Enhancing thermal performance of water-air cross flow heat exchangers through upstream nozzle design and unit division

Abstract

Improving water-air cross-flow heat exchangers' (HXs') thermal performance is essential for raising energy efficiency in a range of industrial applications. In order to accomplish this, prior research has mostly concentrated on altering interior geometries or flow configurations. Nevertheless, scarce are the studies about the possibilities of manipulating external airflow. This work presents and assesses a unique method for externally altering airflow arrangements in order to maximize the thermal performance of water-air cross-flow HXs. In contrast to conventional techniques that focus on internal adjustments, this study suggests a novel exterior approach that divides the HX into several smaller, face-to-face units inside the airflow and uses an upstream nozzle to boost airflow velocity over a smaller region. The goal of this design is to increase thermal efficiency without changing the HX's internal structure. To mimic the operation of a double-passage HX under various circumstances, a two-dimensional computational model was created and verified. The model evaluated the proposed HX designs' and the conventional designs' thermal performance over a variety of water flow rates and air velocities. According to the simulations, the suggested design can increase thermal performance by up to 6.1 % when compared to the conventional HX setup. Interestingly, these improvements are particularly noticeable at greater water flow rates (12,000 L/h) and moderate mean air velocities (6 m/s). Crucially, these enhancements are made without causing extra pressure drop, highlighting the design's potential for real-world uses.