Air Inlet Angle Research Articles

Experimental Investigation of Heat Transfer and Resistance Characteristics of a Finned Oval-Tube Heat Exchanger With Different Air Inlet Angles

The air inlet flow direction is not orthogonal to the heat exchanger surface in many cases. To study the performance of the heat transfer and pressure drop of a heat exchanger with different air inlet angles, this paper shows the experimental system about a finned oval-tube heat exchanger inclined toward the air incoming flow direction. The heat transfer and pressure drop characteristics of four air inlet angles (90°, 60°, 45°, and 30°) are studied separately for the Reynolds number ranging from 1300 to 13000 in this study. The experimental correlations of Nusselt number and resistance coefficient of the air side are acquired. The results show that the overall heat transfer coefficients become smaller and smaller with the decrease of the air inlet angles, while the pressure drops have significant changes. The heat transfer performances of the heat exchanger under the three inclined air inlet angles are worse than that at 90°. Among the three inclined angles, the performance at 45° is the best under identical mass flow rate criterion and at low Reynolds number under identical pressure drop criterion; that at 60° is the best at large Reynolds under identical pressure drop criterion. Finally, some conclusions are attained about the effects of the air inlet angles on the heat transfer and pressure drop performance of the finned oval-tube heat exchanger.

Experimental study of the effect of air inlet angle on the air-side performance for cross-flow finned oval-tube heat exchangers

An experimental system was built to study the heat transfer and resistance characteristics of two finned oval-tube heat exchangers (HE1: Double rows of tubes, HE2: Three rows of tubes.) inclined towards the air incoming flow direction. Four air inlet angles (90°, 60°, 45° and 30°) are investigated separately to acquire the heat transfer and pressure drop performances for Reynolds number ranging from 1300 to 13,000. The experimental correlations of Nusselt number and resistance coefficient of the air side are obtained, and the comprehensive comparisons of heat transfer performance are carried out. The results show that whether the heat transfer performance for heat exchangers positioned obliquely is improved or not is depended on not only their inclined angles, but also their structures.

Numerical Simulation of 3-D Chemical Non-Equilibrium Flow in the Afterburning Chamber of Solid Ducked Rocket

In order to reveal the complex turbulent combustion processes in the afterburning chamber of Solid Ducked Rocket (SDR), Based on the fundamental equations of hydrokinetics and elementary principles of radical reaction kinetics, using multi-component chemical reaction equation of containing Mg and Al components, the numerical simulation of chemical non-equilibrium flow in the afterburning chamber of SDR is processed and effects of the air inlet angle on the afterburning chamber is studied by using Fluent software. The results show that pressure distribution is more balanced, temperature distribution is very uneven and flow is extremely complicated in the afterburning chamber. Combustion efficiency can be increased by improving the air inlet angle.

Verification of Model Reliability in a Double-Grate Biomass Boiler

A double-grate biomass direct-fired boiler is designed and modified with connected reciprocating grate and oscillation grate based on a 48t/h boiler current operation status. Ribbon and smoke are used in the cold experiments which are based on the reformed hot conditions to verify the model reliability. To have well comparison with the model result, the air ratio and inlet angle of the second air are changed and used to obtain the characteristics of the flow field of the actual grate boiler furnace. And it is the best working condition that the ratio of the air distribution primary air: second air: ignition air is 4: 4: 2, frontwall second air: backwall second air is 5: 5, the inlet angle of the frontwall second air rises 10°, the inlet angle of the backwall second air is in equilibrium position.

On the Use of Venturi Tubes in Aeration

AbstractThe ecological quality of water depends largely on the amount of oxygen that the water can hold. The higher the level of dissolved oxygen, the better the quality of a water system. By measuring dissolved oxygen, scientists determine the quality of water and health of an ecosystem. Oxygen enters water by entrainment of air bubbles. Many industrial and environmental processes involve the aeration of a liquid by such entrainment of air bubbles. Venturi aeration is a method of aeration that has become popular in recent years. When a minimal amount of differential pressure exists between the inlet and outlet sides of a venturi tube, a vacuum (air suction) occurs at the suction holes of the venturi tube. The present paper describes the effect of Reynolds Number, air inlet hole diameter, inlet diameter, pipe length, and angle of pipe downstream of the venturi tube, on the air injection rate. It is observed from the results that venturi tubes have high air injection efficiencies. Therefore, venturi tubes can be used as highly effective aerators in ponds, lakes, fish hatcheries, water treatment plants, etc.

An investigation of design parameter and atomization mechanism for air shrouded injectors

With increasing requirements for the less harmful exhaust emissions and the better fuel economy, the conventional injectors in gasoline engines can be replaced by the air shrouded injector in order to provide improved combustion in engine operations. To find out the optimal shape of air shrouded atomizer attached to the conventional injector nozzle, the critical design parameters such as droplet size, fuel and air inlet angles, and injection angles were investigated based on experimental analyses. To explain the characteristics of fuel atomization, these experimental approaches were carried out using a Phase Doppler Particle Analyzer (PDPA) system. The droplet sizes of injected air fuel mixture were obtained by using the beam diffraction phenomenon. In order to improve the atomization effect, the various atomizers were investigated. The Sauter Mean Diameter (SMD) measured at the predetermined locations outside the atomizer represented the performance of fuel atomization. The experimental results show that the design factors and atomization mechanism needed for developing air shrouded injectors. The suggested design parameters in this paper can be a useful reference in the early design stage.