Geometrical study of ventilation system openings of pump room in nuclear power plant

Fire safety is important throughout the lifetime of nuclear power plant (NPP), from design to construction throughout plant operation. The integrity of the shutdown cables located in the pump room in NPPs is very important in the fire protection system. Therefore, the present numerically study investigates the effect of outlet vent opening geometry and the location of the ventilation system specifications on the heat transfer in pump room during a fire. Three-dimensional ANSYS- FLUENT Computational Fluid Dynamics with Realizable k–ε turbulence model is employed in the present work. The results found that the geometry (aspect ratio) of the outlet opening vent has major effects on the shutdown cable protection from fire according to their locations. Furthermore, as the aspect ratio for outlet vent decreases, then the suction of hot gasses from the upper half of the room is improved. Consequently, the temperature of the heat source and target decreases. When the two inlet and outlet vents are located at a same lower level from the ground the inlet velocity should be 1.25 m/s, while, when the two vents are located at two different level the inlet velocity should be 0.75 m/s in order to protect the shutdown cable insulation. Keywords: Nuclear power plant, Numerical, CFD, Pump room, Vents location

Enhancing the performance of photovoltaic panels by water cooling

The objective of the research is to minimize the amount of water and electrical energy needed for cooling of the solar panels, especially in hot arid regions, e.g., desert areas in Egypt. A cooling system has been developed based on water spraying of PV panels. A mathematical model has been used to determine when to start cooling of the PV panels as the temperature of the panels reaches the maximum allowable temperature (MAT). A cooling model has been developed to determine how long it takes to cool down the PV panels to its normal operating temperature, i.e., 35 °C, based on the proposed cooling system. Both models, the heating rate model and the cooling rate model, are validated experimentally. Based on the heating and cooling rate models, it is found that the PV panels yield the highest output energy if cooling of the panels starts when the temperature of the PV panels reaches a maximum allowable temperature (MAT) of 45 °C. The MAT is a compromise temperature between the output energy from the PV panels and the energy needed for cooling