Browsing by Author "Wolde, Ian"

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    An innovative strategy for improvement of energy efficiency in cement production by means of stratified thermal energy storage integration
    (Elsevier Ltd., 2025) Wolde, Ian; Famiglietti, Antonio; Abbas, Rubén; Cardemil Iglesias, José Miguel
    The cement industry represents a heavy emission source due to its large heat demands in its high-temperature processes, as well as a substantial source of CO2 emissions due to the ongoing chemical reactions. The primary air going into the combustion chambers could be pre-heated using available waste heat from the raw mill. However, batch operation imposes a challenge in supplying a continuous heat flow. Therefore, medium-tohigh-temperature thermal energy storage technologies could be assessed using pinch analysis to design and determine the operating parameters of a heat network with storage, aiming to facilitate the use of waste heat. Using a European cement plant as a reference, an assessment of a heat recovery system with storage is presented based on primary air preheating. The system is assessed considering thermal energy storage technologies that commonly present thermal stratification in order to reduce costs by working with a single storage tank. Air and thermal oil are evaluated as heat transfer fluids, and different filler materials for storage are considered for thermocline thermal energy storage systems. Results show that low-cost media such as copper slags could recover the system’s investment in less than a year, providing savings in the plant heat demand of up to 1.04%.
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    Transient modeling of stratified thermal storage tanks: Comparison of 1D models and the Advanced Flowrate Distribution method
    (2024) Riebel, Adrian; Wolde, Ian; Escobar, Rodrigo; Barraza, Rodrigo; Cardemil, Jose M.
    Thermal energy storage (TES) is one of the key technologies for enabling a higher deployment of renewable energy. In this context, the present study analyzes the modeling strategies of one of the most common TES systems: stratified thermal storage tanks. These systems are essential to many solar thermal installations and heat pumps, among other clean energy technologies. Three different one-dimensional tank models are compared by their computing speed and resilience to long time steps. Two of the models analyzed are numerical, one being explicit and the other one implicit, and the other is analytical. The models are validated against data from experiments carried out considering small-scale stratified tanks, showing that their performance can be improved by using the Advanced Flowrate Distribution (AFD) method. The results show that the analytical model maintains its accuracy with longer time steps and is robust against divergence. Conversely, the numerical models show equivalent performance for short time steps, while the computation time is reduced. Although the AFD method shows promising results by achieving an improvement of 43% in terms of Dynamic Time Warping, its parameter optimization must be generalized for different tank designs, flow rates, and temperatures.