PCM thermal storage in buildings: A state of art,

Abstract A comprehensive review of various possible methods for heating and cooling in buildings are discussed in this paper. The thermal performance of various types of systems like PCM trombe wall, PCM wallboards, PCM shutters, PCM building blocks, air-based heating systems, floor heating, ceiling boards, etc., is presented in this paper. All systems have good potential for heating and cooling in building through phase change materials and also very beneficial to reduce the energy demand of the buildings.

Optical absorptivity and thermal conductivity analysis of silver nanoparticle dispersed salt hydrate PCM

Thermal energy storage using phase change materials (PCM) s are of notable technique towards improving the utilization of solar energy mix within the global energy consumption. Major problem with solar power is its intermittent nature. Phase change materials acts as a thermal battery to store thermal energy received from the sun, and use the same during absence of sun. In spite of numerous advantages PCM suffers due to low thermal conductivity and specifically organic PCMs are flammable in nature. In this particular research investigation, we choose inorganic salt hydrate PCM and disperse silver nanoparticle to enhance their thermal characteristics. Sodium phosphate dibasic dodecahydrate (SPDD) is the opted inorganic salt hydrate PCM. Silver nanoparticle dispersed SPDD PCM are prepared at different composition of SPDD-0.3Ag%, SPDD-0.5Ag% and SPDD-0.7 Ag% using a two-step water bath sonication process. The prepared samples are explored experimentally using FTIR spectroscopy and UV-VIS Spectroscopy to evaluate their chemical and optical absorptivity behavior. Thermal conductivity of the composite inorganic salt hydrate PCM are determined using numerical model available in the literature. Results ensure better optical absorptivity and thermal conductivity for the composite salt hydrate sample with higher concentration of silver nanoparticle. Prepared composite PCM are expected to enhance the thermal energy storage with significance to contribute towards sustainable development goal of clean and affordable energy

Integration of emerging PCMs and nano-enhanced PCMs with different solar water heating systems for sustainable energy future: A systematic review

Solar water heaters (SWHs) are primarily used to generate hot water to meet daily needs in domestic and industrial applications. Due to its technical and economic practicality, solar water heating has been widely exploited for use of solar energy. However, the inconsistent availability of solar radiation and lack of energy storage facilities restrict its utilization. Thermal energy storage materials (Phase change materials and nano-enhanced phase change materials) are key solutions for effectively harvesting thermal energy from solar radiation. Integrating phase-change materials (PCMs) and nano-enhanced phase-change materials (NE-PCMs) with SWHs overcome the constraint of only being used during the daytime and making them more efficient. The main aim of this systematic review article is to summarize and highlights the key results of recent studies on SWHs integrated with PCMs and NE-PCMs for domestic and industrial water heating applications. This study also highlights the technical issues associated with SWH systems. In addition, the perspectives, recommendations, and future improvements of the SWH systems integrated with PCMs and NE-PCMs are explored to overcome the technical barriers to their practical use. In conclusion, the thermal performance of SWHs with the help of PCMs and NE-PCMs increased significantly, and the cost of the system was reduced, resulting in a shorter payback period compared to conventional SWHs. Also, there is a considerable reduction in CO2 emissions from an environmental perspective. It is intended that this study will provide new insights to the researchers to design and develop highly efficient SWH systems

PCM-assisted energy storage systems for solar-thermal applications: Review of the associated problems and their mitigation strategies

Latent heat energy storage (LHES) system is identified as one of the major research areas in recent years to be used in various solar-thermal applications. However, there are various challenges associated i.e., low thermal conductivity, leakage issues, stabilization concerns, etc. In this work, a comprehensive review of studies dealing with these problems and their mitigation strategies. Various design parameters influencing the performance of PCM-assisted systems are also discussed. This article further presents a detailed review of several mathematical models, based on system enthalpy and heat capacity-based modeling schemes along with the techno-economic analysis. The review results reflect the application of porous foams increasing thermal conductivity values of PCM composites relative to pure PCM working mediums. Moreover, the use of extended surfaces with appropriate geometries reduces the phase transition durations for the working medium significantly which enhances the thermal performance. Additionally, PCM encapsulations are identified as one of the widely accepted procedures intensifying the thermal performance of energy storage systems. However, the selection of appropriate encapsulation shell material and shell geometries are some of the important factors to be considered to ensure optimum system performance. This review focuses on the significant aspects of PCM encapsulation design parameters for several solar-thermal systems

Thermal energy harvesting of highly conductive graphene‑enhanced parain phase change material

Solar energy is the most plentiful renewable energy source that has the capability to keep up with the growing demand. When the sun’s energy is not available, thermal energy storage (TES) using phase change material (PCM) is a promising technique for storage and utilization. However, PCM’s low thermal conductivity may limit its use. The use of nanomaterials to enhance the thermal conductivity is one of the prominent solutions to overcome this issue. This research work reports that graphene nanoparticles (0.1%, 0.3%, 0.5%, 0.7% and 1% mass) enhanced paraffin wax (PW) to improve the thermophysical properties and transmittance capability. Thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FTIR) and ultra-violet visible spectroscope (UV–VIS) were used for the characterization of the base PCM and nano-enhanced phase change materials (NePCM) composites. A significant improvement of 110% in thermal conductivity was obtained at 0.7% mass ratio compared to base PW without compromising the prepared composites’ latent heat storage (LHS) capacity. TGA and FTIR outcomes demonstrated excellent thermal and chemical stability, respectively. To check the thermal reliability of composite, the PW and nanocomposite were subjected to repeated thermal cycling. The outcome evidence that the NePCM composite had consistent thermal energy storage properties even after repeated thermal cycles. The composite’s light transmission was drastically lowered by 56.34% (PW/Gr-0.5) compared to base PW, resulting in PW/Gr composite has better thermal reliability in relation to thermal conductivity and LHS than base PCM, which can be used specifically in photovoltaic thermal systems and TES

Concentrated Photovoltaic Thermal (CPVT) systems : Recent advancements in clean energy applications, thermal management and storage

Solar spectrum utilization can effectively deliver a significant stake in the next century's energy demand, which lies in tandem with Sustainable Development Goals. Solar energy is a promising, sustainable, and cleaner energy source. The photovoltaic thermal system is a solar spectrum utilization technique that can generate thermal and electrical energy, but the recovered thermal energy can primarily contribute to low-temperature utilizations. This study's motivation lies in the great potential of Concentrated Photovoltaic Thermal systems in providing high-grade thermal energy and increasing the overall system efficiency. This paper collectively reviews advanced thermal management techniques such as using phase change materials and nanofluids to avert overheating of the solar panel. A comprehensive review of Concentrated Photovoltaic Thermal systems like desalination, greenhouse heating which help in attaining Sustainable Development Goals, is also summarized. Heat transfer fluid selection is critical in thermal management, and accordingly, a comparison of various cooling methods is also made. The current article is a novel attempt to deliver a comprehensive review of the recent advancements in thermal management, commercial applications involving clean energy usage, technical challenges involved, economic and environmental impacts of Concentrated Photovoltaic Thermal systems. Multigeneration Concentrated Photovoltaic Thermal systems are environment-friendly, and the carbon dioxide emission per kilowatt-hour is almost half for concentrating systems compared with photovoltaic systems. The locational and environmental dependency of these systems makes them unattractive for some general applications. For better validation of analytical results, more experimental researches are essential in this area

Solar energy utilization techniques, policies, potentials, progresses, challenges and recommendations in asean countries

Sustainable development goals not only contributes towards a clean environment but also towards better climatic conditions. Within Asia next to China and India, the Association of Southeast Asian Nations (ASEAN) are the actively developing countries in terms of economy and technologies. On the verge of achieving development, the ASEAN countries highly depend on fossil fuels for their energy needs. The ASEAN countries have taken visionary steps towards increasing the renewable energy mix with the conventional grid without hampering the ongoing development; this study presents the solar energy utilization policies, potential, progresses, and challenges adopted in ASEAN countries; furthermore, in these nations there is a huge potential of solar energy being located near the equator, therefore, they should focus on both solar to electrical and solar to thermal energy applications; however, in order to meet the peak demand and ensure the reliability of renewable energy like solar power, the development of advanced energy storage systems could be the key areas, and concrete efforts are required. Therefore, this article is a spotlight on government policies and goals focusing on energy potential, major progress in terms of energy storage and challenges in implementation of renewable energy systems in ASEAN countries; furthermore the recommended highlights on policies to accelerate the exploitation of renewable energy usage among the people are also discussed in detail, besides, the insights on reduction of carbon footprints over the next decade through incorporation of advanced energy storage systems. The issues discussed in this article will be helpful for exploring the desired energy storage systems and energy policies to be followed, which will eventually attract the stakeholders for small and medium-scale entrepreneurs for the development of renewable energy business in the region, if implemented on the ground

Opportunities and challenges in sustainable treatment and resource reuse of sewage sludge: A review

Sludge or waste activated sludge (WAS) generated from wastewater treatment plants may be considered a nuisance. It is a key source for secondary environmental contamination on account of the presence of diverse pollutants (polycyclic aromatic hydrocarbons, dioxins, furans, heavy metals, etc.). Innovative and cost-effective sludge treatment pathways are a prerequisite for the safe and environment-friendly disposal of WAS. This article delivers an assessment of the leading disposal (volume reduction) and energy recovery routes such as anaerobic digestion, incineration, pyrolysis, gasification and enhanced digestion using microbial fuel cell along with their comparative evaluation, to measure their suitability for different sludge compositions and resources availability. Furthermore, the authors shed light on the bio-refinery and resource recovery approaches to extract value added products and nutrients from WAS, and control options for metal elements and micro-pollutants in sewage sludge. Recovery of enzymes, bio-plastics, bio-pesticides, proteins and phosphorus are discussed as a means to visualize sludge as a potential opportunity instead of a nuisance

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo