Research Of The Numerical Simulation On Hot Air Heating For Large Workshop

For large workshop, the form of hot air heating has many kinds of advantages, such as small thermal inertia, fast heating process, simple equipments and lower investment, so this form of heating is widely used, and particularly it will be the preferred way for the situations like combining with mechanical ventilation or in the situation we must adopt the full fresh air system due to fire, explosion and health requirements. As a result of this, the relevant technical specifications have made the principled rules on the air distribution modes, the position of the diffusions, and the speed of supplied air.In many air distribution modes of hot air heating, setting single supply air outlets and inlets is the form with least investment. In order to further understand the heating effect of this way of air distribution, this paper applies the method of CFD(Computational Fluid Dynamics), use Computational Fluid Dynamics software FLUENT to give the numerical simulation of the hot air heating’s velocity field and temperature field in large workshop, and analyzes the simulation results. In the process of numerical simulation, we can carry out the study by changing the velocity, the angle and the temperature of air supply, and select the most ideal supply air velocity and temperature by comparing kinds of working conditions. Because the workshop is located in cold region, there won’t set heating in non-working time when adopting hot air heating,and if there is a fixed working point within 2 m or 2 m distance from the window, the radiator should be appropriately installed below the window, so this paper also simulates the way of compound heating, namely the radiators provide the 5 ℃ Celsius temperature on duty in non-work time, and in work time, hot air heating that will work in the condition with rational supply air velocity and temperature and radiator temperature heating will work together to give the needed temperature in the workspace.The research results show that if we adopt the hot air heating way with setting single supply air outlets and inlets in the workshop with a high floor height, when the height of air supply is 0.5 H and remains the same, the hot air heating under the rated can not only achieve a good heating effect, but also can save about 15 % energy comparing the traditional radiator heating. By changing the angle of supply air downward tilt 15 °and increasing the velocity of supply air can reduce the heat transfer inside the plant, improve the temperature distribution in vertical direction, so as to improve the temperature of the workspace. But when supply air rate is too high, the workplace will be in the air distribution area, and the reflux wind speed will be exceed 0.75 m/s which is set in related technical regulations, thus the thermal comfort of the staff will be reduced. To a certain extent, adopting the composite way of hot air and radiator heating will solve the problem of low temperature near the window workspace and the needed temperature on duty at night, but compound heating is less ideal in energy-saving than hot air heating. This research conclusion will provide the beneficial references for hot air heating engineering design.