EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER COEFFICIENT AND FRICTION

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 8, August 2017, pp , Article ID: IJMET_08_08_012 Available online at me.com/ijmet/issues.asp?jtype=ijmet&vtype=8&i IType=8 ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER COEFFICIENT AND FRICTION FACTOR IN A DOUBLE PIPE HEAT EXCHANGER WITH AND WITHOUT TWISTED TAPE INSERTS USING ZNO-PROPLYENE GLYCOL NANO FLUID T. Vijaya sagar Dept. of Mechanical Engineering K L University Guntur, Andhra Pradesh, India Dr.Y.Appalanaidu Dept. of Mechanical Engineering K L University Guntur, Andhra Pradesh, India ABSTRACT Heat transfer coefficient and friction factor of ZnO Nanofluid passing in the double pipe heat exchanger with and without twisted tapes along with wire coil are placed in the experimental investigation. The ratio of the base fluids are 60:40 water and Propylene glycol are considered. The volume concentrations of ZnO Nanofluid 0.15, 0.25, and 0.4 % are taken. The double pipe heat exchanger has an inner tube in which different twisted tape configurations are inserted, the twist ratios are 10, 5, and 3 are taken. The flow rates are taken for cold and hot water, the ranging of cold and hot water are to and Kg/Sec are taken in the experimental study. The results shows that the Nusselt number for double pipe heat exchanger was increased at 0.4% concentration of ZnO Nanofluid with twisted tape at the ratio of H/D= 3 the heat transfer enhanced by 23.56% and the friction factor was increased by 15.32% compared with the base fluid. The Reynolds number ranging from 3000 to The error ranging of 5 of the experiment. Keywords: Double pipe heat exchanger, Heat transfer, Friction factor, Nanofluid, Twisted tape, Wire coil. Cite this Article: T. Vijaya sagar, Dr.Y.Appalanaidu, Experimental investigation of heat transfer coefficient and friction factor in a double pipe heat exchanger with and without twisted tape inserts using zno-proplyene glycol nanofluid, International Journal of Mechanical Engineering and Technology 8(8), 2017, pp T/issues.asp?JType=IJMET&VType=8&IType=8

2 T. Vijaya Sagar,Dr.Y.Appalanaidu 1. INTRODUCTION Heat exchangers are the equipment that is commonly used to transfer heat between two passing fluids at different temperatures without any mixing of fluids with each other. Transfer of energy from one fluid to another fluid can be done modes of heat transfer. Heat exchangers with the convective heat transfer of fluid inside the tubes are frequently used in the many engineering applications like heavy industries, power plants, automotive, chemical industries, metallurgical, electronics components, refrigeration s, air conditions and duct systems. Enhancement of heat transfer intensity in all types of thermo technical apparatus is of very important for industries. For the savings of power generations, it also leads to a moderating in size and weight. Up to the present work, several heat transfer enhancement techniques have been developed. Twisted tapes is one of the most important element of enhancement techniques. The combination of water and propylene glycol are being used as the coolant due to advantages of new technologies there are a number of improvements in the field engineering applications including the enhancement of heat transfer capabilities. Tubes with rough surfaces have much higher heat transfer coefficients than tubes with smooth surfaces. Therefore, tubes surfaces are often intentionally roughened, corrugated, or finned in order to enhance the convection heat transfer coefficient and thus the convection heat transfer rate. Turbulence flow in tube the heat transfer has been increased as much 40% by roughening the surface. Among many techniques investigated for augmentation of heat transfer rates inside circular tubes, a wide span of inserts has been utilized, specifically, when turbulence flow is considered. The inserts investigated that included coil wire inserts, brush inserts, mesh inserts, strips inserts, twisted tapes inserts etc. Augmentation of convective heat transfer in internal flow with tape placed in tubes is a well approved technique hire in industrial particles. The present investigation is aimed at studying the frictional and heat transfer characteristics in turbulent region using varying width twisted tape with coil spring placed under constant will heat flux. The objective of using varying width twisted tapes is to minimize the pressure drops associated with full width twisted tapes without seriously impairing the heat transfer augmentation rates and to achieve material ranges.however, due to micron size of particles there were several problems like sedimentation and erosion of tubes and pumps while in transmit. In the resent past the availability of Nano material s renewed the interest in the application of Nanofluids. The suitability and performance of the conventional fluids can be enhanced by introducing Nano particles like Al 2 O 3, TiO 2, ZnO and CuO, by converting them in to Nanofluids. [1] Chandra Sekhara teddy: The experimental carried out by heat transfer coefficient and friction factor for Tio 2 Nanofluid passing in a double pipe heat exchanger with and without heical coil placed are experimentally studied. The volume concentrations are % to 0.02% of Nanofluid are taken and the based fluid ratio are 60:40 for water and ethylene glycol. The heat transfer coefficient and friction factor are enhanced by 10.83% and 8.73% at 0.02% concentration when compared to base fluid without helical coil. Heat transfer coefficient and friction factor further get enhanced by 13.85% and 10.69% respectively for 0.02% concentration Nanofluid when compared to base fluid flowing in a tube with helical coil placed P/d = 2.5. [2] P.V.Durga Prasad and Gupta: The experimental carried out by investigation on heat transfer enhancement on U-bend heat exchanger and twisted tape using water Al 2 O 3 Nanofluid. The volume concentration of Nanofluid are 0.01% and 0.03% are taken. Twist ratio for twisted tapes are ranging between 5 and 20. The results showed that the Nusselt number of entire pipes for 0.03% concentration of Nanofluid with twisted tapes placed is 95 editor@iaeme.com

3 Experimental investigation of heat transfer coefficient and friction factor in a double pipe heat exchanger with and without twisted tape inserts using zno-proplyene glycol nanofluid enhanced by 31.28% compared to the water. The friction factor increased by 1.23 times compared with the water while placing the twisted tapes H/D = 5. [3] Hasanpour, Farhadi and Sedighi: The experimental carried out by which has inner tube filled with various categories of twisted tapes. From conventional to modified types which includes perforated V-cut and U-cut types. The twist ratios are 3, 5 and 7 and the Reynolds number range from 5000 to The results showed that the Nusselt number and friction factor for all cases of twisted tapes corrugated tube are more than the empty corrugated tube. [4] V. Chandraprabu and Sankaranarayanan: The experimental carried out by heat transfer performance of Nanofluid Al 2 O 3 water and CuO water is expressed by using the condensing unit of an air conditioner. The volume concentrations of Nanofluid are 1, 2, 3, and 4. Two nanofluids shows better heat transfer rate than does the base fluid. The Cuo water Nanofluids better heat transfer rate than Al 2 O 3 water Nanofluids. [5] P.V.Durga Prasad and gupta: In this study the volume concentrations of Al 2 O 3 Nanofluid are 0 to 0.03%, and longitudinal strip placed of aspect ratios are 1, 2, 4, and 12 are taken. The results shows that the Nusselt number and friction factor of entire pipes for 0.03% concentration of Nanofluid with longitudinal strip placed ratio of 1 enhances by 47.35% and 1.21 times compared with base fluid. [6] Hamid and Mohammadiun: In this study of Al 2 O 3 /ethylene glycol (EG) are taken, The three different volume concentrations of Al 2 O 3 Nanofluid are 0.5, 1, and 1.5% and at three different twist ratios of twist tapes y/w = 2, 3.6 and 5 are taken. The results shows that utilization of twists together with Nanofluid tends to increase the heat transfer and friction factor, the thermal performances factor 4.2 is found with the use of Al 2 O 3 /EG Nanofluid at concentration at 0.5% by volume is corrugated tube together with twisted tape at twist ratio 2. [7] Kushalkamboj and rohitsharma: In this study experimentally investigated the heat transfer augmentation by means of divergent-convergent spring coil turbulent and tried to find the optimum pitch which augmentation heat transfer is maximum. The pitch ratios are 5, 10 and 15cm. The Nusselt number enhanced by 26.76% and maximum friction factor is 66.87% at pitch ratio=5cm, thermalperformance factor maximum is at pitch ratio=15. [8] SarmadA.Abdal Hussein: Experimentally Investigation of heat transfer and friction factor of double pipe heat exchanger, inserted semi circular disc baffles with spacing of 15cm and 45cm carriedout for turbulent flow. The semi circular disc baffles 15 and 45cm the heat transfer rate by 1.9 and 1.3 times of smooth tube are placed. The results shows that the inserted tape with 15cm has maximum friction factor than that with 45cm and the experimental data with average error of 7.8% for nusselt number and 6.5%for friction factor. [9] Anil Singh Yadav: Investigation on double pipe heat exchanger with and without twisted tapes at different mass flow rate. As compared to conventional heat exchanger, the augmented has heat exchanger has shown a significant improvement in heat transfer coefficient by 40% for half-length twisted tape. At the equal mass flow rate heat transfer performance of half-length twisted tape is maximum compared to smooth tube. The results shows that on unit pressure drop basis the heat transfer performance of smooth tube is maximum compared to twisted tape, thermal performance of smooth tube is better than halflength twisted tape by times. [10] Madhav Mishra and Nayak: Experimentally investigation of effectiveness and overall heat transfer coefficient of double pipe heat exchanger. Triangular baffles of 100mm and 50mm pitches enhance the average effectiveness by 1.42 and 1.62 times in parallel flow 96 editor@iaeme.com

4 T. Vijaya Sagar,Dr.Y.Appalanaidu and in counter flow are and The average heat transfer rate are 1.6 and 1.9 times in parallel flow and in counter flow are 1.48 and 1.67 that of smooth tube respectively. [11] Swathi and Kishore: Experimentally investigation of effectiveness in double pipe heat exchanger, setup-1 rectangular fins and twisted tapes insert inside pipe, setup-2 only twisted tapes without fins insert outside pipe. Effectiveness is higher for setup-1 heat exchanger then setup-2 heat exchanger. LMTD and Turbulence increased for setup-1 heat exchanger than setup-2 heat exchanger. So by using fins in addition to twisted tapes effectiveness can be enhanced. [12] Amar Raj and Sing Suri: Multiple square perforated with square wing twisted tape, the width ratio is wd/wt to The results showed that the maximum value increases at 6.96 and 8.34 times nusselt number and friction factor at depth ratio of with compare to plain tube. [13] BehroutRaei: fully developed turbulence slow heat transfer and the pressure drop behavior of Al 2 O 3 / water. The volume concentrations of nanofluids are 0.05 to 0,15 are taken. The results shows enhancement of heat transfer and friction factor are 23 and 25% at 0.15 volume concentration compare with base fluid. [14] K.M. Elshazly: Thermal performance of shell and coil heat exchanger with different ferent coil torsions. Five helical coil tubes ranging between < and > are taken. The volume concentration of nanofluid are 0 to 2% are taken. The results shows that reduces the coil torsion and enhance heat transfer rate of Nanofluid. [15] Byung-Hee chen: Alumin Nanofluid and transformer oil of which flow through double pipe heat exchanger system in the laminar flow enhances the heat transfer coefficient. At highest concentration the heat transfer rate is increases. The data on the mixture of propylene glycol and water based Nanofluid passing in a tube with inserts twisted tapes with coil springs is not available in the literature. Therefore, the focus of the present work is on the estimation heat transfer coefficient and friction factor of propylene glycol and water mixture based on ZnO Nanofluid passing in double pipe heat exchanger with twisted tapes with coil spring are placed in investigation. The experiments on heat transfer are conducted by the Reynolds number range from 3000 to Based on the experimental data generalized correlations are proposed for Nusselt number and friction factor. 2. PREPARATION OF ZNO NANOFLUID Preparation of Nanofluids is one of the key tasks for enhancing the heat transfer by using nanofluids in many applications.particle agglomeration and particles dispersion in base fluid are two key factors to look upon for preparing a stable nanofluid, particle agglomeration leads to increase in particle size and particles should be well dispersed so that there will be no settlement in the base fluid and generally there are two methods for preparation of one step method and two step method. The Zno (Zinc oxide) nano particles used in this study were purchased from Sigma-Aldrich having 50nm nearly spherical particles. The two step method is used for preparing the nanofluid.the base fluid used in this experiment is water -propylene glycol mixture (60:40). Firstly, the nano particles are dissolved in the base fluid and of 20litres and constantly stirred for 45 min and for eliminating the agglomeration and for the proper dispersion of the nano particles the fluid is sonicated for 2h.the nano fluids are prepared in three different concentrations (i.e. 0.15%, 0.25% and 0.4%) the amount of particles required for each concentration is calculated by: 97 editor@iaeme.com

5 Experimental investigation of heat transfer coefficient and friction factor in a doublee pipe heat exchanger with and withoutt twisted tape inserts using zno-proplyene glycol nanofluid 100 (1) ρ ρ 1 ρ (2) C 1 C C (3) A) Thermal conductivity of Nanofluid: Thermal conductivity is one of the important parameter which has a impact on the heat transfer enhancement.the effective thermal conductivity of Nanofluid is measured by KD2 PRO thermal property meter.which is done by probe (Read time- 60 Seconds).the values of k for Nanofluid and base fluid are measured at different temperatures to predict the Thermal conductivity of Nanofluids is calculated using the following equation given by Hamilton and Crosser: (4) In the above equations, p,, refer to the volumetric concentration,particle, viscosity and density subscripts basefluid and Nanofluid refer to the base fluid and Nanofluid respectively. z is the empirical shape factor as the Nano particles used in this investigation are nearly spherical z is taken as 3 cp is the specific heat. Figure 1 Figure 1 represents the comparison between the ratio of thermal conductivity of Nanofluid to the base fluid and the double pipe heat exchanger inlet temperatures from the literature thermal conductivity of Nano fluid found to be increasing with increase in temperature and Nano particle volume concentration. in the above graph the two trends depicts the measured k value of 0.4% nanofluid and theoretical values of k obtained from hamilton-crosser model

6 T. Vijaya Sagar,Dr.Y.Appalanaidu.the measured values are much higher than the prediction. probably because these classical models do not account for the parameters like particle size, Brownian motion and Nano layering.which are important to consider in Nanofluids. B) Viscosity of Nanofluid : The viscosity of the Nano fluid is measured by using the rotary viscometer (BROOKFIELD).the reading were taken at different concentrations and temperatures of Nano fluid. The viscosity of the Nano fluid increases with increase in the particle concentration and decreases with the increase in temperature. is observed from the measurements and the literature as well. Figure 2 Figure 2 represents the comparison between the viscosity and the fluid inlet temperatures of the double pipe heat exchanger temperature is an important parameter to consider for the viscosity of Nanofluids. The viscosity of the Nanofluids decreased with increased in temperature. The graph depicts that the Nanofluid of highest concentration i.e., 0.4% at lowest temperature shows highest value of viscosity and vice versa. 3. EXPERIMENTAL SETUP The experimental unit consists of flow meters, thermocouple, u tube manometer data logger, receiving tanks(hot, cold) induction motor of 0.5 Hp capacity.the test section consists of concentric pipes and u bend made of stainless steel inner diameter of inner tube is cm length of test section is 2m,u bend radius of 0.32m. As surface area related to bend is very small compared to surface of concentric pipes so heat transfer in bend region can be neglected. Two motors of 0.5Hp capacity are used to pump the Nanofluid and hot Fluid, The hot fluid is pumped through the annulus of the concentric tube and Nanofluid flows through inner tube. Flow meter of maximum kg/sec are used to control the flow rates and throughout the experiment masss flow rate of hot water is kept constant kg/sec and flow rates of Nanofluid is varied from to Kg/sec. The surface area related to bend region is relatively small compared to areas of inner and outer tubes. In order to measure the temperature a total of four (4) thermocouple are used and thermocouple needles are placed in the inlet and outlets of pipes.

7 Experimental investigation of heat transfer coefficient and friction factor in a double pipe heat exchanger with and withoutt twisted tape inserts using zno-proplyene glycol nanofluid 1 Hot water Tank 3 Induction Motors 0.5Hp 5 U-Tube manometer 7 Coil Heaters ZnO Nano fluid flow Figure 3 2 ZnO Nano fluid Tank 4 Flow control valves 6 Flow meter Hot water flow Figure 3 (a) [H/D=3] Figure 3 (b) [H/D=5] Figure 3 (c) [H/D=10] The thermocouple readings are recorded by using multi point digital temperature indicator. In order to minimize the heat loss from the system to atmosphere it is insulated the outer surface of annulus tube is wounded with asbestos rope. The tank capacities of both Nanofluid and hot water are of 20 ltrs capacity made of stainless steel. Pressure drop across

8 T. Vijaya Sagar,Dr.Y.Appalanaidu the inner tube of test section is calculated by a u tube manometer with mercury as a Manometric fluid. The tubes in the test section were cleaned with distilled water prior to using Nanofluid. The Thermo physical properties of the Nanofluid are estimated at bulk mean temperature. Primary purpose of the work is to place twisted tape with wire coils in the inner tube of the test section and this passive augmentation technique is to generate a swirl / turbulent flow and they obstruct the flow leading to more fluid mixing for high heat transfer enhancement. Three variations of Twist Ratios are shown in figure 3 (a),3(b),3(c) and spring pitch was kept constant for all twisted tape configurations. 4. THEORETICAL ANALYSIS Data reduction Measurement of Heat transfer coefficient: The heat transfer coefficient for hot fluid as follows as: (5) Where Q h is the heat transfer coefficient at hot fluid, m h is the mass flow rate at hot fluid, Cp h is the specific heat at hot fluid and T hi and T ho are the inlet and outlet temperatures at hot fluid. The heat coefficient for cold fluid follows as: (6) Where Q c is the heat transfer coefficient at cold fluid, m c is the mass flow rate at cold fluid, Cpc is the specific heat at cold fluid and T ci and T co are the inlet and outlet temperatures at cold fluid. The average heat transfer coefficient follows as: (7) Where Q avg is the average heat transfer coefficient, Q h is the heat transfer at hot fluid and Q c is the heat transfer coefficient at cold fluid. The temperature difference at LMTD follows as: (8) Where is the temperature difference at LMTD, T hi is the hot inlet temperature, T ci is the cold inlet temperature, T ho is the hot outlet temperature and T co is the cold outlet temperature. The Nusselt number follows as: (9) editor@iaeme.com

9 Experimental investigation of heat transfer coefficient and friction factor in a double pipe heat exchanger with and without twisted tape inserts using zno-proplyene glycol nanofluid Where Nu Exp is the Nusselt number at experimental, h exp is the heat transfer rate, D is the diameter and k is the thermal conductivity. The heat transfer rate is given follow as: (10) (11) L (12) (13) Where h exp is the experimental heat transfer rate, Q avg is the average heat transfer coefficient, is the difference in temperature and A i is the area at inner side. (14). = (15) Where N u is the Nusselt number, Re is the Reynolds number and Pr is the Prandlt number. Measurement of friction factor: = (16) = (17) Where f exp is the experimental friction factor, P is the mean pressure, L is the length, D is the diameter, is the density, V is the volume and Re is the Reynolds number. 5. RESULTS AND DISCUSSIONS: a) Base Fluid data: The setup is validated before conducting experiment by using base fluid Distilled water and propylene glycol (60:40) ratio. and the results were plotted for Nusselt number and friction factor with equation number 15 of Dittus- Boelter and equation number 17 Blasius.the difference between experimental and theoretical data were found to be 5% for Nusselt number and 8% for friction factor as shown in figure 4 and figure 5. sselt Number, Nu Renolds Number Re Nu D- B Nu Exp Figure 4

10 T. Vijaya Sagar,Dr.Y.Appalanaidu Friction factor f Renolds Number Re nu nu exp Figure 5 b) Base Fluid with twisted tape configuration: Now the experiment is conducted with base fluid on different twisted tape configurations. Compared to the plain tube the Nusselt number and friction factor is more for twist ratio configuration H/D=3. The data obtained is shown in figure 6 and figure 7. Figure 6 Friction factor f f Exp f 10 TT f 5 TT f 3 TT Renolds Number Re Figure 7

11 Experimental investigation of heat transfer coefficient and friction factor in a double pipe heat exchanger with and without twisted tape inserts using zno-proplyene glycol nanofluid c) ZnONano Fluid data: 0.06 friction factor f f base fluid f 0.15% f 0.25% f 0.4% Reynolds number Re Figure 9 Now the experiment is conducted with ZnO Nanofluid of 0.15, 0.25, 0.40 % volume concentrations in a tube and the Nu values are estimated from equation 9 and shown in figure. From the graph it is known that for ZnO Nanofluid 0.4% volume concentration the Nusselt number enhancement is 13.7% and 19.72% within Reynolds number of 3000 and 8000 as shown in figure 8. another graphical plot of frictional factor for the same volume concentrations is shown in figure 9. There was a pressure drop across the test section and it was compared to the base fluid for 0.4% volume concentration it is increased by 9.72% and 11.48% with Reynolds number ranging between 3000 and Figure 8 d) ZnONano Fluid with twisted tape configuration: From figure 10 the experimental data for Zno Nanofluid 0.4% volume concentration the Nusselt number enhancement obtained were 14.1% & 20.96% at twisted tape configuration H/D=10 and for H/D=3 the Nusselt number enhancement obtained were 15.21% & 23.56% with Reynolds number between 3000 and It is observed from data that Nusselt number at twisted tape configuration H/D=3 exhibits higher values. By introducing the twisted tape configuration it produces swirl / turbulent flow in the tube which gives higher fluid mixing, so higher the convective heat transfer. Further friction factor analysis for the ZnO Nanofluid of 0.4% and 0.15% volume concentration with different twisted tape configurations are obtained were more compared to base fluid as shown in figure 11. observations from figure 11 are for 0.4% volume concentration and twisted tape configuration H/D=3 friction factor enhancement at Reynolds number 3000 is 12.16% and at Reynolds number 8000 is 15.32% that of base fluid. It was found that friction factor decreases with increase in Reynolds number and volume concentration, and decreases with Twist ratio. Nusselt Number Nu Nu 0.15% H/D=15 Nu 0.15% H/D=10 Nu 0.15% H/D=5 Nu 0.25% H/D=15 Nu 0.25% H/D=10 Nu 0.25% H/D=5 Renolds Number Re Nu 0.4% H/D=15 Figure 10

12 T. Vijaya Sagar,Dr.Y.Appalanaidu friction factor, f Renolds Number, Re f 0.15% H/D=15 f 0.15% H/D=10 f 0.15% H/D=5 f 0.25% H/D=15 f 0.25% H/D=10 f 0.25% H/D=5 f 0.4% H/D=15 f 0.4% H/D=10 Figure CONCLUSION The experimental results of the heat transfer enhancement by using ZnO nanofluid in a double pipe heat exchanger fitted twisted tape with wire coil inserts leads to following conclusions. Compared to the base fluid in a tube and 0.4% volume concentration of nanofluid in a tube with twisted tape configuration of H/D=3 the Nusselt number improvement is 15.21% and 23.56% with in the Reynolds number of 3000 and The friction factor of 0.4% Zno nanofluid flowing in a tube with twisted tape configuration of H/D=3 increases 12.16% at a Reynolds number of 3000 and 15.32% increase at a Reynolds number of 8000 compared to identical concentration fluid without twisted tape inserts. REFERENCES [1] M. Chandra Sekhara Reddy, Veeredhi Vasudeva Rao, Experimental investigation of heat transfer coefficient and friction factor of ethylene glycol water based TiO2 nanofluid in double pipe heat exchanger with and without helical coil inserts, International Communications in Heat and Mass Transfer Volume 50, January 2014, Pages [2] P.V. Durga Prasad, A.V.S.S.K.S. Gupta, Experimental investigation on enhancement of heat transfer using Al2O3/ water nanofluid in a u-tube with twisted tape inserts, International Communications in Heat and Mass Transfer 75 (2016) [3] A. Hasanpour, M. Farhadi, K. Sedighi, Experimental heat transfer and pressure drop study on typical, perforated, V-cut and U-cut twisted tapes in a helically corrugated heat exchanger, International Communications in Heat and Mass Transfer 71 (2016) [4] V. Chandraprabu,G. Sankaranarayanan,S. Iniyan,S. Suresh,Heat Transfer Enhancement Characteristics of Al2O3/Water and CuO/Water Nanofluids in a Tube in Tube Condenser Fitted With an Air Conditioning System An Experimental Comparison,. [DOI: / ]. [5] P. V. Durga Prasad, A. V. S. S. K. S. Gupta, L. Syam Sundar, Manoj Kumar Singh, and Antonio C. M. Sousa,Heat Transfer and Friction Factor of Al2O3 Nanofluid Flow in a Double Pipe U-Tube Heat Exchanger and with Longitudinal Strip Inserts: An Experimental Study,Journal of Nanofluids Vol. 4, pp , 2015 [6] Hamid Mohammadiun Mohammad Mohammadiun Mohammad Hazbehian Heydar Maddah,Experimental study of ethylene glycol-based Al2O3 nanofluid turbulent heat

13 Experimental investigation of heat transfer coefficient and friction factor in a double pipe heat exchanger with and without twisted tape inserts using zno-proplyene glycol nanofluid transfer enhancement in the corrugated tube with twisted tapes,heat Mass Transfer (2016) 52: [7] Kushal Kamboj, Gurjeet Singh, Rohit Sharma, Dilbagh Panchal, Jaspreet Hira,Heat transfer augmentation in double pipe heat exchanger using mechanical turbulators, Heat Mass Transfer DOI /s x. [8] Sarmad A. Abdal Hussein,Experimental Investigation of Double Pipe Heat Exchanger by using Semi Circular Disc Baffles,International Journal of Computer Applications ( ) Volume 115 No. 4, April 2015 [9] Anil Singh Yadav, Effect of Half Length Twisted-Tape Turbulators on Heat Transfer and Pressure Drop Characteristics inside a Double Pipe U-Bend Heat Exchanger, Jordan Journal of Mechanical and Industrial Engineering, Volume 3, Number 1, March ISSN Pages [10] Madhav Mishra1, U. K Nayak, Experimental investigations of double pipe heat exchanger with triangular baffles, International Research Journal of Engineering and Technology, Volume: 03 Issue: 08 Aug-2016 [11] Swathi Juturu, J. Kishore, Comparison of Effectiveness of Two Different Setups of Double Pipe Heat Exchangers, International Journal for Research in Applied Science & Engineering Technology, Volume 3 Issue IX, September 2015 [12] Amar Raj Singh Suria, Anil Kumara, Rajesh Maithani, Effect of square wings in multiple square perforated twisted tapes on fluid flow and heat transfer of heat exchanger tube,case Studies in Thermal Engineering, Volume 10, September 2017, Pages [13] Behrouz Raei1, Farhad Shahraki1, Mohammad Jamialahmadi, S. M. Peyghambarzadeh, Experimental study on the heat transfer and flow properties of c-al2o3/water nanofluid in a double-tube heat exchanger, J Therm Anal Calorim (2017) 127: [14] K. M. Elshazly, R. Y. Sakr, R. K. Ali, M. R. Salem, Effect of γ Al2O3/water nanofluid on the thermal performance of shell and coil heat exchanger with different coil torsions. Heat Mass Transfer, DOI /s [15] Byung-Hee Chun, Hyun Uk Kang, and Sung Hyun Kim, Effect of alumina nano particles in the fluid on heat transfer in double-pipe heat exchanger system, Korean J. Chem. Eng., 25(5), (2008). [16] Peddi Dilleswara Rao and B. Nageswara Rao. CFD Simulations and Validation Through Test Data of a Double Pipe Counter Flow Heat Exchanger. International Journal of Mechanical Engineering and Technology, 8(5), 2017, pp [17] Kalapala Lokesh, N. Somasankar, Sk. Azharuddin, K. Uma Maheswara Rao, M. Hari Krishna, M. Siva Sankar Mani Kumar, Heat Transfer Enhancement of Double Pipe Heat Exchanger using Twisted Tape Inserts. International Journal of Mechanical Engineering and Technology, 8(5), 2017, pp editor@iaeme.com