Heat Exchanger with Twisted Barrier CFD Simulation

Description

Heat Exchanger with Twisted Barrier, ANSYS Fluent CFD Simulation Training

The present problem simulates heat transfer within a heat exchanger in three dimensions using ANSYS Fluent software. In this simulation, the HEX consists of two parts; the upper part is for the passage of the hot current, and the lower part is for the passage of the cold current. Also, a twisted barrier is used inside the HEX to affect the flow rate of hot and cold water and, consequently, increase the heat transfer between them. Hot water flow with a speed of 5 ms-1 and temperature of 340 K enters from the upper part of the HEX, and cold water flow enters with a speed of 5 ms-1 and temperature of 300 K from the lower part. This work investigates the heat transfer process between the cold and hot sides of the HEX.

Heat Exchanger Geometry & Mesh

The present model is designed in three dimensions using Design Modeler software. The present model is related to a heat exchanger, consisting of two parts (the hot part at the top and the cold part at the bottom), and a twisted barrier is used inside it.

We carry out the model’s meshing using ANSYS Meshing software. The mesh type is unstructured. The element number is 1201056. The following figure shows the mesh.

Heat Exchanger CFD Simulation

We consider several assumptions to simulate the present model:

• We perform a pressure-based solver.
• The simulation is steady.
• The gravity effect on the fluid is ignored.

The following table represents a summary of the defining steps of the problem and its solution:

Models (Heat Exchanger)
Viscous		k-epsilon
	k-epsilon model	standard
	near wall treatment	standard wall functions
Energy		On
Boundary conditions (Heat Exchanger)
Hot Inlet		Velocity Inlet
	velocity magnitude	5 m.s-1
	temperature	340 K
Cold Inlet		Velocity Inlet
	velocity magnitude	5 m.s-1
	temperature	300 K
Hot Outlet		Pressure Outlet
	gauge pressure	0 pascal
Cold Outlet		Pressure Outlet
	gauge pressure	0 pascal
Middle Wall		Wall
	wall motion	stationary wall
	thermal condition	coupled
Other Walls		Wall
	wall motion	stationary wall
	heat flux	0 W.m-2
Methods (Heat Exchanger)
Pressure-Velocity Coupling		SIMPLE
	Pressure	second order
	momentum	second order upwind
	turbulent kinetic energy	first order upwind
	turbulent dissipation rate	first order upwind
	energy	second order upwind
Initialization (Heat Exchanger)
Initialization methods		Standard
	gauge pressure	0 Pascal
	x-velocity	5 m.s-1
	y-velocity & z-velocity	0 m.s-1
	temperature	340 K (patch)

Heat Exchanger with Twisted Barrier Results & Discussions

At the end of the solution process, two-dimensional and three-dimensional counters related to pressure, velocity, and temperature inside the heat exchanger are obtained. Two-dimensional and three-dimensional path lines and two-dimensional and three-dimensional velocity vectors are also obtained. The results show that heat transfer has occurred between the cold and hot sides of the heat exchanger.