CFD Simulation of Frost on Horizontal Cold Surfaces

Summary

Here, we present a numerical model for simulating frost formation on horizontal cold surfaces using a Eulerian multiphase model with the Lee phase change approach. The model dynamically updates frost volume fraction to capture density variation and is validated against experimental data on frost thickness, density, and distribution.

Abstract

Frost formation is a common phenomenon observed across many different fields, including refrigeration, construction, and natural gas processing. However, due to its complex nature, developing an accurate and reliable numerical model remains a significant challenge. Despite previous efforts to tackle this issue, current models still have certain limitations. This paper introduces a modified numerical model for frost formation, developed based on the fundamental mechanisms underlying frost formation. The model utilizes an Eulerian multiphase flow approach coupled with the Lee phase change model. In addition, the approach for determining the maximum frost volume fraction is updated, enabling the model to consider density variations during the frosting process. The model is rigorously validated by comparing it with experimental data on thickness, density, and distribution from various studies. The results indicate that the mean absolute relative deviation (MARD) for frost thickness is 8.97%, while the MARD for density is 16.06%. Furthermore, the frost morphology predicted by the model closely matches the experimental observations reported in the reference.

Introduction

Frost formation is a common phenomenon observed across many different fields. The accumulation of frost on heat exchanger surfaces significantly impairs heat transfer efficiency¹, obstructs fluid flow, and disrupts the overall performance of heat exchangers², ultimately hindering their normal operation³. Therefore, understanding the mechanisms and behavior of frost formation is critical for addressing this problem in refrigeration systems⁴. In recent decades, a substantial body of research has been dedicated to investigating the causes and characteristics of frost formation....

Protocol

1. Physical model and mesh

1. Open SpaceClaim, select the Sketch tab, and choose the Rectangle option under the Create function.
2. Create a 2D geometric model on the XOY plane with a length of 500 mm along the x-axis and a width of 15 mm along the y-axis.
3. Open ICEM, go to the File tab, select Geometry tab, then choose the Open Geometry and import the 2D geometry model.
4. Select the Boundary of the 2D Model, open the Create Part function under the Parts tab, and assign names to the different boundaries.
5. Sele....

Results

The proposed modified numerical model effectively captures the key features of frost formation. It is based on the fundamental mechanisms underlying frost growth and employs an Eulerian multiphase flow approach, coupled with the Lee phase change model. This approach allows the model to update the maximum frost volume fraction, thereby accounting for density variations throughout the frosting process. The simulations show that the model is rigorously validated by comparing its predictions of frost thickness, density, and .......

Discussion

This study develops a numerical model capable of simulating frost formation on a low-temperature, horizontal cold surface by dynamically adjusting the upper limit of the volume fraction in accordance with both time and operating conditions, thereby reproducing variations in frost density. Although the validation presented here is confined to conventional cold-surface temperatures, the model guarantees that the maximum deviation between simulated and experimental frost thickness does not exceed -20% (MARD = 8.97%), and th.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Fluent	ANSYS
ICEM	Dassault system
SpaceClaim	ANSYS