In this presentation related about natural convective heat transfer incresed by using different nano particles. in this fluid is called nanofluids. Nanofluids improve the heat transfer rate of base fluid.

Published on: **Mar 3, 2016**

Published in:
Engineering

- 1. NATURAL CONVECTIVE HEAT TRANSFER BY Al2O3 &PbO NANOFLUIDS GUIDED BY: Mr.S.SANKARA KUMAR. M.E SUBMITTED BY: P.MANIKANDAN S.KRISHNAN M.ALAGAPPAPANDIAN G.BALA SINGH
- 2. INTRODUCTION • Heat transfers are used in many industrial area. • Natural Convective Heat Transfer by Nano Fluids is nothing but exchange of thermal energy and heat between the physical system by nano fluids. • Convective heat transfer is the transfer of heat by movement of fluids. • Nano fluids, a name conceived by Dr.Choi , in Argonne National Laboratory, to describe a fluid consisting of solid nano particles with size less than 100nm suspended on it with solid volume fractions typically less than 4%.
- 3. OBJECTIVES • To improve the heat transfer rate of base fluid by adding nano particles. • To determine the heat transfer coefficient of natural convection of nanofluids in a tube. • Water/oil has been chosen as base fluid. • By varying volume concentration of nanofluid, various thermal conductivity rate can be obtain. • In addition, Al2o3 nano particles are stable in various PH value.
- 4. SYNTHESIS METHODOLOGY • THREE DIFFERENT STEPS FOR SYNTHESIS OF NANOFLUIDS: • By mixing of nano powder directly in base fluid. • By acid treatment of base fluid. • By adding surfactants (surface active agent) to the base fluid.
- 5. General preparation for nanofluids All the above methods followed by magnetic stirring with sonic process about 2hours
- 6. DIRECT MIXING METHOD Directly mixing nano powder with base fluid. This method followed by magnetic stirring. It causes poor suspension stability. Nano powder settle down due to gravity . Particle settlement depends upon type of nano powder used. This method is more suitable for oxide nano particles (e.g. Al2O3, CUO, PbO ,etc. . , )
- 7. ACID TREATMENT OF BASE FLUID By decreasing ph value by adding suitable acid with base fluid. By this method nano fluid with uniform particle dispersion can be obtain. But, causes corrosion to pipe wall.
- 8. ADDING SURFACTANTS TO THE BASE FLUID In this method a small amount of suitable surfactant, generally 1/10 of mass of nano powder is added to base fluid. Some surfactants are ethylene oxide, soap, natural oil, etc . . , It gives stable suspension with uniform particle dispersion Suspension state for long time without settling down can obtain.
- 9. • Volume Concentration: The volume concentration for nanofluid is calculated by (Φ) (wnp/ρnp) Φ= (wnp/ρnp)+(wbf/ρbf) Wnp-weight of nano particle(kg) ρnp-density of nano particle(kg/m3) wbf-weight of base fluid(liters) ρbf- ρnp-density of base fluid(kg/m3)
- 10. SAMPLE CALCULATION FOR PREPARATION • The weight of nano particle required for preparation of 100ml cuo nanofluid of a particular volume concentration, using water as base fluid is calculated by formula . (wcuo/6300) Φ= (wcuo/6300)+(100/1000)
- 11. Volume concentration (Φ) (%) Wcuo (g) [for 100ml] 0.1 0.60872 0.2 1.21865 0.3 1.82981 0.4 2.44228 0.5 3.05582 0.6 3.6706 0.7 4.28676 0.8 4.90409 By changing the volume concentration thermal conductivity rate can be obtain
- 12. SYNTHETIC PROCESS Selection of nano particle and base fluid (al2o3/pbo & water/oil) Preparation of nanofluid by any one of above method Conducting experiment by varying volume concentration (Φ) & note down the readings Determine the heat transfer coefficient of nanofluid and traditional fluid Comparison of heat transfer coefficient between nanofluid and traditional fluid is done
- 13. LITERATURE SURVEY • Many researches are carried out to improve the heat transfer rate of base fluids using nano fluids. • VisineeTrisakri shows the use of additives is a technique applied to enhance the heat transfer performance of base fluids. Recently as an innovative material, nanometer-sized particles have been used in suspension in conventional heat transfer fluids. The suspended metallic or nonmetallic nanoparticles change the transport properties and heat transfer characteristics of base fluid.
- 14. • (Li et al., 2009). A 40% increase in thermal conductivity was found in the Cu oil-based nanofluids with 0.3% volume concentration. • (Eastman et al., 1997).The Al2O3 water-based nanofluids exhibited a 29% enhancement of thermal conductivity for the 5% volume concentration nanofluids. • Pak andCho studied the heat transfer performance of Al2O3 and TiO2nano particles suspended in water and expressed that convective heat transfer coefficient is 12% smaller than that of pure water at 3% volume fraction.
- 15. • Heris et al investigated laminar flow of cuo/water al2o3/water nanofluid through copper tube it results heat transfer coefficient increases with increasing volume concentration. • Yang et al ,investigate convective heat transfer of graphite nanofluid in copper tube . Inexpertly it result heat transfer coefficient increases and thermal conductivity decreases . the reasons is the size of particle is average diameter of 1-2ᶣm and thickness 2-3nm . Apart from thermal conductivity particle shape is an important factor.
- 16. RELATED TO OUR PROJECT • Natural convective heat transfer investigation was done by Putra et al & Wen and Ding has found that it decreases in overall heat transfer coefficient due to deterioration increases with particle concentrations . • This will overcome by changing the base fluid or preparation method.
- 17. • Nano particle – Al2O3 & Pbo • Base fluid – water/oil • Volume concentration – 0.5 to 0.8% • Method of preparation ; 1. acid treatment. 2. Adding surfactants.
- 18. EXPERMENTATION • Initially Nanofluids are prepared and stored in storage tank. • Now it allow to pass through pipes. • At the pipe connected with copper tube heater and thermocouples. • The heater is switched on it tends to produced the heat it measure by thermocouple. • When the nanofluid reaches the heater it absorbs heat from the heater. • The thermocouple measure the absorbing heat of nanofluid from heater.
- 19. • The thermocouple is measured heat in copper tube heater and inlet/outlet heat of nanofluid. • The temperature are noted down in a tabular column. • The above steps are followed to traditional fluid
- 20. SYSTEMATIC LAYOUT
- 21. JOURNALS • Analysis of heat transfer coefficient of nano fluids (Mr.V.N.Anbazhagan , IJERT 2013) • Convective Heat Transfer Enhancement in Nanofluids (American scientific publishers) -experimental study
- 22. • A Review on Nanofluids: Preparation, Stability Mechanisms and Applications (Wei Yu, Huaqing Xai) -method of preparation • Heat transfer characteristics of nanofluids: a review (Xiang-Qi Wang, Arun S. Mujumdar).