PRESSURE DROP STUDIES IN WAVY CORRUGATED PLATE HEAT EXCHANGERS

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 6, Issue 12, Dec 2015, pp , Article ID: IJMET_06_12_006 Available online at ISSN Print: and ISSN Online: IAEME Publication PRESSURE DROP STUDIES IN WAVY CORRUGATED PLATE HEAT EXCHANGERS Dr. B Sreedhara Rao, M Mayuri, Y Sarasija, G Rohini Dept. of Chem. Engineering, CBIT, Hyderabad R.C Sastry Dept. of Chem. Engineering, NIT, Warangal ABSTRACT Wavy type heat exchangers are one of the prominent corrugated plate heat exchangers. The experimental studies have been carried out on wavy type heat exchangers with glycerol and water as test fluids. The experimental work involves in studying the various factors affecting the fluid flow mostly Friction factor and Pressure Drop, where the energy losses are calculated across the wavy type corrugated plate heat exchanger. The pressure drop studies were carried out in a corrugated plate heat exchanger with different corrugation angles of 30, 40 and 50 and corrugation channel spacing of 15 mm. It has been found that the pressure drop increases with an increase in the corrugation angle and viscosity of test fluid. Experimental data has been plotted for pressure drop against Reynolds number and observed that the pressure drop increases with increase in the corrugated angle. Key words: Corrugated Plate Heat Exchanger, Pressure Drop, Reynolds Number, Friction Factor Cite this Article: Dr. B Sreedhara Rao, M Mayuri, Y Sarasija, G Rohini and R.C Sastry. Pressure Drop Studies In Wavy Corrugated Plate Heat Exchangers, International Journal of Mechanical Engineering and Technology, 6(12), 2015, pp INTRODUCTION Heat exchangers are one of the prime equipments used in many chemical, food, pharmaceutical and dairy industries. There are many types of heat exchangers in use like plate heat exchanger, shell and tube heat exchangers. The use of corrugated plate heat exchangers is very less due to the limited availability of literature. The Corrugated Plate heat exchanger leads to increased heat transfer due to large surface area and corrugation angle [1], as the corrugated angle is high the pressure drop is 60 editor@iaeme.com

2 Pressure Drop Studies In Wavy Corrugated Plate Heat Exchangers also high.variations in the velocity results in occurrence of pressure drop and heat transfer. C. Albanakis et.al [3] have conducted the experimental studies on the effect of heat transfer on pressure drop and stated that the effect of angle is much significant on the Pressure drop. In the present experimental investigations pressure drop variations with respect to Reynolds number for various concentrations of glycerol as test fluid with corrugation angles of 30, 40 & 50 are studied. 2. EXPERIMENTAL METHODOLOGY The experiment deals with the factors affecting the rate of heat transfer such as pressure drop, friction factor, Reynolds number for a glycerol-water system. It is carried out at different flow rates of glycerol for a fixed flow rate of water. Here water is the hot fluid and glycerol is considered to be the test fluid.the corrugated plates used are of angles 30, 40 and 50 for different concentrations of glycerol. The same process is carried out with water to have a brief idea of the variations occurring at different angles with respect to glycerol Experimental Setup Figure 1 The Experimental Setup Fig 1.The equipment consists of a test box, test fluid collection tank, hot water tank, two motors and two rotameters in which we regulate the flow rates of the hot and cold fluids respectively. The test box is composed of three sinusoidal plates welded together. The plates are as shown in Fig2.it consists of two channels and three plates welded together, through the two different channels the hot fluid and test fluid flow. The inlet, outlet and the wall temperatures of the fluid have been recorded by means of a digital temperature indicator with the help of 7 thermocouples welded at different locations on the surface of the corrugated plate, Figure 2 Sinusoidal plates welded together[2] 61 editor@iaeme.com

3 Dr. B Sreedhara Rao, M Mayuri, Y Sarasija, G Rohini and R.C Sastry 2.2. Materials Used We have used 60%, 50% and 40% glycerol solutions and by using a digital U-tube manometer the pressure drop have been recorded and the values are tabulated. The density of the glycerol solution has been taken from the literature. Table No 1 Glycerol-water system fluid properties Properties At k WATER GLY40% GLY50% GLY60% Density (Kg/M 3 ) Viscosity (Ns/M 2 ) Thermal Conductivity (W/M-K) Specific Heat (Kj/Kg-K) The experiment is run for different concentrations of glycerol as mentioned earlier at different corrugation angles. The two rotameters kept are useful in regulating the required flow rates. The hot fluid flow rate and temperature are kept constant throughout the experimental studies. The same procedure is followed for different corrugated plates at different viscosities of test fluid. The corrugation angle and the viscosity of the fluid are two important considerations in a corrugated plate heat exchanger Specifications Equivalent length of the channel = 30cm Width of the channel = 10cm Spacing of the channel containing test fluid=15cm Material used in construction is stainless steel 3. RESULTS AND DISCUSSION The Experimental data obtained is plotted for Pressure Drop against Reynolds Number to describe the variations in the Pressure drop with respect to Reynolds Number which describes the fluid flow characteristics. The plots obtained show that as the viscosity and corrugation angle of the test fluid increase the Pressure drop also increases [2]. The plate with the lesser corrugated angle i.e 30 plate has shown much lesser Pressure drop The several factors affecting Pressure drop are the corrugation angle, viscosity of the test fluid, friction factor. The variation of Friction factor and the Pressure drop with corrugation angle has been analysed. Further, the variation of friction factor and Pressure drop with Reynolds number for different corrugation angles using different test fluids have been compared. For an efficient operation, the energy losses and power consumption should be minimum. As the corrugation angle increases, pressure drop offered by the channel increases. We now consider a case dealing with 60% concentrated glycerol solution for different corrugated plates having corrugated angles of 30, 40, 50 respectively and the variation of pressure drop with Reynolds number would be as shown in fig editor@iaeme.com

4 Pressure Drop Studies In Wavy Corrugated Plate Heat Exchangers Figure 3 Pressure Drop Vs Reynolds No for 60% Concentration Now further we procced by taking 50% concentration of glycerol solution for different corrugated plates with corrugated angles of 30,40 and 50 respectively, behaviour of the pressure drop with Reynolds number can be shown in the obtained plot as shown in Fig-4. Figure 4 Pressure Drop Vs Reynolds No for 50% Concentration We can say that the pressure drop increases with respect to Reynolds number and also we observe few fluctuations because of experimental conditions. Further we discuss about the variation of pressure drop with Reynolds number for 40% concentration of glycerol for different corrugated plates with corrugated angles of 30,40 and 50 respectively. The variation of the pressure drop with Reynolds number can be represented as shown in the obtained plot as shown in the Fig-5. Figure 5 Pressure Drop Vs Reynolds No for 40% Concentration 63 editor@iaeme.com

5 Dr. B Sreedhara Rao, M Mayuri, Y Sarasija, G Rohini and R.C Sastry Studying the behaviour of Pressure Drop with Reynolds number by taking glycerol at different concentrations for different corrugated angles. We proceed by taking the test fluid as water itself and study the behaviour of the Pressure drop with respect to Reynolds number for water at different corrugated angles and the variation can be as shown in the Fig-6 Figure 6 Pressure Drop Vs Reynolds No for water water system All the above obtained plots clearly state that as the corrugation angle is high the Pressure drop increases and thereby increases the load on the motor which results in high energy losses, also as the Reynolds number is increasing the flow pattern is turbulent thereby paving a way for higher pressure drop as the turbulence increases at higher flow rates. With reference to the above results obtained we find that the Pressure drop was found to be much lesser in case of 30 corrugated plate, now we compare the variation of Pressure drop with Reynolds number for different concentrations of glycerol used and water at a corrugated angle of 30 the variations are as shown in the Fig-7 Figure 7 Pressure drop Vs Reynolds number for 30 angle at different concentrations of glycerol, water. 4. GOODNESS OF FIT Curve fitting has been done using a software, in which a 4th degree polynomial is found to be the best fit for the experimental data. The R-square value for each plot on an average is ranging between to editor@iaeme.com

6 Pressure Drop Studies In Wavy Corrugated Plate Heat Exchangers 5. CONCLUSIONS The experimental results state that there is a higher pressure drop at higher viscosities and higher corrugated angle i.e. 50. If the pressure drop is high it results in higher energy losses. As per the experimental data obtained there exists two types of fluid flows Laminar and turbulent, the laminar flow prevails in the beginning i.e. for lesser flow rates of test fluids and on increasing the flow rate it becomes a turbulent flow. It is noticed that the pressure drop is increasing with an increase in the flow rate at different corrugated angles. The plate with corrugated angle of 30 has shown lesser pressure drop when compared to 50 and 40 degree plates. The 40 corrugated plate has given optimum results. Amongst all the three corrugated plates the 30 plate is found to be efficient based on this experimental study in terms of pressure drop. 6. REFERENCES [1] Nishimura T., Yano K., Yoshino T., Kawamura Y., Occurance and structure of Taylor-Goertler vortices induced in two-dimensional wavy channels for steady flow, J. Chemical Engineering Jpn., , [2] B. Sreedhara Rao, S. Varun, MVS Murali Krishna, R. C. Sastry, Pressure Drop Studies of Newtonian Fluid in a corrugated plate heat exchanger International Journal of Mechanical Engineering and Applications 2014; pg-42 [3] C.Albanakis, K. Yakinthos, K.Kritikos D.Missirlis, A.Goulas, P. Storm The effect of heat transfer on the pressure drop through a heat exchanger for aero engine applications [4] B. SreedharaRao, Varun S, Surywanshi G D, R C Sastry, Experimental Heat Transfer Studies of Water in Corrugated Plate Heat Exchangers: Effect of Corrugation Angle,Volume No. 3 Issue No.7, IJSET@2014 Page Nishimura T., Murakami S., arakawa S., Kawamura Y., Flow observation and mass transfer characteristics in symmetrical wavy-walled channels at moderate Reynolds numbers for steady flow, Int. J. Heat Mass Transfer 33, , 1990 [5] Dr. B. Sreedhara Rao, M. Mayuri, D. Krishna Kant, Himanshu V Dr. M. V. S. Murali Krishna and Prof. R. C. Sastry. Heat Transfer Studies In Wavy Corrugated Plate Heat Exchangers, International Journal of Advanced Research in Engineering and Technology, 6(11), 2015, pp [6] Mahadev M Biradar. Two Fluid Electromagneto Convective Flow and Heat Transfer between Vertical Wavy Wall and A Parallel Flat Wall, International Journal of Advanced Research in Engineering and Technology, 6(4), 2015, pp editor@iaeme.com