Infrared heat-pump drying

Deng, Y., Y. Liu, B. Qian, S. Su, J. Wu, X. Song, and H. Yang, 2011b. Impact of far-infrared radiation-assisted heat pump drying on chemical compositions and physical properties of squid (Hlex illecebrosus) fillets. European Food Research and Technology, 232(5), 761-768. 

Deng, Y, J. Wu, S. Su, Z. Liu, L. Ren, and Y. Zhang, 201 la. Effect of far-infrared assisted heat pump drying on water status and moisture sorption isotherm of squid (Illex illecebrosus) fillets. Drying Technology, 29(13), 1580-1586. 

The method is essentially the same as that described in synthesis A. The quantities of bis(trimethylsilyl)amine (0.10 mole) and butyllithium (0.093 mole) are again used, but the solvent is 100 mL of dry benzene (sodium-dried and distilled from calcium hydride). The addition of the anhydrous FeCls (9.8 g, 0.06 mole) leads to a slight warming of the reaction mixture. After 24 hours of stirring at room temperature, by which time the solution has assumed a dark-green coloration, the contents are briefly heated to reflux with an infrared lamp and the mixture is filtered. Concentration of the filtrate produces a mass of dark-green needle crystals, which are filtered, washed with a small amount of cold benzene, pumped dry, and sealed into ampules under vacuum. The yield of tris-[bis(trimethylsilyl)amido]iron(III) is about 10 g (62%). Satisfactory analyses have not been obtained due to this compound s high reactivity to air and moisture. 

An infrared-augmented heat pump dryer (HPD) can be used for faster removal of surface moisture during the initial stages of drying, followed by intermittent drying over the rest of the drying process. Therefore, an IR-assisted HPD offers the advantage of compactness, simplicity, ease of control, and low equipment cost when both surface and internal moisture are present (Mujumdar 2000). 

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. 

After this period, the dropping funnel and the vacuum takeoff are replaced by the short-path distillation assembly shown in Figure 2. The system is protected by a Drierite tube and the benzene is distilled under reduced pressure (water aspirator). After the benzene is removed, the benzene-containing receiver is replaced with a clean, dry flask, and the system is connected to an eflScient vacuum pump. The pressure in the system is reduced to 0.02 mm., and the flask is immersed deeply in an oil bath (Figure 2) heated to about 200°. After about 1 ml. of fluid forerun is collected, the diethylaluminum cyanide distils at 162° (0.02 mm.) (Note 7) and is collected in a tared 200-ml. receiver by heating the side arm and the adaptor with a stream of hot air or an infrared lamp (Note 8). After all the distillate is collected in the receiver (Note 9), dry nitrogen is admitted to the evacuated apparatus and the receiver is stoppered and weighed. Diethylaluminum cyanide is obtained usually as a pale yellow syrup (Note 10) in 60-80% yield (26.7-35.6 g.) (Note 11). 

Rapid boiling causes cooling, which tends to decrease the rate of boiling to the point where bumping can be very bad. The external application of sufficient heat by means of an infrared lamp is very effective in overcoming the trouble and in maintaining steady ebulhtion. About one-half of the volume of the liquid in the reaction tube is slowly pumped away in order to remove dissolved phosgene and chlorine. All of the liquid is not pumped away, as otherwise solid chlorocarbons will deposit. The tube is removed to an efficient dry-box, opened, and the product filtered and washed with carbon tetrachloride. None of the chlorides reported appear to be appreciably soluble in carbon tetrachloride. ... 

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