464 Summaries of other CHISA papers

important interdependent processes including raw material treatment, granulation, milling and refinement to be performed simultaneously.

Those are complex drying procedures developed at the Heat and Mass Transfer Institute, BSSR Academy of Sciences certified as USSR A.C. No. 350513, BI 28, 1972; A.C. No. 733728, BI 18, 1980; A.C. No. 958813, BI 34, 1982; A.C. No. 958814, BI 34, 1982. They involve combined hydrodynamics of falling fluidised bed drying and convection-radiation heat supply the latter implying several operations (mixing, granulation and drying) in one apparatus.

Based on the suggested procedures, pilot and then commercial installations have been designed which are now in mass production, A.C. No. 5785348, BI No. 40, 1977, USSR.

It is shown that the apparatus of continuous operation of the Heat and Mass Transfer Institute systems are superior in their technological and economical factors to the dryers applied in the field.

The theoretical and experimental results enable one to conclude on the reliable and promising application of the complex continuous-operation and dryers of the Heat and Mass Transfer Institute system not only in medical but also in chemical, food and other industries.

THE SURVEY OF THE PROCESS AND CONNECTION ARRANGEMENT FOR THE SOLVENT RECOVERY

R. T6R6S, E. VASANrrS-VERGA and T. VIRAG Res. Inst. Techn. Chem., Hung. Acad. Sci., Budapest, Hungary

For the recovery of solvent vapours being released during drying of materials containing solvent the condensation in a closed cycle has been studied.

The drying has been performed in a spouted-bed drier, where the drying medium emerging from the dryer is recirculated into the dryer by a closed cycle after the condensation of its solvent vapour. For the realisation of the condensation and for the heating of the drying medium again to the necessary drying temperature of a heat pump with a compressor (0.9 kW power consumption) has been constructed (also in the research institute for Technical Chemistry of Hungarian Academy of Sciences) and built in the closed cycle of the drying medium.

The developed process and connection arrangement for the recovery of the solvent content and also the heat of condensation of the drying medium is given in detail.

The process taking place in the connected system of spouted-bed dryer and heat pump can be clearly followed on the presented l - x diagram. For the model substances like carbon tetrachioride and ethanol solvents and nitrogen inert gas in the closed cycle have been used. The efficiency of the solvent recovery has been about 70-95%. This shows the economical application of the heat pump for the solvent recovery. The operation in a closed cycle has an environmental advantage, too, because no solvent is emitted into the atmosphere.

SPRAY COOLING OF HOT SURFACES

K. BAUCKHAGE

Univ. Bremen, Bremen, FRG

Spray cooling by water droplets plays an important role in the steel and metal-works industries. The heat flux density at a hot surface can be strongly influenced by the mass velocity of the atomised water, especially at high surface temperature (above the burnout point).

Measurements of the local heat transfer coefficients give a true picture of local water-mass- velocities beyond the spray nozzle, if the size- and velocity-distributions of the droplets are in agreement with the required impulse for destroying

(a) the vapour film of the film boiling regime and (b) the sublayer of vapour between droplets and hot surface.

Experimental results will be exposed and the consequences for spray cooling will be discussed.