CFD study to improve PV cell performance by forced air: Modern design

A theoretical study was conducted on the performance of photovoltaic cells by forced airflow on the cell base. The study was conducted using numerical simulation software (ANSYS- cfx) to select the best model for its manufacture. The simulation results showed that the air guides model is the best, directing the largest amount of air to the base of the cell and the lowest cost and available in local markets. Air guides shall be installed inside an aluminum channel fixed to the bottom of the cell base and the channel dimensions shall be selected according to the dimensions of the photovoltaic cell to be cooled. A numerical study determine the best number and best location of the air guides inside the duct channel and the tilt angle of air guides and showed that the optimum number of pneumatic guides is (18) in a position (70 mm) from the base of the channel and at a 45-mile angle with the horizon

Improving building energy efficiency through ventilated hollow core slab systems

The increasing desire for comfort and healthy indoor environment, as well as improvements in energy standards in recent years, have stressed the need to make an active use of the building mass to achieve the maximum energy saving This is why the application of ventilated hollow-core slab systems (VHCS) can be considered as one of the innovative approaches. These systems have precast concrete slabs with tubular voids directing ventilation air on its length. In the present study Solving this system numerically using the ANSYS fluent program to study the temperature distribution and air flow in the 3-D test model of the present study to determine the feasibility of applying this system in an arid climate especially in Iraq by checking the inlet velocity and temperature and to predict the impact of these operating parameters on human comfort and energy savings. The study aimed to provide a numerical analysis of a conditioned zone's temperature distribution using VHCS. The investigation was carried out on a scale model room of size (1 m × 1.2 m × 1 m) with a scale factor of ¼. Four distinct scenarios were examined: the first two cases occurred during a no-load time in the night when there were no internal or external loads and examined the effects of changes in inlet temperatures and air velocities. The remaining two scenarios were conducted during an occupied period with internal heat gain of 630 W/m2 and external heat gain of 800 W/m2 based on the SHGC for the summer season of Iraq. As previously demonstrated, setting the inlet velocity to 1 m/s resulted in an optimal temperature and velocity distribution in the main flow, irrespective of changes in the external and internal loads and temperatures of the supply core. The findings shown that input air velocity and temperature affect heat remove efficiency. In addition, numerical outcomes have also illustrated that the Thermal Active VHCS System, while used in combination with ventilation strategies, could indeed regulate the space conditions by cooling down the building's ceiling, thus eradicating stored heat. All investigations found VHCS systems suitable for air conditioning in dry and hot locations. The systems are known for their ease of use, simplicity, high performance, comfort, and energy savings. They can also reduce peak loads to boost structural energy efficiency

Model to identify comfortable cloth fabric for human body during thermal stress due to physical exercise

Physical exercise enhances heat generation in human skin and subcutaneous tissues causing thermal stress. This thermal stress causes discomfort in the human body and deteriorates the physical performance of the human subjects. Appropriate choice of cloth for outer covering of human body is necessary to prevent this to provide comfort during the thermal stress. A mathematical model is proposed in this study to analyze the thermal stresses in human skin and subcutaneous tissues covered with various different cloth fabrics. The model considers four compartments namely cloth, epidermis, dermis, subcutaneous tissues. The bioheat equation along with appropriate boundary condition is employed in this model for one dimensional unsteady state case. The numerical simulation is performed using forward and central finite difference formulas. The findings have been utilized to examine how different types of fabric impact thermal stress experienced by the layers of human skin during physical activity. The polyester is found to be superior in comparison to cotton fabric as it shows less thermal stress and thus can be concluded to be more comfortable as a dress material