بهبود انتقال حرارت در مبدل حرارتي پوسته لوله اي با كمك لوله هايي با سطح مقطع غير دايروي

Improving heat transfer in the shell & tube heat exchanger with the non-circular cross section tubes

ﯾﮑﯽ از ﭘﺮﮐﺎرﺑﺮد ﺗﺮﯾﻦ ﻣﺒﺪل ﺣﺮارﺗﯽ، ﻣﺒﺪل ﺣﺮارﺗﯽ ﭘﻮﺳﺘﻪ ﻟﻮﻟﻪ اي اﺳﺖ. ﻫﺪف از اﻧﺠﺎم اﯾﻦ ﺗﺤﻘﯿﻖ، اﻓﺰاﯾﺶ اﻧﺘﻘﺎل ﺣﺮارت و ﮐﺎﻫﺶ اﻓﺖ ﻓﺸﺎر ﺑﺎ ﺗﻐﯿﯿﺮ در ﺳﻄﺢ ﻣﻘﻄﻊ ﻟﻮﻟﻪ ﻫﺎي ﻣﺒﺪل ﺣﺮارﺗﯽ ﺑﻮد. در اﯾﻦ ﭘﮋوﻫﺶ، از ﻟﻮﻟﻪ ﻫﺎﯾﯽ ﺑﺎ ﺳﻄﺢ ﻣﻘﻄﻊ داﯾﺮوي، ﺑﯿﻀﻮي ﺑﺎ زاوﯾﻪ ﺣﻤﻠﻪ 0 و ﺑﯿﻀﻮي ﺑﺎ زاوﯾﻪ ﺣﻤﻠﻪ 90 اﺳﺘﻔﺎده ﺷﺪ. ﺑﺮاي Re ﺑﯿﻦ 3000 ﺗﺎ 15000 ﻣﻘﺪار اﻓﺖ ﻓﺸﺎر و ﺿﺮﯾﺐ اﻧﺘﻘﺎل ﺣﺮارت را ﺑﺮرﺳﯽ ﺷﺪ و ﺳﭙﺲ ﻣﺪل ﺗﺮﮐﯿﺒﯽ ﺷﺎﻣﻞ دو ﺣﺎﻟﺖ: ﺣﺎﻟﺖ اول: ﻟﻮﻟﻪ ﻫﺎي داﯾﺮوي در ﻣﺮﮐﺰ ﭘﻮﺳﺘﻪ و ﻟﻮﻟﻪ ﻫﺎي ﺑﯿﻀﻮي ﺑﺎ زاوﯾﻪ ﺣﻤﻠﻪ 90 در اﻃﺮاف ﭘﻮﺳﺘﻪ و ﺣﺎﻟﺖ دوم: ﻟﻮﻟﻪ ﻫﺎي ﺑﯿﻀﻮي ﺑﺎ زاوﯾﻪ ﺣﻤﻠﻪ 90 در ﻣﺮﮐﺰ ﭘﻮﺳﺘﻪ و ﻟﻮﻟﻪ ﻫﺎي داﯾﺮوي در اﻃﺮاف ﭘﻮﺳﺘﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﻗﺮار ﮔﺮﻓﺘﻪ ﺷﺪ، ﮐﻪ ﻧﺸﺎن دﻫﻨﺪه اﻓﺰاﯾﺶ اﻧﺘﻘﺎل ﺣﺮارت در ﻟﻮﻟﻪ ﻫﺎي ﺑﯿﻀﻮي ﺑﻪ ﺧﺼﻮص ﻟﻮﻟﻪ ﻫﺎي ﺑﯿﻀﻮي ﺑﺎ زاوﯾﻪ ﺣﻤﻠﻪ 90 ﻧﺴﺒﺖ ﺑﻪ داﯾﺮوي اﺳﺖ درﺣﺎﻟﯿﮑﻪ ﻟﻮﻟﻪ ﻫﺎي داﯾﺮوي ﮐﻤﺘﺮﯾﻦ اﻓﺖ ﻓﺸﺎر را داﺷﺘﻨﺪ. اﺳﺘﻔﺎده از ﺣﺎﻟﺖ ﺗﺮﮐﯿﺒﯽ اول )°STHE- CT&ET90 ( و ﺣﺎﻟﺖ دوم )STHE- ET90 °& CT ( اﮔﺮ ﭼﻪ ﻣﻮﺟﺐ اﻓﺰاﯾﺶ اﻧﺘﻘﺎل ﺣﺮارت ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﺮاﺑﺮ ﺑﺎ 10% و 3% ﻧﺴﺒﺖ ﺑﻪ ﺣﺎﻟﺖ STHE- CT ﻣﯽﺷﻮد وﻟﯿﮑﻦ ﻣﻮﺟﺐ اﻓﺰاﯾﺶ اﻓﺖ ﻓﺸﺎر ﻧﯿﺰ ﺧﻮاﻫﺪ ﺷﺪ.

One of the most common used heat exchangers is the shell & tube heat exchanger. It has many usages in the oil and gas, petrochemical and pharmaceutical industries. The heat exchanger is the best which has the highest heat transfer rate with the lowest energy consumption. In this research, we want to increase heat transfer and reduce pressure drop by changing the cross section of tubes. We used tubes with different cross section; circular , ellipse with 0° attack angle and ellipse with 90°attack angle. We study pressure drop and heat transfer coefficient for Re between 3000 to 15000. Then two combined models are examined. Case 1: Circular tubes in the center of the shell and elliptical tubes with 90° attack angle around the shell, case 2: Elliptical tubes with 90° attack angle in the center of the shell and circular tubes around the shell. Which indicates an increase in heat transfer in elliptical tubes, especially elliptical tubes with 90° attack angle compared to the circular, while circular tubes have the lowest pressure drop. However the heat transfer in the case 1 (STHE-CT&ET90°) and the case 2 (STHE-ET90°&CT) increase by 10% and 3% compared to the STHE-CT respectively, it caused increasing the pressure drop.