Date of Award

2-2024

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical and Aerospace Engineering

First Advisor

Dr. Fadi Alnaimat

Second Advisor

Dr. Bobby Mathew

Abstract

The integration of latent thermal energy storage into concentrated solar power plants represents a promising solution for efficiently harnessing excessive solar energy during daylight hours and subsequently utilizing it during the nighttime when solar energy generation is limited or non-existent, all while catering to consistent energy demands. The core objective of enhancing latent thermal energy storage revolves around elevating its thermal capacity and minimizing the melting time, thus making it a more effective energy storage solution. This is achieved by employing three distinct organic phase change materials: Octadecanoic (PCM1), RT58 (PCM2) and Dodecanoic (PCM3), each characterized by variations in their thermal properties, particularly their melting temperatures. The 3D modeling and simulation of latent thermal energy storage are carried out using Ansys Fluent, with the heat transfer fluid being air or water and the phase change material being housed within sealed containers. During the charging process, the hot fluid is used to elevate the temperature of the phase change material, storing thermal energy by transitioning its phase from a solid to a liquid state. Furthermore, the determination of the optimal thermal energy storage efficiency necessitates exploring how alterations in geometrical configurations and operational conditions, such as temperature and velocity, impact overall system efficiency. In this extensive investigation, the utilization of a combination of three distinct organic phase change materials in the latent thermal energy storage system has demonstrated a significant reduction in melting time by 15.5% and increases efficiency by 6.9% compared to a configuration with a single PCM in each container. Elevating the temperature of the incoming heat transfer fluid by half has proven to be a crucial factor, resulting in a reduction in the melting time by 56% and increases efficiency by 7.8%. However, it is essential to note that increasing the velocity of the HTF by 22.2% decreases melting time by 10% but lowers efficiency by 1.1%. The substitution of water for air as the HTF has shown remarkable improvements reduction in melting time by 67.6% and increases efficiency by 8.2%. Model 2 increases melting time by 10% and efficiency by 0.9%.

Arabic Abstract


ﺗﺤﻠﯿﻞ ﻧﻈﺮي ﺑﺎﺳﺘﺨﺪام اﻟﻤﺤﺎﻛﺎة ﻟﺜﻼﺛﺔ ﻣﻮاد ﻣﺘﻐﯿﺮة اﻟﺤﺎﻟﺔ ﻓﻲ ﺧﺰان اﻟﻄﺎﻗﺔ اﻟﺤﺮارﯾﺔ اﻟﻜﺎﻣﻦ اﻟﻤﺴﺘﺨﺪم ﻓﻲ اﻟﻤﺤﻄﺎت اﻟﺸﻤﺴﯿﺔ اﻟﻤﺮﻛﺰة

ان اﺳﺘﺨﺪام اﻟﺨﺰان اﻟﺤﺮاري اﻟﻜﺎﻣﻦ ﻓﻲ اﻟﻤﺤﻄﺎت اﻟﺸﻤﺴﯿﺔ اﻟﻤﺮﻛﺰة ﺑﺸﻜﻞ ﻣﺘﻜﺎﻣﻞ ﯾﺸﻜﻞ ﺣﻞ واﻋﺪ ﻻﺳﺘﻐﻼل اﻟﻔﺎﺋﺾ ﻣﻦ اﻟﻄﺎﻗﺔ اﻟﺸﻤﺴﯿﺔ ﺧﻼل ﺳﺎﻋﺎت وﻗﺖ اﻟﻨﮭﺎر وﻣﻦ ﺛﻢ اﺳﺘﮭﻼﻛﮭﺎ ﺧﻼل اﻟﻠﯿﻞ ﻋﻨﺪﻣﺎ ﯾﺼﺒﺢ ﺗﻮﻟﯿﺪ اﻟﻄﺎﻗﺔ اﻟﺸﻤﺴﯿﺔ ﻣﺤﺪود او ﻣﻨﻌﺪم، ﻛﻞ ذﻟﻚ ﻟﺘﻘﺪﯾﻢ ﻣﺼﺪر ﻣﻦ طﺎﻗﺔ ﯾﻐﻄﻲ اﻟﺤﺎﺟﺔ. اﻟﮭﺪف اﻟﺮﺋﯿﺴﻲ ھﻮ ﺗﺤﺴﯿﻦ أداء اﻟﺨﺰان اﻟﺤﺮاري اﻟﻜﺎﻣﻦ ﻣﻦ ﺧﻼل زﯾﺎدة اﻟﻘﺪرة اﻟﺤﺮارﯾﺔ وﺗﻘﻠﯿﻞ اﻟﻮﻗﺖ اﻟﻤﻄﻠﻮب ﻟﻠﺬوﺑﺎن. ﻟﺘﺤﻘﯿﻖ ذﻟﻚ ﯾﺠﺐ ﺗﻮظﯿﻒ ﺛﻼث ﻣﻮاد ﻋﻀﻮﯾﺔ ﻣﺨﺘﻠﻔﺔ ﻣﻦ اﻟﻤﻮاد اﻟﺘﻲ ﺗﻐﯿﺮ ﻣﻦ ﺣﺎﻟﺘﮭﺎ ﻋﻨﺪ ﺗﻌﺮﺿﮭﺎ ﻟﻠﺤﺮارة ﻣﺜﻞ: ﺣﻤﺾ اﻟﺴﺘﺮﯾﻚ،RT58 وﺣﻤﺾ اﻟﻠﻮرﯾﻚ، ﻛﻞ ﻣﻨﮭﺎ ﯾﺘﻤﯿﺰ ﺑﺎﺧﺘﻼف ﻓﻲ ﻣﻮاﺻﻔﺎﺗﮭﺎ اﻟﺤﺮارﯾﺔ، وﺧﺼﻮﺻﺎ ﻓﻲ درﺟﺔ ﺣﺮارة اﻟﺬوﺑﺎن. اﻟﺘﺼﻤﯿﻢ ﺛﻼﺛﻲ اﻻﺑﻌﺎد واﻟﻤﺤﺎﻛﺎة ﻟﻠﺨﺰان اﻟﺤﺮاري ﻣﺨّﺰن اﻟﻄﺎﻗﺔ ﺗﻢ ﺗﻨﻔﯿﺬھﺎ ﻣﻦ ﺧﻼل اﻟﺒﺮﻧﺎﻣﺞ Ansys Fluent، ﻣﻊ وﺟﻮد اﻟﮭﻮاء واﻟﻤﺎء ﻛﻤﺎﺋﻊ ﻣﺮﺗﻔﻊ اﻟﺤﺮارة ﻛﻤﺎ ان اﻟﻤﻮاد ﻣﺘﻐﯿﺮة اﻟﺤﺎﻟﺔ ﺗﺘﻮاﺟﺪ داﺧﻞ ﺣﯿﺰ ﻣﺤﻜﻮم اﻻﻏﻼق. ﺧﻼل ﻋﻤﻠﯿﺔ اﻟﺸﺤﻦ، اﻟﻤﺎﺋﻊ ﻣﺮﺗﻔﻊ اﻟﺤﺮارة ﯾﻘﻮم ﺑﺮﻓﻊ درﺟﺔ ﺣﺮارة اﻟﻤﻮاد ﻣﺘﻐﯿﺮة اﻟﺤﺎﻟﺔ، ﺑﺤﯿﺚ ﯾﺘﻢ ﺗﺨﺰﯾﻦ اﻟﻄﺎﻗﺔ اﻟﺤﺮارﯾﺔ ﻟﺘﻐﯿﯿﺮ ﺣﺎﻟﺔ اﻟﻤﻮاد ﻣﻦ اﻟﺼﻠﺒﺔ اﻟﻰ اﻟﺴﺎﺋﻠﺔ. ﻟﺘﺤﺪﯾﺪ اﻟﻈﺮوف اﻟﻤﺜﺎﻟﯿﺔ ﻟﻠﻌﻤﻞ ﻣﻦ ﺣﯿﺚ اﻋﻠﻰ ﻛﻔﺎءة ﻣﻄﻠﻮﺑﺔ ﺗﻢ اﺳﺘﻜﺸﺎف ﺗﺼﺎﻣﯿﻢ وظﺮوف ﻋﻤﻞ ﻣﺘﺨﻠﻔﺔ، ﻣﺜﻞ درﺟﺔ ﺣﺮارة وﺳﺮﻋﺔ اﻟﻤﺎﺋﻊ، وﺗﺄﺛﯿﺮ ﻛﻞ ﻣﻨﮭﻤﺎ ﻋﻠﻰ اﻟﻜﻔﺎءة اﻟﻜﻠﯿﺔ ﻟﻠﻨﻈﺎم. ﻓﻲ ھﺬه اﻟﺪراﺳﺔ اﻟﺪﻗﯿﻘﺔ ﺗﺒﯿﻦ ان اﺳﺘﺨﺪام اﻟﺨﺰان اﻟﺤﺮاري اﻟﻜﺎﻣﻦ ﻣﻦ ﺛﻼث ﻣﻮاد ﻣﺘﻐﯿﺮة اﻟﺤﺎﻟﺔ اظﮭﺮ وﻗﺘﺎ اﻗﻞ ﻟﻠﺬوﺑﺎن ﺑﻤﻘﺪار 15.5% وﺗﺤﺴﻦ ﻓﻲ ﻛﻔﺎءة اﻟﻨﻈﺎم 6.9% ﻣﻘﺎرﻧﺔ ﻣﻊ اﻟﺨﺰان اﻟﺤﺮاري اﻟﻜﺎﻣﻦ اﻟﻤﻜﻮن ﻣﻦ ﻣﺎدة واﺣﺪة ﻣﺘﻐﯿﺮة اﻟﺤﺎﻟﺔ. رﻓﻊ اﻟﺤﺮارة ﻟﻠﻤﺎﺋﻊ اﻟﺤﺎر اﻟﻘﺎد م ﻟﻠﻨﺼﻒ اﺛﺒﺖ ﺗﺤﺴﻦ واﺿﺢ ﺑﺎﻷداء ﺑﺤﯿﺚ ﻗﻞ وﻗﺖ اﻟﺬوﺑﺎن ﺑﻨﺴﺒﺔ 56%ﻣﻠﺤﻮظﺔ وزادت اﻟﻜﻔﺎءة ﺑﻤﻘﺪار7.8%. اﻣﺎ ﺗﺄﺛﯿﺮ زﯾﺎدة اﻟﺴﺮﻋﺔ ﺑﻨﺴﺒﺔ 22.2% ﻗﻠﻞ وﻗﺖ اﻟﺬوﺑﺎن 10% وﺗﻘﻠﯿﻞ اﻟﻜﻔﺎءة ﺑﺸﻜﻞ طﻔﯿﻒ 1.1% . ان اﺳﺘﺒﺪال اﻟﻤﺎﺋﻊ اﻟﺴﺎﺧﻦ ﺑﺎﻟﻤﺎء اظﮭﺮ ﺗﺤﺴﻦ ﻣﻠﺤﻮظ ﻓﻲ وﻗﺖ اﻟﺬوﺑﺎن ﺑﻤﻘﺪار 67.6%وزﯾﺎدة ﻓﻲ اﻟﻜﻔﺎءة ﺑﻘﯿﻤﺔ 8.2%. ﻛﻤﺎ ﺗﻮظﯿﻒ اﻟﺘﺼﻤﯿﻢ اﻟﺜﺎﻧﻮي ﻛﺎن ﻟﮫ ﺗﺄﺛﯿﺮ ﺑﺰﯾﺎدة وﻗﺖ اﻟﺬوﺑﺎن 10% وﺗﺤﺴﯿﻦ اﻟﻜﻔﺎءة 10%.

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