Planar Heat Exchanger with Mixing Tabs Simulation, ANSYS Fluent Training

Project description

In this project, a 3D simulation of a 4-layer planar heat exchanger with mixeing tabs in each layer is investigated. Steady hot (T=286.5K) and cold (T=276.5K) water flows enter the planar domain and moving through the heat exchanging region and generating vortex flows by colliding with the mixing tabs. Also, the residance time of the fluids and the contact surfaces increase in existance of these mixing tabs, which lead to a more heat transfer between the hot and cold flows. Both flows exit the heat exchanging domain with approximately equal temperature (T=282K).

Planar Heat Exchanger with Mixing Tabs Geometry and mesh

Geometry of the heat exchanger is designed in Design Modeler and grid generation is done in Ansys meshing. Inlet and outlet boundary conditions of both hot and cold flow are shown below. The mesh type is unstructured and element number is 4017548.

Planar Heat Exchanger CFD simulation settings

Critical assumptions:

• Solver type is assumed Pressure Based.
• Time formulation is assumed Steady.
• Gravity effects is neglected.

Models (mixing tabs)
Energy	On
Viscous	Standard K-epsilon (Standard wall functions)
Materials
Fluid	Definition method	Fluent Database
Boundary conditions (mixing tabs)
Hot-Inlet	Type	Mass flow inlet
	Mass flow rate	0.0045 kg/s
	Turbulent intensity	5%
	Turbulent viscosity ratio	10
	Temperature	286.5 K
Cold inlet	Type	Mass flow inlet
	Mass flow rate	0.00361 kg/s
	Turbulent intensity	5%
	Turbulent viscosity ratio	10
	Temperature	276.5 K
Solver configurations (mixing tabs)
Pressure-velocity coupling	Scheme	SIMPLE
Spatial discretization	Gradient	Least square cell-based
	Pressure	Standard
	Momentum	Second order Upwind
	Turbulent kinetic energy	First order Upwind
	Turbulent dissipation rate	First order Upwind
	Energy	Second order Upwind
Initialization	Type	Hybrid initialization

Results and discussion

Results including temperature, velocity and streamline contours are obtained for each of 4 layers. Layers are planes parallel to XY Plane which are assigned 1 to 4 as increase of their Z. Layers 1 and 3 are regions where cold flow is heated up and layers 2 and 4 are regions where hot flow is cooled down. Hot flow’s temperature at inlet and outlet is 286.2 K and 282.213 K respectively. Cold flow’s temperature at inlet and outlet is 276.5 K and 282.325 K respectively.

Using  it can be obtained that heat transfer rate from hot flow is equal to 93.8503W and heat transfer rate from cold flow is equal to -94.754W which can be taken as equal with reasonable approximation.

There is a mesh file in this product. By the way, the Training File presents how to solve the problem and extract all desired results.