Heat Exchanger Research Paper 35136j

Design Analysis and Performance Evaluation of Conical Coil in Coil Heat Exchanger at zero Phase Shifts. Bhushan. Pawar1, Akash Bhise2 P.G student, Heat Power Engineering, Department of Mechanical Engineering, 2 Assistant Professor, Department of Mechanical Engineering, Dhole Patil College of Engineering,Wagholi,Pune

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Abstract—The Conical tube heat exchanger design is a challenge to manufacture so also difficult to clean over time for maintenance. The problem of fouling can be dealt as proposed in our project , namely to prevent scaling and fouling by addition of variable pitch where in the shape geometry of the spiral will be changed from a flat spiral to a conical frustum . The geometry of the tubes plays a significant part in design and development of the heat exchanger. Project work discusses the development of such heat exchanger where in the copper tube is wound in a conical shape and water to heated is always ed from top of cone to bottom of cone , and the cones are connected in parallel. The paper discusses the combined thermal and structural analysis of the cone heat exchanger and also the testing of the system in zero phase shift condition is discussed in the paper.

average mean temperature difference between the two fluids for the entire heat exchanger. Due to the curvature of the tube, a centrifugal force is generated as fluid flows through the curved tubes. Secondary flows produced by the centrifugal force have great ability to enhance the heat transfer rate. Helical and spiral coils are the common known types of curved tubes which have been extensively used in a wide variety of applications.

Index —Conical coil tube heat exchanger, Fouling, scaling, Thermal and structural analysis, Zero phase shift.

INTRODUCTION 1. A heat exchanger is a device used to transfer heat between one or more fluids. The fluids are separated by a solid wall to avoid intermixing or they may have direct . They are widely used in space heating, refrigeration, air-conditioning, , petrochemical plants, chemical plants, petroleum refineries, natural-gas processing, power stations heat recovery processes, dairy processes and sewage treatment. The best real world example of a heat exchanger is observed in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows across the coils, which cools the coolant and heats the incoming air. Heat transfer in a heat exchanger there is usually convection between each fluid and conduction through the wall separating the two fluids. During the analysis of heat exchangers, it is beneficial to work on overall heat transfer coefficient U that s for the overall contribution of all these effects on heat transfer. The rate of heat transfer between the two fluids at any location in a heat exchanger depends on the magnitude of the temperature difference at that location, which varies continuously along the length of heat exchanger. In the analysis of heat exchangers, it is usually convenient to work with the logarithmic mean temperature difference LMTD, which is an equivalent

Figure No. 1 Conical Coil Heat Exchanger 2. LITERATURE REVIEW N. D. Shirgire et al [1] studied about fluid to fluid heat exchange is taken into consideration. Most of the investigations and analysis on heat transfer coefficients are for constant wall temperature or constant heat flux. The, overall heat transfer coefficient, effectiveness, effect of cold water flow rate on effectiveness of heat exchanger when hot water mass flow rate is kept constant and effect of hot water flow rate on effectiveness when cold water flow rate kept constant are studied and compared for parallel flow, counter flow arrangement of Helical coil and Straight tube heat exchangers. All readings were taken at attainment of the steady state condition of heat exchanger. The results indicates that the heat transfer coefficient is influenced by the geometry of the heat exchanger. The discussion suggests that Helical coil heat exchanger are superior in all aspect studied here. V.C. Momale et al [2] worked for the inside heat transfer coefficient (hi) and outside heat transfer coefficient (ho) from

the different research paper were compared. For the calculation of heat transfer coefficient MATLAB code is developed for the same. The values of heat transfer coefficient for inner side has agreement between each other, however outside heat transfer coefficient has no agreement is found. H. N. Deshpande et al [3] An attempt was made to change the curvature ratio continuously throughout the coil by using a conical shaped coil in order to decrease the critical Reynolds number. Numerical results of conical coil are compared with straight helical coil by using ANSYS fluent for mass flow rate through coil 0.07kg/s and 0.05 kg/s through shell. From the Numerical analysis it is observed that conical coil gives 8.71% more heat transfer than straight coil. The various mass flow rates through coil are taken as 0.01 kg/s, 0.02 kg/s, 0.05 kg/s, 0.07 kg/s, 0.09 kg/s, 0.1 kg/s keeping mass flow rate through shell 0.05 kg/s constant also tube inlet and shell inlet temperatures maintained same 42ºC and 27ºC respectively and for same mass flow rate heat transfer rate calculated numerically. MOHAME ALIT et al [4] experimental study has been made on steady state natural convection heat transfer from vertical helical coiled tubes. Average heat transfer coefficients were obtained for turbulent natural convection to water. The experimental study has been carried out for four coil diameter to tube diameter ratios, for five and ten coil turns, and for five pitch to outer diameter ratios. The data is correlated and compared with the Rayleigh number for two different coil sets. The heat transfer coefficient decreases with coil length for tube diameter d, = 0.012 m, but increases with coil length for do = 0.00s m. A critical D/do is obtained for a maximum heat transfer coefficient for tube diameter of 0.012 m with either five or ten coil turns. Yan Ke et al [5] the heat transfer characteristic of conical spiral tube bundle was investigated with numerical simulation method. Different grid strategies and boundary layers were used and the results of numerical simulation were verified via the foregoing experiment data with a tolerance less than 5%. The effect of structural parameters on heat transfer rates and characteristic of conical spiral tube is studied and discussed. The fluid flow characteristics inside the tube of different cross sections was also studied. The results indicate that the cone angle and cross section have significant effect on tube heat transfer, while the helical pitch has little influence on heat transfer enhancement. The contours of the fluid flow inside the tube indicate that the center of the axial fluid flow offsets to the outer surface of the tube, and the secondary fluid flow is complicated. There exists four independent parts of secondary flow in each cross section and the flow directions are different from each other. Timothy J. Rennie et al [6] an experimental study of a double-pipe helical heat exchanger was performed. Two heat exchanger sizes with both parallel flow and counter flow arrangements were tested. Flow rates in the inner tube and in the annulus were changed and temperature variation was recorded. Overall heat transfer coefficients were calculated and heat transfer coefficients in the inner tube and the annulus

region were determined using Wilson plots. Nusselt numbers were determined for the inner tube and the annulus. The inner Nusselt number as compared to the literature values. Though the boundary conditions were different, a reasonable comparison was found. The Nusselt number in the annulus region was compared to the numerical data. The experimental data fit well with the numerical study for the larger size heat exchanger. But, some differences were observed between the numerical and experimental data for the smaller size coil ; however these differences may have been due to the nature of the Wilson plots. Overall, for the most part in this study the results confirmed the validation of previous numerical work. Pramod S. Purandare et al [7] presents parametric analysis of the helical coiled heat exchanger with various correlations given by different researchers for specific conditions. The analysis is carried out for laminar and turbulent region separately for tube side heat transfer coefficient and Nusselt number. The calculations are worked out as per the data reduction procedure applied for helical coil configuration and the results are tabulated for heat transfer analysis. Bibave Tejas et al [8] the methodology for the design of helical cone coil heat exchanger is suggested. Available correlation of heat transfer coefficient by different researchers for calculation of heat transfer coefficient are used. The values of heat transfer coefficient for inner side has agreement between each other, however outside heat transfer coefficient has no agreement. Also Computational fluid dynamics study of the helical cone cool heat exchanger is carried out to visualize the nature of fluid flow inside the coil and shell, temperature variation from inlet to outlet for parallel and counter flow arrangement for different mass flow rates and Different inlet and outlet temperature conditions Zaid S. Kareem et al [9] Studied about Computational Fluid Dynamics approach employed for water flowing at Reynolds number in an arrangement of spirally corrugated tubes. This article aimed at the determination of the thermal performance of unique smooth corrugation profile. The Performance Evaluation Criteria were decided and calculated for corrugated tubes, and the simulation results of both Nusselt number and friction factor were compared with those of standard plain and corrugated tubes for validation purposes. Results showed the best thermal performance range of 1.8–2.3 for the tube which has the severity of 45.455 · 10_3 for Reynolds number range of 100–700. The heat transfer enhancement effective range was 21.684%–60.5402% with friction factor increase of 19.2– 36.4%. This indicated that this creative corrugation can enhance the heat transfer rates significantly with appreciably increasing friction factor. Ashkan Alimoradi et al [10] studied about calculations of the heat transfer and entropy generation have been performed for the steady state forced convection heat transfer in shell and helically coiled tube heat exchangers. The effect of geometrical parameters of the heat exchanger including: tube diameter , coil diameter , diameter of the inlet of shell , shell diameter (d, height of the coil , height of the shell , pitch and the distance between the inlet and outlet of the shell on the heat transfer rate and entropy generation has been investigated simultaneously. The critical and optimal values of these

parameters have been obtained which minimize and maximize the COD (heat transfer rate per entropy generation), respectively.

3. OBJECTIVES

it will be pertaining to the performance parameters of conical coil copper tube heat exchanger and effect of phase angle change and Testing of twin conical coil heat exchanger in counter flow to determine • LMTD • Capacity ratio • Effectiveness • Overall Heat transfer Coefficient To study the Graphs: • LMTD Vs Flow rate of water (kg/sec) • Capacity ratio Vs Flow rate of water (kg/sec) • Effectiveness Vs Flow rate of water (kg/sec) • Overall Heat transfer Coefficient Vs Flow rate of water (kg/sec) 3.1 DESCRIPTION The experiments will be carried out on the twin conical copper coil heat exchanger initially without changing phase angle and the different heat transfer characteristics will be calculate and then the same is done by changing phase angle. Experimentation on twin conical coil exchanger in counter flow configuration to determine LMTD Capacity ratio Effectiveness Overall Heat transfer Coefficient

SPECIFICATIONS OF HEAT EXCHANGER Outside diameter of inner tube 6.4 mm Inside side diameter of inner tube 5.4 mm Pitch diameter 125 mm Radial pitch 30 mm Inside diameter of shell 160 mm Outside diameter of shell 170 mm Overall length of shell 400 mm Material of inner tube Copper Material of shell Copper

Figure No 4 Steady State Thermal Analysis

Figure No 2 Conical heat exchanger in parallel Figure No 5 Total Heat Flux Analysis

Figure No 3 Conical heat exchanger in phase angle changed

The total flux is 9.511 watt transferred from the coil.

Fig No 6 Static Structural Analysis Maximum combined stress induced is 243.73 Mpa which is well below the maximum allowable stress of 400 Pa hence the coil is safe. 4.EXPERIMENTAL SET UP

Graph of Temperature Gradient Vs mass flow rate

The temperature gradient is seen to gradually increase with increase in mass flow rate due to better intermixing of particles and lesser effect of boundary layer as the water spirals down the cones.

Graph of Heat carried by water Vs mass flow rate

The heat carried by the water is seen to gradually increase with increase in mass flow rate due to better intermixing of particles and lesser effect of boundary layer as the water spirals down the cones Result Table : Graph of Effectiveness vs. mass flow rate SR. NO. 1. 2. 3. 4. 5.

Mass flow rate Kg/sec 0.00469 0.005051 0.005472 0.005794 0.006156

Temperature gradient 17.8 19.2 21..4 23.5 26

Heat carried by water ( KJ) 0.82808727 1.00488 1.28005131 1.63994113 1.97932888

Effectiveness

0.220235977 0.267255319 0.340439179 0.436154556 0.526417256

Effectiveness is the measure of performance of the coil in coil system as to the ratio of the heat carried by the water as to the heat input by the burner system, here in the effectiveness of

the system is seen to gradually increase with increase in mass flow rate due to better intermixing of particles and lesser effect of boundary layer as the water spirals down the cones. CONCLUSION  The temperature gradient is seen to gradually increase with increase in mass flow rate due to better intermixing of particles and lesser effect of boundary layer as the water spirals down the cones.  The temperature gradient is seen to gradually increase with increase in mass flow rate due to better intermixing of particles and lesser effect of boundary layer as the water spirals down the cones.  The effectiveness of the system is seen to gradually increase with increase in mass flow rate due to better intermixing of particles and lesser effect of boundary layer as the water spirals down the cones

REFERENCES Books: [1] Yunus Cengel, “Heat Transfer: A Practical Approach”, Tata McGrawHill. [2] Ramesh K. Shah, Dusan P. Sekulic , “ Fundamentals of Heat Exchanger Design”, Wiley-InterScience Publication.

Periodicals: [1] N. D. Shirgire. et.al, “Comparative Study and Analysis between Helical Coil and Straight Tube Heat Exchanger,” Int. Journal of Engineering Research and Applications www.ijera.com ISSN : 2248-9622, Vol. 4, Issue 8 ( Version 2) , pp.130-133, August, 2014. [2] V.C. Momale .et.al,“Analysis of Heat Transfer Coefficients for Helical Coil Heat Exchanger,” International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME) Volume -6, Issue-1-2, 2017. [3] H. N. Deshpande.et.al, “Comparative Numerical Analysis of Straight and Conical Coil Heat Exchanger,” GRD Journals- Global Research and Development Journal for Engineering | Volume 2 Issue 11 October, 2017. [4] MOHAME ALIT .et.al, “Experimental investigation of natural convection from vertical helical coiled tubes Helwan University,” Faculty of Engineering and Technology, El-Mattaria, P.O. 11718, Cairo, Egypt Received 10 August 1992 and in final form 8 June, 1993. [5] Yan Ke .et.al, “Numerical simulation on heat transfer characteristic of conical spiral tube bundle,” ELSEVIER Applied Thermal Engineering 31,pp 284-292, 2011. [6] Timothy J. Rennie et.al, Experimental studies of a double-pipe helical heat exchanger, ELSEVIER Experimental Thermal and Fluid Science 29, pp 919– 924, 2005. [7]P.S. Purandare et.al,“Parametric Analysis of Helical Coil Heat Exchanger,” International Journal of Engineering Research & Technology Vol. 1 Issue 8, October, 2012. [8] Bibave Tejas et.al, “Design of conical coil heat exchanger”, Global journal of engineering science and researches , February, 2016.