.Greenhouses.Flows.HeatTransfer.PipeFreeConvection

Information

The magnitude of convective heat from the heating pipes to the air depends on the pipe position, which implies a free exchange (i.e. pipes in free air) or a hindered exchange (i.e. pipes situated close to the canopy and near the floor). In free convection, the Nusselt (Nu) number describing the exchange process can be defined as a function of the Rayleigh (Ra) number [1]. Therefore, the free exchange is modeled based on the Nu-Ra relation. The hindered exchange, considered to be forced, is modeled by experimental correlations derived by [2]. The user should indicate which exchange is modeled by means of the Boolean parameter 'freePipe'. The diameter of the pipes and the installed pipe length per ground area are also parameters, required to compute the heat exchange coefficient.