Our work: We focus on experimental and numerical studies of heat transfer. A major focus area is on porous media, such as packed beds used in Thermal Energy Storage. Our studies range from the microscale (e.g. pore scale analysis)  to the macroscale (e.g. lab scale analysis). 

Click here to find out details on recent projects:

  1. Local temperature and velocity measurements in packed beds
  2. Experimental and numerical studies in packed bed thermal energy storage- lab scale
  3. Numerical studies of thermal cycles with supercritical carbon dioxide (sCO2) as heat transfer fluid

Local Temperature and Velocity in Packed Beds

We are using experimental and numerical techniques to study velocity and temperature in packed beds. In typical approaches to non-isothermal flows in packed bed, thermocouples are used to measure the temperature at a few spots in the bed or the fluid temperature at the inlet/outlet. The velocity in empirical correlations is often the empty bed velocity, and no detailed information is available on flow through the pores. This lack of data leads to a lack of understanding and inaccurate design correlations.

Using magnetic resonance microscopy in the Magnetic Resonance Laboratory, we are able to measure the velocity and heat transfer behavior together in the bed non-invasively. This study is under NSF Award 1511045. We use encapsulated wax particles to make the packed bed. When these are heated and the wax melts, more signal is generated and this 'light-on/light-off' effect can be imaged. An example experimental result for velocity and melt front is shown below in one cross-section.

NMR in packed beds

[With permission from Elsevier - M.E. Skuntz, D. Perera, J.E. Maneval, J.D. Seymour, R. Anderson, Melt-front propagation and velocity profiles in packed beds of phase-change materials measured by magnetic resonance imaging, Chemical Engineering Science 190 (2018) 164-172.]

These experimental results can be used to verify numerical models. To compare at the pore scale, we use discrete element method (DEM) models to generate numerical packed beds. This solid domain is then coupled with computational fluid dynamics to solve for the heat transfer and fluid flow behavior. The example below is from Dinal Perera's MS thesis based on DEM-CFD modeling.

DEM MS Thesis

Thermal Energy Storage in Packed Beds- Lab Scale

Storing excess thermal energy from the sun can be useful in a range of applications including electricity production in concentrated solar power (CSP) plants, desalination, and enhanced oil recovery. Storage allows the heat to be utilized when the sun is no longer shining. A packed bed filled with a solid storage media is one method to store the thermal energy. Our lab-scale setup allows for a range of flow configurations, packing materials, and cycling conditions to be studied experimentally with air up to 300oC. The temperatures inside the bed and on the vessel walls are measured, and thermal exergy efficiencies are calculated.


These experimental results are used in conjunction with numerical models. Two modeling approaches are used: a one-equation approach that assumes local thermal equilibrium between the phases (via Star-CCM+) and a two-equation model that solves for the fluid and solid temperatures individually (via Matlab codes). Experimental and model results are shown here with alumina as the solid storage material and air as the heat transfer fluid. The spatial temperature distribution is determined over time. The solid lines connect experimental data points and are included for visualization.

TES exp and model

[With permission from Elsevier - M.M.S. Al-Azawii, C. Theade, M. Danczyk, E. Johnson, R. Anderson, Experimental study on the cyclic behavior of thermal energy storage in an air-alumina packed bed, Journal of Energy Storage, 18C (2018) 239-249.]

Supercritical CO2 in TES

Supercritical carbon dioxide (sCO2) is emerging as a potential fluid in supercritical Brayton cycles. Excess thermal energy could be stored in a packed bed, similar to the air-alumina system described above. Our recent numerical work has focused on the exergetic efficiency of a commercial-scale packed bed TES unit undergoing several charge-discharge cycles. Our recent analysis is here. A 2D axi-symmetric model solves for the temperature in the bed, insulation, and vessel over time.

sCO2 graphical abstract

[Shown here with permission from Elsevier]