Optimizing Design and Analysis on The Helically Coiled Tube Heat Exchanger By Providing Fins

Heat exchangers are an essential part in an assortment of mechanical settings, for example, cooling frameworks, force plants, refineries, and in this way ceaseless endeavor are made to expand their heat transfer efficiencies. Optimize design of helical coil heat exchanger by using fins and the Compare pressure & temperature by conventional design. The final outcome of the study increase the total heat transfer rate inside the domain. And increase the pressure drop inside the domain. The water outlet temperature decrease up to 315k and cold outlet temperature increase up to 320 k. and total pressure drop increase with the temperature increases. Finally the CFD data were compared with previous data the total pressure drop increase up to 0.65 bar for case-2.the overall efficiency of the system incites up to 5% to 6%. Keyword: heat exchanger, helically coil, CFD, ANSYS.


I. INTRODUCTION
Heat exchangers are an essential part in an assortment of mechanical settings, for example, cooling frameworks, force plants, refineries, and in this way ceaseless endeavor are made to expand their heat transfer efficiencies. The design of heat exchangers is quite complicated, as it needs exact analysis of heat transfer rate and pressure drop estimations apart from issues such as long-term performance and the economic aspect of the equipment. The major challenge in designing a heat exchanger is to make the equipment compact and achieve a high heat transfer rate using minimum pumping power. [5][6][7] Techniques for heat transfer augmentation are relevant to several engineering applications. In recent years, the high cost of energy and material has resulted in an increased effort aimed at producing more efficient heat exchange equipment. Furthermore, sometimes there is a need for miniaturization of a heat exchanger in specific applications, such as space application, through an augmentation of heat transfer. Heat transfer enhancement is one of the most promising methods to optimize heat transfer equipment and to increase heat recovery in industrial processes. Heat transfer enhancement techniques have been extensively developed to improve the thermal performance of heat exchanger systems with a view to reducing the size and cost of the systems. Swirl flow is the one of the enhancement techniques widely applied to heating or cooling systems in many engineering applications. Heat transfer enhancement techniques are classified as the -Passive Methods, Active Methods, and Compound Methods. [8][9][10] These methods are commonly used in areas such as process industries, heating and cooling in evaporators, air-conditioning equipment, refrigerators, radiators for space vehicles, automobiles, etc. The rate of heat transfer can be increased passively by increasing the surface area, roughness, and by changing the boundary conditions.

II. LITERATURE REVIEW
HamidKiani Salmi et al. [1] In this study, thermal and hydraulic attributes of an ecofriendly grapheme nanofluid flowing within a countercurrent spiral heat exchanger are www.ijoscience.com evaluated. The cold water flows in one side while the hot nanofluid or hot base fluid moves in the other side of heat exchanger. The heat transfer rate and overall heat transfer coefficient enhance with increasing either Reynolds number or concentration. The results show that the value of effectiveness is much great (higher than 0.85) in all cases under investigation. Moreover, the effectiveness and number of transfer units decrease by increasing the Reynolds number. The pressure drop intensifies with the Reynolds number increment, and the nanofluid demonstrates a greater pressure drop than the base fluid especially at higher Reynolds numbers.

Mehdi Bahiraei et al. [2]
Heat exchangers have already proven to be important devices for thermal systems in many industrial sectors. In order to improve the efficiency of heat exchangers, nanofluids have recently been used as refrigerants. As for the unique properties of nanofluids, research in this area has seen remarkable growth. This article summarizes recent research on the use of nanofluids in heat exchangers, including that conducted on plate heat exchangers, dual tube heat exchangers, shell and tube heat exchangers and exchangers.

Nima Mazaheri et al. [3]
In the present work, attempts are made to numerically study the hydrothermal properties and energy efficiency of a hybrid nanofluid with graphene-nanoplate-platinum composite powder in a three-tube heat exchanger with fins inserted. The nanofluid flows from the side of the inner ring, while cold water and normal water flow respectively from the side of the tube and from the side of the outer ring. The fins are fixed to the outer surface of the inner tube. The overall heat transfer coefficient, efficiency and heat transfer rate of the heat exchanger are improved by increasing the concentration of nanoparticles and the height of the fins and decreasing the spacing of the fins.

Reza Rahmani et al. [4]
This article summarizes recent research on the use of nanofluids in heat exchangers, including that conducted on plate heat exchangers, dual tube heat exchangers, shell and tube heat exchangers and exchangers. In the meantime, some fascinating aspects of the combination of nanofluids with heat exchangers are presented. In addition, challenges and opportunities for future research are presented and discussed.

III. OBJECTIVE
There are following objective of the present work.
 Optimize design of helical coil heat exchanger by using fins  Compare pressure & temperature by conventional design  Optimize rate of heat exchanger by best proposed design IV. METHODOLOGY

1) STEPS OF WORKING
Step 1: Collecting information and data related to helically coiled tube heat exchanger.
Step 2: A fully parametric model of the helically coiled tube heat exchanger Step 3: Model obtained in Step 2 is analyzed using ANSYS 18.2.
Step 4: Finally, we compare the results obtained from ANSYS.

2) Finite elements analysis
Finite elements analysis is a branch of fluid mechanics that uses numerical analysis and data structures to solve and analyze problems that involve solid structure. For the present work ANSYS 18.2 software used.

ANSYS Capabilities:
In finite element analysis ANSYS software is used that helps engineers for performing the following tasks:  To build computer prototype, components, transfer CAD models of structures in a system products.  Enhances the profile of structural member with shape optimization.  Physical responses, such as stress levels, temperature distributions, or electromagnetic field scan be studied.  To reduce production costs optimization of design is done early in the development process.  Testing of prototypes is done in environments where it otherwise would be undesirable or impossible (for example, biomedical applications). Graphical user interface (GUI) in ANSYS gives users an easy, interactive approach to documentation, program functions, commands, and reference material. To navigate through the ANSYS program an intuitive menu system is used by users. Input data can be given using a mouse, a keyboard, or a combination of both.

3) STEPS OF ANSYS ANALYSIS
The different analysis steps involved in ANSYS are mentioned below.

PREPROCESSOR
The model setup is basically done in preprocessor. The different steps in pre-processing are  Build the model  Define materials  Generation of element mesh 2. BUILDING THE MODEL

6) Meshing
The modeling of the test section is meshed with ANSYS 18.2. The coarser meshing is created throughout the effective length of the tube.     Table 4.5 Details of meshing.

Result:-
In this study calculated the total pressure drop at differnet volume concentrations with the Dean number range of 1300-2000. www.ijoscience.com   www.ijoscience.com  Graph:-5 pressure drop graph VI. CONCLUSION In this analysis, the heat transfer and pressure drop of a double helically coiled tube heat exchanger handling MWCNT/water nanofluids have been studied with CFD software package. Initially, hot and cold water are used to check the simulation and recorded the pressure and temperature of MWCNT/water of nanofluids at 0.2%, 0.4% and 0.6% volume concentrations with the Dean number range of 1300-2000. The final outcome of the study increase the total heat transfer rate inside the domain. And increase the pressure drop inside the domain. The water outlet temperature decrease up to 315k and cold outlet temperature increase up to 320 k. and total pressure drop increase with the temperature increases. Finally the CFD data were compared with previous data the total pressure drop increase up to 0.65 bar for case-2.the overall efficiency of the system incites up to 5% to 6%.