Effect of air velocity on two types of vertical annular concentric heat exchanger flow configurations for air conditioning systems

Refrigerants used in conventional air conditioning systems contribute to ozone layer depletion and global warming. The Earth Air Heat Exchanger (EAHE) system offers a passive cooling alternative that reduces environmental impact. Airflow velocity is one of many important factors affecting the performance of the EAHE system. This paper investigates the effect of airflow velocity on the performance of EAHE systems in air conditioning applications. The modeling is performed using the finite volume method, with the EAHE type being the vertical annular concentric heat exchanger, for two types of airflow configurations. The first type is fresh air entering through the inner pipe, while the second type enters through the outer pipe. The analysis was conducted by varying the airflow velocity from 0.75 to 2 m/s in increments of 0.25 m/s using a simulation program. The inner and outer diameters of the pipe are 1.25 and 4 inches. The simulation results for two airflow configuration types show that an increase in airflow velocity of 0.25 m/s reduces the system effectiveness by 31% for type 1 and 29.43% for type 2. These results indicate that type 2 is more effective at maintaining performance under increasing airflow velocities, making it a better option for energy-efficient cooling.