Numerical Study on Natural Ventilation Characteristics of a Partial-Cylinder Opening for One-Sided-Windcatcher of Variable Air-Feeding Orientations in Taif, Saudi Arabia

To provide a clean and cheap source of natural ventilation in windy and arid zones, a windcatcher facility is the best option. This paper aims to study the effect of the inlet opening angle of a new windcatcher model with different values ranging from 60° to 90° for three different feeding orientations at leading-down, central-up, and trailing-down locations. The ventilation performance of the new one-sided windcatcher is numerically examined using CFD simulations, where the 3D RANS and k-epsilon equations are applied at different wind speeds. The flow features of the new models are analyzed and compared with a basic traditional model based on the induced air distribution, aerodynamic losses, and ventilation rates. Results revealed that the sharp edge of the inlet opening leads to an increase in the flow separation and recirculation zone, especially when the opening angle is increased. The highest pressure coefficient is achieved by the trailing-down model compared with the other windcatcher models at an opening angle of 90°. The total pressure drop and ventilation rates increase in all the new windcatcher models due to the increase in the opening angle from 60° to 90°. At identical conditions, with an opening angle of 90° and wind speed of 5 m/s, the trailing-down model achieved a higher pressure coefficient than the leading-down and central-up models by 20.55% and 37.37%, respectively. Furthermore, the trailing-down model could provide higher ventilation rates than the central-up and leading-down models by 31% and 42%, respectively. Finally, the trailing-down windcatcher model can be recommended as the best choice to provide natural ventilation at Taif City in Saudi Arabia.

HYDRAULIC JUSTIFICATION FOR THE OPERATION OF THE DEVICE FOR ALLUVIATION OFNARROW-PROFILEDAMS

The construction of protective dams is the most effective means of combating flooding. There are various ways to build protective dams. The alluvial method of constructing protective dams can significantly reduce the cost of their construction. The article describes a method and device for alluvial narrow-profile dams that allows the use of bottom sediments as a building material. The method includes clearing the riverbed from bottom sediments with dredging operations,improving the fl ow capacity during floods. The work is carried out by a dredger and the developed soil in the form of pulp is delivered to the alluvial device. The alluvial device ensures the separation of large fractions of soil from the general flow of pulp and allows the formation of a narrow-profile dam with stable slopes and an antifiltration core. The article offers hydraulic calculations that allow us to justify the design and technological parameters of the method and device for alluvial narrow-profile dams: the values of the fl ow rate and the average speed of the pulp movement in the distribution unit of the device are determined; the dimensions of the inlet opening of the bell are justified; the time of alluvium of one map is determined; the number of outlet openings in the distribution slurry pipelines is justified and their location is specified. Nomograms are constructed that allow us to determine the optimal modes of alluvial dams – the length of the pulp pipeline, the height of the pulp rise, and the time of fi lling the alluvial map.

Optimization study on Electrical Enclosure with Forced Convection cooling using Computational Fluid Dynamics

Any electronic walled in area comprises of heat creating electronic components, as heat produced by the electronic parts in a fenced in area decreases the life of electronic segments prompting serious harm or disappointment of the framework. Research shows that each 10°c rise above room temperature of the enclosure, the life of the electronic parts decreases. Thus for any electronic frameworks, cooling turns into a significant structure interest, practical and ideal answer for hold the electronic parts to its working limit. Therefore, in the present work CFD simulation has been carried out using ANSYS Fluent by considering a typical Aluminum Electrical enclosure of volume (150mm X 600mm X 250mm) with total internal heat dissipation of 84W. With those values into consideration the surface area of enclosure, enclosure temperature rise, air flow requirement in an enclosure is calculated and based on which the fan is selected. Also optimization study has been carried out by changing the inlet opening position, exhaust fan location and providing baffle at inlet opening location. The results obtained from analysis are validated with analytical results.

A Study on the Thermal Performance of Air-Type BIPVT Collectors Applied to Demonstration Building

Research on existing air-type PVT (photovoltaic/thermal) collectors has mainly focused on improving the efficiency of the collector itself and on using the energy produced by the collector in heating and cooling facilities and building energy. The first consideration in an air-type PVT system applied to a building facade is the collector arrangement and the flow path considering the collector performance. It is necessary to design the flow inside the air-type BIPVT (building integrated photovoltaic/thermal) collector so that it runs smoothly so as not to cause a dead space and a pressure drop inside the collector, which deteriorate the thermal performance. This study analyzed the thermal characteristics of an air-type BIPVT collector applied to a demonstration building (educational buildings) according to the air flow path and inlet opening ratio. For this purpose, the uniformity of the airflow in the collector was compared through the NX computational fluid dynamics (CFD) program, and the acquired thermal calories and thermal efficiency of the BIPVT collector were compared and analyzed. Based on the simulation results, the temperature and thermal characteristics of the BIPVT collector were compared.

Effect of Inlet Location on Ventilation Flow Through a Room Fitted With Solar Chimney

Solar chimney (thermal chimney) is a device which absorbs solar radiation to heat the air. The heated air, becoming buoyant, rises through the chimney’s passage and induces further air currents. When fitted to a building, solar chimney can thus induce fresh outside air to flow through the building for ventilation. Because only natural means (solar radiation here) are involved to cause the air flow, solar chimney is considered a natural-ventilation device. This work investigates computationally natural ventilation induced by a roof-mounted solar chimney through a real-sized 3-dimensional room, using a commercial CFD (Computational Fluid Dynamics) software package which employs the Finite Volume Method. Chien’s turbulence model of low-Reynolds-number K-ε is used in a Reynolds-Averaged Navier-Stokes (RANS) formulation. Computational domain that includes regions outside the room’s inlet opening and chimney’s exit allows for employing realistic boundary conditions for the computational model. Ventilation rate and air-flow pattern through the room are considered in terms of the location of the room’s inlet opening. It is found that while ventilation flow-rate through the room is higher with the room-inlet opening being located high on the wall opposite to the chimney’s entrance, a room-inlet opening being located near the ground results in better flow pattern with more flow through the living area in the lower part of the room.