Analysis of a nozzle condensation drying cycle

摘要

Of the total energy required for U.S. manufacturing processes, a significant portion is used for industrial drying processes, estimated at 12%. Often these industrial dryers operate without any provisions for heat recovery. This means that almost all the energy consumed by the dryer is essentially thrown away. Without the ability to recover the latent heat of the water vapor in the air, significant reductions in dryer energy usage cannot be made. In an attempt to recover the latent heat of the water vapor, a closed drying cycle is proposed, which uses a nozzle as the means to recover this energy from moist-saturated air. This nozzle condensation drying cycle (NCDC) is composed of the following components: dryer, nozzle, diffuser, air-water separator, heat exchanger and compressor. Analysis of this drying cycle shows that ideally this cycle requires a third of the energy compared with an ideal open cycle heated dryer or a heat pump dehumidification cycle. However, when equipment isentropic efficiencies are included, the energy costs are of the same order as that for the other two non-ideal cycles, but with as much as six times less heat exchange requirements. The cycle can be operated at varying conditions, allowing for a single design to be utilized for various applications. Other than the advantage of lower heat exchanger equipment costs, other advantages are in applications that require drying of hazardous liquids from a product.