Black tea places topmost position consumption wise. Drying is one of the important steps involved in the black tea production to stop oxidation and to reduce moisture content. A numerical model for drying black tea in a single tray dryer considering the combined influence of operating conditions is presently absent in the drying community. Therefore, a FEM based 2-dimensional heat and mass transfer drying model with convective boundary interactions is developed to determine optimum drying conditions for drying of black tea. Drying at air temperature of 120 degrees C and airflow velocities of 0.9 m/s and 1.5 m/s, and drying at air temperature of 130 degrees C and airflow velocities of 0.3 m/s, 0.9 m/s, and 1.5 m/s show satisfactory drying for a tea bed thickness of 10 mm. Increasing temperature from 120 degrees C to 130 degrees C reduces drying time by 27.77% and 28.70%, respectively for airflow velocities of 0.9 m/s and 1.5 m/s. Also, the drying time is reduced by 9.57%, 6.53%, and 5.70% at 130 degrees C for 0.3 m/s, 0.9 m/s and 1.5 m/s of flow velocities on reducing the thickness from 20 mm to 10 mm, respectively. Results show that temperature is the most significant parameter because it affects more than other operating parameters. However, changes in airflow velocity and bed thickness at higher temperatures also impact significantly. The present drying results provide quantitative insights that may assist in designing and operating of a single tray tea dryer/slow speed conveyor tea dryer/single tray indirect solar tea dryer in forced mode of operation.

Liquid jets are essential in many heat removal applications due to their capacity to remove heat at a high rate per unit contact area. This paper mainly focusing on the graphene based nano fluid jet cooling strategy for cooling of internal combustion piston and cylinder walls. This study also examined the cooling of hot plates with flat and uneven surfaces. Experiments were conducted in which a fully developed turbulent liquid jet cooling upon a heated surface under a constant heat flux condition. Various metal specimen like Inconel, stainless steel (SS) and copper (Cu) with flat surfaces has been examined. The liquid jet was issued through a 40 cm long straight nozzle with diameters of 4 mm, 6 mm, or 8 mm. To ensure fully developed flow at the outlet, the length-to-diameter ratio of the nozzle was maintained above 50. The nanofluid was selected based on an extensive review of the literature, which indicates that it is one of the most suitable heat transfer fluids compared to water, owing to its superior dimensional stability, dispersion stability, safety, availability, and cost-effectiveness. Graphene nanofluids with concentrations of 0.1

Energy-efficient heating, ventilation, and air conditioning (HVAC) solutions are necessary to mitigate the growing energy demand from the building sector globally. To improve HVAC energy efficiency and thermal comfort, the present study employed an experimental approach to determine the efficacy of the developed novel thermal energy storage-integrated fan coil unit system (TES-FCUs) for space heating applications in cold regions. Different performance indicators, including heating capacity, time constant, room temperature fluctuations, heat retention time, and thermal comfort index, have been evaluated to analyze the system's performance under 18 different operating conditions and achieve energy savings while enhancing thermal comfort. The heat-driven system resulted in a variable heating capacity of 1.77 kW to 4.53 kW with varying flow rates (3 to 7 L/minute), FCU speeds (750 to 1000 m3/hr), and air circulation fan effects. The findings show that adding air circulation fans improves temperature uniformity, increases the standard effective temperature by 6.7 %, and results in a neutral thermal sensation, with a predicted mean vote (PMV) and percentage of dissatisfied (PPD) values of -0.11 and 5 %, respectively. A higher water flow rate and FCU speed improves heat exchange efficiency, resulting in lower time constant values. The thermal stability and repeatability of the phase change materialbased shell and tube type TES system are evident from the steady mean temperature ranges of 90-98 degrees C during charging cycles and 57-63 degrees C during discharging cycles, respectively. The study demonstrated the feasibility of the novel TES-FCUs as a sustainable heating solution for cold regions.

The intermittent availability of solar energy necessitates efficient energy storage systems to ensure a continuous and reliable energy supply. Among the available technologies, latent heat thermal energy storage (LHTES) systems are particularly promising due to their high energy storage density and operational feasibility for various thermal applications. In this context, the present study experimentally investigates the real-time heat transfer behaviour and thermal performance of a shell-and-multi-tube LHTES system designed for medium-temperature solar-assisted cooking applications involving boiling. The LHTES unit employs solar salt as the phase change material, with a mean melting point of 231.09 °C. A custom-built experimental setup was developed to evaluate the transient thermal behaviour of medium-temperature LHTES systems under realistic and dynamically varying operating conditions. The system's performance is analysed during standalone charging and discharging, simultaneous charging and discharging, and prolonged idle operation, based on temperature distribution, phase transition characteristics, transient thermal response, and thermal losses. The results showed that the LHTES unit achieved a storage efficiency of 46% during charging and up to 79% during discharging, while simultaneous charging-discharging operation exhibited stable thermal behaviour with an efficiency of 56%. Furthermore, 4.66 kWh of thermal energy was retained after 36 h during idle operation, demonstrating the capability of the system to provide delayed thermal energy supply. Overall, the findings provide improved insight into the transient thermal characteristics of LHES systems and highlight their potential for applications requiring continuous and reliable medium-temperature thermal energy delivery.

The hour ahead forecasting of global horizontal irradiance (GHI) is essential for integrating the electrical energy produced from solar photovoltaic (SPV) plants into electrical grids. Solar energy is highly intermittent and diurnal in nature. The electrical energy produced from the SPV plants cannot be directly integrated into the electrical grid since it causes grid instability. In order to alleviate this issue, GHI forecasting is critical. In this study, advanced deep learning techniques such as Long Short-Term Memory (LSTM), Convolutional Neural Networks (CNN), Gated Recurrent Unit (GRU), Bidirectional Long Short-Term Memory (BiLSTM), U-net, Extreme Gradient Boosting (XG Boost), Gaussian Processing Regression (GPR), hybrid models, and an ensemble model are used to forecast the hour ahead Global Horizontal Irradiance. The weather parameters for this study are obtained from Solcast®. The models used were hyper-tuned to determine the optimal configuration of the architecture. Root mean square error (RMSE), mean absolute error (MAE), coefficient of determination (R2), and forecast skill (FSRMSE) are used to assess the model’s performance. A smart persistence model is used as a baseline model for comparison. The proposed ensemble model yields the FSRMSE 27.80

A developing country like India has an ambitious target of expanding their solar energy systems in the future for generating power and process heat applications. Hence, it is integral for a developing country such as India to have a robust technique to predict the shortwave radiation in the future to effectively manage the demand and supply. Weather Research Forecasting - Solar (WRF-Solar) is employed in this study to predict the Global Horizontal Irradiance (GHI) for 14 days ahead and results are validated with the Solcast (R) data. Four shortwave parameterization schemes such as Dudhia, Goddard Fluid Dynamics Laboratory (GFDL), New Goddard, and Rapid Radiative Transfer Model in General Circulation Model (RRTMG) have been tested for various climatic regions in India such as warm & humid, hot & dry and composite to find out the optimal configuration that improves the accuracy of GHI prediction. It has also been performed for different seasons in a year to conduct the sensitivity analysis of the parameterization schemes. In the warm & humid climatic zone, the Dudhia scheme outperformed the other three schemes by yielding less mean Root Mean Square Error (RMSE) of 133.67 W/m2, then followed by New Goddard, RRTMG and GDFL with increased mean RMSE of 6.67 %, 7.07 %, and 7.61 % respectively. In Composite climatic zone, the RRTMG scheme performed better than the other three schemes by yielding less mean RMSE of 134.58 W/m2, then followed by Dudhia, New Goddard and GFDL with increased mean RMSE of 3.02 %, 4.18 %, and 12.02 % respectively. For hot and dry climatic zone, the Dudhia scheme performed better than the other three schemes by yielding less mean RMSE of 133.20 W/m2, then followed by GFDL, RRTMG and New Goddard with an increased mean RMSE of 0.61 %, 4.10 %, and 5.71 % respectively. Despite the climatic conditions, all the schemes performed better in the summer season due to clear skies and below average in the monsoon season due to overcast conditions. The findings of the research are more beneficial to the stakeholders indulged in power generation using solar energy and grid operators for efficient operation in grid integration along with the management of demand and supply.

The promising prospects of high-temperature latent heat storage (HT-LHS) systems are accentuated by their advantages, including significant energy storage density, superior energetic efficiency, quasi-isothermal functionality, and seamless integration with renewable energy systems such as 3rd Gen Concentrated Solar Plant and Thermophotovoltaic systems. This study evaluates the thermo-economic performance of a proposed HT-LHS system having silicon as phase change material (PCM). A single thermal cell and a complete LHS system (consisting of several thermal cells) integrated with the supercritical CO2 cycle are considered for the thermal and economic analyses, respectively. Furthermore, the charging performance of an equivalent thermal cell is compared with a specific Li-ion cell. Notably, a single thermal cell’s gravimetric and volumetric energy densities surpass those of the specific Li-ion cell by approximately fourfold. Moreover, the charging time of the equivalent thermal cell, with minimal heat flow, is notably shorter than that of the Li-ion cell with comparable capacity. In terms of the levelized cost of electricity (LCoE), the HT-LHS technology demonstrates a significantly lower price of 9.547 Rs/kWh when storing 200 MWh of energy. Sensitivity analysis of LCoE reveals the opposite effect of loan repayment years (LOY) compared to other economic parameters. LCoE varies by 23.1%,16.43%,14.4%, and 8.06% by changing Return on equity (ROE), interest rate on the loan (IOL), Operation and maintenance cost, and discount rate from −40% to 40%.

Given the growing global demand for energy-efficient and environmentally sustainable cooling solutions, adsorption cooling systems, driven by low-grade heat sources such as waste heat, solar energy, and bio energy, offer a promising alternative. However, their commercialization is hindered by their relatively low performance metrics, including specific cooling power and coefficient of performance, leading to larger system sizes and higher costs. This review paper aims to fill the existing research gaps by concentrating on the advancements in adsorbent bed configurations, with the goal of enhancing performance and expanding the range of earlier investigations. The review discusses the heat and mass transfer processes within the bed, factors affecting adsorption dynamics and performance, modelling techniques and simulation tools to predict performance and optimize them. The review examines different configurations for the adsorbent beds, including multibed configurations, multistage operation modes, and innovative designs such as finned adsorbent beds, coated and metal additive adsorbent bed heat exchangers, aerogel bed structure, metal foam, triply periodic minimal surface and fluidized adsorbent beds. The review highlights significant advancements in bed design, such as metal additive-incorporated beds that increase specific cooling power by up to 40 % and triply periodic minimal surface configurations that improve performance by 12.4 % compared to conventional finned beds. Additionally, the review examines operating parameters that influence system performance, such as cycle time, inlet temperatures, and flow rates. This comprehensive review, covering advancements from 2000 to 2024, aims to bridge research gaps to facilitate future studies and broader adoption of adsorption cooling technologies.

Complex metal hydrides are reported as suitable for thermal energy storage at higher temperatures. In this analysis, complex metal hydrides are selected for the dual metal hydride based thermal energy storage system. Mg2NiH4 and NaMgH2F are selected as low and high temperature metal hydrides. Magnesium nickel alloy sample is physically characterized for X-ray diffraction and scanning electron microscope analysis followed the measurement of pressure composition isotherm between the temperature range of 250-300 degrees C. Numerical investigation is performed to analyze the heat transfer characteristics along with thermal energy absorption 550 degrees C and energy desorption at 500 degrees C. The effect of thermal conductivity enhancement of high temperature metal hydride on heat transfer and performance characteristics are studied in this numerical analysis. The energy absorption increased from 246.32 kJ to 251.35 kJ and energy desorption increased from 232.62 kJ to 239.06 with variation in thermal conductivity from 0.5 W/m.K to 4 W/m.K. Maximum energy storage efficiency 95.11 % is obtained from the dual metal hydride system. The heat transfer and performance comparison of single and dual metal hydride systems with the same energy storage media is performed. A maximum of 33 degrees C temperature variation of energy storage media is found in a single metal hydride system whereas it is observed 4 degrees C in the dual metal hydride system.

The diurnal and volatile nature of global horizontal irradiance has a significant effect on the power production from solar photovoltaic plants. Hence, it leads to gird instability. In order to alleviate the grid instability by managing the demand and supply efficiently, the accurate forecasting of global horizontal irradiance is essential. Advanced deep learning and ensemble techniques are not widely applied and tested in solar radiation forecasting. In order to fill the research gaps, this study proposes hybrid models like Bidirectional Long Short-Term Memory (BiLSTM) with CNN and U-net architecture. The novel ensemble algorithm consists of Long Short-Term Memory (LSTM), Convolutional Neural Network (CNN), and Extreme Gradient Boosting (XG Boost). The other models such as smart persistence, XG Boost, Gaussian Process Regression (GPR), LSTM, CNN, Gated Recurrent Unit (GRU), BiLSTM, CNN-LSTM are also used to forecast the hour-ahead GHI. The ensemble model has the lowest Root Mean Square Error (RMSE) of 35.02 W/m2, 47.41 W/m2, 56.59 W/m2, Mean Absolute Error (MAE) of 18.84 W/m2, 25.46 W/m2, 36.10 W/m2, Coefficient of Determination (R2) of 0.9745, 0.9745, 0.9625, and Forecast Skill (FS) of 0.5342, 0.4525, and 0.1961 for the hot and dry climatic zone, composite climatic zone, and warm and humid climatic zone, respectively.

Tea being a non-alcoholic drink places second among all the drinks. Black tea is the highest consumed tea worldwide. Black tea is of two types: Orthodox and Crush-Tea-Curl. Drying is a crucial step in black tea processing. It reduces moisture content. Tea drying especially arrests the oxidation reaction started during oxidation. In the current study, cylindrical tea particle is considered under a natural hot air-drying environment. Orthodox tea particle can be considered cylindrical in shape. A finite difference method-based explicit scheme is used to discretize the governing and boundary conditions. Drying temperatures of 160°C, and 170°C give acceptable moisture content in the drying duration of 1800 s (approx.) and 1500 s – 1800 s, respectively. Drying at 160°C and 170°C gives mean moisture contents of 0.063 g/g (d.b.) and 0.038 g/g (d.b.), respectively in 1800 s. Drying at higher temperatures shows faster moisture ratio reduction as compared to lower drying temperatures. Moisture ratios corresponding to 160°C and 170°C are found to be 0.017 and 0.003, respectively for 1800 s.

The intermittent presence of solar radiation on the earth and intermittent end-use demand emphasizes the need to investigate latent heat storage for simultaneous heat accumulation and retrieval operations. Initially, this study underlines the impact of cascading the multiple phase change materials in a single storage unit. Furthermore, extensive investigations are performed to understand the flexibility of the cascade latent heat storage for continuous and stable end-use energy supply in solar thermal applications. The present study uncovers the potential of cascade latent heat storage for real-time medium-temperature solar thermal applications (simultaneous charging and discharging). Two storages (each of 1 MJ latent thermal capacity) are designed, i.e., single-stage NaNO3 storage and a 2-stage cascade latent heat storage with NaNO3 and NaNO2 as the storage mediums in the consecutive stages. The storage is designed to support the end-use temperature of 513 K (highest temperature required in cooking). Three-dimensional models are prepared, and the enthalpy porosity technique is adopted to understand the phase transition dynamics of the storage. The cascading of the phase change materials curtails the energy accumulation time of the storage by 35.6 %. Starting from the state of complete solidification, the cascade storage maintains a 2.6 times faster melting rate compared to the NaNO3 storage, along with the required end-use temperature during simultaneous charging and discharging operation. Moreover, starting from the state of complete melting, cascade latent heat storage retains 2.3 times more latent thermal energy than the NaNO3 storage along with the required end-use temperature. Both the storages attain a steady state (thermal stability) of the charging process in which minimal variation of the temperature of the phase change materials is observed. The cascading of the phase change materials is the potential method for faster energy accumulation during charging and simultaneous charging and discharging operations.

Thermal energy storage using metal hydrides have the potential for storing high temperature thermal energy with minimal heat losses. Unit weight of NaMgH2F is used in the analysis for thermal energy storage in the temperature range of 773 K to 823 K. The energy sorption performance characteristics have been studied using NaMgH2F as energy storage media. Different initial temperatures of the metal hydride reactor, i.e., 773 K, 798 K, and 823 K, are considered for heat transfer and energy sorption analysis. Metal hydride reactors with two different heat transfer fluid flow configurations with the same heat transfer area have been studied to analyze the heat transfer within the reactor along with energy storage performance characteristics. Heat transfer fluid flow configuration 1 has only axial heat transfer fluid tubes, while a circumferential heat transfer fluid jacket is included in configuration 2 along with axial heat transfer fluid. Flow configuration 2 has shown better storage and heat transfer results. The energy storage efficiency at 773 K, 798 K, and 823 K initial reactor temperatures for configuration 1 are 93.2 %, 93.7 %, and 94.4 %, respectively, and 95.2 %, 95.8 %, and 96.4 %, respectively, for configuration 2.

Thermochemical energy storage system is known for good thermal stability and high energy storage density. Metal hydride based thermochemical energy storage systems are reported to store thermal energy at higher temperatures. In this analysis, NaMgH2F and Mg2NiH4 are used as high temperature and low-temperature metal hydrides. One kg of NaMgH2F is used as thermal energy storage media, while Mg2NiH4 is used as hydrogen storage media. The analysis includes the study of energy charging and discharging characteristics with heat transfer phenomenon in metal hydride with variation in thermal conductivity of high temperature metal hydride bed. With the increase in thermal conductivity of high temperature metal hydride bed, the heat transfer between heat transfer fluid and metal hydride bed during the energy charging and discharging process has improved. A marginal increase in thermal energy stored and discharged in/from the metal hydride bed system has been observed with an increase in the thermal conductivity of the metal hydride bed. Thermal energy stored in the MH beds for thermal conductivity of 0.5 W/m K, 0.75 W/m K, and 1 W/mK, are 270.88 kJ, 273.39 kJ, and 274.96 kJ, respectively. The energy desorbed from the system for thermal conductivity 0.5 W/mK, 0.75 W/mK, and 1 W/mK are observed as 251.25 kJ, 258.22 kJ, and 260.57 kJ, respectively. The three cases of thermal conductivity have reported an energy storage efficiency of 92.75%, 94.45%, and 94.77%, respectively.

Phase change material based thermal energy storage is a better choice due to its high energy density and charging and discharging occur at nearly constant temperature. In the present study, solar salt (60 % NaNO3 + 40 % KNO3) is considered as the storage media. Various passive performance enhancement techniques are analyzed by attaching fins (rectangular, triangular, and T-shaped fins) and grooves (circular, triangular, and square grooves) on the shell side for charging of the storage media. To quantitatively assess the impact of fins and shell configurations on the performance of latent heat storage system, complete melting time, maximum rise in phase change material temperature, and the portion of total energy utilized for the phase change are used as performance evaluation indexes. In particular, focus is given to justify the contribution of the average circulation velocity of phase change material to melting rate. The results indicate that fins significantly reduce both the melting time and the maximum temperature rise in the PCM domain as compared to various shell configurations. In comparison with all studied configurations, rectangular fin with 3.81 cm radial length have maximum reduction in melting time of 7.4 % and triangular fin with 3.81 cm radial length have a maximum reduction in temperature rise of 33 K. The study shows that increasing fin radial length enhances charging performance. Although melting starts earlier in the base configuration, fins complete melting faster by distributing heat inward. Raising the heat flux from 0.5 kW/m2 to 14 kW/m2 shortened the charging time by 21.8 times but also caused significant superheating, increasing the local maximum temperature of the phase change material from 512 K to 723 K, with the proportion of superheated energy rising from 2.8 % to 22.9 % of the total heat input.

The need for the present study arises from the limited availability of thermal energy storage systems capable of operating with a single heat source while delivering stable heat outputs at multiple temperatures suited to diverse end-use applications. To meet this objective, a novel two-stage cascade latent heat storage unit was developed using a shell-and-multiple-tube arrangement. The system was specifically designed to support an indoor cooking setup composed of three dedicated cooking units: a cooking plate, a frying pan, and a cooking vessel, each requiring distinct operating temperatures. During testing, the storage system consistently delivered heat at 473 K, 452 K, and 373 K to the respective cooking units, allowing baking, frying, and boiling tasks to be completed within 4 min, 4 min, and 13 min, respectively. The total energy retrieved from the CLHS from stage 1 and stage 2 is 57.04 % and 42.96 % of the stored heat, respectively. The system achieved a cyclic thermal efficiency of 55.82 % and an end-use efficiency of 38.24 %, confirming its ability to manage and utilize heat effectively across multiple temperature levels. A thermal delay was observed in the lower parts of the unit due to uneven phase change material distribution, likely caused by buoyancy effects, suggesting the need for further optimization of the heat transfer design. Overall, the results confirm the feasibility of using a cascade latent heat storage approach for community-scale solar cooking, providing a flexible solution for varied thermal needs beyond the scope of traditional solar cookers.

Due to high energy density, latent heat storage technologies are capturing the attention of researchers worldwide. The downsides of storage media's significantly low thermal conductivity can be overcome by various methods, and cascade storage is one of them. In the existing literature, charging and discharging of multi-PCM (cascade latent heat storage) are analyzed separately. In this study, efforts are made to understand the actual behavior of multi-PCM systems for simultaneous charging and discharging. This research investigates the potential of cascade latent heat storage for medium-temperature solar thermal applications such as solar cooking. The comparative investigation between single (NaNO3) and multiple PCM-based (NaNO3 and NaNO2) storages is done for simultaneous melting and solidification cycles. A melting rate augmentation of 2.6 times is observed in cascade storage compared to the NaNO3 storage in real-time operation. Furthermore, it is observed that horizontal cascade storage outshines the vertical cascade storage by 20.2% in terms of melting rate.

Climate change has been a major existential threat to humanity, and much-debated predictions of its devastating consequences are becoming a reality. The various natural hazards and disasters are a cause of grave concern, and there is a need to study these hazards, their impact on the society, the nation’s economy, and various other vulnerabilities in the future. There is a huge gap in understanding the impact of climate change on the society, and it seems that we all are living in a state of denial. So, there is a strong need to combine all available data in one document to give a holistic view of actual problem. Therefore, this paper, will review the various likely vulnerabilities in front of India and how climate change will exacerbate the Natural hazards. It will also bring out the likely impacts of climate change on the India’s economy.Moreover, it’s evident from this review that India’s vulnerability to climate change and consequential hazards is greatly amplified because of its socioeconomic, demographic, and geographic characteristics and large population, which strain the existing infrastructure. Various findings based on review of data is also listed at the end to give the consolidated outcomings of the review, which highlight the major threats as heat waves, erratic precipitation, cyclones and floods. The paper will also highlight how developing countries like India are spearheading the drive to decrease the carbon footprint and prevent further impacts on the climate.