Sensible Heat Storage Materials Research Articles

Analysis of energy storage materials for developments in solar cookers.

Solar energy is accessible freely and can be utilized for many household and industrial applications. The consumption of solar energy for cooking applications has found significant success. Various innovations have been employed in facilitating cooking during off-sunshine hours. Thermal energy storage helps in overcoming the fluctuations in the supply of energy required for cooking during different time periods of the day. This study focuses on the different types of thermal energy storage mediums that are currently utilized in solar cooking. Primarily, oils and pebbles are most commonly used as sensible heat storage (SHS) while organic phase change materials (PCMs) are used as latent heat thermal energy storage materials (LHTES). The properties and performances of various SHS and latent heat storage (LHS) mediums have been compared for their suitable utilization. SHS materials are cost-effective but have lower thermal gradient compared to LHTES materials. The energy storage capability of LHTES is high while degradation with the increasing number of charging and discharging cycles is also considerable. The melting point should be close to the utilization temperature for being used as LHTES as thermal diffusivity of the materials greatly influences the performance of solar cookers. The cooking time is lower for solar cooking systems equipped with energy storage compared to non-equipped cooking systems. It is recognized that the use of energy storage has been proved as a huge advantage to solar cooking systems, however, the design, and heat transfer characteristics of the cooking vessel along with the storage material type and volume must be optimized in order to make this technology more influential.

Analysis of energy storage materials for developments in solar cookers

Solar energy is accessible freely and can be utilized for many household and industrial applications. The consumption of solar energy for cooking applications has found significant success. Various innovations have been employed in facilitating cooking during off-sunshine hours. Thermal energy storage helps in overcoming the fluctuations in the supply of energy required for cooking during different time periods of the day. This study focuses on the different types of thermal energy storage mediums that are currently utilized in solar cooking. Primarily, oils and pebbles are most commonly used as sensible heat storage (SHS) while organic phase change materials (PCMs) are used as latent heat thermal energy storage materials (LHTES). The properties and performances of various SHS and latent heat storage (LHS) mediums have been compared for their suitable utilization. SHS materials are cost-effective but have lower thermal gradient compared to LHTES materials. The energy storage capability of LHTES is high while degradation with the increasing number of charging and discharging cycles is also considerable. The melting point should be close to the utilization temperature for being used as LHTES as thermal diffusivity of the materials greatly influences the performance of solar cookers. The cooking time is lower for solar cooking systems equipped with energy storage compared to non-equipped cooking systems. It is recognized that the use of energy storage has been proved as a huge advantage to solar cooking systems, however, the design, and heat transfer characteristics of the cooking vessel along with the storage material type and volume must be optimized in order to make this technology more influential.

Experimental analysis of evacuated tube solar air heater (ETSAH) with inbuilt sensible thermal energy storage

AbstractIn the present work, an evacuated tube solar air heater (ETSAH) with inbuilt sensible heat storage material (SHSM) is experimentally evaluated. The system comprises two sets each having 50 evacuated tubes with an H‐type arrangement and a total collector area of 16.92 m2. For the purpose of hot air generation, ETSAH is simultaneously connected in series and in parallel with and without the use of reflectors. Three different mass flow rates of 122.90, 164.87, and 212.83 kg/h were fixed to get 12 diverse cases of ETSAH operation. The highest hot air temperature reported by the system is 121.7°C when it was connected in series with conventional reflectors at 212.83 kg/h of flow rate and 469 W/m2 average solar intensity. The system reported an overall average energy efficiency of 49.76% and an exergy efficiency of 17.97% with the highest average hot air temperature difference of 56.12°C from 09:00 to 20:00 h. Without the incorporation of any additional SHSM, the average hot air temperature delivered by ETSAH (when under the neighbor building shadow) is 49.73°C logged from 17:00 to 20:00 h. The economic analysis is also carried out to ensure its practical application and feasibility. For the best system performance, the annual cost of hot air generation is 0.0194 Rs./kg (0.0002433 $/kg).

Parametric analysis of a sensible heat storage unit in an indirect solar dryer using computational fluid dynamics

The non-continuity of the drying process after sunset is one of the most significant limitations with solar dryers that has an impact on product quality and drying time. To overcome this problem, we installed a Thermal Energy Storage (TES) unit in an indirect solar dryer. Given the economic advantages offered by Sensible Heat Storage (SHS) systems and their availability, they are the best option to consider in a drying application. In this paper, we investigated a SHS unit integrated within a solar dryer under real meteorological conditions in eastern Morocco. The solar dryer with a storage system was simulated using the Computational Fluid Dynamics (CFD) approach, which was validated using experimental data from the literature. The research is mainly focused on the amount of material required, the proper porosity of the packed bed, and the overall performance of the solar dryer for various types of SHS materials. The obtained results proved that when compared to the case without storage, the efficiency of the solar dryer with sensible heat storage increased by about 2.47% at night. Regarding the study of different materials, granite stones showed better performance with a porosity of 40% and a packed bed thickness of 15 cm, where the temperature differences between the two cases with and without storage reached almost 5° at night.

Preparation of high temperature sensible heat storage materials from reduced vanadium tailings and graphite

The experimental study on the preparation of high temperature (>500 °C) sensible heat storage materials (SHS) was conducted through the means of sintering method, in which vanadium tailings after carbothermic reduction used as the main matrix, graphite as the thermal conductivity modifier, and clay as the auxiliary material. The phase analysis by XRD shows that the main phases of the SHS materials without clay addition are aluminosilicate, sodium aluminoslicate, ilmenite and graphite, while additional phases of quartz and carbonate were observed if clay is added. With the graphite addition ranging from 0 to 15%, the density and hardness of the SHS materials without clay addition generally shows decreasing tendency while both properties behave increasing first and then decreasing in the SHS materials with clay addition. In addition, with increase of graphite, thermal conductivity of material without adding clay gradually increases in a range of 0.54 ∼ 1.54 W·m−1·K−1, while thermal conductivity of materials with adding clay remains unchanged first and then increases in the range of 0.754 ∼ 1.922 W·m−1·K−1.Thermal analysis shows that when the graphite content is 3 ∼ 5%, both SHS materials without or with clay have moderate specific heat capacity and high thermal capacity (>1.2 MJ m−3·K) at temperate above 500 °C, and high heat storage density (>200 kJ kg−1) in the temperature range of 500 °C ∼ 750 °C, indicating SHS materials prepared in this study can be considered for application in high temperature storage system.

Investigation of performance enhancement of solar still incorporated with Gallus gallus domesticus cascara as sensible heat storage material.

In this research work, the conventional single slope still (CSS) with egg shells of breed Gallus gallus domesticus cascara as sensible heat storage (SHS) material are studied experimentally to enhance the yield. In this experimental investigation, the proposed single slope still (PSS) with SHS material was made in comparison with the CSS to evaluate the productivity of fresh water under the same ambient conditions. Comparatively, this PSS has higher thermal conductivity than the CSS. The yield obtained from the PSS is 2.46L/m2, while the yield from the CSS is 2.07L/m2. The average rate at which the rise of output fresh water obtained from the PSS is 18% more than the fresh water output obtained from the CSS. The daily energy efficiency of the PSS is 26.07%, and for the CSS, it is only 22.25%. The daily exergy efficiency of the PSS is 2.36%, and for the CSS, it is only 1.67%. Since using the egg shell will employ as organic waste management and modification in this still is economical, less initial, and maintenance cost.

Solar still with evacuated tubes and calcium stones to enhance the yield: An experimental investigation

Present research study shows the evacuated tubes coupled with solar still to enhance the yield. Basin area of 1-meter square taken for the experiments and 14 evacuated tubes have been used at a lower side of the still. Calcium stones as sensible heat storage material (SHSM) have also been utilized to enhance the yield in present work. Three modes of experiments have been performed namely conventional solar still (CSS), solar still with evacuated tubes (SSET) and solar still with evacuated tubes and calcium stones (SSETCS) during January to June 2019 at Patan District, Gujarat. Groundwater was taken as feed water in present experiments. It was examined that the average yield was enhanced by 113.52 % and 104.68 % by use of SSET and SSETCS. The payback time (PBT) also determined in current work, and it was 237 for SSETCS. At last, it was concluded that the calcium stones are good SHSM to reduce water quantity and accumulate the heat during the daytime.

Performance analysis of conventional triple basin solar still with evacuated heat pipes, corrugated sheets and storage materials

Present research article examines the experimental analysis of conventional triple basin solar still (CTBSS) with evacuated heat pipes (EVHPP), corrugated sheets (CS) as absorber and sensible heat storage materials (SHSM). Nearby available materials like pebbles and granite gravel have taken as storage materials in current research work. Corrugated sheets (CS) used to enhance surface area and distillate output both in the present investigation. The investigations have carried out in three cases like (CTBSS), CTBSS with EVHPP and pebbles and CTBSS with EVHPP and granite gravel., From the six-month investigations, it has been found that the maximum distillate output obtained from the lower basin of CTBSS as compared with remaining two. Also, the present system obtained 19 kg/m2/day average distillate output for CTBSS with EVHPP and granite gravel.

Performance of solar aluminium can air heater using sensible heat storage

Abstract The current research purpose is to study the solar air heater using aluminium cans with aluminium scraps and pebble stones as sensible heat storage material (SHM). The solar intensity, temperature difference of air inlet and outlet, heat transfer coefficient between aluminium can and flowing air and instantaneous thermal efficiency were studied for the mass flow rates of 0.025 kg/s and 0.0916 kg/s. Results reveals that the outlet temperature is 1.5 °C higher than the ambient after the sunset when SHM was used. The instantaneous efficiency and heat transfer coefficient were found to be better for 0.025 kg/s with aluminium scraps than the other cases.

Experimental investigation of the performance of a novel solar dryer for drying medicinal plants in Western Himalayan region

This paper presents the experimental investigation of indirect forced convection solar dryer integrated with sensible heat storage material (SHSM) and phase change material (PCM) in meteorological environment of Himalayas (latitude 30.91 °N). The iron scrap mixed with gravel is placed on absorber plate and copper tubes comprising of engine oil have been used as SHSM in the solar collector. The Paraffin RT-42 as a PCM has been used in the drying chamber. Experimentations of Valeriana Jatamansi (a medicinal herb) drying have been conducted and its moisture content reduced from initial value of 89% to 9%. Using SHSM and PCM simultaneously the overall drying rate observed 0.051 kg/hr which was almost double as compared to 0.028 kg/hr and 0.018 kg/hr with no use of thermal storage medium and traditional shade drying, respectively. The drying time to reach the saturation level of 9% was recorded as 120 h in comparison to 216 and 336 h, respectively and the dried rhizomes of good quality in terms of essential oil and bio-medical compounds are obtained. From the experimental results rehydration capacity and total Valepotriates were found 7.11 and 3.47% as compared to 6.18 and 3.31%, respectively in case of traditional shade drying. The solar collector without SHSM possess an average energy and exergy efficiency 9.8% and 0.14%, respectively. The respective energy and exergy efficiency achieved with SHSM are 26.10 and 0.81%.

INVESTIGATION OF COMBINATION BETWEEN LATENT AND SENSIBLE HEAT STORAGE MATERIALS ON THE PERFORMANCE OF FLAT PLATE SOLAR AIR HEATER

In this work, a combination between latent heat storage materials (LHSm) and sensibleheat storage materials (SHSm) as new storage heat material in flat plate solar air heater wastested experimentally. PCM (paraffin wax) at a certain ratios (10%) and (20%) were used asLHSm with a pure cement (base material) as SHSm. The experimental tests was doneindoor at irradiance of (1000W/m2) with forced convection, the mass flow rate of air are(0.5kg/min) and (1.13kg/min). The results indicated that the enhancing thermo-physicalproperties of adding pure cement by a certain ratios of paraffin wax led to enhancement inthermal energy stored. The percentage increasing in storage heat duration time was (29%)for compound cement with (10%PCM), (38.4%) for compound cement with (20%PCM),compared with pure cement at (0.5kg/min) air mass flow rate. And at (1.13kg/min) air massflow rate, it was (33.3%) for compound cement with (10%PCM) and (52.6%) for compoundcement with (20%PCM) compared with pure cement.

Performance tests on lab–scale sensible heat storage prototypes

This paper presents the performance tests on lab-scale sensible heat storage (SHS) prototypes made up of cast steel and concrete. Thermal storage performances of the prototypes in terms of charging/discharging times and energy storage/discharge rates have been estimated at various operating temperatures and heat transfer fluid (HTF) flow rates. These prototypes were designed in the form of a shell-and-tube type heat exchanger with a heat storage capacity of 15 MJ. Five different concrete mix designs were studied and the mix design M30 was selected for thermal storage, as they possess high compressive strength-cost ratio. Heat transfer enhancement in the concrete prototypes was incorporated by welding longitudinal fins on the HTF tubes. Hi-tech Therm 60 was used as heat transfer fluid. The charging and discharging times of cast steel (M1) prototype in the temperature range of 353–413 K were 1263 and1803 s, respectively. The effective charging/discharging time of the concrete prototype with copper tubes (M2) and concrete prototype with MS tubes (M3) prototypes in the temperature range of 353–433 K were 5210/6297 s and 7160/7780 s, respectively. The storage performance of the system highly depends on the operating temperature range due to the temperature dependence of the thermo-physical properties of the SHS materials and the HTF.

Thermal performance evaluation of solar cooker with latent and sensible heat storage unit for evening cooking

This paper presents an investigation of thermal performance of phase change material (PCM) in combination with different sensible heat storage materials (SHSMs) in a solar cooker based on parabolic dish collector for evening cooking. In the experimental set-up, a pressure cooker is placed at the centre of two concentric pots containing PCM in the inner pot and different SHSMs in the outer pot. During sunshine hours, this unit (solar cooker) is placed on a plate of parabolic dish collector for storing the thermal energy in the SHSMs. In the evening, the solar cooker is kept in an insulator box and loaded with cooking food, where the PCM deliver heat to the food. It has been found that PCM-Sand and PCM-Stone pebble cases store 3 to 3.5 times more heat as compared to PCM-Iron grits and PCM-Iron ball cases. The PCM assists in cooking while the outer material assists PCM in maintain its performance.

Effect of Waste Heat Recovery on Drying Characteristics of Sliced Ginger in a Natural Convection Dryer

In the present work, quality drying characteristics of sliced ginger were studied utilizing the concept of waste heat recovery in a biomass operated natural convection dryer with sensible heat storage material (SHSM) and phase change material (PCM). Ginger slices (2 and 4mm thick) were dried from initial moisture content (MC) 88-90% (w.b.) to final moisture content 11-12% (w.b.) with hot air maintained at temperature 600C, air velocity 0.2m/sec, atmospheric average relative humidity 74% and ambient temperature 250C. It was observed that the biomass consumption and melting time of PCM were significantly reduced due to the use of waste heat. The optimum drying time was found to be 5.5h for 2mm thick ginger slices. Color, texture and aroma were found better in treated sample.

Selection of materials for high temperature sensible energy storage

Availability of thermal energy storage systems (TES) is a key to ensuring continuous power supply from solar thermal power plants. The application of sensible heat storage (SHS) in solid media is an attractive economic option, but is dependent on identifying suitable SHS media. Given the growing number of new materials available today, finding a suitable material is a time-consuming and difficult process. This paper demonstrates the use of a materials selection software package and identifies suitable SHS materials for high temperature (>500°C) TES systems. The environmental performance of some selected materials was also evaluated using the package.Common materials such as alumina, silicon carbide, high temperature concrete, graphite, cast iron and steel were found to be highly suitable for SHS for the duty considered (500–750°C). For cost comparison, a simple heat exchanger, consisting of a packed bed of the materials (in brick or block form) heated by an inert gas, was considered. On the basis of equivalent gas phase heat transfer, high alumina cement concrete blocks had the lowest cost, followed by a common refractory brick at <US$ 10/kWh (thermal).High temperature concretes, such as the high alumina cement-based materials and alumina–silicate geoploymers, were identified as having potential for SHS media as they are cheap composite materials. Their thermo–physical properties could be optimised for SHS by a suitable choice of aggregates, binders and additives.