Autoignition and combustion characteristics of heptane droplets with the addition of aluminium nanoparticles at elevated temperatures

Javed, Irfan,Baek, Seung Wook,Waheed, Khalid Elsevier 2015 Combustion and Flame Vol.162 No.1

<P><B>Abstract</B></P> <P>We investigate the effects of high ambient temperatures and various concentrations of nanoparticles (NPs) on the autoignition and combustion characteristics of heptane-based nanofluid droplets. A single, heptane (<I>n</I>-C<SUB>7</SUB>H<SUB>16</SUB>) droplet containing 0.5%, 2.5%, or 5.0% by mass of aluminium (Al) NPs mounted on a silicon carbide fibre was exposed to a rapid increase in temperature (from room temperature to temperatures in the range 600–850°C) at atmospheric pressure and under normal gravity, and the autoignition and combustion characteristics were observed. The ignition delay, burn rate, and combustion characteristics of pure and stabilised heptane droplets were also examined for comparison. The results show that, as with the pure heptane droplets, the ignition delay of the NP-laden heptane droplets (<I>n</I>-Al/heptane) followed an Arrhenius temperature dependence. The reduction in the ignition delay time with increasing temperature depended on the loading of NPs in the droplet. The overall activation energy obtained for dilute NP concentrations (0.5% by mass) was smaller, and that for dense (2.5% and 5.0%) concentrations of NPs was larger, than that of the pure heptane droplets. Consequently, the addition of 0.5% Al NPs to heptane resulted in ignition at 600°C, which is not observed with stabilised heptane or 2.5% and 5.0% <I>n</I>-Al/heptane droplets. At higher temperatures, the ignition delay of the <I>n</I>-Al/heptane droplets was comparable to that of pure heptane droplets. The combustion of the <I>n</I>-Al/heptane droplets did not follow the classical <I>d</I> <SUP>2</SUP>-law, in contrast to the combustion of the pure and stabilised heptane droplets. Regardless of the NP concentration, the <I>n</I>-Al/heptane droplets exhibited disruptive burning behaviour, which was characterised by multiple expansions and ruptures or ‘microexplosions’. During these microexplosions, the NPs were ejected from the droplets, and the intensity of the microexplosions increased with increasing temperature; consequently, the burning time and total combustion time of the droplet was reduced. Due to these intense and frequent microexplosions, almost no residue from the Al NPs remained on the fibre following combustion, and a separate Al flame was not observed. The average gasification (burn) rate of the <I>n</I>-Al/heptane droplets remained equal to that of pure heptane droplets at relatively low temperatures (600–700°C); however, at higher temperatures (750–850°C), it was significantly faster than that of the pure heptane droplets.</P>

Autoignition and combustion characteristics of kerosene droplets with dilute concentrations of aluminum nanoparticles at elevated temperatures

Javed, Irfan,Baek, Seung Wook,Waheed, Khalid Elsevier 2015 Combustion and Flame Vol.162 No.3

<P><B>Abstract</B></P> <P>In this experimental study, we investigated the effects of high ambient temperatures and dilute concentrations of nanoparticles (NPs) on the autoignition and combustion characteristics of kerosene-based nanofluid droplets. An isolated kerosene droplet containing 0.1%, 0.5% or 1.0% by weight of aluminum (Al) NPs suspended on a silicon carbide (SiC) fiber was suddenly exposed to an elevated temperature (in range 400–800°C) at atmospheric pressure (0.1MPa) under normal gravity, and the autoignition and combustion characteristics were examined. The ignition delay time, burning rate constant and combustion characteristics of pure and stabilized kerosene droplets were also observed for comparison. The results indicate that, similar to pure kerosene droplets, the ignition delay time of NP-laden kerosene (<I>n</I>-Al/kerosene) droplets also followed the Arrhenius expression and decreased exponentially with increasing temperature. However, the addition of dilute concentrations of Al NPs to kerosene reduced the ignition delay and lowered the minimum ignition temperature to 600°C, at which pure kerosene droplets of the same initial diameter were not ignited. In contrast to the combustion of pure and stabilized kerosene droplets, the combustion of <I>n</I>-Al/kerosene droplets exhibited disruptive behavior characterized by sudden reductions in the droplet diameter without any prior expansions caused by multiple-time bubble formation and their subsequent rupture at or near the droplet’s surface. This bubble pop-up resulted in droplet trembling and fragmentation and ultimately led to enhancement in gasification, vapor accumulation and envelope flame disturbance. The NPs were also brought out of the droplets through these disruptions. Consequently, the burning time and total combustion time of the droplets were reduced, and almost no residue remained on the fiber following combustion. Thus, the combustion rate of <I>n</I>-Al/kerosene droplets was substantially enhanced compared with pure kerosene droplets at all tested temperatures.</P>

Investigation of LPG Combustion: Effect of Addition of Carbon Black and Alumina on Radiative Heat Flux

Khalid Waheed,Seung wook Baek,Irfan Javed,Yupiter Kristiyanto 한국연소학회 2013 KOSCOSYMPOSIUM논문집 Vol.2013 No.12

Particulate matter in industrial furnaces plays important role in extracting heat from flame. Effects of particle addition to LPG combustion was investigated in this research. Higher hear fluxes were obtained with addition of combustible carbon black and non-combustible alumina particles. These particles were introduce to the flame in suspension form with dilute concentrations of 0.1 wt. % and 0.5 wt. %. Higher radiative heat flux fractions were observed with addition of particles to LPG combustion with maximum increase comes with addition of noncombustible alumina particles.

An Enhanced Technique for Vertical Handover of Multimedia Traffic between WLAN and EVDO

Khurram Javed,Umar Saleem,Khalid Hussain,Muhammad Sher 한국정보기술융합학회 2010 JoC Vol.1 No.1

Investigations on Thermal Radiative Characteristics of LPG Combustion: Effect of Alumina Nanoparticles Addition

Waheed, Khalid,Baek, Seung Wook,Javed, Irfan,Kristiyanto, Yupiter Gordon and Breach Science Publishers 2015 Combustion science and technology Vol.187 No.6

Analysis of diesel hydrocarbon decomposition using efficient indigenous bacterial isolate: Bacterial growth and biodegradation kinetics

Shazra Khalid,Aneela Iqbal,Asif Javed,Jamshaid Rashid,Ihsan ul Haq,Mohamed Abou El-Fetouh Barakat,Rajeev Kumar 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.11

Industrialization and urbanization have increased the demand for petroleum hydrocarbons; hence the likelihood of contamination of air, soil, and water bodies increases. The survival and biodegradation capabilities of fifteen bacterial isolates were tested in a harsh diesel environment. The bacteria were isolated from soil samples and identified by 16S rRNA gene sequencing. The biodegradation capability of isolates was performed in batch experiments, and diesel degradation analyses were conducted on gas chromatography-mass spectroscopy (GC-MS). The results revealed that only two bacterial isolates (A1 and E5) sufficiently consumed diesel hydrocarbons as a carbon-based energy source. 16S rRNA sequencing identified both isolates as Bacillus genera. An average of 60% of 3% (v/v) diesel was degraded in about 16 hours. Bacillus sp. E5 strain could degrade about 72% and 68% heavier compounds of C24 and C26. The Monod kinetic model for Bacillus sp. E5 utilizing diesel as a substrate showed maximum specific bacterial growth rate (μmax) as 0.1131 hr-1 at 1%, while 0.1287 hr-1 for 3% diesel. Results suggest that the isolated bacterial strain Bacillus sp. E5 has bioremediation potential and can be used as an alternative method for cleaning contaminated petroleum hydrocarbon field sites for sustainable development.

Performance of Holstein cows subjected to different cooling sessions during subtropical summer

Bah Musa,Javed Khalid,Pasha Talat Naseer,Shahid Muhammad Qamer 아세아·태평양축산학회 2022 Animal Bioscience Vol.35 No.11

Objective: This study aimed to determine the effect of different cooling sessions (CSs) as a water conservation strategy on physiological, and production responses and welfare in Holstein Friesian cows during subtropical summer in Pakistan. Methods: Twenty-one cows were subjected to three CS in a completely randomized design. The treatments were: i) eleven hours continuous cooling with sprinklers - control (CNT), ii) four CS, and iii) two CS. The CNT represented the practices of the commercial dairy farms in the area, while the other CSs were used as water reduction strategies. Each CS lasted for 1 h with a 12 min cycle (3 min water on and 9 min off) with a sprinkler flow rate of 1.25 L/min. Results: The average temperature humidity index of the shed and the outside open area were 81.9 and 82.5, respectively. The results showed that both physiological responses were highest in the 2CS group followed by the CNT and the 4CS (p = 0.001). The CNT and 4CS groups had similar milk yield (p = 0.040). The 4CS group had more lying and eating times than the CNT and 2CS groups (p = 0.000). The cortisol level in the 2CS group was 2.0 and 2.2 μg/dL more than the CNT and the 4CS groups, respectively (p = 0.000). Conclusion: In conclusion, the 4CS was more efficient in cooling the cows and had better welfare, as it yielded similar milk yield, and better physiological responses than the CNT despite using 90% less water. Objective: This study aimed to determine the effect of different cooling sessions (CSs) as a water conservation strategy on physiological, and production responses and welfare in Holstein Friesian cows during subtropical summer in Pakistan.Methods: Twenty-one cows were subjected to three CS in a completely randomized design. The treatments were: i) eleven hours continuous cooling with sprinklers - control (CNT), ii) four CS, and iii) two CS. The CNT represented the practices of the commercial dairy farms in the area, while the other CSs were used as water reduction strategies. Each CS lasted for 1 h with a 12 min cycle (3 min water on and 9 min off) with a sprinkler flow rate of 1.25 L/min.Results: The average temperature humidity index of the shed and the outside open area were 81.9 and 82.5, respectively. The results showed that both physiological responses were highest in the 2CS group followed by the CNT and the 4CS (p = 0.001). The CNT and 4CS groups had similar milk yield (p = 0.040). The 4CS group had more lying and eating times than the CNT and 2CS groups (p = 0.000). The cortisol level in the 2CS group was 2.0 and 2.2 μg/dL more than the CNT and the 4CS groups, respectively (p = 0.000).Conclusion: In conclusion, the 4CS was more efficient in cooling the cows and had better welfare, as it yielded similar milk yield, and better physiological responses than the CNT despite using 90% less water.

An Experimental Study on the Shear Strengthening of Reinforced Concrete Deep Beams with Carbon Fiber Reinforced Polymers

Muhammad Afaq Javed,Muhammad Irfan,Sumera Khalid,Yulong Chen,Saeed Ahmed 대한토목학회 2016 KSCE Journal of Civil Engineering Vol.20 No.7

In recent years, Fiber Reinforced Polymers (FRP) have emerged as useful materials for structural strengthening and rehabilitation. The main aspire of this research is towards evaluating the efficiency of Carbon Fiber Reinforced Polymers (CFRP) in enhancing the shear strength of deep beams. The research work included construction and testing of eight (08) reinforced concrete deep beams. Two of the beams, designated as control beams, were without any shear reinforcement. Remaining six beams were divided into three groups, with each group having two identical beams. Beams in one of these groups were strengthened with conventional type of steel web reinforcement. Remaining two groups were strengthened externally by CFRP sheets with different orientations of CFRP. Magnitude of load causing shear cracks to initiate, and the failure load of each beam was recorded. Significant increase in overall load carrying capacities was observed with both CFRP sheets and web steel reinforcement. CFRP was found to be considerably effective in delaying the initial appearance of shear cracks, thereby improving the serviceability limit state of beams. Beams with CFRP orientation perpendicular to the shear cracks showed higher increment in shear strength. In conclusion, CFRP laminates could effectively be used to strengthen existing RC structures deficient in shear strength, and also to reduce/replace internal steel web reinforcement in new RC structures. Material cost comparison of CFRP reinforced beams with conventional web reinforcement is presented, and the general cost effectiveness of structural rehabilitation by means of CFRP is also discussed.