Numerical Assessment on Fin Design Parameters Employed for Augmentation of Natural Convection and Fluid Flow in a Horizontal Latent Heat Thermal Energy Storage Unit
- 1 Department of Physics, Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Stockholm, Sweden
- 2 Department of Physics, Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Stockholm, Sweden
- 3 Department of Energy Technology, KTH Royal Institute of Technology (KTH), Stockholm, Sweden
Abstract
The present work focus on the thermal performance of a horizontal concentric heat exchanger, which is numerically investigated to evaluate the heat transfer enhancement process by adding fins with different configurations. As a part of this investigation, the melting process is simulated from the onset of phase change to the offset involving physics of natural convection in PCM fluid pool. The investigation is carried out by ANSYS Fluent code, which is an efficient numerical analysis tool for investigating fluid flow and convective heat transfer phenomena during PCM melting process. The attention is mainly focused on the extension of contact area between the PCM body and cylindrical capsule to enhance heat transfer rates to PCM bodies during the melting process by employing longitudinal fins in the enclosed capsule. Two commercial PCMs: RT50 and C58, are introduced in a 2D cylindrical pipe with their thermo-physical properties as input for modelling. The selected modelling approach is validated against experimental result with respect to the total enthalpy changes that qualify our model to run in the proceeding calculation. It is ensured that an isothermal boundary condition (373 K) is applied to the inner pipe throughout the series of simulation cases and the corresponding Rayleigh number (Ra) ranges from 10 4 - 10 5 and Prandtl number (Pr) 0.05 - 0.07. Finally, parametric study is carried out to evaluate the effect of length, thickness and number of longitudinal fins on the thermal performance of PCM-LHTES (Latent Heat Thermal Energy Storage) system associated with the physics of natural convection process during PCM melting.
- Esapour, M., Hosseini, M.J., Ranjbar, A.A., Pahamli, Y. and Bahrampoury, R. (2016) Phase Change in Multi-Tube Heat Exchangers. Renewable Energy, 85, 1017-1025. https://doi.org/10.1016/j.renene.2015.07.063
- Ibrahima, N.I., Al-Sulaimana, F.A., Rahmana, S., Yilbasb, B.S. and Sahin, A.Z. (2017) Heat Transfer Enhancement of Phase Change Materials for Thermal Energy Storage Applications: A Critical Review. Renewable and Sustainable Energy Reviews, 74, 26-50. https://doi.org/10.1016/j.rser.2017.01.169
- Arena, S., Cau, G. and Palomba, C. (2015) CFD Simulation of Melting and Solidification of PCM in Thermal Energy Storage Systems of Different Geometry. Journal of Physics: Conference Series, 655, Article ID: 012051. https://doi.org/10.1088/1742-6596/655/1/012051
- Lamberg, P., Lehtiniem, R. and Henell, A.-M. (2004) Numerical and Experimental Investigation of Melting and Freezing Processes in Phase Change Material Storage. International Journal of Thermal Sciences, 43, 277-287. https://doi.org/10.1016/j.ijthermalsci.2003.07.001
- Shmueli, H., Ziskind, G. and Letan, R. (2010) Melting in a Vertical Cylindrical Tube: Numerical Investigation and Comparison with Experiments. International Journal of Heat and Mass Transfer, 53, 4082-4091. https://doi.org/10.1016/j.ijheatmasstransfer.2010.05.028
- Kulacki, F.A. and Goldstein, R.J. (1972) Thermal Convection in a Horizontal Fluid Layer with Uniform Volumetric Energy Sources. Journal of Fluid Mechanics, 55, 271-287.
- Kulacki, F.A. and Nagle, M.E. (1975) Natural Convection in a Horizontal Fluid Layer with Volumetric Energy Sources. Journal of Heat Transfer, 97, 204-211. https://doi.org/10.1115/1.3450342
- Kulacki, F.A. and Emara, A.A. (1975) High Reynolds Number Convection in Enclosed Fluid Layers with Internal Heat Sources. US NRC Report NUREG-75/065.
- Seeniraj, R.V., Velraj, R. and Narasimhan, N.L. (2002) Thermal Analysis of a Finned-Tube LHTS Module for a Solar Dynamic Power System. Heat and Mass Transfer, 38, 409-417. https://doi.org/10.1007/s002310100268
- Agyenim, F., Eames, P. and Smyth, M. (2009) A Comparison of Heat Transfer Enhancement in a Medium Temperature Thermal Energy Storage Heat Exchanger Using Fins. Sol Energy, 83, 1509-1520. https://doi.org/10.1016/j.solener.2009.04.007
- Lacroix, M. (1993) Study of the Heat Transfer Behavior of a Latent Heat Thermal Energy Storage Unit with a Finned Tube. International Journal of Heat and Mass Transfer, 36, 2083-2092. https://doi.org/10.1016/S0017-9310(05)80139-5