Efficiency, energy and economic analysis of twisted tape inserts in a thermosyphon solar flat plate collector with Cu nanofluids

Heat transfer, friction factor and efficiency of a thermosyphon type flat plate collector with and without twisted tape inserts were analyzed experimentally. Water based Cu nanofluids were used as the absorber fluid to receive the heat from solar radiation into the flat plate collector. The experiments were conducted for volume concentrations of 0.1% and 0.3% and twist ratios of H/D = 5, 10 and 15. Results reveal that the heat transfer rate and efficiency of nanofluids increase with the increase of particle volume concentrations. The Nusselt number of 0.3% nanofluid is enhanced up to 20.46%, and it is further enhanced up to 46.90% with twisted tape insert of H/D = 5 with a maximum friction factor penalty of 1.477-times compared to plain collector. The efficiency of the solar collector with water is 52% and it is enhanced to 58% for 0.3% nanofluid, whereas it is further enhanced to 64% for 0.3% nanofluid with twisted tape insert of H/D = 5. Empirical correlations are proposed based on the experimental data for the friction factor and Nusselt number with a standard deviation of less than ±6.5%. The study indicates that for 100 units of solar flat plate collector the use of 0.1% and 0.3% Cu nanofluids leads to weight savings of 284 kg and 567 kg, respectively. The total weight of 100 units of solar flat plate collector is further saved by 767 kg, 1050 kg and 1250 kg for 0.3% nanofluid with twisted tape inserts of H/D = 15, H/D = 10 and H/D = 5, respectively. The collector cost is reduced by 5.66% and 11.33% for 0.1% and 0.3% nanofluids, and it is further reduced to 25% for 0.3% nanofluid with a twisted tape insert of H/D = 5.publishe

The Cobalt Oxide-Based Composite Nanomaterial Synthesis and Its Biomedical and Engineering Applications

The magnetic nanoparticles (NPs) are offering a wide range of applications in medical and engineering fields. Among all the magnetic nanoparticles, cobalt oxide (Co3O4) nanoparticles and its composite-based nanoparticles are attracting more interest from researchers because of its unique mechanical, thermal, and magnetic properties. The aim of this book is to bring together a number of recent contributions regarding the cobalt oxide-based composite nanoparticles from several researchers all over the world. The latest research results, innovations, and methodologies are reported in the book in order to support the discussion and to circulate ideas and knowledge about the applications of these materials in medical and engineering applications. This chapter presents the methodology for the synthesis and characterization and applications of cobalt oxide-based composite nanoparticles. The detailed analysis related to toxicity of these nanocomposite materials is also included in this book chapter

Combination of Co3O4 deposited rGO hybrid nanofluids and longitudinal strip inserts: thermal properties, heat transfer, friction factor, and thermal performance evaluations

The reduced-graphene oxide/cobalt oxide hybrid nanoparticles were prepared based on the in-situ/chemical co-precipitation technique, and they were analyzed by transmission electron microscope, x-ray diffraction, and magnetometer techniques. The hybrid nanofluids were prepared with particle loadings of 0.05%, 0.1%, and 0.2% by dispersing synthesized reduced-graphene oxide/cobalt oxide in distilled water and their physical properties were measured. The thermal performance of the nanofluids was studied, when they flow in the turbulent regime through a circular tube. The thermal performance was also evaluated when straight (longitudinal) strip inserts with aspect ratios of 1, 2, and 4, were used inside the circular. These straight strip inserts by increasing the flow turbulence intensity act as turbulators. Results indicate that with a dilution of 0.2% concentration of hybrid nanoparticles in water, the Nusselt number is enhanced by 25.65%, and it is further enhanced by 110.56% with a straight strip insert of aspect ratio 1. The use of hybrid nanofluids and straight strip inserts leads to a slight penalty in fluid friction. For 0.2% concentration of hybrid nanoparticles in water, the penalty in friction factor is 11%, and it is further increased to 69.8% with 0.2% particle loadings and a straight strip insert of aspect ratio1. Moreover, the thermal performance factor of hybrid nanofluids with and without straight strip inserts presents values higher than 1, which shows the benefit of the prepared hybrid nanofluids in a turbulent flow. A general form of regression equations are developed based on the experimental data.publishe

Solar energy absorbed thermosyphon flat plate collector analysis using Cu/H2O nanofluid – an experimental study

An experimental investigation was conducted aiming to determine the heat transfer, friction and instantaneous collector thermal efficiency of a thermosyphon (natural circulation) solar water heating system using as working fluids of water and the Cu/H2O nanofluid. The Cu nanoparticles were synthesized using the chemical reduction method and characterized by the x-ray diffraction and transmission electron microscopy techniques. The stable Cu/H2O nanofluid was prepared for the volume concentrations of 0.1% and 0.3%. The empirical correlations developed for Nusselt number and friction factor for the Cu/H2O nanofluid fit the experimental data with a deviation of less than ±3.5% and ±2.5%, respectively. The results of present experimental investigation were presented at various Reynolds number and particle volume concentrations under thermosyphon conditions. The comparison indicates that the heat transfer enhancement obtained with the Cu/H2O nanofluid for the thermosyphon is higher than that for the plain tube collector and increases with the increase of particle volume concentration. The overall thermal performance of the thermosyphon increases when the operating fluid is Cu/H2O nanofluid as compared to water.publishe