Engkos A. Kosasih

Effect of Hot Air Reservoir and Insulator Tray in the Development of Vacuum Freeze Drying

The Objective of this work is to know effect of inserting hot air from reservoir to the process of vacuum freeze drying. Tentacle of jelly fish as sample with constant weight 50 g and placed at insulator and teflon container which isolated, the samples were freeze dried with condition at experiment varying between inserting and without inserting hot air at temperature 27°C and also heating from heat loss condenser. The result of experiment shows that while inserting hot air into vacuum freeze drying make pressure rise in until pressure reach 40 mbar. And this phenomena make material evaporation and this event cant be done in vacuum freeze drying. And when without hot air reservoir the pressure can reach 3.5 mbar and the subimation can be done in this process. Vacuum freeze drying process without hot air reservoir need time 12.5 hours and for vacuum freeze drying with hot air reservoir need time 11 hour to drying 50 g of jelly fish tentacle. For process with insulator tray the material can be done in 22,7 hour with internal freezing. From this experiment can be concluded that for vacuum freeze drying with inserting hot air need more ability of vacuum pump specially in flowrate and ultimate vacuum to keep the chamber pressure below triple point condition.

Active technique by suction to control the flow structure over a van model

Today research trend in car aerodynamics are carried out from the point of view of the durable development. Some car companies have the objective to develop control solution that enable to reduce the aerodynamic drag of vehicle. It provides the possibility to modify the flow separation to reduce the development of the swirling structures around the vehicle. In this study, a family van is modeled with a modified form of Ahmeds body by changing the orientation of the flow from its original form (modified/reversed Ahmed Body). This model is equipped with a suction on the rear side to comprehensively examine the pressure field modifications that occur. The investigation combines computational and experimental work. The computational simulation used is k-epsilon flow turbulence model. The reversed Ahmed body used in the investigation has slant angle (φ) 35° at the front part. In the computational work, meshing type is tetra/hybrid element with hex core type and the grid number is more than 1.7 million in orde...

Analysis of water mist density profile for two nozzle interaction using image processing technique

Popularity of water mist is increasing for a variety of applications within the broad areas of fire suppression and surface cooling. The present study has been focused on characterizing the water-mist spray for a nozzle and interaction of two nozzles in a 5 cm distance to each other. Full-cone nozzle were operated at medium operative pressure of 6, 10 and 15 bars with expected volume mean diameter of 110 μm. The aim of these works is to investigate a quantitative description of density profile for a nozzle and interaction of two nozzle employing optical techniques by image processing technique. The main characteristics of the mist spray was defined by using the gray level in certain areas. The measurement indicates that higher throw length can be achieved at higher pressure. In the case of two nozzle interaction, the uniform density profile was identified at shorter distance from the nozzle tip at higher water pressure, and the technique for capturing density profile two nozzle interaction was validated w...