Landfills all around the world are one of the major sources that contribute towards global warming and climate change. Although landfilling should be prioritized last in the waste management hierarchy due to highest greenhouse gas emissions as compared to other waste management systems it is still very common around the world. In this study, methane emissions are estimated by applying First Order Decay model to landfills in Pakistan over the latest data available by Pakistan Environmental Protection Agency. Results demonstrate that nearly 14.18 Gg of methane is emitted from the landfills in Pakistan each year. By combusting this methane in the form of biogas collected from the landfills as a waste management scheme we can reduce greenhouse effect up to ~88%. Same percentage is observed when we apply the similar analysis over the potentially improved practice. Also, Pakistan is facing severe economic crises due to continuous increasing gap between energy demand and supply. Demand is increasing exponentially while supply is observed to remain constant over the last few years due to frozen capacity in spite of having significant renewable/alternate energy resources. Current electricity shortfall has reached up to 6000 MW. Present operational landfills in Pakistan can only contribute up to ~0.1% to cater the total deficit which does not make any significant difference but if 75% of the total waste generated today is collected and 50% of it landfilled then Pakistan has the potential to produce ~83.17 MW of power that can contribute up to 1.4% to overcome the current power shortage. The outcomes of this paper may also be applicable to other developing countries having similar resources

As oil and gas field development moves further into deep seas, maximizing hydrocarbon extraction at an acceptable cost is one of the greatest challenges facing the industry today. In this regard, considerable attention has been given to understanding the flow behavior in long and deep flow line risers of different topologies through transient multiphase simulation. However, the application of the large diameter to the above scenario is still an unresolved issue creating a great deal of uncertainty. This is mainly due to the limitation of the available experimental and field data being confined to much smaller diameters.In view of the aforementioned, an experimental campaign to investigate the flow behavior in a 254-mm nominal-diameter horizontal flow line vertical riser has been performed. A numerical model to study the dynamic behavior of the large-diameter horizontal flow line vertical riser system is also developed using OLGA software with the intention of identifying the capability of this software. This article presents the comparison of the simulation and experimental data in terms of near riser base and flow line pressure variations along with flow regime predictions. The existence of the multiple roots in the OLGA code is also reported for the first time. Additionally, a review on the state-of-the-art application of the code and analysis of the numerical experiment performance of the code are included.

An experimental investigation of adiabatic upward co‐current air–water two‐phase flow has been carried out to determine the flow patterns in a 12.2=m‐high and 250=mm nominal diameter vertical pipe. The visual observations of flow patterns were supplemented by statistical analysis of the time‐averaged void fraction determined by pressure drop method. Four flow patterns were identified in the vertical test section, namely dispersed bubbly, bubbly, agitated bubblyand churn/forth flow within the experimental superficial velocity range ( ja = 0.18–2.2 m/s and jw = 0.18–1.2 m/s). Conventional slug flow consisting of smooth bullet‐shaped bubbles (Taylor bubble) and liquid slugs was never observed; instead, agitated bubbly flow was the most dominant flow pattern in relevant superficial velocity range. On the basis of the visual and statistically extracted information, a flow pattern map was developed and compared with the existing flow pattern maps. Available flow regime transition models compared against the present experimental data yielded poor agreement with none of the existing models predicting the transitions as a whole. A satisfactory agreement was obtained with other large diameter studies with inconsistencies mainly attributable to confusion in the identification of the flow patterns. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

Citrus canker (CC), caused by one of the most destructive subfamilies of the bacterial phytopathogen Xanthomonas citri subsp. Citri (Xcc), poses a serious threat to the significantly important citrus fruit crop grown worldwide. This has been the subject of ongoing epidemiological and disease management research. Currently, five different forms have been identified of CC, in which Canker A (Xanthomonas citri subsp. citri) being the most harmful and infecting the majority of citrus cultivars. Severe infection symptoms include leaf loss, premature fruit drop, dieback, severe fruit blemishing or discoloration, and a decrease in fruit quality. The infection spreads rapidly through wind, rain splash, and warm and humid climates. The study of the chromosomal and plasmid DNA of bacterium has revealed the evolutionary pattern among the pathovars, and research on the Xcc genome has advanced our understanding of how the bacteria specifically recognize and infect plants, spread within the host, and propagates itself. Quarantine or exclusion programs, which prohibit the introduction of infected citrus plant material into existing stock, are still in use. Other measures include eliminating sources of inoculum, using resistant hosts, applying copper spray for protection, and implementing windbreak systems. The main focus of this study is to highlight the most recent developments in the fields of Xcc pathogenesis, epidemiology, symptoms, detection and identification, host range, spread, susceptibility, and management. Additionally, it presents an analysis of the economic impact of this disease on the citrus industry and suggests strategies to reduce its spread, including the need for international collaboration and research to reduce the impact of this disease on the global citrus industry.

Recently, due to an increase in production demand in nuclear and oil and gas industries, the requirement to migrate toward larger pipe sizes for future developments has become essential. However, it is interesting to note that almost all the research on two-phase gas-liquid flow in vertical pipe upflow is based on small-diameter pipes (D 100 mm), and the experimental work on the two-phase gas-liquid flow in large-diameter (D > 100 mm) vertical pipes is scarce. Under the above circumstances, the application of modeling tools=correlations based on small-diameter pipes in predicting flow behavior (flow pattern, void fraction, and pressure gradient) poses severe challenges in terms of accuracy. The results presented in this article are motivated by the need to introduce the research work done to the industries where the data pertaining to large-diameter vertical pipes are scarce and there is a lack of understanding of two-phase gas-liquid flow behavior in large-diameter (D > 100 mm) vertical pipes.The unique aspect of the results presented here is that the experimental data have been generated for a 254-mm inner diameter vertical pipe that forms an excellent basis for the assessment of modeling tools=correlations. This article (i) presents the results of a systematic investigation of the flow patterns in large-diameter vertical pipes and identifies the transition between subsequent flow patterns, (ii) compares it directly with the existing large-(150 mm) and small-diameter data (28 mm and 32 mm) in the same airwater superficial velocity range, (iii) exemplifies that the existing available empirical correlations=models=codes are significantly in error when applied to large-diameter vertical pipes for predictions, and last (iv) assesses the predictive capability of a well-known commercial multiphase flow simulator.

No abstract

No abstract

Carbon Capture and Storage (CCS) is indeed a very effective technology in reducing the CO2 concentrations from the atmosphere and possesses massive potential for mitigating climate change. Over the years CCS processes has evolved, however, it is still believed to be in initial phase and appears as a new idea to many under developed countries. Today CCS appears as the only applicable solution to reduce Gigatonnes (Gt) CO2 emissions besides burning the fossil fuels for energy. The application, however, is not as straightforward as it appears. The high costs and potential risks associated leaves the vision of mitigating climate change through CCS under obscurity, thereby, making the future of CCS a bit vague. This paper aims to project the near future of CCS by the analysis of present CCS prospects, CO2 capturing and storage processes, risks and problems associated, and more importantly the economics encompassing a CCS project. The paper begins with the brief overview of Carbon Capture and Storage (CCS), followed by a comparison of different capturing processes, storage mechanisms, potential problems and risk complications; a comparison of renewables in contrast with CCS is provided. Lastly, the economics and costs of present CCS prospects in different parts of world are discussed. All work is done to make future inferences about CCS, how this evolving technology can be made economically feasible also, and what will be the impacts and consequences on the climate change (increasing GHG concentrations) had no government, public and private sectors consideration been given to CCS, and will the environment be ever safe without CCS.