Addison Hockins

Bio: Addison Hockins is an academic researcher from Gannon University. The author has contributed to research in topics: Latent heat & Thermal energy storage. The author has an hindex of 2, co-authored 5 publications receiving 11 citations.

An experimental study on the effect of annular and radial fins on thermal performance of a latent heat thermal energy storage unit

Abstract: Latent heat thermal energy storage (LHTES) has been used to deal with the cyclical nature of energy production through solar means. One problem with LHTES systems is the PCM having a low thermal conductivity. This results in low heat transfer rate prolonging the charging and discharging cycles. In the current study, the thermal characteristics of a latent heat thermal energy storage system enhanced with annular and radial fins are investigated experimentally. Rubitherm RT-55 is used as the phase change material (PCM) and is enclosed within a vertical cylindrical container. Water is used as the heat transfer fluid (HTF) which is circulated in a copper pipe that passes through the center of the container. Different numbers of annular and radial fins attached to the central pipe, all containing the same volume of copper are studied. The effects of these configurations on the thermal performance of the latent heat thermal energy storage system during the charging and discharging processes is monitored. The no-fin benchmark case took 47.87 h to charge the LHTES unit and 42.5 h to discharge. The ten-annular fins charged the system 84.1% faster and discharged the system 68.21% faster. The twenty-annular fin case reduced the charging time by 85.8% and the discharging by 68.58%. The four-fin radial case was found to decrease the charging time by 81.9% and 70.0%; whereas the eight-fin radial case was found to have the greatest decrease the charging and discharging times, being 86.6% and 80.1%, respectively.

Experimental study of a latent heat thermal energy storage system assisted by varying annular fins

Abstract: Latent heat thermal energy storage (LHTES) systems can be used to alleviate the intermittent nature of solar power by allowing energy to be stored and released when needed. LHTES systems utilize phase change materials (PCMs) for energy storage, and a frequent problem with most PCMs is the low thermal conductivity. Annular fins of variable diameter are used to increase the heat transfer rate to and from the PCM. A shell and tube heat exchanger filled with PCM uses a central pipe with annular fins to carry the heat transfer fluid through the system. All fin configurations in this study contain the same volume of copper but are designed differently. The benchmark case with no fins had charging and discharging times of 47.87 and 42.5 h, respectively. The ten-annular fin cases include: uniform fins, increasing fin diameter from top to bottom, and decreasing fin diameter from top to bottom which decreased the charging time by 84.1 %, 85.77 %, and 58.5 %, respectively. These cases decreased the discharging time by 68.21 %, 65.34 %, and 44.0 %, respectively. Similar designs with twenty annular fins decreased the charging time by 85.50 %, 89.45 %, and 71.00 %, respectively. These cases decreased the discharging time by 68.58 %, 77.41 %, and 44.28 %, respectively. • Experimental study of latent heat thermal energy storage system enhanced by fins. • Effect of uniform and varying annular fin length on thermal performance is studied. • Each fin configuration contains equal volumes of copper and PCM. • Increased fin surface area at base of PCM decreased charging and discharging time.

Experimental and Numerical Study of a Latent Heat Thermal Energy Storage Unit Enhanced by Fins

Abstract: Latent heat thermal energy storage (LHTES) systems are used to store thermal energy and release it for later use by melting or solidifying a phase change material (PCM). One problem associated with latent heat thermal energy storage systems is the low thermal conductivity of most commercially aviable phase change materials. This can have a significant negative effect on the thermal performance of the system by leading to a longer charging or discharging process. Several passive heat transfer enhancement techniques are used to resolve this issue. Common passive heat transfer enhancement techniques include inserting fins and extended surfaces into the PCM, embedding heat pipes or other two-phase heat transfer devices within the PCM, dispersion of highly conductive nanoparticles in the PCM, and impregnation of highly conductive porous media with the PCM. The current study analyzes the effect of a fin-based enhancement technique on the thermal performance of a latent heat thermal energy storage unit. Copper fins are attached annually around the central pipe inside the PCM. A transient two-dimensional numerical model technique is developed using ANSYS FLUENT 19.0 to simulate the operation of the system. Baseline tests have been conducted experimentally for a system without fins to validate the numerical model. The results obtained from the numerical modeling are in good agreement with those of the experimental testing. Based on the experimental testing, the total charging time of the system using hot water at 70°C and flow rate of 7.57 L/min is around 47.9 hours which is very close to the prediction by the numerical model which is 48 hours. Numerical modeling of the system with 10 fins and 20 fins found that the charging time was decreased by 68.9% and 73.7%, respectively. The discharging time was also decreased by 73.2% and 79.1%, respectively.

Experimental and Numerical Study of a Latent Heat Thermal Energy Storage System Enhanced with Fins

Abstract: Extended Abstract The lack of a dispatchable energy supply makes transitioning from fossil fuels to green energy alternatives such as solar and wind energy extremely difficult. One solution to remedy this problem is the introduction of a latent heat thermal energy storage (LHTES) unit into an energy system to continue to provide energy long after the original source is gone. LHTES units utilize phase change materials (PCM) as storage media that melt and solidify in the presence of thermal energy. LHTES units using only pure PCMs take a long time to charge and discharge due to PCM low thermal conductivity, making their application in energy systems more difficult. The introduction of thermal conductivity enhancement techniques such as fins, nanoparticles and metallic foam decreases charging and discharging time and increases the thermal efficiency of LHTES units [1-3]. The current study numerically and experimentally analyses a LHTES unit containing Rubitherm RT55 as the PCM and enhanced with fins. Different configurations of metallic fins were examined to maximize the heat transfer to the PCM. These configurations were compared to the operation of the LHTES unit without any enhancement. Both the charging and the discharging cycles of the LHTES unit were studied. The experimental results were compared to numerical simulations completed by ANSYS Fluent 17.0 commercial CFD package. Finding an optimal configuration of a LHTES unit containing PCM and fins allows such units to be integrated with an alternative energy system making the alternative energy more reliable and comparable to their fossil fuel counterpart. The PCM in this study is stored in a cylindrical container which was of 30.48 cm tall with an inner diameter of 19.05 cm, with a copper pipe that transports the heat transfer fluid at the center of the container. The system is initialized from room temperature (22 °C) and is charged with water at 70 °C. Firstly, the numerical data was compared to the experimental to provide verification for the model. The comparison indicated that the numerical predictions were in good agreement with the experimental data. Two configurations of 10 annular fins and 20 annular fins attached to the central pipe were analysed numerically. These two cases were compared to a benchmark case using no fins. The no-fin case using 70°C HTF took approximately 48 hours to charge. This benchmark was then compared to the finned cases. The 10-fin case took roughly 15 hours to charge, while the 20-fin case took 12 hours and 40 minutes to fully charge. The resulting percent decreases in charging times were 68.9% and 73.7%, respectively. When evaluating the discharging cycle of the heat exchanger, it was found that the case utilizing no fins took about 42.5 hours to completely discharge. The 10-fin case took 11 hours and 20 minutes, a 73.2% decrease in total charging time. The 20-fin case had the fastest discharge cycle, which was 8 hours and 50 minutes, a 79.1% decrease when compared to the no-fin case. A case can be made that gains in efficiency when using the 20-fin case are offset by the manufacturing cost and difficulty when creating and assembling the fin geometry.

Nano-Enhanced Phase Change Materials in Latent Heat Thermal Energy Storage Systems: A Review

Abstract: Latent heat thermal energy storage systems (LHTES) are useful for solar energy storage and many other applications, but there is an issue with phase change materials (PCMs) having low thermal conductivity. This can be enhanced with fins, metal foam, heat pipes, multiple PCMs, and nanoparticles (NPs). This paper reviews nano-enhanced PCM (NePCM) alone and with additional enhancements. Low, middle, and high temperature PCM are classified, and the achievements and limitations of works are assessed. The review is categorized based upon enhancements: solely NPs, NPs and fins, NPs and heat pipes, NPs with highly conductive porous materials, NPs and multiple PCMs, and nano-encapsulated PCMs. Both experimental and numerical methods are considered, focusing on how well NPs enhanced the system. Generally, NPs have been proven to enhance PCM, with some types more effective than others. Middle and high temperatures are lacking compared to low temperature, as well as combined enhancement studies. Al2O3, copper, and carbon are some of the most studied NP materials, and paraffin PCM is the most common by far. Some studies found NPs to be insignificant in comparison to other enhancements, but many others found them to be beneficial. This article also suggests future work for NePCM and LHTES systems.

Strategies for phase change material application in latent heat thermal energy storage enhancement: Status and prospect

Abstract: The use of phase change materials (PCMs) has enormous potential to store thermal energy from a low-temperature heat source as well as from waste heat as latent heat. The amount of latent heat in PCM is much higher than sensible heat. Therefore, this significant latent heat supply can partially fulfil the energy demand for certain applications. PCMs can supply energy during the power crisis. PCMs are also helping to meet the basic need of life during natural calamities. The enhancement of the thermal properties of PCM can improve the use of PCM as a sustainable resource. In this study, the different processes of thermal property enhancement according to the application are reported and presented in a compiled form. The study reflects that using additives and encapsulation, a change in thermal conductivity, phase change temperature, and latent heat of solid-liquid phase change can be achieved. The changes in size and shape of the PCM container cavity are also reported. There is an improvement in thermal energy storage capacity with an increase in the heat transfer area of the cavity. The review reveals that the encapsulated PCM and PCM composite can give a better performance in latent heat thermal energy storage compared to complicated shaped energy storage devices. Therefore, this complied study will help to select the PCM or PCM composite and in design of LHTES for a specific application. • Review on application of phase change materials • Review on latent heat thermal storage capacity improvement using PCM composite • Review on effect of the shape of LHTES unit

An experimental study on the effect of annular and radial fins on thermal performance of a latent heat thermal energy storage unit

Abstract: Latent heat thermal energy storage (LHTES) has been used to deal with the cyclical nature of energy production through solar means. One problem with LHTES systems is the PCM having a low thermal conductivity. This results in low heat transfer rate prolonging the charging and discharging cycles. In the current study, the thermal characteristics of a latent heat thermal energy storage system enhanced with annular and radial fins are investigated experimentally. Rubitherm RT-55 is used as the phase change material (PCM) and is enclosed within a vertical cylindrical container. Water is used as the heat transfer fluid (HTF) which is circulated in a copper pipe that passes through the center of the container. Different numbers of annular and radial fins attached to the central pipe, all containing the same volume of copper are studied. The effects of these configurations on the thermal performance of the latent heat thermal energy storage system during the charging and discharging processes is monitored. The no-fin benchmark case took 47.87 h to charge the LHTES unit and 42.5 h to discharge. The ten-annular fins charged the system 84.1% faster and discharged the system 68.21% faster. The twenty-annular fin case reduced the charging time by 85.8% and the discharging by 68.58%. The four-fin radial case was found to decrease the charging time by 81.9% and 70.0%; whereas the eight-fin radial case was found to have the greatest decrease the charging and discharging times, being 86.6% and 80.1%, respectively.