Heat Exchanger CFD Simulation Training Course, ANSYS Fluent

Ansys Spaceclaim

ANSY Meshing

CFD Simulation of Spiral Heat Exchangers and Training in ANSYS Fluent

The present issue is with using ANSYS Fluent software to simulate a spiral heat exchanger. Heat transmission is effected by the temperature difference between the two water flows in this spiral channel, which uses two paths for cold and hot water respectively. While the cold current enters the heat exchanger environment (laterally) and exits from the central part of the heat exchanger in a direction perpendicular to the input path, the hot flow enters the heat exchanger and exits the heat exchanger environment (laterally) in a direction perpendicular to the inlet area. Between two 0.01 m thick steel hot and cold flow pathways are the coil plates. Likewise constructed of steel is the model's outer wall.

Inference

Several assumptions are applied in the current simulation:

Pressure-Based is the solver and the simulation is steady-state. Furthermore taken into account is the 9.81 kg.s-1 gravity influence of Earth on the model.

In spiral heat exchanger geometry and mesh

The current model (a spiral heat exchanger) has its 3-D geometry created by the Design Modeller programme. The current model has a separation plate inside the cylinder, which separates the hot and cold fluid flow into two different regions. Likewise, an inlet and an outlet cross-section for each of the two spaces produced define the path of the inlet and outlet flow, and their construction is such that the inlet and outlet flow routes are perpendicular to one another. Software called ICEM meshes the current model. Elements were numbered 450631 and the mesh was unstructured.

Design Modeler and ANSYS Meshing

One type of heat exchanger is the plate heat exchanger, which uses metal plates in the centre and parallel series plates on either side to transfer heat from one fluid to another. Between two neighbouring plates, the fluid moves through a channel. The fluids are exposed to a larger surface area, which is the advantage of a Plate Heat Exchanger over conventional heat exchangers.

Four solid plates with four pipes positioned at their corners make up this project's model. Even though the fluid (water) is moving back and forth through the pipes at the same speed, its temperature is 20 and 40 degrees Celsius, respectively.

The solution's geometry is created using the Design Modeller software, and all the solids come from the same portion. The dimensions of the solids are 2*2 metres with a thickness of 0.2 metres. The dimensions of the pipe are 0.2 metres in diameter and 1.1 metres in length. The solution's meshes are generated using the Ansys meshing software. There are a total of 22,163,379 elements, and none of them are organised.

Because the fluid is incompressible, the pressure-based solver has been used. Additionally, the simulation has operated in steady-state form since it is not time-dependent. Furthermore, the effects of gravity are disregarded. Convection in the pipes and solids allow heat to be transferred throughout the domain. This led researchers to focus on conjugated heat transfer (CHT).

The solution procedure culminates in the acquisition of two-dimensional contours and vectors pertaining to heat, turbulence kinetic energy, velocity, and water pressure. The 200k and 400k pipes represent high and low temperatures, respectively, and show the water flowing through them in opposite directions.

Convection, which occurs between fluid and pipe walls, is the primary mechanism for heat transfer. The next step is conduction. The conduction phenomenon allows the heat from the water to move through the solid.

You can see the temperature gradient in the figures through the contour lines. One crucial characteristic that affects heat transfer is fluid velocity. The amount of heat transferred via convection increases as the flow rate of water increases.

The Chevron Plate Heat Exchanger is being numerically simulated using the ANSYS Fluent programme.

Using the Design Modeller programme, we created the three-dimensional model.

Elements with a value of 638892 were used to mesh the model in the ANSYS programme.

To take heat exchanger heat transfer into account, the energy equation is triggered.

The challenge replicates a reverse cross-flow plate heat exchanger using ANSYS Fluent.

The 3-D model is designed with Design Modeller.

Model meshing is done with ANSYS Meshing software with 155000 elements.

Ethylene Glycon is a temperature-dependent polynomial working fluid.

The problem uses the ANSYS Fluent programme to simulate heat transport inside a shell and tube heat exchanger with a spiral buffer. A heat exchanger is a device that transfers heat between hot and cold fluids. Plate and shell and tube heat exchangers are the two most prevalent types in the business. Shell and tube heat exchangers have a cylindrical outer shell and inner tubes inside.

One of the cold or hot fluids passes through the gap between the tubes and the outer shell, while the other fluid flows through the inner space of the inner tubes in the same direction, or vice versa. Buffers inside the shell's fluid flow route can help improve heat transmission between two fluids.

The employment of buffers in the flow of fluid generates turbulence in the fluid flow through the shell and further contact of the fluid with the tubes, resulting in increased heat transfer; however, it also causes a pressure decrease in the fluid and fluid deposition in the shell. As a result, the use of helical baffles decreases pressure drop and sedimentation within the heat exchanger while also improving heat transfer between the two fluids.

In the current form, the heat exchanger is made up of seven internal tubes and a spiral buffer within the shell. Water with a flow rate of 0.5 kg.s-1 and a temperature of 300 K enters the shell through the shell inlet and is exchanged with tubes at a constant temperature of 450 K.

In actuality, it is assumed that the cold flow passes through the shell and the hot flow through the inner tubes; nevertheless, for the sake of simplicity, the model assumes that the temperature of the hot fluid flowing through the tubes during the operation remains constant at 450 K.

Shell and Tube: HEX Geometry and Mesh

The current 3-D model was created using Design Modeller software. The model is a shell and tube heat exchanger, with an exterior shell and seven inside tubes. The shell's diameter is 3 cm, and its length is 60 cm. A spiral buffer is utilised inside the shell and between the two tubes. The figure below depicts a view of the geometry.

The model was meshed using ANSYS Meshing software, with an unstructured mesh type. The element number is 1629340, and the precision of the cells along the tube walls is higher. The figure below depicts a view of the mesh.

To model the current problem, various assumptions are considered:

The simulation is in steady state.

The solver is pressure-based.

Gravity has an effect on fluid flow of 9.81 m.s-2 along the y-axis downward.

The solution procedure yields two- and three-dimensional contours of pressure, temperature, and velocity, as well as two- and three-dimensional velocity vectors and path lines.

The issue at hand utilises the ANSYS Fluent software to simulate heat transfer within a Finned Tube heat exchanger through numerical means.

The 3-D model is created utilising the Design Modeller software.

The ANSYS Mesh software was utilised to mesh the model, and the number of elements is 890710.

Activating the Energy Equation permits the consideration of heat transfer.

ANSYS Fluent software is used to look into a 3D CFD modelling of a 4-layer plate heat exchanger for this project. Water flows that are steady and hot (T=286.2K) or cold (T=276.5K) enter the flat area and move through the heat-exchanging area. The difference in temperatures goes down because these flows trade heat. The temperatures of both flows as they leave the heat-exchanging domain are about the same (T=282K).

Plate Heat Exchanger Shapes and Mesh

Design Modeller is used to make the heat exchanger's shape, and Ansys Mesh is used to make the grid. The conditions at the inlet and exit of both hot and cold flow are shown below. The element number is 2273000, and the type of mesh is "unstructured."

Important assumptions:

It is assumed that the method type is Pressure Based.

The way time is expressed is thought to be steady.

The forces of gravity are ignored.

For each of the 4 layers, results are found, such as temperature, speed, and streamlined outlines. The Z values of layers go from 1 to 4 as they get bigger. Layers are lines that run parallel to the XY plane. Layers 1 and 3 are places where hot flow gets warmer, and Layers 2 and 4 are places where hot flow gets cooler. The temperature of the hot flow is 286.2 K at the inlet and 281.213 K at the exit. The temperature of cold flow is 276.5 K at the inlet and 282.725 K at the exit. One way to find out is that the heat transfer rate from the hot flow is 93.8503W and the heat transfer rate from the cold flow is -93.9754W. These numbers are pretty close to being the same.

The challenge simulates a Shell and Helical Tube Heat Exchanger using ANSYS Fluent.

We use Design Modeller to create the 3-D model.

Model meshing with ANSYS Meshing software yields 1796590 elements.

To address heat transfer, activate the Energy Equation.

The challenge mimics Planar Heat Exchanger with Mixing Tabs using ANSYS Fluent.

The 3-D model is designed with Design Modeller.

We mesh the model with ANSYS Meshing software, element number 4017548.

Heat exchanger heat transport is considered via the Energy Equation.

The challenge mimics the Double Pipe Counter Flow Heat Exchanger using ANSYS Fluent.

We use Design Modeller to create the 3-D model.

Model meshing with ANSYS Meshing software yields 115635 elements.

To address heat transfer, activate the Energy Equation.

Heat Transfer in Vertical Shell and Tube Heat Exchanger is simulated using ANSYS Fluent.

The 3-D model is designed with Design Modeller.

We mesh the model with ANSYS Meshing software, element number 3915382.

To address heat transfer, activate the Energy Equation.

The challenge mimics Triple Heat Exchanger with ANSYS Fluent.

The 3-D model is designed with Design Modeller.

We mesh the model with ANSYS Meshing and use element number 1946903.

Heat exchanger heat transport is considered via the Energy Equation.