Fine nanoparticles in the size range of 1-100 nm are suspended with the traditional heat transfer fluids like water, ethylene glycol, oil etc. is called nanofluid. These traditional heat transfer fluids are called base fluids. The term nanofluid was given by Choi in 1995 to describe new class of nanotechnology which is based on heat transfer fluids that exhibit thermal properties excellent to those of traditional heat transfer fluids. Nanofluids are supposed to have better heat transfer properties than traditional heat transfer fluids which make it useful in cooling application. Pump is use to circulate the coolant in most of the cooling systems. Thus pumping power requirement is an important issue in the selection of coolant. This pumping power requirement is based on the viscosity of fluid. Moreover the heat transfer coefficient of a fluid is also influenced by the viscosity of the fluid. The goal of nanofluid technology is to achieve the highest possible thermal properties at smallest possible concentration by uniform dispersion and stable suspension of nanoparticles (Das et al. 2008). The materials used for making nanoparticles are, such as oxide ceramics (Al2O3, CuO), TiO2, nitride ceramics (AlN,SiN), carbide ceramics (SiC,TiC), metals (Cu,Ag,Au), semiconductors (TiO2,SiC), Cabon nanotubes and composite materials such as alloyed nanoparticles Al60Cu30. 19 Nanoparticles can be manufactured by mainly two processes 1. Physical process 2.Chemical process. The physical process includes inert gas condensation and mechanical grinding. Chemical processes include chemical vapour deposition, chemical precipitation, micro emulsions, thermal spray and spray prolysis. 2.2 NANOFLUIDS APPLICATIONS Nanofluids are used in following fields (Wo... ... middle of paper ... .... Two Step Method C.G. Granqvist, and R.A. Buhrman (1976) found the two- step process in which nanoparticles are first produced as a dry powder by inert gas condensation and in the second step dispersion of dry nanoparticle powder into a base fluid, like water, oil or ethylene glycol. Romano et al (1997) reported an advantage of the two-step process is that the inert-gas condensation technique has been scaled up to commercial nanopowder production. A deficiency of this method is the 21 tendency of nanopowder to agglomerate during storage and dispersion in the base fluids, particularly with heavier metallic nanoparticles. Surfactants and other surface-stabilization additives can be used to achieve more homogeneous and more stable suspensions. In addition to mechanical mixing, ultra-sonic mixers can be used to break up agglomerates and give more uniform dispersions.
An emulsion is the forcing of substances that would not normally mix. In this experiment, multiple oil-in-water emulsions were performed. An oil-in-water emulsion is when there are little droplets of oil dispersed throughout water. The most common type of emulsion includes fats and water. A temporary emulsion was formed from this experiment. A temporary emulsion has to be shaken or mixed in some form to stay together (later on it will separate). This similar idea is used with salad dressings.
With knowledge of a pool boiling curve, it is possible to predict the amount of heat transfer induced by the boiling of a fluid. The level of heat transfer that can be obtained for engineering applications is highly dependent on the difference in temperature between the heating surface and the surrounding fluid. The shape of this curve is dependent on the shape of heating surface as well as the material properties of the heated surface and fluid. Both empirical constants and dimensionless numbers are used to form a boiling curve. Optimal operation conditions for an application can be predicted with the understanding of how different factors can shape the boiling curve [1].
In order to study the aspects of fluid mechanics that need to be taken into account when constructing our cooling tower, a breakdown of different behaviours of fluids under different conditions must be performed and tested against the flow rate. The experimental design would have to explore the influence of the length of the flow pipe as well as the density and temperature on the flow rate of the fluid.
The viscosity of pure liquids affects on temperature, pressure, density, and surface tension (Dutt et al, 2007). When the temperature drops the particles slow down and come closer together, the forces of attraction between them will increase and so make it harder for them to flow past each other. Thus, Dynamic viscosity of liquids increases with decreasing temperature (Binder et al, 2007).
Choi, C. H. (2013). Synthesis of colloidal metal oxide nanocrystals and nanostructured surfaces using a continuous flow microreactor system and their applications in two-phase boiling heat transfer.
Water has thermostatic properties which allows it to moderate changes in temperature. The property of thermal inertia allows a substance, such as water, to resist change in temperature whether energy is gained or lost. The property of ice means that ice provides a moderating thermostatic effect even if it doesn’t get warm enough to melt. The property of water and air movement describes how water and air currents keep the equator from boiling.
Nano-thermal analysis methods are also known as micro-thermal procedures and they use the principle of characterizing highly localized materials on a micrometer. The characterization is then changed from a micrometer scale to a sub-micrometer scale with the temperature being regulated to the specified units. The application of nano-thermal analysis methods started towards the end of the 20th century. Although it has been applied in several other fields including microelectronics, its application in pharmaceuticals has not been that popular.
Aerogel is a synthetic porous ultra-light material derived from a gel, in which the liquid component of the gel has been replaced with a gas, resulting in a solid with extremely low density and low thermal conductivity. Nicknames include "frozen smoke", "solid smoke", "solid air" or "blue smoke" owing to its translucent quality and the way light scatters in the material. However, it feels like Styrofoam to the touch.
Works Cited Although heat and temperature are correlated terms in daily speech, there is a crucial difference in their definitions in the study of physics. In specific, heat is a form of thermal energy that can be transformed from one object to another; whereas temperature is a measurement of the average kinetic energy of the particles in a sample of matter (“Methods of Heat Transfer”, n.d.). Heat transfer indicates the movement of heat energy from one place to another caused by the difference in temperature (“Chapter 16: Heat Transfer”, n.d.). Heat will always move from the hotter object to the cooler one, until they both reach the same temperature, indicating thermal equilibrium (“Chapter 16: Heat Transfer”, n.d.). There are three primary mechanisms for heat transfer, including convection, conduction, and radiation.
Viscosity is the resistance of a fluid to flow. The molecules experience friction due to the molecular interaction among them. Different fluids with different viscosities flow at a different speed the more force the more viscous fluids of a fluid to flow is known to be the amount of thickness in any fluid for, example water would have low amount of viscosity and honey being thicker would have a high viscosity. Although viscosity can be known to be different depending on the density of the liquid. Force is required for any object to to travel the more viscosity that is in any liquid the more force is required
Lubricant is constantly circulated to and from a cooler part of the system, although lubricants may be used to warm as well as to cool when a regulated temperature is required. This circulating flow also determines the amount of heat that is carried away in any given unit of time. High flow systems can carry away a lot of heat and have the additional benefit of reducing the thermal stress on the
There are 2 types of granulation: Wet granulation and dry granulation. As the name suggests, wet granulation requires a liquid to be used in the process of agglomeration whereas dry granulation doesn’t require any liquid. Both these processes will be discussed in detail in the upcoming sections.
Ultrasonic is the universally accepted technique to study the physico-chemical properties of the liquids, liquid mixtures, electrolytic solutions and polymeric solutions. Liquids, liquid-mixtures and solutions find wide applications in medical, pharmaceutical, chemical, lather, textile, nuclear and solvent, solution related industries. The study and understanding of the thermodynamic properties of liquid mixtures and solutions are more essential for their applications in these industries. The measurements of ultrasonic velocity in the combination of density and viscosity have been used to study the molecular interactions in liquid mixtures and solutions.
In addition, the viscosity of the liquid will change the behavior of the contents even further because you will not only have a mixed phase of liquid/gas but also different viscosities in other words different measures of the fluid’s resistance. Viscous forces in a fluid are proportional to the rate at which the fluid velocity changes in space. The viscosity thus changes the liquids ease of moving around inside the cylinder. The higher the viscosity, the slower are the fluctuations in
Physics is the branch of science, which deals with the motion, and the causes of the motion on a specific body. However, what causes this motion? The answer is forces that are in action. This subject of motion under forces is termed as Mechanics. Every object around us shows some type of motion, for example Sun and the other planets are going in circular motion and many other examples are all undergoing in the action of some kind of forces. The motion of fluids or liquids under the action of some forces is termed as fluid mechanics. Fluids may include any type of liquids, gasses, or plasma. The study of these phases and their motion is very important and they have been widely used in many modern life applications.