CHEMICAL ENGINEERING TRANSACTIONS VOL. 81, 2020 A publication of The Italian Association of Chemical Engineering Online at www.cetjournal.it Guest Editors: Petar S. Varbanov, Qiuwang Wang, Min Zeng, Panos Seferlis, Ting Ma, Jiří J. Klemeš Copyright © 2020, AIDIC Servizi S.r.l. ISBN 978-88-95608-79-2; ISSN 2283-9216 Metaheuristic Design Optimization of the Air-PCM Thermal Storage Unit for Solar Air Systems Lubomír Klimeš a, *, René Kesler b , Pavel Charvát c a Sustainable Process Integration Laboratory – SPIL, NETME Centre, Brno University of Technology, Technicka 2896/2, 61669 Brno, Czech Republic b Institute of Mathematics, Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2896/2, 61669 Brno, Czech Republic c Energy Institute, Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2896/2, 61669 Brno, Czech Republic klimes@fme.vutbr.cz Phase change materials (PCMs) and thermal energy storage (TES) represent a way toward sustainable utilization of renewable energy resources. An air-PCM thermal storage unit integrated in solar systems is a device, which employs the latent heat TES to balance between the demand and supply of heat (or cold) for space heating (or cooling) in buildings. Previously published studies demonstrate that this approach is viable but design parameters of the unit need to be optimized. In the paper, a computer model of the heat storage unit was developed and coupled to metaheuristic nature-inspired optimization algorithms with the aim of design optimization of the TES unit. The unit consisted of flat plates made of a PCM, which was macro-encapsulated in aluminium containers. The energy balance and control volume methods were used to build the model and the effective heat capacity technique was applied for phase change modelling. The model was created in Python, validated against experimental data and an open-source optimization library DEAP with metaheuristics was used as an optimization solver. A design optimization problem was specified with including the arrangement of the PCM plates and their thickness. Results showed that the DEAP library and metaheuristics are well applicable for the solution of this kind of optimization problem. 1. Introduction In recent years, there is an increasing effort of the society toward the utilization of renewable energy resources as a way for minimization of fossil fuel consumption and greenhouse gas production. Currently, a considerable amount of energy is used in the form of heat, especially in buildings and households for space heating. It is well reported that buildings account for about 40 % of the overall energy consumption, see e.g. the review presented by Li et al. (2019). As for increasing the share of renewable energy resources and their utilization to buildings, solar energy seems to be a good candidate as the conversion of solar energy into heat is easy and technically as well as technologically inexpensive. However, a crucial issue related to solar energy is that very often there is a mismatch between energy supply and demand. In other words, the Sun providing solar energy is available during the day but in many cases Sun’s solar energy would be much appreciated in the late afternoon, evening, or at night when the demand for space heating arises. One of promising approaches coping with the mismatch between heat supply and demand is thermal energy storage. The main idea is rather simple: the use of a suitable media allowing for heat accumulation and storage. Once there is a demand, heat is released. Even though sensible heat storage materials such as pebbles can be employed, latent heat thermal energy storage (LHTES) turns out to be more efficient. The LHTES utilizes a material, which undergoes the phase. Since the latent heat of phase change is significantly higher than the sensible heat in the same temperature interval, a relatively high thermal capacity in a narrow temperature range can be achieved. The materials for LHTES are commonly referred to as phase change materials (PCMs) and there is a wide range of PCMs commercially available at the market for various applications with different temperature ranges. Organic PCMs such as paraffin as well as inorganic PCMs such as salt hydrates are typical DOI: 10.3303/CET2081035 Paper Received: 31/03/2020; Revised: 08/06/2020; Accepted: 12/06/2020 Please cite this article as: Klimeš L., Kesler R., Charvát P., 2020, Metaheuristic Design Optimization of the Air-PCM Thermal Storage Unit for Solar Air Systems, Chemical Engineering Transactions, 81, 205-210 DOI:10.3303/CET2081035 205