Benefits of Nanotechnology The use of nanotechnology has increased effectiveness in removing contaminants even at low concentrations. Specificity toward target contaminants has been increased. Nanotechnology has made removal of new contaminants possible. Contaminants that were previously impossible to remove could now be removed such as heavy metals. Nanotechnology has made things simples, helps to reduce the number of steps, materials and energy needed to purify water, making it easier to implement.
Shell-and-tube heat exchangers are the most common type of thermal equipment employed in chemical process industries. This widespread use can be justified by its versatility, robustness and reliability. Despite the technological advances of other exchanger types (e.g., plate-and-frame, spiral, lamella, etc. ), shell-and-tube heat exchangers will maintain a central position in industrial activities in the next years
Rahul Kharat, Nitin Bhardwaj*, R.S. Jha have developed a correlation of heat transfer coefficient for helical coil heat exchanger to take into account of experimental and CFD results of different functional dependent variables such as gap between the concentric coil, tube diameter and coil diameter which strongly effects the heat treansfer within error band of 3-4%. The heat transfer coefficient is validated for a wide range of Reynolds number from 20,000 and 1,50,000 and specific ratio is from 0.55 to 2.25 that covers the most engineering helical coil heat exchanger
Nanotechnology is the engineering of functional systems at the molecular scale. The study and building of matter and molecules is involved. This happens at the scale of 0.1 to 100 nanometers. A nanometer is a type of measure and an idea of is its equivalence would be a strand of hair which is 50 000 nanometers in terms of diameter and a nylon fibre which 30 000 nanometers. This should give a clear picture of how small a nanometer is.
2.11 Nanoparticles: Nanoparticles are particles between 1 and 100 nanometer in size (nanometer is unit of length in metric system equivalent to one billionth of a meter (0.000, 000,001) representation is nm. 2.12 Base fluid: In nanofluids the base fluids are the fluids in which nanoparticles are to be adjourned. Some common base fluids are water, oil etc. 2.13 CNT: The carbon nanotubes (CNTs) are hollow cylindrical nano configurations whose walls are composed of heavy sheets of carbon. 2.14 SWNT: Single wall nanotubes have a very trivial diameter as matched to their length.
This was expected because as the cold water flow rate increased, more heat transfer was occurring throughout the heat exchanger between the hot and cold streams. The plate heat exchanger was observed to have much higher overall heat transfer coefficient values than either the shell-and-tube or the double pipe. This was attributed to the plate heat exchanger having larger temperature differences from the increased outlet cold stream and the decreased outlet hot stream compared to the other heat exchangers. Thereby, the overall heat transfer coefficient significantly increased for the plate heat exchanger. The shell-and-tube and the double pipe heat exchangers did not have as large a difference in temperature change, thereby resulting in similar overall heat transfer coefficient values.
In these potential conditions, the photogenerated holes are able to either directly oxidize the absorbed pollutants or oxidize the hydroxyl groups located at the TiO2 surface to form •OH radicals, whose redox potential is only slightly decreased (Fujishima et al., 2000). In addition, it is possible to increase the number of •OH radicals by adding into the photoreactor H2O2 or O3 which can be photolyzed by UV irradiation. During the heterogeneous photocatalytic process, the TiO2 catalyst can be utilized either under dispersed form (powder, aqueous suspension) or in thin film form (fixed TiO2 catalytic layer on solid support). However, a drawback of the dispersed form is the progressive formation of dark catalytic sludge, which diminishes the efficiency of UV irradiation and reduces the photoreactor performances. In contrast, for TiO2 films, there is no need to separate the catalytic particles at the end of the process, but the catalytic layer must be very stable and
The nanotechnology potentially makes the human to rendering to recent and increasing hazards due to some individual properties such as its very small size and high ratio of area to mass. Nanotechnology is the competent invention of materials and systems in nanometer length scale, and exploits the rising properties and phenomenon which have been developed in nano scale. The word “nano” means 10-9, so a nanometer is one-billionth of a meter. One description of nanoscience is the study of atoms, molecules and substance, the size of which is in the range of about 1 to 100 nm (nanometer)[1,2]. To understand in better ways, an individual human DNA molecule has a diameter of 2 to 12 nm, hair is of the order of 10,000 to 50,000 nm and viruses usually
Nanotechnology is a nano science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers. Nanoscience and nanotechnology are the study and application of highly small things and can be used across all the other science fields, such as materials science, biology, physics, chemistry, and engineering (Sukumaran et al., 2012). Fundamental concepts of nanotechnology: It’s very hard to imagine really small nanotechnology is. One nanometer is a billionth of a meter, or 10-9 of a meter. Here are a few examples given below: • There are 25,400,000 nanometers in an inch • The newspaper sheet is about 100,000 nanometers thick • The comparative scale, if a marble stone was a nanometer, and then one meter would be the size of the earth.