnetial for cold chain applications.

EnergyPlus, IDA ICE and TRNSYS predictive simulation accuracy for building thermal behaviour evaluation by using an experimental campaign in solar test boxes with and without a PCM module

For the design of new buildings or buildings undergoing major renovations, the use of building performance simulation (BPS) tools is a key instrument to sizing the envelope or to select the best solution to be integrated. Nowadays, many BPS tools are available and are used by researchers and designers, each of which was independently validated, by considering different operating conditions, and rarely were directly compared in the same conditions. The objective of this work is to evaluate the prediction accuracy of the most popular BPS tools, namely TRNSYS, EnergyPlus and IDA ICE, by means of a comparison of the simulated results and the experimental measurements detected under real operating conditions. For this issue, two different small-scale solar test boxes (STBs) with one glazed wall exposed to the outdoor environment of Rome were employed for the experimental investigation. The envelope of the reference STB is insulated and made by conventional materials. In the other case, the STB floor is equipped also with a commercial phase change material (PCM) panel. Both STBs were equipped with a data acquisition system to detect the internal air temperature, the glass external and internal surface temperature and, for the PCM-based STB, also the PCM floor internal surface temperature.A wide description and comparison of the mathematical models used by the three BPS tools are provided, followed by a geometric, weather data, technical and heat transfer parameters alignment was developed to put all the tools in the same conditions. Three different experimental campaign periods were considered and used for the evaluation of each BPS tool accuracy.Some common accuracy indices were used for the comparison, such as the R2, RMSE and normalized RMSE, and an overall accuracy index that summarizes the previous ones in the different experimental campaign periods. The results have shown have highlighted the most accurate mathematical models for the prediction of the dynamic thermal behaviour of the STB in the absence and presence of a PCM. In the absence of PCM in the STB, all the three tools are comparable providing high overall accuracy index in all periods with a rank variable as a function of the period owing to the different treatment of the solar radiation modelling. In the presence of PCM in the STB, IDA ICE leads to the highest overall accuracy index in all periods. Unlike to IDA ICE, TRNSYS and EnergyPlus do not take into account the PCM hysteresis phenomenon. Instead, TRNSYS model provides the worst accuracy since it neglects both hysteresis and phase change temperature range, that is instead implemented both in IDA ICE and EnergyPlus. However, TRNSYS predictions can be retained acceptable for a preliminary evaluation since only low data and very low computational cost is required.

Conduction paths of backbones for thermal enhancement of nanocomposite phase change materials

Thermal energy storage (TES) based on phase change materials (PCMs) has become a research hot spot due to its high energy storage density and maintained operating temperature during the phase change. However, as PCM has a poor thermal conductivity that can be as low as 0.2~0.5 W/m·K, the charging/discharging processes of PCM modules are significantly restrained, which severely affects the application of the TES technology in industrial sectors. This study concerns the improvement of the effective thermal conductivity of composite PCM formed by adding nanoparticles with high thermal conductivity into different PCMs. A theoretical model is established to reveal the intrinsic mechanism for the promotion of thermal conductivity of composite PCM consisting of nanoparticles. The results show that aggregation and interfacial thermal resistance are the main reasons for the change of the thermal conductivity. By forming effective conduction paths composed of backbones in the composite PCM, the average thermal conductivity can be improved significantly, which can be as high as 10~50 W/m·K with a wide range of volume fraction of the additives.

Optimization of the internal fin in a phase-change-material module for battery thermal management

As an excellent option that has wide application in the thermal management system to ensure the safety of lithium-ion batteries, phase change material (PCM) cooling technology is highly desirable but the low thermal conductivity of PCMs limits its application. Herein, a series of experiments are conducted with and without fins to investigate the effects of fin configurations. The experimental results show that longitudinal fins are beneficial for dissipating the accumulated heat at the bottom and air convection with the ambient, while circular fins present better heat conduction due to their larger surface area. Regarding the fin number, in a limited-space module, increasing fins does not necessary mean an increase in fin efficiency, while the use of four longitudinal fins displays the highest efficiency for 18650-battery module in the current work, resulting a temperature drop from 36.9 to 34.2 °C in the rectangular finned module. Finally, based on these conclusions, an optimized PCM module combining various fins is designed and tested for its thermal performance, where a greater balance between the heat absorption and heat dissipation is obtained with lower maximum battery temperature and smaller temperature range. The Tmax in the optimized finned module is 29.1 °C at 1 C charging rate, decreasing by 5.5%, in comparison to that of the rectangular-finned module. Such an experimental study can not only provide new references for the experimental data in the practical battery module but also broaden minds on the design for PCM-based finned modules.

Numerical investigations of fin efficacy for phase change material (PCM) based thermal control module

Solid-liquid phase change process has large isothermal heat absorption capacity. Hence, phase change materials (PCM) has potential to achieve thermal control of electronic devices during pulsed heat load generation. Usually, PCM has a disadvantage of low thermal conductivity. Hence, fins are used to improve thermal conductivity of PCM module. Numerical investigations are performed to find the most effective fin configuration which would limit critical temperature (Tcr) of thermal control module (TCM). The important fin parameters under consideration are size, number, shape and % mass of fins. Six different fin geometries are examined: rectangular, triangular, circular-prisms and rectangular, triangular, circular-frustum pyramids. Numerical model is validated with previously reported experimental results in literature. Results show that Tcr decreases as number of fins increased from 9 to 100 and then further reduction in Tcr ceases. For respective % mass of fins, Tcr values for all prism geometries are lower than for all frustum geometries. Considering an extended active period up to 14 min, lowest Tcr values are achieved for 20% mass of fins. It is observed that thermal performance of TCM is highly influenced by area enhancement ratio (Af) which is highest for triangular prism geometry leading to lowest Tcr.

Thermal performance of PCM and branch-structured fins for cylindrical power battery in a high-temperature environment

Battery modules with phase change material (PCM) cooling inevitably suffer from heat-storage saturation and poor secondary-heat dissipation, especially in high-temperature environments or hot regions. To optimize thermal management, this study firstly explores the thermal behaviors of PCMs with different phase change temperatures (PCTs) in a high-temperature environment. The experimental results show that a PCM with a PCT of 46 °C offers the best cooling effect at a high ambient temperature of 40 °C in this study. For example, the maximum temperature of a cell without PCM reaches 53.3 °C, whereas that of the cell with PCMs having PCTs 40, 46, and 55 °C, are 59.2, 51.6, and 57.5 °C, respectively, during the dynamic cycling process. Nevertheless, the application of above PCM is still unsatisfying because the maximum temperature of the battery in the PCM module exhibits obvious increasing trend with cycles in 40 °C environment. On this basis, several novel fins with multiple heat-flow channels (of V, Y and X shapes) are designed and introduced into the PCM module to enhance the secondary heat dissipation capability. These fins with innovative branch structures deliver excellent performance in alleviating the battery temperature than the traditional rectangular fins, which can be attributed to the ability of the branch structures to increase the heat transfer area by adding heat transfer channels. The results of this work show that the X-shape delivers the best performance in a high-temperature environment of 40 °C by maintaining the maximum temperature of the cell below 47 °C.

Integrating Two-Stage Phase Change Material Thermal Storage for Cascaded Waste Heat Recovery of Diesel-Engine-Powered Distributed Generation Systems: A Case Study

Thermal energy storage using the latent heat of phase change materials (PCMs) is a promising technique to solve the time mismatch between the availability and usage of flue gas heat in distributed generation systems (DGSs). A diesel-engine-powered DGS integrated with two-stage tube-type PCM modules for exhaust gas heat recovery was developed and studied. Energy and exergy analysis for the PCM storage unit was carried out to verify the effectiveness of the PCM modules for heat recovery and to highlight the merits of the cascaded configuration through a practical engineering case. Furthermore, the performance of the DGS was evaluated to study the contribution of PCM storage to improving system efficiency. The results showed that 56.4% energy and 48.3% exergy of the input flue gas were stored by the two-stage storage unit. Additional integration of the low-temperature PCM module to the high-temperature module improved the average storage efficiency from 33.6% to 62.3% for energy and 33.1% to 50.8% for exergy. By utilizing the stored energy for heating water, the thermal efficiency of the diesel engine was increased from the original 35.8% to 41.9%, while the exergy efficiency was improved from 29.5% to 29.7%.