PCM in Three-Layer Tube Heat Exchanger Simulation

A detailed computational fluid dynamics analysis of thermal energy storage using Erythritol phase change material (PCM) in a three-layer tube heat exchanger with copper fins. This simulation captures the complex phase transition dynamics and heat transfer mechanisms over an extended time period, demonstrating the effectiveness of PCM systems for thermal energy management applications.

Phase Change Material for Thermal Energy Storage

This simulation investigates the thermal behavior and phase transition dynamics of Erythritol PCM embedded in a three-layer tube heat exchanger. The study demonstrates how PCMs can effectively store and release thermal energy through latent heat mechanisms, providing valuable insights into their application for sustainable energy management.

PCM Working Principles

• Energy Storage Mechanism: Latent heat absorption during solid-to-liquid transition
• Energy Release Process: Heat dissipation during liquid-to-solid transformation
• Thermal Regulation: Temperature stabilization through phase change properties
• Diurnal Applications: Solar energy capture during day and release during night

Heat Exchanger Design and Configuration

System Architecture

• Exchanger Type: Three-layer tube heat exchanger with enhanced surfaces
• Material Selection: Copper tubes and fins for superior thermal conductivity
• PCM Medium: Erythritol as the phase change material in storage layer
• Heat Transfer Fluid: Liquid silicone circulating through inner tube
• Enhancement Features: Copper fins for improved thermal conductance

Computational Domain

• Mesh Characteristics: Hybrid structured/unstructured grid with 107,718 elements
• Domain Components: Inner tube flow path, copper tube walls, fins, PCM region
• Boundary Interfaces: Coupled wall conditions between different materials

Simulation Methodology and Physical Models

Phase Change Modeling Approach

• Model Selection: Solidification and Melting module for phase transition simulation
• Simulation Duration: Extended 12,000-second analysis to capture complete phase dynamics
• Time Step Configuration: Appropriate stepping for phase change resolution

Material Properties and Parameters

• PCM Characteristics: Erythritol with defined:
  • Solidus and liquidus temperatures
  • Latent heat of fusion
  • Density, specific heat, and thermal conductivity
• Heat Transfer Fluid: Liquid silicone at 343.15K with 1 m/s inlet velocity
• Structural Components: Copper with high thermal conductivity for tubes and fins

Boundary Conditions

• Inlet Conditions: 1 m/s velocity, 343.15K temperature for silicone fluid
• Outer Walls: Adiabatic condition (zero heat flux)
• Inner Walls: Automatically coupled thermal interfaces
• Initial Conditions: Starting temperature and phase distribution

Results and Performance Analysis

Thermal Evolution and Phase Dynamics

• Temperature Distribution: Visualization of thermal gradients throughout the PCM medium
• Phase Front Progression: Tracking of solid-liquid interface movement over time
• Liquid Fraction Development: Quantification of PCM melting progression
• Heat Transfer Pathways: Analysis of conduction through fins and convection in liquid regions

Performance Characteristics

• Energy Storage Capacity: Evaluation of thermal energy absorbed as latent heat
• System Response: Transient behavior during the charging cycle
• Fin Effectiveness: Impact of extended surfaces on heat transfer enhancement
• Thermal Penetration: Heat distribution patterns from tube surface into PCM volume

Engineering Insights

• Design Considerations: Optimization guidance for fin geometry and spacing
• Operational Parameters: Influence of flow rate and inlet temperature
• System Efficiency: Balance between thermal performance and material utilization
• Application Potential: Suitability for various thermal management scenarios

This comprehensive simulation provides valuable insights into the behavior of PCM-based thermal energy storage systems, highlighting the critical role of enhanced heat transfer surfaces in overcoming the inherent thermal conductivity limitations of phase change materials. The results demonstrate the effectiveness of copper fins in accelerating the charging process and improving overall system performance, offering practical design guidance for thermal energy storage applications ranging from building climate control to industrial waste heat recovery systems.