SASTech - Technical Journal of RUAS

Air conditioning has become a standard option on most vehicles enhancing comfort and safety. Modern systems feature automatic climate control, integrated cooling, heating, de-misting and de-frosting, air filtering, and humidity control. These systems improve passenger thermal comfort and safety.

Passenger thermal comfort is mainly influenced by the inside cabin temperature. Cabin temperature in turn depends on the cabin size, number and shape of airvents and mass flow rate of the total HVAC system, and the interior materials of dashboard, trims and seatings. Normally airvents in passenger car have manual adjustment of the vanes to set the airflow direction. An attempt has been made to make these airvents operate automatically as per the cabin temperature. The concept named dynamic airvents has been suggested in a passenger hatch and assessed by CFD analysis using commercial code FLUENT (ANSYS 13). The simulation done for all the airvents has been validated with the experimental test results. With the help of CFD simulations it is shown that dynamic airvents provide a better thermal comfort for passengers. Airflow pattern has been studied and compared with the steady airvent model. Airflow for 1 and 2 cycles of the vane movement has been simulated. The movement of the vanes is given for central vertical, horizontal vanes and side horizontal vanes. The airflow velocity due to the dynamic nature of the vanes has enhanced towards the rear passenger. Cabin cool down analysis with the dynamic vents has been done to study the effect of cooling inside the cabin. Comparison with the baseline airvents has shown that cabin cool down is achieved faster with dynamic vents. With dynamic airvents an average cabin temperature drop by almost 3°C is achieved within 25 minutes compared to the baseline. The airflow velocity, directivity and temperature drop rate with dynamic airvents is observed to be better than in the case of steady airvents.