Enhancement of Temperature Distribution and Heat Transfer Coefficient of Ribbed Tube by Simulation

The heat transfer from surface may in general be enhanced by increasing the heat transfer coefficient between a surface and its surrounding or by increasing heat transfer area of the surface or by both. The main objective of the study and calculate the total heat transfer coefficient. Improve the heat transfer rate by using ANSYS CFD. During the CFD calculations of the flow in internally ribbed tubes. And calculated the temperature distribution and pressure inside the tube by using ansys. The model was created using CatiaV5 and meshed with Ansys, and the flow analysis is done with Ansys 19.2. The results showing that the heat transfer is increased. The enthalpy and temperature increase with flow is advancing when compare with normal boiler tube. In this study the total heat transfer rate of the pipe increase with the increase the rib height. Total heat transfer rate increase up to 7.7kw. The study show that the improvement in furnace heat transfer can be achieved by changing the internal rib design.


INTRODUCTION
The heat transfer from surface may in general be enhanced by increasing the heat transfer coefficient between a surface and its surrounding or by increasing heat transfer area of the surface or by both. Ribs used in cooling channel and heat exchanger channel are most commonly used passive heat transfer techniques. So that the work related to fluid flow and heat transfer in ribbed channel is go so far. This heat transfer augmentation technique are applied to many industrial application such as shell and tube type heat exchanger , electronic cooling devices, thermal regenerators, and internal cooling system of gas turbine. Each rib on downstream separates the flow, recirculate, and impinges on channel wall and these are the main reason for heat transfer enhancement in such channel. The use of rib in heat exchanger not only increase the heat transfer rate but also substantial the pressure loss [1] [3]. The rib arrangement and geometry resulting in different heat transfer distribution by altering the flow field. Therefore by making the modification in rib geometry we can increase the heat transfer rate but at the same time we need to consider the pressure drop also because it increases significantly.
The study of improved heat transfer performance is referred to as heat transfer augmentation, enhancement. The common thermo hydraulic goals are to reduce the size of a heat exchanger required for a specified heat duty and to upgrade the capacity of an existing heat exchanger, also to reduce the pumping power. Heat transfer enhancement techniques are commonly used in areas such as process industries heating and cooling in evaporators, thermal power plants, air conditioning equipment's, refrigerators and radiators for space vehicles, automobiles.
II. LITERATURE REVIEW Sławomir Grądziel et al. [4] This paper puts forward modelling thermal and flow phenomena in internally rifled tubes. The proposed model is a distributed parameter model based on solving balance equations describing the principles of the mass, momentum and energy conservation. The model enables an analysis of transient-state processes. The aim of the calculations is, among others, to find the distribution of the fluid enthalpy, mass flow and pressure in internally rifled tubes and to determine the heat transfer coefficient.
Alireza Taklifi et al. [5] in this paper presented are the effect of various inclination angles on heat transfer of water at subcritical and supercritical operating pressures is investigated experimentally. These operating conditions covered subcritical, near critical and supercritical water flows and also refers to low mass flux conditions. The inclination angles were 5, 20, 30, 45 and 90 (vertical) degrees respecting to horizontal plane. The heat flux was kept constant along the test tube by controlling of electric heating. As a result the inner wall temperature and convective heat transfer coefficient variations with respect to heated length and bulk enthalpy of fluid were considered in order to study the heat transfer characteristics of various flows at different inclinations.
Aadel A. R. Al Kumait et al. [6] The study is accomplished by using the finite volume method, and its objective involves finding a low friction factor and high heat transfer enhancement in the presence of TiO 2/water nanofluids. The helical ribbed tubes with a 5.89 mm pitch distance gave higher turbulent kinetic energy due to a stronger swirl intensity, resulting in a thinner thermal boundary layer and a higher Nusselt number with uniform distribution.
Tao Zhang et al. [7] in this paper presented are the turbulent supercritical water flow characteristics within different grooves are obtained using a validated low-Reynolds number κε turbulence model. The effects of groove angle, groove depth, groove pitch-to-depth ratio, and thermophysical properties on turbulent flow and heat transfer of supercritical water are discussed. The results show that a groove angle γ = 120° presents the best heat transfer performance among the three groove angles. The lower groove depth and higher groove pitch-to-depth ratio suppress the enhancement of heat transfer.
III. OBJECTIVE  The main objective of the study and calculate the total heat transfer coefficient.  Improve the heat transfer rate by using ANSYS CFD.  During the CFD calculations of the flow in internally ribbed tubes.  Calculated the temperature distribution and pressure inside the tube by using ansys.

IV. METHODOLOGY A. CFD Analysis on Pipe
This paper presents the calculation results of thermal and flow phenomena occurring in internally rifled tubes for a medium with supercritical parameters. The results were obtained by means of a numerical analysis and CFD. The CFD modelling was carried out using the Ansys Fluent software package

B. Mathematical model
Equations describing the principles of the mass, momentum and energy conservation, respectively, will be solved to determine the distribution of the mass flow (mass flux) and the medium enthalpy (temperature) along the tube. The base balance equations are expressed in [4]. After appropriate reductions and transformations, mass, momentum and energy equations are written so that space derivatives should be obtained on the left side of the equations, whereas time derivatives occurring on the right side are replaced with backward difference quotients. This system of ordinary differential equations is solved using the Runge-Kutta method. After the changes described above are introduced, the energy balance equation takes the following form: The fluid density is found as a function of enthalpy and pressure: Solving the mass and momentum conservation equations, the following is obtained, respectively: The fluid temperature history is found as a function of enthalpy and pressure: Subscript "j" in Equations (1)(2)(3)(4)(5)