Problem statement: When a vehicle is parked under the direct sun, the accumulated heat is affecting many interiors inside the vehicle cabin, such as the vinyl materials of the dashboard, the leather covers and the electronic components. Also, it represents an uncomfortable operating period for the passengers. The studies under this topic are entitled by the vehicle manufacturers as "Vehicle Cabin Comfort". Approach: In the present study, experimental and numerical analyses were conducted. The experimental results were obtained from measurements on a salon car parked in unshaded area. Six different cases had been investigated consisting of full windows closing case, four different windows opening settings and sun shade usage case. The temperature at 12 different locations inside the car had been recorded for many days and the mean values are used as initial and boundary conditions to run the 3-D computational simulation. The CFD simulation was carried out by FLUENT software. Results: Both experimental and CFD simulation results revealed that the most hot air was accumulated in the top part of the cabin and natural circulation take place with large scale cavity due to natural heat transfer from the dashboard and the rear windshield. The drop down of the front side windows by 20 mm caused reduction in the front air gap by 20%. The sunshade on the front had considerably reduced the heat accumulation inside the cabin, where the dashboard surface temperature dropped by 26% and the maximum air temperature was found to be 27% lower. Conclusion: The use of the sunshade and/or dropdown windows on both sides reduced the heat accumulation due to fresh air exchange with the exterior environment.

Bileaflet mechanical heart valves (BMHVs) are widely used to replace diseased heart valves. However, patients may suffer from implant complications, such as platelet aggregation and damage to blood cells, which could lead to BMHV failure. These complications are related to the blood flow patterns in the BMHV. A three-dimensional computational fluid dynamic (CFD) model was developed to investigate blood hydrodynamics and shear stresses at different cardiac cycles. A user-defined function (UDF) code was developed to model the valve leaflet motion. This UDF updates the tetrahedral mesh according to the location of the valve leaflet, which enables modeling of complicated moving geometries and achieves solution convergence with ease without the need to adjust the relaxation factor values. The agreement between the experimental and numerical results indicates that the developed model could be used with confidence to simulate BMHV motion and blood flow. Furthermore, valve leaflet and valve pivot were found to be continuously exposed to shear stresses higher than 52.3 Pa which according to previous research findings may cause damage to blood platelets.

No abstract

No abstract

The contribution of alkaline/Surfactant/Polymer to the stability of produced crude oil emulsions is neither fully understood nor thoroughly investigated although there have been reports from previous projects that implicate risk produced water treatment. This study focuses on water in oil (w/o) emulsions imposed by ASP flooding for an EOR field in Malaysia to understand the stability of the emulsion layer under typical process conditions. A series of laboratory experiments was conducted to investigate the effects of different ASP concentration that is reported to break through into the separator feed and results in the growth of a rag layer. The samples in the experiments were prepared at 50 °C, 60 °C and 70 °C to represent the temperature range of actual field conditions. Emulsion stabilities were measured at different time from 30 minutes to 24 hours in different time step, depending upon the liberation of water volume fraction. The results demonstrated that ASP concentration plays a significant role in the stabilization of emulsion. The increase in the viscosity due to the presence of polymers, which decreased the rising velocity of oil droplets, and the presence of surfactants, reduced the coalescence of oil droplets. Emulsions were exceptionally stable at high polymer concentration compared with surfactants. However, emulsion stability decreased at low polymer concentrations even in combination with high surfactant concentrations. Among the three components in ASP, polymer induced a higher effect on the stabilization of the emulsion. Moreover, the temperature subsequently affected the instability of the emulsion, in which the destabilization of emulsion which had less amount of surfactant was higher at 70 °C compared with 50 °C and 60 °C. Surprisingly, it is found that increase in temperature had insignificantly affected the destabilization of emulsion containing high amount of surfactant, around 400ppm.

No abstract

In this work, the slug flow regime in an air-water horizontal pipe flow has been simulated using the CFD technique. The variables identified to characterise the slug regime are the slug length and slug initiation. Additionally, the pressure drop and the pressure distribution within the simulated pipe segment have been predicted. The volume of fluid method was employed assuming unsteady, immiscible airwater flow, constant fluid properties and coaxial flow. The model was developed in the STAR-CCM+ environment, and the grid was designed in the three dimensional domain using directed mesh. A grid independency study was carried out through the monitoring of the water velocity at the outlet section. 104,000 hexahedral cells for the entire geometry were decided on as the best combination of computing time and accuracy. The simulated pipe segment was 8 m long and had a 0.074 m internal diameter. Three cases of air-water volume fractions have been investigated, where the water flow rate was pre-set at 0.0028 m 3 /s, and the air flow rate was varied at three dissimilar values of 0.0105, 0.0120 and 0.015 m 3 /s. These flow rates were converted to superficial velocities and used as boundary conditions at the inlet of the pipe. The simulation was validated by bench marking with a Baker chart, and it had successfully predicted the slug parameters. The computational fluid dynamics simulation results revealed that the slug length and pressure were increasing as the air superficial velocity increased. The slug initiation position was observed to end up being shifted to a closer position to the inlet. It was believed that the strength of the slug was high at the initiation stage and reduced as the slug progressed to the end of the pipe. The pressure gradient of the flow was realised to increase as the gas flow rate was increasing, which in turn was a result of the higher mean velocity.

No abstract