Exergy Analysis of a Flat Plate Solar Collector in Combination with Heat Pipe

ABSTRACT: The use of solar collectors in combination with heat pipes is rapidly growing in recent years. Heat pipes, as heat transfer components, have undeniable advantages in comparison with other alternatives. The most important advantage is their high rate of heat transfer at minor temperature differences. Although there have been numerous studies on the heat analysis or first thermodynamic analysis of flat plate solar collectors in combination with heat pipes, the exergy analysis of these collectors is needed to be investigated. In this work, energy and exergy analysis of a flat plate solar collector with a heat pipe is conducted theoretically. Next, the exergy efficiency of pulsating heat pipe flat plate solar collectors (PHPFPSC) is compared with conventional collectors by using the experimental data. The results indicate that the use of heat pipes for heat transfer from the absorption plate to the water reservoir has significantly higher availability and exergy efficiency than the case with conventional collectors with intermediate fluid

Numerical Study of Ferrofluid Forced Convection Heat Transfer in Tube with Magnetic Field

This research study presents a numerical study on forced convection heat transfer of an aqueous ferrofluid passing through a circular copper tube in the presence of an alternating magnetic field. The flow passes through the tube under a uniform heat flux and laminar flow conditions. The primary objective was to intensify the particle migration and disturbance of the boundary layer by utilizing the magnetic field effect on the nanoparticles for more heat transfer enhancement. Complicated convection regimes caused by interactions between magnetic nanoparticles under various conditions were studied. The process of heat transfer was examined with different volume concentrations and under different frequencies of the applied magnetic field in detail. The convective heat transfer coefficient for distilled water and ferrofluid was measured and compared under various conditions. The results showed that applying an alternating magnetic field can enhance the convective heat transfer rate. The effects of magnetic field, volume concentration and Reynolds Number on the convective heat transfer coefficient were widely investigated, and the optimum conditions were obtained. Increasing the alternating magnetic field frequency and the volume fraction led to better heat transfer enhancement. The effect of the magnetic field in low Reynolds numbers was higher. The results showed that the modeling data were in a very good agreement with experimental data. The maximum error was around 10%