This paper studied the stack effect in courtyards in buildings through the pressure difference between the top and the bottom in the courtyard through three-dimensional (3D) numerical simulations, which would provide engineering guidance for the fire protection design of courtyards in buildings. During the fire, the stronger the stack effect was, the pressure difference between the top and the bottom was more significant, the fire smoke reached the top of the courtyard more quickly, and the temperature and the smoke concentration at the top were influenced in a shorter time. The influence of the size of the courtyard in the stack effect was investigated. It was found that the stack effect was linearly negatively related to the width of the cross section W and the length of the cross section L, exponentially negatively related with the area of the cross section A, while it was exponentially positively related to the height of the courtyard H. The change in the walls without windows (W) affected ΔP max and the stack effect more significantly compared with the change in walls with windows (L). When L/W ≤ 1, the stack effect was strengthened as L/W increased; when L/W > 1, the stack effect was weakened as L/W increased. The stack effect was the most significant when L/W = 1.

This investigation deals with buoyancy-induced convection of air in an open-cell aluminum foam under different orientations. Metal foam samples with a porosity of 93% and pore densities of 2, 4, 8, and 16 pores per cm (PPC) were used. The average heat transfer coefficient was determined for several values of the angle of inclination of the base plate, ranging from the vertical to the horizontal, with the foam facing upwards as well as downwards. The heat transfer coefficient was found to depend on the pore density, the thickness of the foam, the orientation of the base plate, and the difference in temperature between the base plate and the ambient. In all cases, the average heat transfer coefficient was found to be higher than that of the base plate without the foam. For a given angle of inclination and foam thickness, the thermal performance of samples with lower pore density was found to be superior. Two empirical correlations for predicting the effective Nusselt number have been proposed, one for the cases where the foam faces upwards and the other for cases where the foam faces downwards, relating the Nusselt number to Rayleigh number, Darcy number, the ratio of the thickness of the foam to the length of the square base plate and the angle of inclination from the vertical in the range of −90 deg (foam facing down) to +90 deg (foam facing up). The correlation predictions were found to match with experimentally determined Nusselt numbers within ±5% when the Rayleigh number ranged from 2500 to 6500.

The effectiveness of the smoke control strategy plays an important role in increasing safety levels when fire accidents occur in road tunnels. This paper introduces clarifications about how the efficiency of smoke extraction control using solid curtains can be increased by placing smoke extraction vents close to the solid curtains. The effect of adding a solid curtain with different heights and at various positions relative to a smoke extraction vent was studied in this paper. A 14.3% increase in the vent flowrate occurs at the time corresponding to the fire peak heat release rate when the distance between the solid curtain and the vent is equivalent to 90% of the tunnel height and when the solid curtain height is equal to 16% of the tunnel height. High temperature and low visibility conditions occur near the solid curtain at the smoke-trapped area when the smoke curtain height exceeds 40% of the tunnel height. Using a solid curtain positioned far away from the vent with a distance equals to 90% of the tunnel height and with a height in the range from 16% to 30% of the tunnel height achieves the best results in terms of suppression of smoke spread and attaining acceptable visibility and temperature levels at the region where the smoke is trapped by the solid curtain.

Fire accidents in road tunnels can form a great danger in the life of people if the evacuation process does not happen effectively. This paper introduces a numerical investigation of fire and evacuation analysis in a road tunnel and provides important insights into the conditions that people are exposed to during evacuation. The fire was assumed to originate from a bus with a fire size of 30 MW at the moment corresponding to the peak heat release rate. Results including smoke distribution, visibility distribution, paths of people during evacuation, people existence density, and people speed are presented and analyzed. One of the important findings of this paper is the estimation of the time available for people to evacuate safely before the approach of the smoke layer to the occupation zone causing deterioration of the visibility values. The discussion introduced a clarification of the connection between the time of exposure to smoke, people speed, and smoke propagation speed. Results showed that the time of exposure to smoke during evacuation can be significantly increased if the fire size is increased especially for persons located within 15 m from the fire location and take more than 2 min to take the decision of evacuation.

Vegetable oil is considered as one among the promising alternatives for diesel fuel as it holds properties very close to diesel fuel. However, straight usage of vegetable oil in compression ignition (CI) engine resulted in inferior performance and emission behavior. This can be improved by modifying the straight vegetable oil into its esters, emulsion, and using them as a fuel in CI engine showcased an improved engine behavior. Waste cooking oil (WCO) is one such kind of vegetable oil gained a lot of attraction globally as it is generated in a large quantity locally. The present investigation aims at analyzing various parameters of single cylinder four stroke CI engine fueled with waste cooking oil biodiesel (WCOB), waste cooking oil biodiesel water emulsion (WCOBE) while the engine is operated with a constant speed of 1500 rpm. Furthermore, an attempt is made to study the impact of nanofluids in the behavior of the engine fueled with WCOB blended with nanofluids (WCOBN50). This work also explored a novel method of producing nanofluids using one-step chemical synthesis method. Copper oxide (CuO) nanofluids were prepared by the above mentioned method and blended with waste cooking oil biodiesel (WCOBN50) using ethylene glycol as a suitable emulsifier. Results revealed that brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) of WCOBN50 are significantly improved when compared to WCOB and WCOBE. Furthermore, a higher reduction in oxides of nitrogen (NO x ), carbon monoxide (CO), hydrocarbon (HC), and smoke emissions were observed with WCOBN50 on comparison with all other tested fuels at different power outputs. It is also identified that one-step chemical synthesis method is a promising technique for preparing nanofluids with a high range of stability.