Experimental thermal performance of deionized water and iron oxide nanofluid for cold thermal storage.

Phase change materials enhance the thermal comfort of buildings by utilizing stored thermal energy. In large air-conditioning systems, ice storage plays a crucial role in managing peak power loads. This experimental study explores the freezing characteristics of deionized water containing suspended iron oxide nanoparticles in spherical containers for cold storage. The synthesized nanofluid phase change material (NFPCM) was investigated for its freezing behavior under surrounding fluid temperatures of - 2 °C and - 6 °C. The uniformity in charging of NFPCM is the unique feature prevalent in the first quarter of the charging, with 50% mass frozen observed. An increased surface heat flux of 200% was achieved using NFPCM at Tsurr = -6 °C. The chiller operational time is optimally reduced by 75% by considering twice the container design's phase change materials. Adding iron oxide nanoparticles and partial charging is suitable for uniform heat transfer for the shorter freezing duration in cooling applications. The novelty of the present study is that the proposed NFPCM nearly nullifies the subcooling effects of deionized water without using nucleating agents. This NFPCM appreciably enhances power competence, yielding large-scale air-conditioning systems' desired economic impact and sustainability. The reported results align with Sustainable Development Goals (7-Affordable and Clean Energy and 13-Climate Action).

Experimental performance and economic analysis of finned solar receiver for parabolic dish solar collector.

The solar receiver is a vital component of concentrated solar collectors that absorbs solar radiation and converts it into heat. One of the challenges the research community faces is minimizing heat loss from the receiver at higher temperatures to maximize the thermal performance of parabolic dish collectors and achieve the system's cost-effectiveness. Cavity receivers have a complex design that makes them more challenging to manufacture and entails higher costs for improved thermal performance. Implementing innovative receiver designs is essential to maximize the absorption of solar radiation and minimize heat losses. In this experimental study, a cost-effective solar receiver was fabricated with fins to study heat transfer. The solar receiver is examined using water as heat transfer fluid with three flow rates of 0.097 kg/s, 0.125 kg/s, and 0.152 kg/s. The residence time of water is increased by adopting integrated fin receiver designs. The provision of fins in the solar receiver enhances heat transfer by increasing the turbulence in the fluid flow and results in higher thermal efficiency. The average energy and exergy efficiencies are 67.81 % and 8.93 %, respectively, with a 0.152 kg/s flow rate. At the highest water flow rate (0.152 kg/s) considered in this study, a lesser heat loss of about 3776.2 W occurred due to the effective heat transfer. The cost metrics, like levelized cost of electricity, net present value, and the payback period, are about 0.21 $/kWh, 923 $, and 3.38 years, respectively, at 0.152 kg/s flow rate. The proposed solar receiver produces optimal thermo-economic performance and lower initial investment for steam generation than other receiver designs. The current experimental study's findings could benefit the entire solar industry by presenting an effective solar receiver design for solar collectors.

Energy and enviro-economic analysis of a solar air heater with wedge turbulators.

Solar air heaters (SAH) convert solar energy to thermal energy for food processing industries and commercial space heating applications, as solar energy is cost-free. In this experimental study, the thermal performance of the solar air heater has been successively improved using different roughness elements over the absorber. The triangle-shaped wedges in three structures (inline, serpentine, and clustered structure) are investigated in this work. Thermal performance comparison is made with a SAH with a plain absorber. A maximum air temperature rise of 19 °C is observed for the SAH with wedges in a clustered structure. The absorber surface temperature for clustered structured roughness elements is 76.8 °C with an average heat loss coefficient of 4.43 W/m2·K. The useful heat absorption using clustered structure wedges is 33%, 17.9%, and 6.6% higher than the SAH with plain, inline, and serpentine structured wedges. SAH's maximum thermal and exergy efficiency with clustered structured elements is 70.4% and 1.64%. The average thermal efficiency of inline, serpentine, and clustered arrangement is 13.3%, 25.3%, and 35.6% higher than the SAH with a plain absorber. The proposed SAH design shows a sustainability index 1.01, and lower payback periods show economic and environmental viability.

A review of emergent intelligent systems for the detection of Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder affecting people worldwide. The PD symptoms are divided into motor and non-motor symptoms. Detection of PD is very crucial and essential. Such challenges can be overcome by applying artificial intelligence to diagnose PD. Many studies have also proposed the implementation of computer-aided diagnosis for the detection of PD. This systematic review comprehensively analyzed all appropriate algorithms for detecting and assessing PD based on the literature from 2012 to 2023 which are conducted as per PRISMA model. This review focused on motor symptoms, namely handwriting dynamics, voice impairments and gait, multimodal features, and brain observation using single photon emission computed tomography, magnetic resonance and electroencephalogram signals. The significant challenges are critically analyzed, and appropriate recommendations are provided. The critical discussion of this review article can be helpful in today's PD community in such a way that it allows clinicians to provide proper treatment and timely medication.

Experimental study of the thermal performance of heat storage-integrated solar receiver for parabolic dish collectors.

Parabolic dish collectors (PDC) efficiently produce hot fluids for medium-temperature applications. Thermal energy storage employs phase change material (PCM) due to its high energy storage density. This experimental research proposes a solar receiver for the PDC with a circular flow path surrounded by PCM-filled metallic tubes. The selected PCM is a eutectic mixture of KNO3 and NaNO3 (60%:40% by wt). At a peak solar radiation of about 950 W/m2, the receiver surface reached a maximum of 300 °C. The modified receiver is tested outdoors with water as a heat transfer fluid (HTF). The energy efficiency of the proposed receiver is about 63.6%, 66.8%, and 75.4% for the HTF at 0.111 kg/s, 0.125 kg/s, and 0.138 kg/s, respectively. The receiver's exergy efficiency is recorded at about 8.11% at 0.138 kg/s. The receiver with a maximum reduction of CO2 emission is about 1.16 tons recorded at 0.138 kg/s. The exergetic sustainability is analyzed using key indicators, like the waste exergy ratio, improvement potential, and sustainability index. The proposed receiver design with PCM effectively produces maximum thermal performance with a PDC.

Review of physicochemical properties and spray characteristics of biodiesel.

The United Nations Sustainable Development Goals by 2030 deal with seventeen goals for the planet's sustainability. The present review focuses on affordable and clean energy through the effective combustion of fuels with minimal pollution. Effective fuel spray characteristics are essential for combustion among various parameters and fuel properties. The inherent nature of the fuel has a functional relationship with the injection and injectors' conditions. Therefore, the study of fuels' physicochemical properties is essential. This review deals with the spray characteristics of biodiesel. Biodiesels in its purest form and blended with diesel, di-n-butyl ether, dimethyl ether, diethyl ether, ethanol, and butanol are considered for the study. The physicochemical properties of biodiesels, injection conditions, and injector constraints are analyzed to understand the spray process. The atomization features such as spray tip penetration, Sauter mean diameter, spray cone angle, spray area, and spray volume are analyzed. The chemical properties of biodiesel are utilized to describe the spray's transient behavior. In addition, supporting systems for spray diagnostics and models are also discussed. The highlighted significant spray challenges features and future research direction benefit the fuel and combustion community.

A case study on the effect of light and colors in the built environment on autistic children's behavior.

Background: The importance of strategies and services by caregivers and family members substantially impact the psychological and emotional wellbeing of autistic children. The rapid research developments in clinical and non-clinical methods benefit the features of autistic children. Among various internal and external factors, the influence of the built environment also impacts the characteristics of autistic children. This study investigates primarily the psychological effect of light and colors on the mood and behavior of autistic children to identify the most favorable and preferred indoor lights and color shades. Methods: A questionnaire survey was conducted at an autism center among autistic children and their parents. This study included autistic children aged between 6 and 16 (45 males, 42 females, mean age 8.7 years, standard deviation 2.3). Eighty-seven participants were involved in the survey to determine the sensory perceptions, intolerance, preferences, and sensitivities of children with an autism spectrum disorder toward colors and lighting. The margin of error at the statistical analysis's 95% confidence level is ± 0.481. Results: As per this case report, the children have various color preferences and respond differently to different shades. Different hues have varying effects on autistic children, with many neutral tones and mellow shades proven to be autistic-friendly with their calming and soothing effect, while bright, bold, and intense colors are refreshing and stimulating. The stimulus of bright-lighting causes behavioral changes in autistic children prone to light sensitivity. Conclusion: The insights gained from this interaction with parents and caretakers of autistic children could be helpful for designers to incorporate specific autistic-friendly design elements that make productive interior spaces. A complete understanding of the effect of factors like color and lighting on the learning ability and engagement of autistic children in an indoor environment is essential for designers and clinicians. The main findings of this study could be helpful for a designer and clinicians to address designing an autism-friendly built environment with a color palette and lighting scheme conducive to their wellbeing and to maximize their cognitive functioning.

Experimental performance enhancement of a flat plate solar collector using straight and twisted flow inserts.

The thermal performance of a flat plate solar collector (FPSC) is limited minimum due to higher heat loss of the collector and poor heat exchange with the heat transfer fluid. The current study investigates the effect of single-slit twisted tape (TT), double-slit TT, and double-slit straight tape passive-insert devices on enhancing the heat transfer of the FPSC at a constant water flow of 0.025 kg/s. Double-slit inserts have a higher heat transfer area and reduced hydraulic diameter than conventional single-slit TT inserts. The double-slit TT insert creates more fluid mixing and turbulence in the flow than a single-slit TT. The convective heat transfer coefficient for double-slit TT, single-slit TT, and the double-slit straight insert is 47.7%, 26.9%, and 8.7% higher than FPSC with the plain absorber. Double-slit TT inserts are observed with improved energy and exergy efficiency by 23.9% and 46.2% compared to conventional collectors without a flow insert. The average energy efficiency of FPSC without inserts is 48.2%, whereas the double-slit TT is 66.5%. The pressure drop is higher for the collector with inserts than for the collector without inserts, which leads to a little more pump power. Thus, passive inserts help to augment heat transfer in the FPSC.

Experimental performance of a finned spherical container in cold thermal storage for tropical buildings.

The heating and cooling of buildings consume almost 40% of global energy consumption. Cooling building spaces require more input energy compared to heating in tropical buildings. The power tariff varies according to the base and peak demands. This research mainly minimizes peak electricity demand by operating cold thermal storage using deionized water as a phase change material (PCM). The experimental work investigates the partial charging of deionized water in an internally finned stainless steel spherical container immersed in a constant temperature bath. Encapsulated PCM is tested with constant bath temperatures of - 6 ℃, - 9 ℃, and - 12 ℃. Radial copper fins with a diameter of 3 mm are attached inside the container. The selected fin lengths are 7.5 mm, 13.5 mm, and 19.5 mm. The fin length of 13.5 mm is significantly reducing the freezing period. An effective reduction in the charging duration of 52% is observed at - 6 ℃ bath temperature. Partial charging is recommended by incorporating twice the amount of PCM in the design stage and utilizing 50% freezing during operation to achieve up to 52% energy savings. Therefore, the current findings help design effective cold storage for large-scale air-conditioning in buildings.

Experimental thermal performance and enviroeconomic analysis of serpentine flow channeled flat plate solar water collector.

The thermal performance of a flat plate solar water collector (FPSWC) depends on the amount of solar energy absorbed by the absorber, the quantity of heat transferred to the heat transfer fluid (HTF), and the fluid residence time in the collector. In this real-time experimental study, the thermal efficiency of the serpentine flow channeled FPSWC is compared with that of a conventional collector. The heat transfer coefficients (HTC) and heat loss coefficients of both configurations are evaluated at three different water mass flow rates (0.0083 kg/s, 0.0167 kg/s, and 0.025 kg/s). The results show that the serpentine flow channeled collector offers higher energy and exergy efficiencies of 78.9% and 6.47%, respectively, at a mass flow rate of 0.025 kg/s due to the continuous surface contact of the HTF with the absorber plate. The conventional collector yields energy and exergy efficiencies of 66.28% and 4.58%, respectively, at similar operating conditions. The peak HTC of the serpentine flow collector is 210 W/m2K, which is 27.3% higher than that of the conventional collector at a maximum flow rate. The maximum HTC is observed at a higher mass flow rate and lower absorber temperature. The heat loss increases when solar radiation intensity increases; the HTC reaches its peak value at the maximum solar radiation intensity. The proposed collector shows a cleaner production of hot water with a lower payback period when compared to a conventional collector, as evident from the enviroeconomic analysis. The findings can contribute to more successful deployments of solar thermal systems.

Experimental study on the electrical performance of a solar photovoltaic panel by water immersion.

The decreased efficiency of a photovoltaic panel due to temperature rise during high solar radiation is one of the major drawbacks. The efficiency drop is due to hotness, which restricts the conversion of incident sun rays into electricity by the silicon cells. Thus, a photovoltaic panel has a negative temperature coefficient that increases the current but drops the voltage potential. In this work, water immersion cooling of the photovoltaic panel is studied to improve panel performance. The module is studied with and without water immersion in a tank made up of acrylic material. The photovoltaic (PV) efficiency is determined at different depths of water immersion (10 to 40 mm) inside the acrylic tank. The solar radiation and thermal and electrical parameters of PV are observed at an interval of 60 min, and besides, the solar radiation is also measured. The electrical efficiency without immersion is about 14.24% at solar radiation of about 725 W/m2. The photovoltaic panel was observed at a temperature of around 30 °C during the water immersion. The panel efficiency with an immersion depth of 10, 20, 30, and 40 mm is approximately 15.02%, 15.54%, 14.58%, and 13.95%, respectively. The results show that the immersion of PV panels in tap water 20 mm increases the PV efficiency by 9.1% compared to the PV without water immersion. The presented experimental results are beneficial to the solar community to improve the PV performance without external power.