Salem Bouhairie and Syed Haq, Heat Transfer Research Inc., discuss how airflow patterns within air-cooled heat exchangers (ACHEs) degrade performance.
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ir-cooled heat exchangers (ACHEs) at hydrocarbon processing or power plant facilities occupy large areas. Non-uniform airflow patterns and non-ideal site installation can affect overall plant performance, sometimes significantly reducing output. Industry guidelines addressing these problems are limited, and in-house rules of thumb are not consistently applicable. Heat Transfer Research Inc. (HTRI) conducts research on many ACHE operational challenges, revealing complexities in phenomena on the airside. Some issues of concern include the following:
June 2022 48 HYDROCARBON ENGINEERING
n Non-uniform approach of air into the ACHE inlet is the most common cause of deficient fan performance, and is often associated with obstructions from buildings, pipelines, or ground equipment. n Wind can direct the heated exhaust air away from or back into the unit. Some plant sites cannot avoid installing ACHEs in known wind corridors. n Hot air recirculation, a form of airside maldistribution, is difficult to predict. It creates temperature pinches that reduce mean temperature differences and subsequently the heat transfer potential of the tubeside process to reject heat to the air.
