SolidWorks Flow Simulation: Heat Exchanger

Introduction to SolidWorks Flow Simulation Tutorial

Objectives of the Tutorial

• The tutorial aims to model a counter-current double pipe heat exchanger using SolidWorks Flow Simulation.

• Key objectives include setting up a heat transfer model, specifying fluid subdomains, defining solid domains, and utilizing custom equations through the equation goals feature.

Problem Description

• The focus is on cooling an ethanol stream entering at 78°C while water flows through the outer pipe at 10°C. The goal is to determine outlet temperatures and velocities for both streams.

• Additional tasks include generating temperature plots, flow trajectory animations, and estimating the logarithmic mean temperature difference using a specific equation.

Creating the 3D Model in SolidWorks

Initial Sketch Setup

• The process begins with creating a 2D sketch that will be transformed into a solid of revolution for the heat exchanger design.

• Essential dimensions are defined in inches, including lengths for inner and outer pipes as well as diameters for accurate modeling.

Geometry Construction

• Lines are drawn to represent inner and outer diameters of the annulus pipe; specific measurements such as radii are established during this phase.

• A construction line serves as the axis of revolution to create both inner and annulus pipes effectively within SolidWorks features menu.

Finalizing Pipe Inlets

Adding Inlet Features

• New planes are created at specified distances from reference points to facilitate drawing additional features like inlet circles on top of existing geometry.

Creating a Heat Exchanger Model

Sketching and Extruding the Pipe

• The process begins with editing a sketch on Plane One, where circles are selected and converted into entities to create a new sketch.

• A pipe is extruded from the newly created sketch using the "Extruded Post Base" feature, selecting "Up to Surface" for direction.

• An extruded cut is created by positioning back on Plane One, converting another circle entity to define an inlet for the pipe.

• The operation is repeated for creating an outlet pipe; sketches are edited again on Plane One to draw two circles of specified diameters.

• A new plane is created by flipping the offset, allowing for further sketches that will also convert entities from previous circles.

Finalizing Pipe Geometry

• After creating additional sketches and converting entities, an extruded ball space feature is used to finalize the pipe geometry.

• Section views are activated to visualize both inlet and outlet pipes clearly as part of the heat exchanger design.

• The model now includes both inlet (for ethanol transport) and outlet (for water transport), completing essential geometry for functionality.

Flow Simulation Setup

• To proceed with flow simulation definition, users must activate the flow simulation add-in through options in their software settings.

• Leads are defined within the model to help determine optimal computational domains for simulations before starting with wizard configurations.

Configuring Simulation Parameters

• In setting up the simulation wizard, users can name their project (e.g., "Speed Exchanger") and select SI units along with Celsius for temperature measurements.

• The analysis type chosen is internal, including heat conduction in solids; working fluids specified include ethanol and water.

• Solid materials are set as copper without changing default configurations; initial conditions specify pressure at one atmosphere but adjust temperature settings accordingly.

Defining Fluid Subdomains

• Concentrations of fluids are established: 0% concentration for water and 100% concentration for ethanol in their respective domains.

• Users can hide or show computational domains as needed during setup; fluid subdomains need defining next based on specific sections of pipes involved in fluid transport.

Setting Up Solid Materials and Boundary Conditions

Inserting Solid Materials

• The process begins with selecting solid materials for the walls, specifically choosing copper as the material.

• The boundary condition type is set to flow openings, ensuring proper selection of boundaries for analysis.

Defining Mass Flow Rate and Initial Conditions

• A mass flow rate of 0.0001 kg/s is defined for the system.

• Initial conditions are established at 78°C with ethanol as the incoming fluid into the pipe.

Defining Additional Boundary Conditions

Setting Inlet and Outlet Parameters

• Another mass flow rate of 0.001 kg/s is set for water at an inlet temperature of 10°C.

• Outlets are configured as pressure openings under atmospheric conditions.

Goals for Temperature Difference Calculation

• The task involves calculating the logarithmic mean temperature difference (LMTD), requiring outlet temperatures from both streams.

• Surface goals are created to measure average temperatures at outlets for both water and ethanol streams.

Calculating Logarithmic Mean Temperature Difference

Setting Up Equations

• Two equations, ΔT1 and ΔT2, are defined to calculate LMTD based on inlet and outlet temperatures.

• The final equation for LMTD is structured using natural logarithm calculations involving ΔT1 and ΔT2.

Running Simulations and Analyzing Results

Mesh Definition and Simulation Execution

• A mesh is defined with a setting of six before running the simulation through the flow simulation menu.

Result Analysis

• After completion, results indicate an average logarithmic mean temperature difference of 42.06°C.

• Outlet temperatures are recorded: water at 25.58°C and ethanol at 43°C.

Finalizing Data Presentation

Displaying Fluid Temperatures and Velocities

• Surface parameters reveal fluid temperature (25.27°C for water; 55.26°C for ethanol).

Creating Visual Representations

Temperature Visualization and Flow Trajectories in Fluid Dynamics

Displaying Temperature and Flow Trajectories

• The display menu is utilized to visualize the internal temperature of the fluid within a system, allowing for adjustments in contour lines for better clarity.

• A flow trajectory plot is created to represent the temperature of the fluid, with specific starting points selected and 100 elements indicated for display.

• A preview of the flow trajectories is generated, with an option to increase arrow sizes for enhanced visibility.

• The animation feature demonstrates how fluid temperature varies along the heat exchanger's axis; increasing mesh elements can improve this visualization.

Estimating Logarithmic Mean Temperature Difference

• The logarithmic mean temperature difference has been calculated at 42.06 degrees Celsius, providing critical data for thermal analysis.

Conclusion and Further Assistance