Analysis Of Boundary Condition Of Numerical Simulation Of Air Conditioning In A Large Space

With the development of computational fluid dynamics and software and hardware of the computer, CFD, which is provided with computing and visual functions, makes it possible for us to achieve the goal of thermal comfort, techniques, and energy conservation. To ensure the credibility of simulation result of CFD that is widely applied to HVAC&R, it is important to ensure the correctness of the mathematical and physical model, the appropriateness of the gridding division, and the preciseness of the calculating. Also, it is essential to logically describe the boundary condition.The thesis, based on the air conditioning design in a large space, say, the Passenger Stand Room of a railway station, studies the 3D numerical simulation of the stratified air conditioning of the Passenger Stand Room, and the temperature field and velocity field of the waiting room by using the STAR-CD computational fluid dynamics software. RNG k-ε turbulent model is used as the computing model;Finite volume method is used to discretize the computed area with upwind differencing scheme put into use;while SIMPLE is adopted to couple the velocity and pressure. This thesis attaches importance to the analysis of the extent of the inlet boundary condition, boundary condition of the wall temperature and curtain wall temperature, etc. to air-conditioning temperature field and velocity field.The orbicular spouts are simulated by using different spout numerical models, which are contrasted to the speed distribution of axes and break by means of the classical jet current formula, thus leading to the formation of the inlet numerical model that can describe orbicular spout inlet boundary condition more accurately. As for the wall temperature boundary condition of the stratified air conditioning in a large space, its description should reflect the actual situation of the wall temperature distribution in the process of CFD simulation that is based on the analysis of the trend of the temperature field and velocity field and the indexation of the thermal comfort. As for the boundary condition of the curtain wall temperature, it is simulated by respectively adopting the idealized adiabatic curtain wall boundary condition description and boundary conditiondescription of heat transfer by convection, which result from the combination of solar radiation permeated through the glass and fluid in the room. It is believed that the latter can reflect the real physical process more veritably, thus ensuring the credibility of the outcome of the simulation. Accordingly, the thesis advances the following argument: that is, in the process of air-conditioning CFD simulation in the similar large space, how to describe, reasonably and veritably, the relevant boundary condition to ensure the correctness and credibility of the simulation result.