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This study investigates the airflow and thermal management of a compact electric energy storage system by using computational fluid dynamic (CFD) simulation. A porous medium model for predicting the flow resistance performance of the battery modules in a battery cabinet is developed. By studying the influence of rack shapes, the effects of heat exchanger arrangements and other parameters on the airflow and battery thermal distribution are analyzed. When applying a larger bottom air channel, the inlet flow uniformity of each battery cabin in the cabinet increases by 5%. Meanwhile, temperature standard deviation decreases by 0.18 while raising the flow rate from 3 m/s to 8 m/s, indicating better temperature uniformity in the battery cabin. When the charge–discharge ratio reaches 0.5 C, the temperature deviation of the entire cabinet significantly increases, reaching 8 K. Furthermore, a rack-level thermal management scheme is proposed to effectively reduce the thermal deviation of the container electric energy storage system and improve the overall temperature uniformity. Results reveal that the rack-level thermal management of the wavy cabinet in the electric storage container can effectively improve the thermal uniformity of the distributed battery cabin, and the overall thermal deviation is controlled within 1.0 K. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) and concentrated solar power (CSP) are the two main methods for capturing solar energy. Egypt has so far focused its energy investments on solar PV technology. However, considering Egypt's hot, dry weather throughout the year, centralized large-scale PV power generation would not be the best option for Egypt's energy needs. In light of the preceding, this study assesses the most suitable CSP technologies (parabolic trough collector, linear Fresnel reflector, and solar power tower (SPT)) for massively centralized power generation in Egypt. There are six potential sites for the construction of these power stations, all of which are close to cities and dispersed around Egypt. This is a result of the region's natural appropriateness for developing solar power facilities, its configuration, and its proximity to the Egyptian electrical system. The levelized cost of electricity (LCOE) and annual water consumption are two of the proposed power plant's key economic factors, which are examined. Additionally, a sensitivity analysis is used to verify the comparative technical analysis, which is based on electrical output and the capacity utilization factor. The results show that the Benban SPT site has both the highest produced energy and the lowest LCOE, with an annual production of 258,789.8 MWh and 11.71 ¢/kWh. [ABSTRACT FROM AUTHOR]

The 6th International Workshop on Heat/Mass Transfer Advances for Energy Conservation and Pollution Control (IWHT2021) was successfully held online from August 13 to 16, 2021, in Harbin, China. The workshop aimed to provide a global platform for the exchange of cutting-edge technological knowledge and research on heat and mass transfer issues related to energy conservation and pollution management. The event featured plenary lectures, keynote lectures, oral presentations, and posters covering various topics such as nuclear energy, advanced energy systems, heat exchangers, and heat/mass transfer enhancement techniques. Nine research papers from the workshop were selected for inclusion in a special issue of Heat Transfer Engineering. The 7th IWHT conference is scheduled to take place in Tokushima, Japan in 2023. [Extracted from the article]

The key technology for the continuous supply of electricity from solar power plants is a thermal energy storage (TES) approach. The selection of the best storage system and the correct thermal storage material remains a significant challenge in solar power research and development. The thermocline TES system is a cost-effective choice for storing latent and sensible heat by comparing it to the liquid storage substance in a two-tank TES system. The study is performed to assess the thermal characteristics of thermocline tank structure by using a hybrid sensible latent heat storage system. The dispersion-concentric simulation studies were first examined using the MATLAB code, and afterward, the current findings of the research were verified. The major goal of this study is to look into and assess the effect of changing the sensible storage material layer of a hybrid sensible, latent heat storage system on the TES tank's thermal performance. The findings reveal that employing a sensible heat storage material with a high specific heat capacity, such as slag pebble, permits the TES tank to charge for the most extended duration feasible and discharge more stored energy with greater efficiency. The recovered energy of hybrid slag pebble phase change materials (HSPPCMs) configuration is 142.6 MWh, which is more significant than all other configurations examined. The HSPPCMs arrangement demonstrates the maximum capacity ratio and the utilization ratio of 82.39 % and 80.91 %. [ABSTRACT FROM AUTHOR]

One of the most common solutions currently available to meet future energy needs in the world is concentrated solar power (CSP) plants combined with thermocline thermal energy storage (TES) tank subsystems. The air rock thermocline TES tank asserts to be an effective and inexpensive TES subsystem for CSP plants. In this study, a discrete element method (DEM) combined with a numerical model of computational fluid dynamics (CFD) was adopted to investigate the thermal performance of a scale model of an air rock thermocline TES tank. The study is carried out to optimize TES thermocline tank's thermal behavior by changing the heat transfer fluid (HTF) inlet velocity. The DEM–CFD coupled model is validated against analytical and experimental data. The results show that the use of the distributor reduced the influence of the wall effect by distributing the HTF in a regular way as the fluid passes through it, especially at high inlet velocity. Moreover, the results show that each TES tank subsystem has a critical velocity at which the tank operates most efficiently. Furthermore, the results demonstrated that the maximum value of the overall cycle efficiency was equal to 70.15% at 10 m/s, while the minimum value was equal to 42.5% at 2 m/s. The highest capacity and utilization ratio are 81.31 and 72.81% at 16 m/s, while the lowest capacity and utilization ratio are 52.01 and 44.75% at 2 m/s. The pumping energy needed to overwhelm the pressure drop rises when the HTF inlet velocity increases. This study can provide an effective reference for the efficient operation regulation and optimal design of the thermocline tank. [ABSTRACT FROM AUTHOR]

A thermal energy storage (TES) approach is the primary technology for ensuring the continuous supply of electricity from solar power plants. In solar power research and development, selecting the best storage device and the right thermal storage content remains a major challenge. As compared to the liquid storage substance in a two-tank TES system, the thermocline TES system is a more cost-effective alternative for storing sensible heat. Centred on the concept of using a thermocline tank in concentrated solar power plants, the current study utilizes a range of solid storage materials as filling materials, with air acting as the heat transfer fluid. The major contribution of this research is to directly compare the thermo-economic efficiency potential of four storage materials (Quartzite, BOF-slag, Magnetite, and River rock) used in the thermocline storage tank in order to meet some design criteria of a CSP plant without the need for parametric studies. The thermo-economic performance of an air rock thermocline TES tank was investigated using a discrete element system combined with a numerical approach of computational fluid dynamics. The Quartzite presents the highest overall efficiency of 70 %, followed by the River rock with 61 %, and BOF-Slag equals 54 %, while Magnetite is the least in a row with 52 % overall efficacy. Based on thermal-economic performance evaluation, the results showed that the storage capacity of the Quartzite is greater by 37.5 %, 51.2 %, 21.2 % than BOF-Slag, River rock, and Magnetite. [ABSTRACT FROM AUTHOR]

In the present study, the phase change material (PCM) layer thickness of the top and bottom PCMs change gradually with constant the middle PCM layer thickness for the three-layers thermocline thermal energy storage (TES) tank. It has been studied using spherical capsules packed with three types of PCMs with different thermophysical properties. A transient two-phase dispersion-concentric (D-C) model is used to calculate the process of phase change inside pellets to identify the temperature allocation. The method of heat transfer among molten salt and PCMs capsules is extensively discussed, with multiple numerical results shown. The results show that the thickness of the PCM layer has a high impact on the thermal performance of the TES tank. As the layer thickness of the top PCM increases, the time required to discharge the thermocline TES tank increases. The (80 % high phase change material (HPCM) -10 % intermediate phase change material (IPCM) - 10 % low phase change material (LPCM)) configuration has 14.6 %, 27.2 %, and 46.8 % higher overall efficiency than (33.3 % HPCM - 33.3 % IPCM -33.3 % LPCM) configuration, (70 % HPCM - 10 % IPCM - 20 % LPCM) configuration, and (10 % HPCM -10 % IPCM - 80 % LPCM) configuration. In contrast, the (80 % HPCM - 10 % IPCM - 10 % LPCM) configuration shows the highest capacity and utilization ratio. [ABSTRACT FROM AUTHOR]

Solar tower power (STP) plants integrated with thermal energy storage (TES) subsystems are expected to be a potential solution to meet the world's future energy needs. Air rock bed TES subsystem emphasizes to be efficient and cheap storage for STP plants. In the present study, the discrete element method (DEM) coupled with the computational fluid dynamics (CFD) model are adopted to study the fluid flow and heat transfer process of an air rock thermocline TES tank. The study is carried out to investigate the thermal behaviour of the TES thermocline tank by changing the Reynolds number. The results show that the temperature difference between both the heat transfer fluid (HTF) and the spheres for charging cycle decreases with increasing of the Reynolds number, but also the total rate of heat transfer increases. The results illustrated that the difference in temperature between the HTF and the spheres for discharging cycle decreases with increase in the Reynolds number and this difference in temperature is less during the discharging cycle than the charging cycle. In addition, the Re = 1,200 case exhibit the optimized behaviour as it possesses the higher matching in temperature distributions of spheres with the temperature profiles of HTF. The Re = 400 shows reduced charging/discharging performance as the low rate of heat transfer between spheres and HTF. [ABSTRACT FROM AUTHOR]

Solar tower power (STP) plants integrated with thermal energy storage (TES) subsystems are expected to be a potential solution to meet the world's future energy needs. Air rock bed TES subsystem emphasizes to be efficient and cheap storage for STP plants. In the present study, the discrete element method (DEM) coupled with the computational fluid dynamics (CFD) model are adopted to study the fluid flow and heat transfer process of an air rock thermocline TES tank prototype. The study is carried out to investigate the thermal behaviour of the TES thermocline tank by changing the Reynolds number. The results demonstrated that the higher void fraction near the wall results in a lower solid mass to absorb thermal energy and the temperature in the nearwall region is much higher than in core region at low Reynolds number but with increasing the Reynolds number this temperature difference decreasing. The results show that the temperature difference between both the HTF and the spheres for charging cycle decreases with increasing of the Reynolds number, but also the total rate of heat transfer increases. The results illustrated that the difference in temperature between both the spheres and the HTF during the discharging cycle decreases with increase in the Reynolds number and this difference in temperature is less during the discharging cycle than the charging cycle. [ABSTRACT FROM AUTHOR]

The current paper investigates the cycle cut-off criterion on the thermal performance of the three-layers thermocline thermal energy storage (TES) tank system which is used in concentrating solar power (CSP) plants. The one dimensional transient dispersion-concentric (D-C) scheme is applied to calculate the phase change inside each capsule. Using MATLAB software, the numerical model equations have been figured out. Five different scenarios have been created to investigate the cycle cut-off criterion on the thermal performance of the TES tank. The results indicate that there are two important aspects to assess system performance which are the temperature distribution during the charging/discharging cycles and the time required to achieve equilibrium conditions. These aspects directly affect the overall power and external efficiency of the storage system and play a key role in understanding the system start up properties and provide insight into storage availability when designing the power cycle for CSP applications. It was also noted that the cycle times and the time required to achieve periodic conditions are very sensitive not only to the storage temperature difference but also to the cutting temperature difference. The difference in the duration of the charge cycle and the corresponding discharge cycle can be attributed to the consideration of a similar cut-off standard. [ABSTRACT FROM AUTHOR]

For optimum performance of battery modules in electric vehicles (EVs), the temperature of the batteries must be well managed and maintained within a definite range. In this paper, a passive thermal management with phase change material (PCM) is evaluated for prismatic Li-ion battery modules under abusive conditions. The proposed model aims to analyse the thermal performance of battery modules in circumstances the PCM content is reduced due to a leakage and some part of the batteries are exposed to ambient. Two different configurations are considered: one with the top of the batteries exposed to open medium with free air convection, and the other with the top of the batteries exposed to close medium with no air circulation. Comparing the two configurations, the former decreases the maximum temperature in the module by 1.17 K, 1.39 K, 1.63 K and 1.86 K for 2, 4, 6 and 8 mm PCM shrink levels. The effects of aluminum sheet (Al) placed at the top of the battery modules and charge/discharge cycles were also studied. [ABSTRACT FROM AUTHOR]