Numerical Study on Long-Distance Heating System Based on High-Velocity Jet at Ambient Temperature for Induced Air Supply

In the long-distance thermal air heating process of large space buildings, there are common problems of thermal air trajectory deflection and low energy efficiency caused by thermal buoyancy. This study proposes an induced air supply system that is easy to design for integration; that is, adding a high-velocity ambient temperature induced airflow above the thermal jet, which can instantly and efficiently suppress the buoyancy of the thermal jet and maintain its axial center temperature, thereby achieving good heating performance. This study uses a numerical simulation method to analyze the effect of the induced airflow and compares the flow field characteristics and heating performance of a single thermal jet and an induced air supply system. The results show that the greater the velocity of the induced airflow, the wider the control range of the thermal jet; the induced airflow can reduce the mixing of the thermal jet and the ambient airflow, and effectively suppress the deflection of the thermal jet and increase its axial center temperature; when the target area is close to the air inlet (y/D ≤ 7.5), the single thermal jet air supply can be used, because too small a deflection height will cause more induced airflow to enter the target area, which will worsen the heating effect. The induced air supply system is best for improving the average temperature of the target area at y/D = 15; as the target distance increases, on the premise of ensuring the blowing feeling, it is possible to consider increasing the induced airflow velocity to obtain a higher heating gain.