PERFORMANCE EVALUATION OF PARALLEL AND COUNTER FLOW HEAT EXCHANGER USING NANOFLUID ABSTARCT Krishna R. Patel [1], D. C. Solanki [2], Rakesh Prajapati [3] Student (M. E. Thermal Engineering) [1], Professor [2], Assistant Professor [3] Department of Mechanical Engineering [1,2,3], Sal Institute of Technology and Engineering Research [1,2,3] E-mail: krishnarpatel1530@gmail.com, dcsolanki_ldce@yahoo.com, rakeshp.prajapati@sal.edu.in Nano Fluids are mixture of nanoparticles in base fluids like water, propylene glycol, ethylene glycol etc. The nanoparticles used in the nanofluids are made up of metals, metal oxides, carbides, carbon etc. Nanofluids have inherent properties that make them possibly very useful in many heat transfer applications like pharmaceutical process, chemical processes etc. Nanofluid show superior thermal conductivity and heat transfer coefficient compared to base fluids, like water.in this work, experiments were conducted for 0.006% and 0.01% of volume concentrations of CuO and Cu nanofluids in a parallel and counter flow double pipe heat exchanger with cold and hot water as base fluids. Hot water is flowing in the inner pipe and cold water flowing in the annulus. Overall heat transfer coefficient for different flow rates, 2, 4 & 6 LPM, and temperatures 40, 50 & 60 is estimated. Keywords Nanofluid, Overall heat transfer coefficient, CuO nanofluid, Cu nanofluid, Double-pipe heat exchanger 1. INTRODUCTION The addition of solid particles into heat transfer medium is one of most useful techniques for enhancing heat transfer, although a major consideration when using suspended millimeter- or micrometer-sized particles is that they cause some problems, like abrasion, clogging, and sedimentation of particles. Compared to heat transfer enhancement through the use of suspended large particles, the use of nanoparticles shown better properties relating to the heat transfer of fluid, because of their very low concentrations and nanometer sizes. Nanofluids consist of base fluid developed with particles of size 1-100 nm (Nanoparticles). Nowadays, Nanofluids are used in wide range of applications like chemical industry, medical application, and biomedical industry, power generation in nuclear reactors and in any application regarding heat removal of industrial applications. Thermal properties of liquids play a important role in heating as well as cooling applications in industrial processes. Research is ongoing for nanofluids which can be used in Microelectronics, Fuel cells, Pharmaceutical industrial processes, Engine cooling, Vehicle thermal management, Domestic refrigerator, air condition systems, Chiller, Heat exchanger, space technology, Defense and ships, and reduction of boiler flue gas temperature, and many more. For heat exchanger, experimental results show an increase in heat transfer coefficient with increase of mass flow rate and thermal conductivity, operating temperature, volume concentration of nanoparticles, and size of nanoparticles. AhmadrezaAbbasi [1] found such application of nanofluid like power generation, industrial, and information technology. Advantages 47
of Nanofluids through heat transfer enhancement have been summarized as efficiency and safety boos in power generation, product size, cost reduction, product quality, reduction in energy consumption and emission. Rohit [2] et did an experimental study on concentric tube heat exchanger using Al 2 O 3 nanofluid 2% and 3% of volume concentrations mixed with water used as a base fluid. The experiment did examine the overall heat transfer coefficient for a fixed heat transfer surface area. It detected that, 3 % nanofluids shown best performance with overall heat transfer coefficient 16% higher than water. K. Vijaya Kumar Reddy [3] et done an experimental investigations in a double pipe heat exchanger with hot and cold water as working fluids. Nusselt number and overall heat transfer coefficient for different cold water mass flow rates are estimated with keeping hot water flow rate constant. All experiments were conducted for 0.05% and 0.1% volume concentrations of ZnO, MgO and CuO nano fluids with water. It is observed that, overall heat transfer coefficient of CuO nanofluid is higher than of MgO & ZnO nanofluids. For CuO nanofluid overall heat transfer coefficient is 1.622 this means the amount of the overall heat transfer coefficient of the nanofluid is62% greater than that of water, base fluid. Vatsal. S. Patel [4] et did study on the effect of addition of 0.5 and 1% of CuO nanoparicles in base cold fluid in a counter flow concentric tube heat exchanger. The heat transfer coefficient and friction factor of the CuO Water nanofluid in turbulent flow are investigated. The results show that the convective heat transfer coefficient of CuO nanofluid is higher than that of the base fluid by about 3.45 9.5%. The heat transfer coefficient is increases with an increase in the mass flow rate of the hot water and nanofluid. LI Qiang [5] did an experiment of Cu nanofluid used in double pipe heat exchanger.experiment was carried out with 0.3%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 2.0% of Volume concentration of Cu nanofluid. Results show that the nanoparticles significantly increase the convective heat transfer coefficient of the base fluid and the friction factor of the nanofluid with the low volume fraction of nanoparticles is nearly not changed. Compared with the base fluid, for sample, the convective heat transfer coefficient is increased about 60% with 2.0 vol% Cu nanoparticles at the same Reynoldsnumber. Considering the factors affecting the convective heat transfer coefficient of the nanofluid, a new correlation for convective heat transfer of nanofluid is established. The literature review concludes that the application of nanofluid in heat exchanger to increase the heat transfer rate is the relatively recent practice and the application of CuO nanofluid and Cu nanofluid to enhance the heat transfer rate of double pipe heat exchanger rate is to be increased. In this experiment, Double pipe heat exchanger is used todetermine the overall heat transfer co-efficient for 0.006% an 0.01% volume concentration of CuO and Cu nanofluids with base fluid distilled water in parallel and counter flow arrangements. 2. PREPARATION OF NANOFLUIDS Nanofluids can be prepare by two methods viz. (1) the single-step method, in which nanoparticles evaporated and directly dispersed into the base fluids and (2) the two-step method, in which the nanoparticles are made firstly and then dispersed into the basefluid. In this experiment two-step method is used to prepare nanofluid. CuO and Cu nanoparticles are purchased from Souvenir Chemicals, Mumbai, India. CuO nanoparticles of 20-30 nm size have 6400 kg/m 3 density and Cu nanoparticles of 20-30 nm size have 8960 kg/m 3 density. Here, CuO and Cu nanoparticles dispersed into the base fluid water with the help of Sodium DodecycleSulphate (SDS)/ Sodium Lauryl Sulphate surfactant. Surfactant only creates a bond with nanoparticles and water, it did not change the properties of base fluid as well as nanoparticles. So, with the help of surfactant, nanoparticles will easily disperse into water and cannot sediment.cuoand Cu nanofluids of 0.006 % and 0.01% vol. con of nanoparticles, 10 grams and 15 grams respectively mixed into the 25 liters of distilled water with 8 grams of surfactant.stirring can be done with the help of the stirrer for minimum 1 hour so that particles cannot settle down to the base of the tank. 48
4. EXPERIMENT PROCEDURE The procedure to evaluate the effect of nanofluid on heat transfer characteristics of double pipe heat exchanger is presented below: Fig 1: CuO Nanofluid 1) Conduct the experiment using distilled water as cold and hot fluid in double pipe heat exchanger. 2) Conduct the experiment with the temperatures 40, 50 and 60 with varying the mass flow rates 2 LPM, 4 LPM and 6 LPM. 3) Calculate the experimental value of overall heat transfer coefficient and the theoretical value of overall heat transfer coefficient as per the calculation steps mentioned below. Fig 2: Cu Nanofluid 3. EXPERIMENTAL SETUP The experimental setup is shown in the figure below. Inner pipe and outer pipes are made from SS304 and diameters are 15.80 mm and 62.71 mm respectively. The length of the pipe is 1.6 meters. Outer pipe contains 12.5 mm thick glass wool insulation.1.5 KW heater is fitted into the hot water tank. The capacity of hot fluid and cold fluid tank is 30 liters. Hot fluid flows into the inner pipe and cold fluid flows into annulus. It has 2 rotameters with measures the flow of fluid 1-10 LPM. There are 4 number of thermocouples for measuring the temperature and one PID controller and one temperature indicator. 4) Empty the distilled water from both the tank of the double pipe heat exchanger. 5) Fill the CuO nanofluid of 0.006% volume concentration into hot fluid tank. Now the CuO nanofluid will work as hot fluid. And the distilled water in the cold fluid tank. 6) Perform the experiment and evaluate the overall heat transfer coefficient with CuO nanofluid of 0.006% vol concentration as per the step number 1 to 4 of experiment procedure. 7) Perform the experiment and evaluate overall heat transfer coefficient with CuO nanofluid of 0.01% volume concentration as per the step number 1 to 4 of experiment procedure. 8) Follow the same experimental procedure for Cu nanofluid of 0.006% and 0.01% of vol. concentration. Compare the overall heat transfer coefficient ofcuo and Cunanofluids with the base fluid distilled water. 5. CALCULATION PROCEDURE Fig 3: Experimental Set-up of Parallel and Counter flow double-pipe heat exchanger 5.1 Calculation steps for properties of Nanofluid: 1) Volume Concentration of Nanoparticles in base fluid: 49
2) Density of Nanofluid: Using Xuan and Roetzel equation, 9) Experimental Overall Heat transfer co-efficient based on inner surface of inner pipe: 3) Specific heat of Nanofluid: Using Pak and Cho equation, 4) Thermal conductivity of Nanofluid: Using Maxwell s equation, 5) Viscosity of Nanofluid: Using Brinkman equation, 10) Reynolds Number (Re): 5.3Calculation steps for Theoretical Evaluation of Overall Heat Transfer Coefficient: 1) Average temperature of hot fluid: 5.2 Calculation steps for Experimental Evaluation of Overall Heat transfer Coefficient: 1) Mass Flow rate of hot fluid: 2) Mass Flow rate of cold fluid: 2) Average temperature of Cold fluid: 3) Find the following properties of hot and cold fluids from property table 4) Mass Flow rate of hot fluid: 3) Heat transferred by hot Fluid to cold fluid: 5) Mass Flow rate of cold fluid: 4) Heat transferred by cold fluid to hot fluid: 5) Average heat transfer: 6) Outer surface Area of Inner pipe: 7) Inner surface Area of Inner pipe: 8) Logarithmic mean temperature difference θ m : For parallel-flow LMTD, 6) Heat transferred by hot Fluid to cold fluid: 7) Heat transferred by cold fluid to hot fluid: 8) Logarithmic mean temperature difference θ m: For parallel-flow LMTD, 9) For Counter-flow LMTD, For Counter-flow LMTD, 10) Reynolds Number: For Inner pipe, 50
Overall heat transfer co-efficient Ui International Journal Of Engineering Innovation And Scientific Research.Vol.1 (3)-P.P- 47-53 ISSN: 2395-6372 900 For Outer pipe, 800 700 600 500 400 300 Average velocity of Fluid ( ) 11) Nusselt Number: For Inner pipe, If Re > 2300, Flow is turbulent, Using Dittus- Boelten equation, For Outer pipe, If Re > 2300, Flow is turbulent, Using Dittus- Boelten equation, If Re < 2300, Flow is Laminar, Then Nu is taken as constant, 5.6 Convective heat transfer co-efficient: For Inner pipe, For Outer pipe, 200 100 0 0 1 2 3 4 5 6 7 water mass flow rate m (LPM) CuO nanofluid (0.006% of vol.con) CuO nanofluid (0.01% of vol.con) Cu nanofluid (0.006% of vol.con) Cu nanofluid (0.01% of vol.con) Fig 4: Overall heat transfer co-efficient vs mass flow rate (Distilled Water, CuO Nano fluid and Cu Nano fluid (0.006% and 0.01% vol. con) system-parallel Flow based on Experimental Data at 60 ) It is shown that the overall heat transfer co-efficient of CuO Nanofluid is 13.33%, 29.3% and 27.4% for 0.006% and 20.5%, 31.2% and 27.5% for 0.01% CuO nanofluid (parallel flow) of 2, 4, and 6 LPM respectively for 60. 12) Theoretical Overall Heat transfer co-efficient based on inner surface of inner pipe: 6. RESULT AND DISCUSSION The overall heat transfer co-efficient is plotted for distilled water, CuO Nanofluid and Cu nanofluid for parallel and counter flow arrangements are as below. 51
Overall heat transfer co-efficient Ui International Journal Of Engineering Innovation And Scientific Research.Vol.1 (3)-P.P- 47-53 ISSN: 2395-6372 900.000 800.000 700.000 600.000 500.000 400.000 300.000 200.000 100.000 0.000 0 2 4 6 8 water mass flow rate m (LPM) CuO nanofluid (0.006% of vol.con) CuO nanofluid (0.01% of vol.con) Cu nanofluid (0.006% of vol.con) Cu nanofluid (0.01% of vol.con) Fig 5: Overall heat transfer co-efficient vs mass flow rate (Distilled Water, CuO Nanofluid and Cu Nanofluid (0.006% and 0.01% vol. con) system- Counter Flow based on Experimental Data at 60 ) It is shown that the overall heat transfer co-efficient of CuO Nanofluid is 8.4%, 28.5% and 32.2% for 0.006% and 13.5%, 30.8% and 32.4% for 0.01% CuO nanofluid (parallel flow) of 2, 4, and 6 LPM respectively for 60. The remaining results are as follows: Parallel flow: 1) The increase in overall heat transfer co-efficient of CuO nanofluid is 12.77%, 24.77% and 26.54% for 0.006% and 15.20%, 25.84% and 27.70% for 0.01% of volume concentration for 2 LPM, 4 LPM, and 6 LPM respectively. 2) The increase in overall heat transfer co-efficient of Cu nanofluid is 15.37%, 26.20% and 38.9% for 0.006% and 19.60%, 27.67% and 40.5% for 0.01% of volume concentration for 2 LPM, 4 LPM, and 6 LPM respectively. Counter Flow: 1) The increase in overall heat transfer co-efficient of CuO nanofluid is 11.63%, 25.16% and 27.46% for 0.006% and 16.04%, 26% and 29% for 0.01% of volume concentration for 2 LPM, 4 LPM, and 6 LPM respectively. 2) The increase in overall heat transfer co-efficient of Cu nanofluid is 24.23%, 29.30% and 39.03% for 0.006% and 29.80%, 29% and 43.07% for 0.01% of volume concentration for 2 LPM, 4 LPM, and 6 LPM respectively. 7. CONCLUSION An experimental investigation is carried out to determine effect of different nanofluids with different volume concentration on the overall heat transfer coefficient of the double-pipe heat exchanger of parallel and counter flow arrangements. It is concluded that increase in overall heat transfer co-efficient of CuO nanofluid is 22.35% and Cu nanofluid is 30.23% compare to distilled water. So, overall heat transfer co-efficient of CuO and Cu Nanofluids is increase with increase in mass flow rate as well as increase in temperature with compare to base fluid distilled water. 8. REFERENCES [1] AhmadrezaAbbasiBaharanchi, Application of nanofluid for heat transfer enhancement, Spring 2013, PID: 2739168, EEE-5425 [2] Rohit S. Khedkar, Shriram S. Sonawane, Kailas L Wasewar, Water to Nanofluids heat transfer in concentric tube heat exchanger: Experimental study, Procedia Engineering 51 (2013) 318 323, Elsevier [3] K.Vijaya Kumar Reddy, Naga SaradaSomanchi, Rangisetty Sri Rama Devi, Ravi Gugulothu and B. SudheerPrem Kumar, Heat Transfer enhancement in a Double Pipe Heat exchanger using Nano fluids, Proceedings of the 17th ISME Conference ISME17, October 3-4, 2015, IIT Delhi, New Delhi, ResearchGate [4] Mr. Vatsal. S. Patel, Dr. Ragesh. G. Kapadia,Dr. Dipak A. Deore, An Experimental Study of Counter Flow Concentric Tube Heat Exchanger using CuO / Water Nanofluid, International 52
Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 www.ijert.org Vol. 2 Issue 6, June 2013 [5] LI Qiang, XUAN Yimin, Convective heat transfer and flow characteristics of Cu-water nanofluid,science in China(Series E), Vol. 45 No. 4 53