Infrared convective drying

Allanic, N., P. Salagnac, and P. Glouannec, 2009a. Optimal constrained control of an infrared-convective drying of a polymer aqueous solution. Chemical Engineering Research and Design, 87(7), 908-914. 

Fernando, W.J.N., H.-C. Low, and A.L. Ahmad, 2011. The effect of infrared on diffusion coefficients and activation energies in convective drying A case study for hanana, cassava and pumpkia Journal of Applied Sciences, 11(21), 3635-3639. 

Kowalski, S.J. and K. Rajewska, 2009. Convective drying enhanced with microwave and infrared radiation. Drying Technology, 27(7), 878-887. 

Thus far, the research work has been primarily aimed at the performance of heat pump dryers for different products. Little work has been reported on the performance of heat pump dryers using external energy sources to compliment it. HPD is primarily a convective drying process. Use of infrared (IR) or radio frequency (RF) sources can be incorporated along with the usual HPD to enhance the drying rates while reducing the thermal load on the heat pump itself. 

The influence of shelf temperature and of sublimation chamber total gas pressure on the drying curve (X(t)) and on the drying rate curve (— ) is discussed below. As observed by many authors during the drying of different types of materials, for example during the convective or infrared reactive drying of thin coating films, the... 

Jain, D., Pathare, P. B., 2004. Selection and evaluation of thin layer drying models for infrared radiative and convective drying of onion slices. Biosystems Eng. 89(3) 289-296. 

Putranto, A., Chen, X. D., Webley P. A., 2010. Infrared and convective drying of thin layer of polyvinyl alcohol. Chem. Eng. Process. 

After its application, the wet coat must be dried. Three different drying principles are used radiation (infrared), convection (hot air), and contact (cylinders). 

The two principal methods of dry-heat sterilization are infrared and convection hot air. Infrared rays will sterilize only surfaces. Sterilization of interior portions must rely on conduction. Convection hot-air sterilizers are normally heated electrically and are of two types gravity or mechanical. In gravity convection units, a fan is used to promote uniformity of heat distribution throughout the chamber. 

Drying may be carried out by direct gas heating, infrared, electric elements with forced air convection, hot air or live steam. 

Water on the plate surface is removed with the sponge rolls for removal of water, and the surface is dried with 90-100°C convectional air, and then further dried with 90-100°C far-infrared heater. 

Dry heat is used to sterihze and depyrogenate components and drug products. The definition of dry heat sterilization is 170 °C for at least 2 hours and a depyrogenation cycle at 250 °C for more than 30 minutes. Typical equipment includes tunnel sterilizers (force convection, infrared, fiame) and microwave sterilizers. An important aspect is the need to ensure air supply is filtered through HEPA filters. Biological indicators such as Bacillus subtilis can be used to gauge the performance of sterilization. 

Following the application of paint, the item is passed through a drying or curing oven. The methods employed include convection, infrared or ultraviolet heating or combinations thereof. The particular methods depend on the types of paints being used, economics, and production requirements. Once dried, the items are sent for inspection and final packaging or assembly. 

The coated foil is then processed to the next step, the drying compartment. The drying compartment essentially consists of a convection heater with two small slits for the traversing of the foil. The surface temperature of the foil is measured by an infrared detector. Temperature control is crudal in this process step, as the aqueous slurry must not be allowed to boil, which would deteriorate the coat evenness. During drying, the coat thickness shrinks (depending on the water content of the... 

Another area of research that could be profitably explored is the use of remote sensing instruments to measure surface temperatures of textile assemblies. Infrared thermovision cameras have been used to visualize temperature distributions over clothed and nude persons in order to study the transport of microorganisms by convective heat flow (112). A variety of less expensive radiometers and radiation pyrometers that are used to measure and automatically control the temperature of textiles during drying and texturing (113, llU, 115) could also assess the thermal behavior of apparel and clothing assemblies and thus elucidate their contribution to thermal comfort indoors. 

All wet coated components must be dried before stoving. This is earned out with infrared radiation or in air convection driers. 

Recent sterilizer developments have led to the use of dry heat sterilizing tunnels where heat transfer is achieved by infrared irradiation or by forced convection in filtered laminar airflow tunnels. Items to be sterilized are placed on a conveyer belt and pass through a high temperature zone (250-300+ °C) over a period of several minutes. 

Stenters (Tenters) and Textile Dryers These are the basic type of dryer used for sheets or webs in the textile industry. The sheet is held by its edges by clips (clip stenter) or pins (pin stenter), which not only suspend the sheet but also keep it taut and regulate its width—a vit consideration in textile drying. Drying is by convection hot air is introduced from one or both sides, passes over the surface of the sheet, and permeates through it. Infrared panels may also be used to supply additional heat. A schematic diagram of the unit is shown in Fig. 12-88. A typical unit is 1.4 m wide and handles 2 to 4 t/h of material. 

It is clear that the MAPE, MAD, MSD values of this model were changed between 0.34-4.8, 0.22-1.63 and 0.08-33.22 respectively. As it can be seen for pine samples the convection method has a better fitness to the model and for spruce infrared drying model fitted the experimental data properly. 

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