Heat transfer of nanoparticle suspensions in turbulent pipe flow is studied theoretically.
The main idea upon which this work is based is that nanofluids behave more like singlephase
fluids than like conventional solidliquid mixtures. This assumption implies that
all the convective heat transfer correlations available in the literature for single-phase
flows can be extended to nanoparticle suspensions, provided that the thermophysical
properties appearing in them are the nanofluid effective properties calculated at the
reference temperature. In this regard, two empirical equations, based on a wide variety
of experimental data reported in the literature, are used for the evaluation of the
nanofluid effective thermal conductivity and dynamic viscosity. Conversely, the other
effective properties are computed by the traditional mixing theory. The novelty of the
present study is that the merits of nanofluids with respect to the corresponding base
liquid are evaluated in terms of global energetic performance, and not simply by the
common point of view of the heat transfer enhancement. Both cases of constant
pumping power and constant heat transfer rate are investigated for different operating
conditions, nanoparticle diameters, and solidliquid combinations. The fundamental
result obtained is the existence of an optimal particle loading for either maximum heat
transfer at constant driving power or minimum cost of operation at constant heat
transfer rate. In particular, for any assigned combination of solid and liquid phases, it is
found that the optimal concentration of suspended nanoparticles increases as the
nanofluid bulk temperature is increased, the Reynolds number of the base fluid is
increased, and the length-to-diameter ratio of the pipe is decreased, while it is
practically independent of the nanoparticle diameter.
The usual design requirements for modern heat transfer equipment are reduced size and
high thermal performance. In this connection, in the past decades a considerable
research effort has been dedicated to the development of advanced methods for heat
transfer enhancement, such as those relying on new geometries and configurations, and
those based on the use of extended surfaces and/or turbulators. On the other hand,
according to a number of studies executed in recent times, a further important
contribution may derive by the replacement of traditional heat transfer fluids, such as
water, ethylene glycol and mineral oils, with nanofluids, i.e., colloidal suspensions of
nano-sized solid particles, whose effective thermal conductivity has been demonstrated
to be higher than that of the corresponding pure base liquid.
The main results of prior work on pipe flow, that is undoubtedly one of the most
investigated topics in the field of convection in nanofluids, clearly show that
nanoparticle suspensions offer better thermal performance than the base liquids at same
Reynolds number, and that heat transfer increases with increasing the nanoparticle
Matter exists in three basic states: solid, liquid, or gas. A substance experiences a phase change when the physical characteristics of that substance change from one state to another state. Perhaps the most recognizable examples of phase changes are those changes from a solid to a liquid or a liquid to a gas. When a substance goes through a phase change, there is a change in the internal energy of the substance but not the temperature of the substance (Serway, et al. 611).
The conclusion of Bernoulli’s experiment? The water flowing through the narrower pipe was faster than the water flowing through the wider pipe. Also, the pressure in the narrow pipe was less than the pressure in the wider pipe. Therefore, when the water was flowing through the wider pipe, its pressure was higher, and when the water flowed through the narrower pipe, its press...
At the age of twenty-four, Norbert Rillieux was a teacher of applied mechanics at a school in Paris. In 1830, he put out a series of papers about steam economy and steam engine work, a prelude to his invention involving steam. In fact, it was during the time that he was writing these papers, most likely, that he created his theory about multiple effect evaporation. Between 1884 and 1854, he created the Rillieux apparatus, a revolutionary invention. In 1864, he patented his first model, and advanced the system for eight more years, and received more patents. It took him ten years to create the final model because he was black, and there were prejudices he had to deal with in addition to his invention.
The thermal storage capacity of a latent heat system for the case of material undergoing a solid-liquid phase change can be seen below (Portaspana, 2011):
Rate is determined on how fast something is being consumed in a reaction, or how
Superfluids all have the unique quality that all their atoms are in the same quantum state. This means they all have the same momentum, and if one moves, they all move. This allows superfluids to move without friction through the tiniest of cracks, and superfluid helium will even flow up the sides of a jar and over the top. This apparant defiance of gravity comes from a special type of surface wave present in superfluid helium, which in effect pushes this extremely thin film up the sides of the container.
This is a great discovery of Bernoulli. It seems to make sense when we apply it to blood vessels. Where the blood moves faster, the more it pushes forward, the less it pushes on the walls. A later more ingenious application for this idea is flying. The airplane was invented after Bernoulli but not due to him. The airplane and Bernoulli’s equation
Pipeline Transportation is a massive mode of transportation for over one hundred countries around the world. As of 2014, there is approximately 2,175,000 miles of pipeline, enough to wrap around the Earth 87 times. Of those millions of miles, 64% of the world’s pipeline is in the United States alone. Pipelines are mostly used for the transportation of both crude and refined petroleum, fuels such as oil, natural gas, and biofuels, and other fluids like water and sewage. Even alcohol is sometimes transported using pipelines. Pipelines are used all around us. Miles of them are running continuously below our feet on a daily basis. The creation of pipeline transportation has been an incredibly help to society both directly and indirectly.
The next type of heat transfer is convection. Convection is heat transferred by a gas or liquid. Such as dumping hot water into a cold glass of water, making the water overall warmer. The last type of heat transfer is radiation.
I will also be looking at more complex concepts and ideas such as Reynolds's number, the effect of temperature on viscosity and liquid density, which we have not met in last year's course. The areas I will be looking into are as follows: 1) The effect of the Pipe Diameter on flow rate. - the effect of Pipe Diameter on liquid flow (turbulent/laminar) 2)
These phases can go from one to another when affected by certain things, which is known as phase changes. To switch from a solid to a liquid, the solid must melt. On the other hand, to switch from a liquid to a solid, freezing must occur. Furthermore, to switch from a liquid to a gas, a process known as evaporation must take place. In contrast, to go from a gas to a liquid, condensation must take place. Furthermore, sublimation must take place for a solid to turn to a gas. Inversely, deposition must occur for a gas to change to a solid.
There are three main variables that determine whether a liquid will posses capillary action. (Davis, 1995)
American Institute of Physics. Vol. 1051 Issue 1 (2008). Academic Search Premier.> 224. http://login.ezproxy1.lib.asu.edu/login?url=http://search.ebscohost.com.ezproxy1.lib.asu.edu/login.aspx?direct=true&db=aph&AN=34874307&site=ehost-live.
Solids, liquids, and gases are the three main, or fundamental phases of matter. Each one has a different density and a different level of stability. What determines the stability of each phase is the bond between it's atoms. The tighter the bond between it's atoms the more stable that phase of matter is. Solids are the most stable form of matter, followed by liquids, and then gases.
that the rate of reaction must be fast enough to make as much of the