ENHANCEMENT OF HEAT TRANSFER IN SHELL AND TUBE HEAT EXCHANGER WITH TABULATOR AND NANOFLUID

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 7, Issue 3, May June 2016, pp , Article ID: IJMET_07_03_012 Available online at Journal Impact Factor (2016): (Calculated by GISI) ISSN Print: and ISSN Online: IAEME Publication ENHANCEMENT OF HEAT TRANSFER IN SHELL AND TUBE HEAT EXCHANGER WITH TABULATOR AND NANOFLUID Qasim S. Mahdi Mechanical Engineering Department, College of Engineering, Al Mustansiriyah University, Baghdad, Iraq Ali Abdulridha Hussein Mechanical Engineering Department, College of Engineering, Al Mustansiriyah University, Baghdad, Iraq ABSTRACT The present work reported the use of variant twisted tapes fitted in a double pipe heat exchanger to improve the fluid mixing that leads to higher heat transfer rate with respect to that of the plain-twisted tape. Heat transfer, flow friction and thermal enhancement factor characteristics in a double pipe heat exchanger fitted with plain and variant twisted tapes using water as working fluid are investigated experimentally. Tests are performed for laminar flow ranges. The experimental data for a plain tube and plain-twisted tapes are validated using the standard correlations available in the literature. Two different variant twisted tapes which include V cut-twisted tape and Horizontal wing cut-twisted tape with twist ratios of y = 2.0, 4.4 and 6.0 are used. In addition, the variation of heat transfer coefficient of copper nanofluids with different of Reynold's number and volume concentration of nanoparticles in plain tube without twisted tape. Based on these studies, the major conclusion has been arrived the Nusselt number, friction factor and thermal enhancement factor of variant twisted tapes are higher than that of plain twisted tape for the twist ratios of 2.0, 4.4 and 6.0 respectively so among the variant twisted tapes used in the present work, the horizontal wing cut-twisted tape give better performance due to the effect of increased turbulence which improves the fluid mixing near the wall of the test tube. By increasing volume concentration of nanoparticles, thermal conductivity increases while the thermal boundary layer thickness decreases. The Maximum thermal enhancement factor for P- TT, V-TT and HW-TT are 3.903, and respectively and enhancement plain twisted tape is better than CuO-nanofluid be three times. Key words: Double Pipe Heat Exchanger, Twisted Tape Insert, Swirling, Passive Methods, Heat Transfer Enhancement, Nanofluid, Turbulent, Laminar Flow, Twist Ratio, Cuo Nanoparticles editor@iaeme.com

2 Qasim S. Mahdi and Ali Abdulridha Hussein Cite this Article: Qasim S. Mahdi and Ali Abdulridha Hussein, Enhancement of Heat Transfer In Shell and Tube Heat Exchanger with Tabulator and Nanofluid. International Journal of Mechanical Engineering and Technology, 7(3), 2016, pp NOMENCLATURE Symbol Description Units Ac Tube cross-sectional area m2 As Tube surface area m2 Cp Specific heat J/kg.K D Diameter of outer tube m de Depth of cut mm Dh Hydraulic diameter m f Friction factor F Correction factor h Heat transfer coefficient W/m2.K H Pitch length based on 180 m h Heat transfer coefficient W/m2.K kf Fluid thermal conductivity W/m.K L Length m m Mass kg Mass flow rate kg/s Nu Average Nusselt number Pr Prandtl number Q Heat transfer rate W Re Reynolds number Sw Swirling conductivity W/m.K T Temperature C, K t Time sec u Velocity vector m/s W Width of twisted tape mm w Width of the cut mm y Twist ratio ΔP Pressure drop Pa editor@iaeme.com

3 Enhancement of Heat Transfer In Shell and Tube Heat Exchanger with Tabulator and Nanofluid Symbol a bf in m nf o out p pp ref S w Subscripts Title annular Base fluid inlet mean Nanofluid Smooth tube outlet particle Pumping power Reference value Surface Wall Greek Symbol Symbol Title Units Fluid Density kg/m 3 Dynamic viscosity kg/m.s Kinematics viscosity m 2 /s φ Volume concentration percentage Ф Heat dissipation term h Difference in level of manometric fluid m ƞ Thermal enhancement factor 1. INTRODUCTION Nowadays, thermal systems are some of the most important systems used in engineering applications. Therefore, different methods have been researched and developed to enhance heat exchange in these systems and reach a high performance thermal operation. Heat transfer rate in conventional heat exchangers can be improved through a variety of augmentation techniques that employs surface enhancements. This improvement in heat transfer rate occurs as a result of the following conditions that are created by the use of enhanced surfaces. These conditions are Interrupting of boundary layer development and rising degree of turbulence, increasing heat transfer area and Generating of swirling and/or secondary flows. Recently, many industrial applications such as refrigeration, automotive and process industries have been employing heat transfer enhancement techniques in order to improve the performance of heat exchangers. Enhancing heat transfer in heat exchangers could lead to many economic and environmental benefits. Energy, material and cost savings are achieved through better heat exchanger designs that reduce its size and improve its efficiency. Watcharin et al. [2006] have studied the heat transfer and pressure drop in a concentric double pipe heat exchanger with twisted tape insertion. The twist ratios used are Y = 5.0 and 7.0. It was observed that the maximum Nusselt numbers over the range studied for using the twisted tapes with ratios Y = 5.0 and 7.0 are 188% and 159%, respectively, when editor@iaeme.com

4 Qasim S. Mahdi and Ali Abdulridha Hussein compared to the plain tube. Yadav [2009] has studied the heat transfer and pressure drop in a U-bend double pipe heat exchanger with half-length twisted tape insertion. Half-length twisted tape was placed inside the inner tube of the heat exchanger in order to introduce swirling flow. It was observed that the tape-induced swirl causes a 40% increase in the heat transfer coefficient of the half-length twisted-tape inserts when compared to plain heat exchanger. However, the thermal performance of plain heat exchanger was found to better than half-length twisted tape by ( ) times. Kapatkar et al. [2010] has examined the influences of fitting full length twisted tape inserts in a plain tube for laminar flow on the heat transfer and friction factor. The Reynolds number range was taken to be from 200 to Showed that full length twisted tapes results in the following Nusselt number improvement are aluminum tapes (50% to 100%), stainless steel tapes (40% to 94%) and insulated tapes (40% to 67%). The isothermal friction factor for the flow with the twisted tape inserts are 340% to 750 % higher as compared with those of smooth tube flow, in the given range of twist ratios. A double pipe heat exchanger fitted with coil wire insert was tested by Shashank and Taji [2013]. The wire is made up of three different materials which are copper (Cu), aluminum (Al) and stainless steel. The study was conducted over a Reynolds number of 4000 to The results showed that heat transfer enhancements were 1.58, 1.41 and 1.31 for copper, aluminum and stainless steel coils respectively. Moreover, the different coil wire inserts resulted in higher friction factor than plain tube by 5.4 to 6.7 times for aluminum, 4.8 to 5.9 times for stainless steel and 4.3 to 5.4 times for copper. Senthilraja and Vijayakumar [2013] utilized a double pipe heat exchanger to experimentally measure the heat transfer coefficient of CuO/Water nanofluid. A CuO nanoparticles were dispersed in a deionized water to create a nanofluid. At room temperature, the nanofluid has a diameter of 27nm at different volume concentrations (0.1% and 0.3%). It was found that as time passes, the heat transfer coefficient increases while increasing the liquid flow rate will result in an increase in the Nusslet number. The nanofluid with concentration of 0.3% provided the highest heat transfer coefficient. In the present study the effect of using twisted tape inserts and nanofluid CuO/water will be investigated experimentally. Twisted tapes with variant twisted tapes cut section and twist ratios as well as nanofluid with different volume concentration were used for enhancement of heat transfer in double pipe heat exchanger. Finally, an empirical correlations based on the experimental results of the present study will be given for prediction the heat transfer (Nusselt number). 2. EXPERIMENTAL APPARATUAS AND PROCEDURE 2.1. Description of Test Rig The external pipe: It is an insulated pipe which has been manufactured from copper material of (51.78 mm) inner diameter, (1.5 m) length and (1.17 mm) thickness. It is insulated from outside by glass wool. Insulation are used to reduce the heat losses to the surrounding. A small hole was made in the external pipe for the thermocouples wires that were installed on the external surface of the inner pipe. The hole was patched with asphalt. Internal pipe: It has been manufactured from copper material of (20.4 mm) inner diameter (1530 mm) length and (0.88 mm) thickness. The pipe contains small vertical (6 mm) ports at its inlet and outlet which are used to measure the difference in pressure. The pressure sampling ports were welded using sliver brazing. The thermocouples are fixed under these ports using metal support and screws to measure editor@iaeme.com

Enhancement of Heat Transfer In Shell and Tube Heat Exchanger with Tabulator and Nanofluid the inlet and outlet temperatures as shown in Figure (1).

5 Enhancement of Heat Transfer In Shell and Tube Heat Exchanger with Tabulator and Nanofluid the inlet and outlet temperatures as shown in Figure (1). A valve is installed on the outlet in order to control and stabilize the flow. Twisted Tapes: In the test run, tapes are used with three different twist ratios y = 2.0, 4.4 and 6.0. Twisted tapes are made from copper strips of thickness 0.9 mm and width 17 mm as shown in table (1) and figure (2). Twist set Table 1 Characteristic dimensions of the turbulators inserted tubes δ mm H mm W mm WR DR No. turn y=h/d i Metal P-TT Copper P-TT Copper P-TT Copper V-TT Copper V-TT Copper V-TT Copper HW-TT Copper HW-TT Copper HW-TT Copper Figure 1 Schematic diagram of experimental test section editor@iaeme.com

Qasim S. Mahdi and Ali Abdulridha Hussein a b c Figure 2

2. Test Procedure In order to evaluate the thermal performance of double pipe heat exchanger, a series of experiments was carried out at different operational and conformational parameters.

18) kg/sec, inlet hot water temperature of ( C and inlet cold water temperature of ( C.

6 Qasim S. Mahdi and Ali Abdulridha Hussein a b c Figure 2 Shapes Twisted Tapes: (a) Plain-Twisted Tapes (P-TT), (b) V cut-twisted Tapes (V-TT), (c) Horizontal wing cut-twisted tape (HW-TT) 2.2. Test Procedure In order to evaluate the thermal performance of double pipe heat exchanger, a series of experiments was carried out at different operational and conformational parameters. Operational parameters demonstrate: hot water flow rate of (0.008, , ,0.0164,0.0192,0.019) kg/sec, cold water flow rate of (0.18) kg/sec, inlet hot water temperature of ( C and inlet cold water temperature of ( C. Runs heater tank of hot water after the water situation and wait for a while, then we take our pump and control a flow rate on flow meter, it put exist after pump, and in the mean time we take our water pump and wait by flow meter existing then, and there many thermocouples at the inlet and outlet of the test tube for both hot and cold tubes, starts registered record temperatures as well as the differential pressure manometer score and when you reach a state of stability takes values recorded after the transfer of the calculator by a small memory, and restore the same steps when insert twisted tapes inside the tube Performance Parameters Present study consists two fluid flow inside heat exchanger in counter flow arrangement as shown in Figure (1). cold water is forced to flow through annuli and hot de-ionized water is passes through inner tube. Steady state condition, insulated outer surface of heat exchange and no phase changer have been assumed during the analysis of present heat exchanger. Under these conditions the heat dissipation of both sides Eiamsa-ard et al. [2006]: Heat transferred to the cold water in the test section Q c = c C pc (T c2 -T c1 ) Heat transferred from the hot water in the test section (1) Q h = h C ph (T h1 -T h2 ) (2) The percentage of heat loss ɛ = (3) editor@iaeme.com

7 Enhancement of Heat Transfer In Shell and Tube Heat Exchanger with Tabulator and Nanofluid The average heat transfer rate for hot and cold water side is taken for internal convective heat transfer coefficient Q avg = The surface area of the inner tube (4) A i = π d i L (5) Logarithmic mean temperature difference The overall heat transfer coefficient U = The annulus side heat transfer coefficient annulus side heat transfer coefficient (h a ) is estimated using the correlation of Dittus Boelter equation (6) (7) Nu a = = Re a 0.8 Pr c 0.3 (8) The inner tube side heat transfer coefficient (h i ) is determined by neglecting the conduction thermal resistance of copper tube wall: The inner tube side Nusselt number (9) Nu i = (10) The Reynolds Number is based on the different flow rates at the inlet of the test section Re i = (11) Friction factor and is related to pressure drop in the test section f = (12) The thermal enhancement factor (ɳ) ɳ = = a Re -b y -c (13) 3. EXPERIMENTAL RESULT 3.1. Comparison of Experimental Results The heat transfer data for the plain tube is compared with literature data obtained using Sieder and Tate (1936) Equation (14) Cengel [2008]. The plain tube data are matching with Sieder and Tate equation with the discrepancy of ± 3% as shown in Figure (3) editor@iaeme.com

8 Qasim S. Mahdi and Ali Abdulridha Hussein The plain tube friction factor is shown in Figure (4) and these data are compared with the data obtained using the Equation (15) Cengel [2008]. The experimental friction factors are matching with the deviation of ± 4% with the results of the Equation (15). (14) (15) Figure 3 Experimental data verification of Nusselt number for plain tube Figure 4 Experimental data verification of friction factor for plain tube In addition, the experimental data of the plain tube are correlated for Nusselt number and friction factor respectively through Equations (16) and (17) as follow; (17) The Equations (16) and (17) are found to represent the experimental data within ±1% for Nusselt number ± 2% for the friction factor also Effect of Plain-Twisted tape The experimental results of the tube fitted with P-TT are compared with the plain tube and its results are validated using the correlations available in the literature for the laminar flow at the inlet to test section. Otherness of Nusselt number, heat transfer coefficient and friction factor with Reynolds number at the inlet to test section for the tube fitted with P-TT of different twist ratios (y = 2.0, 4.4 and 6.0) and plain tube are depicted in Figures (5) and (6) respectively. By referring to the Figure (5) it can be observed that Nusselt number, heat transfer coefficient increases with the increasing Reynolds number and also the result showed that the use of lower twist ratio yields higher Nusselt number than that of the higher twist ratio. This happens because the lower twist ratio creates stronger swirl flow which makes the thinner boundary layer along the pipe wall. Therefore more heat transfer through the thinner boundary layer. The swirl flow also creates the fluctuation of the energy between fluid layers and as a result the heat energy readily moves across (16) editor@iaeme.com

9 Enhancement of Heat Transfer In Shell and Tube Heat Exchanger with Tabulator and Nanofluid the fluid layers. Moreover, the residential time of flow increases with stronger swirl level which causes, the flow to have more time for exchanging the heat between the core and the wall. Over the range studied, the mean Nusselt number for P-TT with twist ratios y = 2.0, 4.4 and 6.0 are respectively , and times better than that for the plain tube. Figure (6) shows that the friction factor decreases continuously with Reynolds number and friction factor for lower twist ratio (y = 2.0) is significantly more than that of the higher twist ratio (y = 4.4 and 6.0) due to stronger swirl flow offered by the P-TT with lower twist ratio. From the experimental results, it can be observed that the friction factors for the P-TT with twist ratio y = 2.0, 4.4 and 6.0 are respectively , and times than that for the plain tube. The experimental data are fitted by the following correlations: (19) The fitted values are agreeing with the experimental data within ±12% and -10% for Nusselt number and friction factor respectively. (18) Figure 5 Nusselt number versus Reynolds number for P-TT with different twist ratio(y) and plain tube Figure 6 Friction factor versus Reynolds number for P-TT with different twist ratio(y) and plain tube 3.3. Effect of V Cut-Twisted Tape This section is focused on the experimental study on the heat transfer and friction factor for the horizontal concentric tube fitted with V-TT with different twist ratios y = 2.0, 4.4 and 6.0 for laminar flow at the inlet of test section. The experimental results of V-TT are compared with plain tube and P-TT. Figure (7) shows the comparison between Nusselt number obtained from the tube fitted with V-TT, P-TT and plain tube. It can be observed from the Figure (7) that, the Nusselt number obtained from the V-TT is higher than those from the P-TT and plain editor@iaeme.com

10 Qasim S. Mahdi and Ali Abdulridha Hussein tube. This means that V-TT generated the secondary flow along with main swirl flow produced by P-TT. Mean Nusselt number for the tube fitted with V-TT of twist ratios y = 2.0, 4.4 and 6.0 are respectively , and times better than that for the plain tube and similarly , and times higher than that of P- TT. The comparison of the friction factor between the V-TT, P-TT and plain tube with the variations of inlet Reynolds number is shown in Figure (8) respectively. It can be clearly seen that the friction factor continues to decrease with increase in hot water Reynolds number. At a given Reynolds number, the friction factor for the tube with V-TT is consistently higher than that of the P-TT and plain tube. This is because of the additional disturbance to the main swirl flow in the form of turbulence which increases the tangential contact between the fluid and the wall. Mean friction factor for the tube fitted with V-TT of twist ratios y = 2.0, 4.4 and 6.0 are respectively 8.817, and times higher than that for the plain tube and , and times higher than that of P-TT with the same twist ratios. The experimental data of heat transfer and friction factor for the tube with V-TT with different twist ratios (y = 2.0, 4.4 and 6.0) are correlated as the function of Reynolds number, Prandtle number and twist ratios are as follows: (21) The deviation between the predicted and experimental Nusselt number and friction factor are respectively ±4% and ±8%. (20) Figure 7 Nusselt number versus Reynolds number for V-TT, P-TT with different twist ratio(y) and plain tube Figure 8 Friction factor versus Reynolds number for V-TT, P-TT with different twist ratio(y) and plain tube 3.4. Effect of Wing Cut-Twisted Tape This section is mainly focussed on the study of the heat transfer enhancement effect by fixing the depth and width ratios and the position of the wing-cut from horizontal direction. The heat transfer and friction factor characteristics of the HW-TT is studied for the twist ratios y = 2.0, 4.4 and 6.0 and the results are compared with those tube editor@iaeme.com

11 Enhancement of Heat Transfer In Shell and Tube Heat Exchanger with Tabulator and Nanofluid fitted with and without P-TT. The experimental results from the HW-TT are correlated for Nusselt number and friction factor. Figure (9) shows the relationship between the Nusselt number and Reynolds number for the tube with HW-TT, P-TT with different twist ratios, y = 2.0, 4.4 and 6.0 and also the plain tube respectively. In general, the HW-TT provide higher Nusselt number than that of P-TT and plain tube depending on the twist ratios used. HW-TT provides additional vortices to the fluid in the vicinity of the tube wall in addition with swirl flow generated by the P-TT and thus leads to a higher heat transfer enhancement in comparison with plain tube and P-TT. On the other hand the use of HW-TT, mean Nusselt numbers for the twist ratios 2.0, 4.4 and 6.0 are respectively , and times of that for the plain tube and , 1.2 and times of that for the tube fitted with P-TT. This may be a consequence of better mixing between the core and the fluid wall due to the more efficient turbulence offered by the HW-TT. The friction factor characteristics at various Reynolds number based on the inlet side of the tube fitted with HW-TT, P-TT and the plain tube is displayed in Figure (10). At a given Reynolds number, the friction factors of all the HW-TT are consistently higher than that of the tube with P-TT and plain tube due to an additional blockage provided by the wings to the flowing fluid in the tube. For a tube with HW- TT, the mean friction factors with twist ratios of 2.0, 4.4 and 6.0 are respectively 9.277, and times of those in the plain tube and 1.363, and times of those in the tube with the P-TT. The experimental data of heat transfer and friction factor for a tube with the HW- TT with different twist ratios are correlated as follows: (23) The deviation of the multiple regressions of Nusselt number and friction factor are +12% and ±12%, respectively. (22) Figure (9) Nusselt number versus Reynolds number for HW-TT, P-TT with different twist ratio(y) and plain tube Figure (10) Friction factor versus Reynolds number for HW-TT, P-TT with different twist ratio(y) and plain tube editor@iaeme.com

12 Qasim S. Mahdi and Ali Abdulridha Hussein 3.5. Comparison of Variant Twisted Tape Inserts The variant twisted tapes performances have been compared based on the thermal enhancement factor because it relates the Nusselt number and friction factor characteristics. Therefore, it is worthy to compare the performance using thermal enhancement factor instead of making the comparisons of the Nussselt number and friction factor of the variant twisted tape used in the present work separately. Figure 11 Thermal enhancement factors versus Reynolds number for PTT, V-TT and HW-TT Figure (11) present the comparison of the variant twisted tapes used in the present work for the twist ratios y = 2.0, 4.4 and 6.0 respectively. The thermal enhancement factor (ƞ for the P-TT, V-TT and HW-TT is expressed in the equation (29), (30) and (31) respectively: 3.6. Inner Nusselt's Number with Nanofluids Performance of double pipe heat exchanger with nanofluids has been studied to show the effect of concentration on heat transfer enhancement. Water cold Reynold's number has been selected as 3300 during nanofluids experiments. Figures (12) show the variation of the Nusselt's number with a Reynold's number of CuO nanofluids. These figures clearly indicate that Nusselt's number increases with increasing both Reynold's number and volume concentration of nanoparticles. The main reason of this enhancement due to the increase in both thermal conductivity and heat transfer coefficient of nanofluid. (24) (25) (26) editor@iaeme.com

13 Enhancement of Heat Transfer In Shell and Tube Heat Exchanger with Tabulator and Nanofluid Figure 12 Variation Nusselt number of CuO/water Nanofluid with Reynolds Number for various volume Concentration Table (2) show the enhancement of Nusselt number with variation in volume of copper-nanofluids. Table 2 Enhancement in Nusselt number of CuO nanofluid Enhancement Concentration Enhancement Concentration % (lit/hr) % % (lit/hr) % CONCLUSIONS The investigation on heat transfer and friction factor characteristics for variant twisted tapes (P-TT, V-TT, HW-TT) fitted in the double pipe heat exchanger, with twist ratios y = 2.0, 4.4 and 6.0 have been studied and presented. According to the past studies, it is observed that modifications on the P-TT i.e. small cuts on the tape, will give an assurance for enhancement of both heat transfer and thermal enhancement. The variant twisted tapes are used based on the concept of introducing a small cuts on the peripheral region of the tape (V-TT and HW-TT). The conclusion arrived the plain tube data of Nusselt number and friction factor were verified with the standard correlations in order to ensure the performance of the experimental set up for laminar editor@iaeme.com

14 Qasim S. Mahdi and Ali Abdulridha Hussein flow. The maximum deviation observed for both the experimental Nusselt number and friction factor is ±4% and ±5% with the standard correlations values respectively. The tape with lower twist ratio (y = 2.0) offered a better thermal enhancement than the tape with higher twist ratio (y = 4.4 and 6.0). The V-TT provides improved heat transfer enhancement than that of P-TT. In the group of variant twisted tapes, HW-TT yields better thermal performance. The Nusselt number enhancement are (240, 183, 159)% for P-TT to y=(2.0, 4.4, 6.0) respectively also (326, 211, 181)% for V-TT to y=(2.0, 4.4, 6.0) respectively in final the enhancement are (348, 232, 196)% for HW- TT to y=(2.0, 4.4, 6.0). REFERENCES [1] Yadav A. S., 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, 3(1), pp , [2] Watcharin Noothong, Effect of Twisted-Tape Inserts on Heat Transfer in A Tube, The 2nd Joint International Conference on Sustainable Energy and Environment (SEE 2006), pp , [3] Kapatkar V. N., A. S. Padalkar and Sanjay Kasbe, Experimental Investigation on Heat Transfer Enhancement in Laminar Flow in Circular Tube Equipped with Different Inserts, AMAE International Journal on Manufacturing and Material science, 1(1), pp. 1 6, [4] Shashank S. Choudhari and Taji S. G., Experimental Studies on Effect of Coil Wire Insert On Heat Transfer Enhancement and Friction Factor of Double Pipe Heat Exchanger, International Journal of Computational Engineering Research, 3, pp , [5] Senthilraja S. and Vijayakumar KCK., Analysis of Heat Transfer Coefficient of CuO/Water Nanofluid using Double Pipe Heat Exchanger. International Journal of Engineering Research and Technology, 6(5), pp , [6] Eiamsa-ard S., Thianpong C. and Promvonge P., Experimental investigation of heat transfer and flow friction in a circular tube fitted with regularly spaced twisted tape elements, Int. Comm. Heat and Mass Transfer, 33(10), pp , [7] Cengel Y. A., Heat and Mass transfer, 5th edition, McGraw-Hill, chapter 8, [8] Mohd. Rehan Khan and Dr. Ajeet Kumar Rai, An Experimental Study of Exergy in A Corrugated Plate Heat Exchanger. International Journal of Mechanical Engineering and Technology, 6(11), 2015, pp [9] Ashish Kumar, Dr. Ajeet Kumar Rai and Vivek Sachan, An Experimental Study of Heat Transfer In A Corrugated Plate Heat Exchanger. International Journal of Mechanical Engineering and Technology, 5(9), 2014, pp [10] Qasim S. Mahdi and Husam Mahdi Had. Experimental and Numerical Investigation of Airflow and Temperature Distribution in A Prototype Cold Storage. International Journal of Mechanical Engineering and Technology, 5(4), 2014, pp editor@iaeme.com

Heat Transfer Enhancement for Double Pipe Heat Exchanger Using Twisted Wire Brush Inserts

Heat Transfer Enhancement for Double Pipe Heat Exchanger Using Twisted Wire Brush Inserts Deepali Gaikwad 1, Kundlik Mali 2 Assistant Professor, Department of Mechanical Engineering, Sinhgad College of