# Heat transfer of nanofluids in turbulent pipe flow

# Heat transfer of nanofluids in turbulent pipe flow

**Length:** 1000 words (2.9 double-spaced pages)

**Rating:** Excellent

#### Essay Preview

More ↓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

### How to Cite this Page

**MLA Citation:**

"Heat transfer of nanofluids in turbulent pipe flow."

__123HelpMe.com__. 24 Feb 2020

<https://www.123helpme.com/view.asp?id=221738>.

## Need Writing Help?

Get feedback on grammar, clarity, concision and logic instantly.

Check your paper »## Essay on The Effect Of Nanofluids On Heat Transfer

- In recent years, numerous studies investigating the effects of nanofluids in heat transfer have been conducted. From this, many things have been concluded that have allowed for the most efficient and progressive experimental design. The topic of thermal conductivity has dominated research in the past few years, investigating specific factors ranging among Brownian motion of particles, flow conditions due to Reynolds numbers, and volume concentration and particle size. Such factors, along with others considered when designing the experimental setup, shall be discussed below.... [tags: Fluid dynamics, Reynolds number, Aerodynamics]

**Research Papers**

1117 words (3.2 pages)

## The Properties of Heat Transfer: Chang and Guo Essay

- The mechanisms of heat transfer enhancement due to a twisted tape include: (1) a reduction of a hydraulic diameter causing resulting in an increase of flow velocity and curvature which in turn increases the shear stress at the wall and drives secondary motions, (2) An increase of fluid mixing between the core and the near-wall flow regions and (3) An extra heat transfer through thermal contact, probably. A high cost of energy and material has resulted in an increased effort aimed at producing more efficient heat exchange equipment.... [tags: friction factor, thermal characteristics]

**Research Papers**

705 words (2 pages)

## Experimental Study of Force Convective Heat Transfer of CuO/water Nanofluid in a Microchannel Heat Sink

- Technology progresses in the fields such as: electronic industries, high power engine and optical device that produce high heat flux is in a way that conventional methods are not able to remove the heat generated by these devices and need to advance cooling methods. There are two ways to improve the cooling processes. The first way is design of new cooling device with smaller channel dimensions that causes enhanced convective heat transfer coefficient due to increased fluid velocity [1, 2]. The use of microchannel as a cooling device for dissipating heat from silicon integrated circuit was first proposed by Tuckerman and Pease [3].... [tags: thermodynamics and technology]

**Research Papers**

661 words (1.9 pages)

## Essay about The Effect Of Heat Transfer On Temperature

- 1.1 GENERAL BACKGROUND Heat transfer is by virtue thermal energy stored in temperature-dependent motion of particles. The exchange of kinetic energy of particles occurs through the boundary between two systems which are at different temperatures from each other or from their surroundings. Heat transfer constantly occurs from a region of high temperature to the region of lower temperature. Heat transfer changes the internal energy of both systems according to the Thermodynamics. The Second Law of Thermodynamics defines the concept of thermodynamic entropy.... [tags: Heat, Thermodynamics, Temperature, Heat transfer]

**Research Papers**

1224 words (3.5 pages)

## The Physics Of Heat Transfer Essay examples

- Introduction Conduction, convection, and radiation are all types of heat transfer in which heat is transferred from a system to its surroundings. As humans, we are in the presence of, and manipulate these heat transfers all the time. Heat transfer is very important to our every day lives as we try to live in a world where the temperature outside is not comfortable and we want our food cooked. Some people go out of their way to get more radiation to get a tan, or use convection while siting in a sauna.... [tags: Heat, Heat transfer, Energy, Temperature]

**Research Papers**

1260 words (3.6 pages)

## Essay on The Effect Of Heat Transfer On A Gun Barrel

- Summary Study of heat transfer in a gun barrel during firing is important for various reasons like estimating cook off temperature and erosion of barrel. This report assesses the heat transfer in a 155mm gun barrel with and without cooling channel using finite element analysis. The analysis was carried out using Pro/Mechanica software. The problem is modelled as a 2 D axisymmetric problem and convective loads and symmetry boundary conditions were used. The analysis was carried out in two phases.... [tags: Heat, Heat transfer, Convection, Thermodynamics]

**Research Papers**

1612 words (4.6 pages)

## Essay on How does Heat Transfer Works

- I chose the topic of heat transfer because I find it really intriguing to learn about. I wanted to look further into how heat from two substances reacts with one another through another material that was placed between them. I will be looking at how to calculate the rate of heat transfer in a one dimensional space. This means that I will only be focusing on two temperatures, one hot and one cold, and a medium of which the heat will pass through. External factors such as other temperatures and time will not be used as they are for three dimensional spaces.... [tags: temperatures, thermodynamics, heat]

**Research Papers**

1141 words (3.3 pages)

## The Theory Of Micro Heat Pipe Essay

- Heat pipes are passive heat transfer devices that can transfer heat at high rates over large distances with extremely small temperature drops without the requirement of external pumping power. They are commonly used for high heat flux applications because of an increased effective conductivity of the material. The basic working of a heat pipe is dependent on the capillary pumping of the fluid from the cold end to the hot end using a wick or a wickless design. Liquid is evaporated at the heated end, the vapor then travels back to the cold end where it condenses and is then recirculated back to the hot end by capillary pumping.... [tags: Heat transfer, Heat, Temperature]

**Research Papers**

1146 words (3.3 pages)

## Essay on Heat Flow Through Glazing Systems

- The characteristic equations for heat transfer in glazing systems are well established. However, when shading devices like venetian blinds are introduced, heat transfer becomes more complex. The complex fenestration construction (CFC) facility in mbox{ESP-r} was developed to manage the complexities associated with using window blinds in buildings. The CFC facility provides an avenue for modelling window blinds and screens. Also, dynamic control of slat-type blinds is permitted within the CFC functionality.... [tags: Heat, Heat transfer, Louver]

**Research Papers**

1599 words (4.6 pages)

## Heat Energy, Convection And Radiation Essay

- Heat energy is transferred through three ways- conduction, convection and radiation. All three are able to transfer heat from one place to another based off of different principles however, are all three are connected by the physics of heat. Let’s start with heat- what exactly is heat. We can understand heat by knowing that “heat is a thermal energy that flows from the warmer areas to the cooler areas, and the thermal energy is the total of all kinetic energies within a given system.” (Soffar, 2015) Now, we can explore the means to which heat is transferred and how each of them occurs.... [tags: Heat, Heat transfer, Energy, Temperature]

**Research Papers**

1473 words (4.2 pages)

et al. [3]. For the turbulent flow regime, which our interest is focused on, increased heat

transfer data were reported by Pak and Cho [4], Xuan and Li [5], Maїga et al. [6],

Behzadmehr et al. [7], Williams et al. [8], and Bianco et al. [9].

However, it must be pointed out that the increase in effective thermal conductivity

consequent to the dispersion of nanoparticles into the base liquid is accompanied by a

contemporary growth of the effective dynamic viscosity, which could represent a

serious limitation. In fact, an excessive increase in pressure drop may result in an

exaggerated pumping power requirement, as detected by Pak and Cho [4], and Williams

et al. [8]. This means that the merits of nanofluids need to be evaluated necessarily in

terms of global energetic performance, and not simply by the common point of view of

the heat transfer enhancement, as pointed out by Gosselin and da Silva [10] in a paper

on external boundary layer flow. Actually, two options are possible. The first option is

aimed at determining how much the heat transfer rate changes as the nanoparticle

volume fraction is increased, keeping constant the pumping power. The second option

has the scope to evaluate in what measure the pumping power changes with increasing

the nanoparticle concentration, for an assigned heat transfer rate. Obviously, the

addition of nanoparticles to the base liquid is advantageous in all those cases in which

either a heat transfer enhancement occurs at a fixed cost of operation or a lower amount

of power is dissipated in friction at same thermal performance.

Framed in this general background, the aim of the present paper is to undertake a

comprehensive theoretical study on the overall energetic performance of nanofluids in

turbulent pipe flow with the primary scope to determine if and when the dispersion of

nanoparticles into a base liquid is beneficial. Both cases of constant driving power and

constant heat transfer rate are investigated for different operating conditions,

nanoparticle diameters, and solidliquid combinations.

Although strictly speaking a nanofluid is a solidliquid mixture, the majority of the

studies performed on this subject are based on the assumption that the nanofluid

behaves more like a single-phase fluid than like a conventional solidliquid mixture. In

fact, since the suspended nanoparticles have usually small size and concentration, the

hypothesis of a solidliquid mixture statistically homogeneous and isotropic can

reasonably be advanced. This means that, under the further assumptions that the

nanoparticles and base liquid are in local thermal equilibrium, and no-slip motion

occurs between the solid and liquid phases, to all intents and purposes the nanofluid can

be treated as a pure fluid. Therefore, all the convective heat transfer correlations

available in the literature for single-phase flows can easily be extended to the

corresponding nanofluid applications, provided that the thermophysical properties

appearing in them are the nanofluid effective properties calculated at the reference

temperature. Notice that a similar approach was previously used by Kim et al. [11],

Gosselin and da Silva [10], Hwang et al. [12], and Corcione [13, 14], mainly for

buoyancy-induced applications. Certainly, the trustworthiness of the results obtained

following this procedure is strongly related to the use of robust theoretical models or

empirical equations able to predict with adequate accuracy the nanofluid effective

properties.