Research in convective heat transfer using suspensions of nanometer-sized solid particles in base liquids started only over the past decade. Recent investigations on nanofluids, as such suspensions are often called, indicate that the suspended nanoparticles markedly change the transport properties and heat transfer characteristics of the suspension. This first part of the review summarizes recent research on theoretical and numerical investigations of various thermal properties and applications of nanofluids

Research in convective heat transfer using suspensions of nanometer-sized solid particles in base liquids started only over the past decade. Recent investigations on nanofluids, as such suspensions are often called, indicate that the suspended nanoparticles markedly change the transport properties and heat transfer characteristics of the suspension. This second part of the review covers fluid flow and heat transfer characteristics of nanofluids in forced and free convection flows and potential applications of nanofluids. Opportunities for future research are identified as well

Over the last decades, the palm oil industry has been growing rapidly due to increasing demands for food, cosmetic, and hygienic products. Aside from producing palm oil, the industry generates a huge quantity of residues (dry and wet) which can be processed to produce biofuel. Driven by the necessity to find an alternative and renewable energy/fuel resources, numerous technologies have been developed and more are being developed to process oil-palm and palm-oil wastes into biofuel. To further develop these technologies, it is essential to understand the current stage of the industry and technology developments. The objective of this paper is to provide an overview of the palm oil industry, review technologies available to process oil palm and palm oil residues into biofuel, and to summarise the challenges that should be overcome for further development. The paper also discusses the research and development needs, technoeconomics, and life cycle analysis of biofuel production from oil-palm and palm-oil wastes.

Low-rank coals (LRCs) constitute about 45% of the total coal reserves and hence will soon be the fossil fuel of choice in many countries despite their high moisture content on mining, which varies from 30% to as high as 66%. It is important to reduce their water content to enhance the heating value and reduce transportation costs while enhancing combustion efficiency, safety, and reduction of emissions on combustion. The level of moisture to be achieved upon drying LRCs depends on the end application; it varies from as low as 0% for hydrogenation processes to 15% for briquetting and gasification processes. Numerous drying technologies have been proposed for drying coal; they include pulse combustion, vacuum, fluid bed, rotary, flash, microwave, and superheated steam drying. Each technology has some pros and cons, which are not always clearly spelled out in the literature. In addition, it is necessary to develop sustainable rather than just cost-effective drying systems for LRC. In this article we assess various coal drying techniques critically and identify their strengths and weaknesses. Some theoretical comparisons of different dryer types are carried out based on energy utilization and carbon footprints. The jury is still out on optimal drying technology for LRC and innovative design concepts should be evaluated before finalizing the selection.