736 Fermentation and Biochemical Engineering Handbook adiabatic operation of constant heat input, the temperature may drop or more likely it will maintain a level (pseudo-wet bulb) temperature Falling rate period-this is the period of drying where the instantaneous drying rate is constantly decreasing Feed material-this is the description of the material being dried before Final moisture content-the desired product moisture level required after completion of the drying process Free flowing-refers to the feed and product characteristics, as in a free flowing powder. This is the state in which the material being dried would not cling to itself, forming large chunks or possibly bridging in a hopper Free moisture--liquid which is promptly removable due to its availabil- ity at the interface between the surface of the particles(solids) and the gas stream Hygroscopic material-solids having an affinity for liquids due to a hemical or physical attraction between the solids and the liquid Initial moisture contenf-the average moisture contained in the wet material before the start of the drying process. If given in percent, specification of wet or dry basis is necessary Plug flow-a term used to describe the breakup of a continuous process into small batch segments. The term may originate from a reactor tube being filled or plugged with small quantities of material using a piston pump The reactor would process the volume of material in each piston cavity like a small batch, yet when the material is viewed as a large quantity, it appears homogene he term is used in conjunction with semi-continuous operations Product-this is the description ofthe solid material after it has been Relative humidity-the percentage of water vapor in a gas stream relative to its saturation level. Example: 100% relative humidity is the complete saturation of a carrier gas stream, whereby any further vapor cannot be absorbed by the gas and will condense or precipitate out in the liquid phase. There is an equilibrium between the liquid solid mass and the gas stream( carrier medium). This equilibrium is a result of a combination of saturation capability of the medium at a given temperature. At higher temperatures, the carrier medium has736 Fermentation and Biochemical Engineering Handbook adiabatic operation ofconstant heat input, the temperature may drop or more likely it will maintain a level (pseudo-wet bulb) temperature. Falling rateperiod-this is the period of drying where the instantaneous drying rate is constantly decreasing. Feed material-this is the description ofthe material being dried before it enters the dryer. Final moisture content-the desired product moisture level required after completion of the drying process. Freeflowing-refers to the feed and product characteristics, as in a free flowing powder. This is the state in which the material being dried would not cling to itself, forming large chunks or possibly bridging in a hopper. Free moisture-liquid which is promptly removable due to its availabil￾ity at the interface between the surface of the particles (solids) and the gas stream. Hygroscopic material-solids having an affinity for liquids due to a chemical or physical attraction between the solids and the liquid. Initial moisture content-the average moisture contained in the wet material before the start of the drying process. If given in percent, specification of wet or dry basis is necessary. Plugflow-a term used to describe the breakup of a continuous process into small batch segments. The term may originate from a reactor tube being filled or plugged with small quantities of material using a piston pump. The reactor would process the volume of material in each piston cavity like a small batch, yet when the material is viewed as a large quantity, it appears homogeneous. The term is used in conjunction with semi-continuous operations. Product-this is the description of the solid material after it has been dried. Relative humidi-the percentage of water vapor in a gas stream relative to it’s saturation level. Example: 100% relative humidity is the complete saturation of a camer gas stream, whereby any further vapor cannot be absorbed by the gas and will condense or precipitate out in the liquid phase. There is an equilibrium between the liquid￾solid mass and the gas stream (carrier medium). This equilibrium is a result of a combination of saturation capability of the medium at agiven temperature. At higher temperatures, the camer medium has