PCM-based Energy Storage Systems Research Articles

Statement of Removal

ABSTRACTStrengthening the thermal response of Phase-Change Materials (PCMs) is an essential and active field of research with promising potential for advanced applications such as solar energy storage, building energy conservation, and thermal management in electronic devices. This article evaluates the efficacy of a new arc-shaped fin array in shell-and-tube heat storage systems to enhance the PCM response during the discharge mode. Different fin geometric parameters including the fin curvature angle, the fin spacing, and the nonuniform angle between fins in the top and bottom sections of the PCM domain were considered to identify the best-performing layout. The analysis shows that increasing the curvature of arc-shaped fins between 60° and 180° and increasing the fin spacing between 5 and 15 mm can significantly reduce solidifying time and improve heat recovery rates. Moreover, the arc-shaped fins are more efficient than conventional longitudinal (+-shaped) fins, which are commonly employed in thermal energy storage applications. Arc-shaped fins can also save discharge time by more than half and improve the rate of heat recovery by almost four times than that of + -shaped fins. The present findings suggest that arc-shaped fins represent a promising design for enhancing the heat-recovery aspects in PCM-based energy storage systems.

Thermal performance and behavior analysis of SiO2, Al2O3 and MgO based nano-enhanced phase-changing materials, latent heat thermal energy storage system

• Rayleigh number increases with buoyancy force. • Stefen number gives the relationship between specific heat and latent heat. • Nano inclusions undermine the energy storage capacity of the LHTSS. • During the charging cycle, conduction dominates the heat transfer. • Phase-changing materials are essential in the storage of solar energy or waste heat. The phase-changing material-based thermal energy storage method is one of the most prominent energy storage techniques used to store waste heat and surplus energy. The efficiency of the PCM-based energy storage system can be further modified by doping of nanoparticles. In the present study, the comparative effects of Al 2 O 3 , MgO, and SiO 2 nanodoping on thermal performance and the overall thermal behavior of PCM-based LHTES systems have been examined experimentally and numerically. Furthermore, the impact of Al 2 O 3 , MgO, and SiO 2- based nanoparticles on the charging and discharging rate, time, heat flux, and overall enthalpy is also studied. It is found that due to the inclusion of Al 2 O 3 , MgO, and SiO 2 nanoparticles, the charging rate is significantly increased by 33.8%, 33.8%, and 41% for Al 2 O 3 , MgO, and SiO 2 NEPCMs, respectively, in comparison to the PCM. The discharging rate is also increased by 19.6%, 25%, and 30% for Al 2 O 3 , MgO, and SiO 2 -based NEPCMs, respectively. However, the inclusion of nanomaterials decreases the control volume and enhances the dynamic viscosity, which further curtails the thermal energy storage capacity of the LHTES system. Also, the optimum value of the nano inclusions is determined by experimenting with SiO 2 doped PCM samples. It was observed that for a 0.1–0.3% rise in volume concentration, charging rates show maximum enhancements, which offers a rapid decline for a 0.3–0.5% rise in volume concentration. Therefore, an optimum volume concentration of 0.3% is established. Furthermore, it was also observed that SiO 2 doped PCM samples show a comparatively better thermal response than the other NEPCM samples, making them highly suitable for commercial applications. However, similar studies are further required to identify such potential nano-inclusions.

Optical fiber fabry-perot sensor based on a singlemode-hollow core-singlemode fiber structure for direct detection of phase transition in n-octadecane

An optical fiber Fabry-Perot sensor to monitor the solid-liquid and liquid-solid phase changes in n-octadecane is investigated. The sensor probe is fabricated by splicing a short section of a hollow core fiber between two single-mode fibers. Light from a broadband source launched into the probe experiences multiple reflections as it travels towards the cleaved end of the probe immersed in the material sample and then back to the detector, creating an output interference spectrum with multiple interference dips. The phase change of the material sample in the vicinity of the fiber probe results in changes of various parameters acting upon the probe (such as temperature, strain or bending) which in turn cause changes in the output interference spectrum. By analyzing the changes in the output spectrum of the probe, such as spectral shift of a selected interference dip, the phase change within a material sample in the vicinity of the fiber probe can be accurately detected. This work is useful for providing a better understanding of the phase change mechanism in phase-change materials (PCMs) and for in-situ phase change detection in PCM-based energy storage systems.

PCM-Based Energy Storage System with High Power Output Using Open Porous Aluminum Foams

Thermal comfort (heating, ventilation and air conditioning, HVAC) and the energy consumption involved with it can put a strain on the driving range of fully electric vehicles (FEV), especially in certain times of the year as midsummer or winter. In order to reduce the energy consumption of HVAC, improved thermal management and adapted means of energy storage are needed. One part of the solution can be the use of phase change materials (PCM) for storing waste heat. For the specific application, however, a high loading/unloading power rate is required, which is challenging as the PCMs exhibit low heat conductivities. In the presented work, a storage demonstrator system was investigated which is part of an HVAC system of a specific fully electric vehicle. The profile of requirements of the system (power, stored capacity and allowed volume) make a new design of the storage necessary. Two demonstrator units, in which the PCM was combined with aluminum foam, were manufactured and their power output in dependency on the fluid flow of the coolant system was compared. An adapted squeeze casting process with polymer placeholders was used for the production of the aluminium foam. This process results in foams with a specific pore structure and allows the in-situ integration of the heat transfer fluid (HTF) pipes. Both newly developed PCM storage systems satisfy the HVAC system requirements.

An experimental study on applying PCMs to disaster-relief prefabricated temporary houses for improving internal thermal environment in summer

During disaster relief reconstructions, prefabricated temporary houses (PTHs) have been extensively used for resettling disaster victims. However, due to the nature of disaster relief, PTHs are normally light-weighted, without an electrical thermal environmental control systems installed. Hence, the thermal environments inside these PTHs can become intolerably hot in summer. Therefore, simple and low cost measures should be applied to disaster-relief PTHs for improving their indoor thermal environments. In this paper, an experimental study on applying PCMs to disaster-relief PTHs is reported. Two different designs of applying PCMs were examined. In Design 1, PCMs were fixed to the internal surfaces of a model PTH and the related experimental results demonstrated that both indoor air temperature and internal surface temperature of the model PTH can be reduced at daytime. However, in Design 2, a movable PCM based energy storage system (PESS) was used and the related experimental results suggested the use of the mobile PESS with a total charge of 148.8 kg PCM helped reduce the average indoor air temperature by 3.2–3.6 °C. The experimental results from both Designs suggested that, due to the nature of disaster relief and since outdoor air at a lower temperature may be the only cooling energy source for charging the PCM, a movable PESS system was preferred, so that it can be moved to outdoor at nighttime for being charged with more cooling energy using lower temperature outdoor air not adversely increasing the air temperature inside PTHs.

Performance improvement of D-sorbitol PCM-based energy storage system with different fins

ABSTRACTThis paper is aimed at enhancing the heat exchange rate in the thermal energy storage system with dissimilar fins and encapsulation materials. Experimentation is done with d-sorbitol as phase change material with different encapsulating materials, copper, stainless steel (SS) and brass, in pin fin, annular fin and rectangular fin. The results are analysed for their thermal performance characteristics during both the charging and discharging processes. During charging, copper encapsulation showed a higher heat energy transfer rate around 2340 kJ. During discharging, a loss of 22% in heat extraction is seen in copper encapsulations, 6% and 19% in brass and SS encapsulations, respectively. These results show that the usage of annular fins is a valuable practice to increase the heat stored and recovered, in a latent heat storage system. The most cost-effective encapsulation is SS balls with annular fins as compared with copper and brass encapsulations.

Thermodynamics and performance evaluation of encapsulated PCM-based energy storage systems for heating application in building

This communication presents the comparative study of two different types of thermal management systems for room’s heating applications using calcium chloride hexahydrate as the thermal energy storage material encapsulated in panels and balls. During the daytime, TMS was outside the test room to store the solar heat in TMS. The solar heat made available to charge the PCM from solid to liquid and to warm the test room throughout the observation period during night time. As the room temperature drops significantly during the night time, so as the level of comfort. Both the thermal management systems have been used to heat the test room during night time and the temperature of the test room has been maintained at thermal comfort level without any conventional source of energy, i.e. using passive system. Also the experimental values were compared with those of the theoretical values and are found in good agreement with each other. Thus, it can be concluded that the experimental study carried out for both the thermal management systems have been validated by theoretical approach or vice versa and hence found to be satisfactory towards the successful operation of these systems.

Thermodynamic Analysis of a Diesel Engine Integrated with a PCM Based Energy Storage System

This work describes the energy and exergy analysis of a diesel engine integrated with a PCM based energy storage system, and provides more realistic and meaningful assessment than the conventional energy analysis. Using actual system data, the assessments of energy and exergy saved, and energy and exergy efficiencies are done. The exergy saved in the overall system is quantified and illustrated using an exergy flow diagram. Also, energy and exergy flow diagrams are compared. It is observed through the analysis that 6.13% of the total energy of the fuel is saved using the TES system. From the exergy analysis, it is identified that only 0.47% of the chemical availability of the fuel is saved. The energy efficiency of the integrated system is found to be varying between 3.19% and 34.15%. In contrast, the exergy efficiency, which incorporates the second law of thermodynamics for the integrated system, ranges from 0.25% to 27.41%.