Heat transfer and thermodynamics analyses of some modified spherical capsules during discharging period


ERDEMİR D.

10th Exergy, Energy and Environment Symposium, Katowice, Poland, 1 - 04 July 2018, pp.1-7

  • Publication Type: Conference Paper / Full Text
  • City: Katowice
  • Country: Poland
  • Page Numbers: pp.1-7

Abstract

Ice thermal energy storage (ITES) systems are commonly used for reducing the cooling cost and equipment capacity. Encapsulated ITES systems are one of the most preferred types among the ITES systems, because of ease to apply and lower initial cost according to other type of ITES systems. Capsule shapes have great impact on the thermal performance of encapsulated ITES system. Spherical capsule provides better thermal performance due to the ratio of its volume to its surface area. Also, there are many modified spherical capsule shapes in order to enhance thermal performance. This paper presents a numerical investigation in order to determine the effect of different modified spherical capsules on the system performance during discharging period. Five different modified spherical capsules were used. FLUENT 17.2 code was used for numerical calculation. At the end of study, it was found that geometrically modified capsules provided higher thermal performance than an ordinary spherical capsule in the equal volume. Dominant effect on this enhancing was the surface areas of capsules. There were no clear differences in velocity and turbulent kinetic energy distributions among all capsule models, since the flow over capsules was low. The lowest discharging time was seen in Capsule A with 668 s, while the longest discharging time was seen in Capsule D with 1490 s. While the energy efficiencies were nearly 99% for all cases, the exergy efficiencies changed between 64% and 84%. Capsule D showed the best thermodynamic performance.