.ClaRa.SubSystems.Furnace.HopperSlice_L4_AdditionalAir.GasHeatTransfer_Wall .ClaRa.SubSystems.Furnace.HopperSlice_L4_AdditionalAir.GasHeatTransfer_Wallmodel GasHeatTransfer_Wall = ClaRa.Basics.ControlVolumes.Fundamentals.HeatTransport.Gas_HT.Radiation.Radiation_gas2Wall_L2;