The core of Chinese greenhouses is a very massive rear wall intended for heat storage during cold nights. The system is similar to the ‘thermally activated building systems’ used in building climate control. To determine the dimensions and material properties of this ‘thermal rear wall’ during the planning phase, FlowMotion was commissioned to simulate the heat transfer both inside and outside the greenhouse.
As this building is a greenhouse where temperatures in the plant area must remain as constant as possible to guarantee maximum yield, it was necessary to determine the temperature and velocity distribution at every point within the greenhouse at every moment over a period of weeks. Thermal building simulation methods were deemed unsuitable, as they can only determine an average temperature per room and only estimate the complex buoyancy effects at the walls. Consequently, CFD (Computational Fluid Dynamics) calculations were applied.
These simulations accounted not only for all heat transfer mechanisms (free convection, conduction, radiation) but also for the changing position of the sun and the covering of the greenhouse’s outer skin during the night.
Through the analysis of the simulation results, the influence of various ‘thermal walls’ could be investigated precisely, which also led to changes in covering times and significant energy savings.
