COFFEE DRYER WITH DEHYDRATED AIR: A TECHNICAL AND ECONOMIC VIABILITY ANALYSIS

ABSTRACT The defects that drying in concrete yards impose on coffee beans and the search for gourmet coffee production have prompted the emergence of new drying technologies. This work verified the technical and economic feasibility of drying coffee with dehumidified air with a refrigerating capacity of 422,908.7 J s-1, compatible with static capacity dryers equal to 75 m3. Considering the sale price of coffee, the cost of electric energy acquisition, the monthly interest rate and maintenance time, expenses that are equivalent to the depreciation of the concrete yard, a central compound rotational design was considered with 28 tests for the feasibility analysis, including the internal rate of return, net present value and the return on investment. The results showed that in the electric drying units, the dried coffee presents fewer broken and defective beans and has higher retention in a No. 17 sieve. With a higher beverage quality and a price 12.11% higher, drying with dehydrated air showed a PBD of 2.27 years and a return of US$ 2.49 million. The optimisation results were 98.98% desirable. It was concluded that it is economically feasible to dry coffee with dehydrated air and without using a concrete yard.

摘要 混凝土堆场干燥工艺对咖啡豆造成的品质缺陷，以及精品咖啡生产的需求，推动了新型咖啡豆干燥技术的涌现。本研究验证了采用制冷量为422908.7 J·s⁻¹的除湿空气开展咖啡豆干燥的技术与经济可行性，该系统适配容积为75 m³的静态容量干燥机。研究综合考量咖啡豆售价、电能采购成本、月利率与维护时长（等效于混凝土堆场的折旧成本），采用包含28组试验的中心复合旋转设计开展可行性分析，分析指标包括内部收益率、净现值与投资回报率。结果表明，电力干燥单元制备的咖啡豆破损豆与缺陷豆占比更低，17号筛网留存率更高。采用除湿空气干燥的咖啡豆饮品品质更优，售价可提升12.11%，其投资回收期（Payback Period, PBD）为2.27年，总收益达249万美元。优化结果的合意度为98.98%。综上，采用除湿空气干燥且无需使用混凝土堆场的咖啡豆干燥方案具备经济可行性。