Why nano fluids are used heat exchanger?
The idea behind development of nanofluids is to use them as thermo fluids in heat exchangers for enhancement of heat transfer coefficient and thus to minimize the size of heat transfer equipments. Nanofluids help in conserving heat energy and heat exchanger material.
Why do we use Nanofluids?
Nanofluids are primarily used for their enhanced thermal properties as coolants in heat transfer equipment such as heat exchangers, electronic cooling system(such as flat plate) and radiators. Heat transfer over flat plate has been analyzed by many researchers.
What is CTP in heat exchanger?
The tube clearance Ct is obtained from Figure 5.21. where CTP is the tube count constant that accounts for the incomplete coverage of the shell diameter by the tubes, due to necessary clearance between the shell and the outer tube circle and tube omissions due to tube pass lanes for multiple pass design [1].
What is UA in heat exchanger?
UA The product of the Overall Heat Transfer Coefficient, and the Total Area available for heat transfer. The Heat Exchanger duty is proportional to the log mean temperature difference, where UA is the proportionality factor. The UA can either be specified, or calculated by HYSYS.
What is Nanofluid thermal conductivity?
Thermal conductivity values recorded were very high, with a thermal conductivity of 1.44 W / m k for Ag2Al–water nanofluid at nanoparticle volume concentration, and a thermal conductivity of 1.35 W / m k for Al2Cu nanofluid at the same nanoparticle volume concentration.
What is meant by Nanofluid?
Nanofluids are suspensions of nanoparticles or nanofibers in a liquid medium. The addition of nanoparticles should substantially enhance the heat capacity of a fluid, and hence nanofluids have been proposed for heat transfer fluids.
What is triangular pitch?
The triangular pitch provides a more compact arrangement, usually resulting in smaller shell, and the strongest header sheet for a specified shell-side flow area. It is preferred when the operating pressure difference between the two fluids is large.
What is tube pitch in heat exchanger?
Tube pitch and clearance: Pitch is the shortest center-to-center distance between adjacent tubes. Commonly 1.25 to 1.5 time the tube diameter. Clearance is the distance between tubes. It should be larger than 25% of the tube diameter. Triangular or square arrangement of tubes are quite common.
What is FT factor?
A ‘ft correction factor’ is defined as a ratio of the true mean temperature difference to the log-mean temperature difference (see Eq(2)). The ‘ft correction factor’ value must be greater than 0.75 for a heat exchanger to be feasible.
How is UA calculated?
That is, UA = 954 BTU/hr-F, where U is the conductance of the building and A is the surface area of the building. When the average outside temperature is greater than 56.5 degrees F, the building heating system is not activated….
| Type of Window | R (ft2-hr-F/BTU) |
|---|---|
| Single-glazed | R = 0.9 |
How is Nanofluid thermal conductivity measured?
The most common techniques for the measurement of effective thermal conductivity of nanofluids are the transient hot-wire method [3], steady-state method [4], cylindrical cell method [5], temperature oscillation method [6], and 3-omega method [7] to name a few.
How do you calculate the thermal conductivity of a Nanofluid?
The thermal conductivity can be calculated then with the next expression [11], [12], [13], [14]:(26) λ = λ 0 λ p + ( n – 1 ) λ 0 – ( n – 1 ) α ( λ 0 – λ p ) λ p + ( n – 1 ) λ 0 + α ( λ 0 – λ p ) , where λ is the mixture thermal conductivity, λ0 is the liquid thermal conductivity, λp is the thermal conductivity of solid …
Are nanofluids suitable for heat transfer enhancement?
From the observed results it is clearly seen, that nanofluids have greater potential for heat transfer enhancement and are highly suited to application in different types of heat exchangers.
How does a nanofluid water exchanger work?
In this exchanger, the nanofluid flows into the pipe and cold water in the annular space of the pipe. The inside pipe is made of a soft steel tube with the inner diameter of 6 mm, outer diameter of 8 mm, and thickness of 2 mm while the outside pipe is of steel tube with the inner diameter of 14 mm, outer diameter of 16 mm, and thickness of 2 mm.
How does volume concentration affect the heat transfer coefficient of nanofluid?
The heat transfer coefficient of the nanofluid increases with an increase in the mass flow rate, also the heat transfer coefficient increases with the increase of the volume concentration of the Al2 O 3 nanofluid, however increasing the volume concentration cause increase in the viscosity of the nanofluid leading to increase in friction factor. 1.
Do nanoparticles affect Nusselt number and heat transfer coefficient in heat exchangers?
Effects of temperature and concentration of nanoparticles on Nusselt number changes and heat transfer coefficient in a double pipe heat exchanger with counter turbulent flow are investigated. Comparison of experimental results with valid theoretical data based on semiempirical equations shows an acceptable agreement.