The total amount of heat produced in the spray drying process is given by QU=Q1+Q2

The total amount of heat produced in the spray drying process is given by QU=Q1+Q2. Q1 is the heat for water evaporation and Q1 = mha*h1a where mha is the required amount of hot (inlet) air and h1a is the enthalpy of inlet air. Q2 is the outlet air heat content and Q2 = mha *(h2a – h3a) where h2a is enthalpy of outlet air and h3a is the enthalpy of ambient air. It can be concluded that there is a transfer of heat during the spray drying process. This relates back to the Fourier’s Law and heat transfer. Spray drying, however, is a convective process. This means that heat is transferred through the bulk movement of molecules within fluids such as gases and liquids. This makes sense since the spray drying process uses liquid feed and drying gas to produce dry particles. When the dry particles are formed, there is heat transfer via convection.
Due to its rapid, continuous, and reproducible abilities, the spray drying technique is very appealing for the laboratory and in the industry. This technique is scalable without making any major modifications. In addition, the final drying step is required in other techniques such as emulsion/solvent evaporation is not needed for spray drying. The technique greatly depends on the fulfillment of two conditions: scalability and cost-effectiveness. Another advantage spray drying has is the possibility to dry a large spectrum of compounds without any major detrimental effects. Heat sensitive substances are included in the spectrum. This is due to the atomization of the liquid which forms into small droplets with high surface area to volume ratio and therefore, leads to a very fast solvent evaporation. An example of this is in a co-current flow setup, the product temperature is 10 to 20 °C below the air outlet temperature.

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