SEMINAR ON

Comparative Study of Cooling Performance of Automobile Radiator Using Al2O3-Water

and Carbon Nanotube-Water Nanofluid

Delivered by:Dibyaranjan PanigrahiRegd.No:12011062937th sem, B.Tech Dept. of Mechanical Engineering

Under the guidiance of:Dr. Prof. P.K. Satapathy

INTRODUCTION WHAT IS NANOFLUID WHY NANOFLUID PREPARATION OF NANOFLUID AUTOMOBILE RADIATORS WHY NANO FLUID IN AUTOMOBILE RADIATORS NANOFLUID PREPARATION(AL2O3 AND CNT WATER) EXPERIMENTAL TEST FACILITIES AND OBSERVATION DATA REDUCTION RESULTS AND DISCUSSION LIMITATIONS CONCLUSION REFERENCES

CONTENTS

INTRODUCTION Usually single phase fluids such as water, engine oil, and

ethylene glycol (EG) possess poor thermal properties. This problem can be overcome by dispersing small particles with high thermal conductivity in these conventional fluids.

The fluids that contain nanosize particles are termed as nanofluids. These fluids found to possess substantially higher thermal conductivities compared to the base fluids.

The comparison of thermal performance for nanofluids CNT-water and Al2O3-water has been reported in the present investigation.

WHAT IS NANOFLUID? Suspended nanoparticles in various base fluids can alter the

fluid flow and heat transfer characteristics of the base fluids. These suspensions of nano sized particles in the base fluids are called nanofluids.

Nanofluids are suspensions of nanoparticles in a base fluid, typically water.

Recent development of nanotechnology brings out a new heat transfer coolant called ‘nanofluids’. These fluids exhibit larger thermal properties than conventional coolants.

The much larger relative surface area of nanoparticles, compared to those of conventional particles, not only significantly improves heat transfer capabilities, but also increases the stability of the suspension.

WHY NANOFLUIDS ? Conventional heat transfer fluids have inherently poor thermal

conductivity compared to solids.

Conventional fluids that contain mm- or cm-sized particles do not work with the emerging “miniaturized” technologies because they can clog the tiny channels of these devices.

Nanofluids are a new class of advanced heat-transfer fluids engineered by dispersing nanoparticles smaller than 100 nm in diameter in conventional heat transfer fluids.

STRUCTURE OF NANO FLUID

Figure 1: ZrO2 in water that producedwith Two Step method

Figure 2: Cu nanoparticles in ethyleneglycol produced with One Step method

PREPARATION OF NANO FLUID Two methods are used . 1.Two-step method 2.Single-step method

1. TWO-STEP METHOD

Two-step method is the most widely used method for preparing nanofluids.

Nanoparticles, Nanofibers, nanotubes or other nanomaterials used in this method are first produced as dry Powders by chemical or physical methods. Then the nanosized powder will be dispersed into a fluid in the second processing step with the help of intensive magnetic force agitation, Ultrasonic agitation, high-shear mixing, homogenizing and ball milling.

2. SINGLE STEP METHOD

To reduce the agglomeration of nanoparticles they developed a one-step physical vapor condensation method to prepare Cu/ethylene glycol nanofluids . The one-step process consists of simultaneously making and dispersing the particles in the fluid.

In this method, the processes of drying, storage, transportation, and dispersion of nanoparticles are avoided, so the agglomeration of nanoparticles is minimized, and the stability of fluids is increased . The one-step processes can prepare uniformly dispersed nanoparticles, and the particles can be stably suspended in the base fluid.

AUTOMOBILE RADIATOR Radiators are heat exchangers used for cooling internal combustion

engines, mainly in automobiles but also in piston-engined aircraft, railway locomotives, motorcycles, stationary generating plant or any similar use of such an engine.

WHY NANOFLUID IN RADIATORS ? In general, the ethylene glycol and water mixture is used as an

automotive coolant in the radiator of automobile engines. These fluids have poor heat transfer performance compared to water because of lower thermal conductivity

This problem can be overcome by dispersing small particles with high thermal conductivity in these conventional fluids.

This improvement in heat removal rate by utilizing nanofluids could reduce the size of the cooling system resulting in increase in the fuel economy. In addition, the smaller size could reduce the drag and leading to lesser fuel consumption

Thermal conductivity of Nanofluids increased by 3 reasons 1.Brownian Motion 2.Interfacial layer 3.Volume fraction of particles

EXPERIMENTAL PROCEDURE

CNT nanofluids with different nanoparticle concentration (ϕ = 0.15%, 0.45%, 0.60%, and 1%) were prepared by the functionalization acid treatment method

Al2O3-water nanofluids were prepared with different nanoparticle concentration (ϕ = 0.15%, 0.45%, 0.60%, and 1%) by simply dispersing specified amounts of nanoparticles in de-ionized water without any surfactant.

EXPERIMENTAL SETUP

The test facility consists of test section ac-power supply coolant supply system Cooling instrumentation

scheme An automobile radiator which is a cross flow heat exchanger is selected as a test section for the present investigation

For this experiment only case studies of AL2O3 water and CNT Nanofluid are taken into consideration.

STEP BY STEP PROCEDURE The radiator consists of 30 serpentine finned tubes with stadium shape

made of Aluminum. Each tube is of 310 mm length, 20 mm width, and 3 mm height (Figs. 2(a) and 2(b)). The total effective heat transfer area of the tube and fins are 0.445 m2.

The closed storage tank of 15 l capacity is used to store coolant. A centrifugal pump is used to supply coolant from the storage tank to the inlet of the test section. The outlet supply from the test section is sent back to the storage tank and used to recirculate through the test section.

The flow rate of the nanofluid is controlled by using bypass valve arrangement and the remaining fluid is sent back to the storage tank. A calibrated flow meter was used to measure the liquid flow rate with the precision of 0.1 l/min. An electrical power supply (220 V, 15 A, ac) is provided to the heating elements (2 kW, 4 Nos.) in order to heat the coolant in the storage tank.

For all the test runs, the inlet temperature is maintained at a constant temperature of 90 °C.

Eight calibrated RTD PT100 type temperature sensors with an accuracy of ±0.1 °C are mounted on the test section to measure outside wall temperature.

RESULTS AND DISCUSSION

CNT-water nanofluid was found to exhibit enormous heat transfer performance compared to Al2O3-water nanofluid for any value of coolant flow rate and nanoparticle concentration.

Compared to water, CNT-water nanofluid (1% by volume) exhibited 45.87%, 66.64%, 76.55%, and 90.76% increase in the Nusselt number at flow rates 2 l/min, 3 l/min, 4 l/min, and 5 l/min, respectively

Al2O3-water nanofluid (1% by volume) exhibited 24.66%, 39.17%, 44.18%, and 52.03% increase in the Nusselt number at coolant flow rates 2 l/min, 3 l/min, 4 l/min, and 5 l/min, respectively, compared to the results with water as a coolant

The heat transfer enhancement of Al2O3-water nanofluid at nanoparticle concentration 0.15%, 0.45%, 0.60%, and 1% are found to be 23.07%, 33.12%, 40.38%, and 52.03%, respectively, compared with water.

The enhancement in heat transfer for CNT-water nanofluid is found to be 39.95%, 57.32%, 69.42%, and 90.76% for the nanoparticle concentration of 0.15%, 0.45%, 0.60%, and 1%, respectively, compared with water.

LIMITATIONS Lower specific heat Specific heat of nanofluids is lower than base fluid . Namburu et al reported that CuO/ethylene glycol nanofluids, SiO2/ethylene glycol nanofluids and Al2O3/ethylene glycol nanofluids exhibit lower specific heat compared to base fluids. An ideal coolant should possess higher value of specific heat which enable the coolant to remove more heat.

High cost of nanofluidsHigher production cost of nanofluids is among the Reasons that may hinder the application of nanofluids in industry. Nanofluids can be produced by either one step or two steps methods. However both methods require advanced and sophisticated equipment's.

Difficulties in production process Another difficulty encountered in nanofluid manufacture is nanoparticles’ tendency to agglomerate into larger particles, which limits the benefits of the high surface area nanoparticles. To counter this tendency, particle dispersion additives are often added to the base fluid with the nanoparticles.

CONCLUSION The nanocoolants found to enhance the thermal performance of the

automobile radiator.

The maximum heat transfer performance for 1.0 vol. % nanoparticle concentration were found to be 90.76% and 52.03% higher for CNT-water and Al2O3-water, respectively, compared with water.

With the increase in the coolant flow rate, the heat transfer performance increases for various coolants, namely, water, CNT-water and Al2O3-water.

The CNT-water nanofluid exhibited enormous enhancement in heat transfer compared to the Al2O3-water nanofluid. This may be due to the fact that carbon nanotubes offer a high thermal conductivity, high aspect ratio, low specific gravity, and large SSA and low thermal resistance as compared Al2O3-water nanofluid.

The effective thermal conductivity of both CNT-water and Al2O3-water nanocoolant increases with the increase in nanoparticles concentration, consequently, increases the cooling performance in automobile radiator.

REFERENCES ChoiU. S., SingerD. A., and WangH. P., 1995, Development and Application of Non-

Newtonian Flows, Vol. 231, ASME, New York, pp. 99–105.

ChoiS., 2006, “Nanofluids for Improved Efficiency in Cooling Systems,” Heavy Vehicle Systems Review, Argonne National Laboratory, Argonne, Illinois.

Kulkarni, D. P., Vajjha, R. S., Das, D. K., and Oliva, D., 2011 “Application of Aluminum Oxide Nanofluids in Diesel Electric Generators Jacket Water Coolant,” Appl. Therm. Eng., 28, pp. 1774–1781. [CrossRef]

Vajjha, R. S., Das, D. K., and Namburu, P. K., 2010, “Numerical Study of Fluid Dynamic and Heat Transfer Performance of Al2O3 and CuO Nanofluids in the Flat Tubes of a Radiator,” Int. J. Heat Fluid Flow, 31, pp. 613–621. [CrossRef]

Peyghambarzadeh, S. M., Hashemabadi, S. H., Jamnani, M. S., and Hoseini, S. H., 2011, “Improving the Cooling Performance of Automobile Radiator With Al2O3/Water Nanofluid,” Appl. Therm. Eng., 31(10), pp. 1833–1838. [CrossRef]

Leong, K. Y., Saidur, R., Kazi, S. N., and Mamun, A. H., 2010, “Performance Investigation of an Automotive Car Radiator Operated With Nanofluid-Based Coolants (Nanofluid as a Coolant in a Radiator),” Appl. Therm. Eng., 30, pp. 2685–2692. [CrossRef]