Models and experiments for energy consumption and quality of green tea drying

Nickson Langat,Thomas Thoruwa,Jeremiah Kiplagat,Brian Plourde,John Abraham,John Wanyoko

doi:10.1002/ese3.49

Abstract

AbstractAn experimental apparatus has been developed to evaluate the drying process of green tea leaves. Tea drying is an energy‐intensive process which results in the removal of leaf moisture; it is essential to the quality of the final product. In order to more efficiently use process energy, a prototype drying system has been built and tested. The prototype incorporates a rotating perforated drum which helps speed the drying process. Experiments were carried out with multiple temperatures, airflow rates, and drum rotation rates; a subset of those results is shown here. In particular, the impact of airflow rate on the process was studied. It was found that as the airflow increased, the drying rate increased, as expected. However, the efficiency of energy use, which was quantified by the Specific Energy Consumption rate, varied considerably with flow. While higher flows led to faster drying, it resulted in a lower energy efficiency. Also, a two parameter predictive model was developed that was able to accurately match the moisture removal rates for a very wide range of flows. This predictive model, which is based on thermal‐fluid fundamentals, can be used to extrapolate the presented results to cases which were not considered.

Highlights

Tea is the most commonly consumed nonwater beverage in the world
The goal of this study is the implementation of Fluidized bed drying (FBD) for green tea drying and the quantification of energy use during the drying stage
A set of experiments have been performed to assess the performance of a prototype rotating tea drying system

Summary

Introduction

Tea is the most commonly consumed nonwater beverage in the world. It is consumed throughout virtually in all regions and has experienced recent significant growth rates in its consumption [1]. Two-third of the world’s tea is categorized as black tea with the remainder mainly comprising green teas with small amounts of others such as oolong, jasmine, and Pu-erh teas constituting the balance. The volumes of tea produced in various parts of the world are large. Worldwide ~4.1 million metric tons (4.1 9 109 kg) are produced with nearly 650,000 tons (6.5 9 108 kg) produced in the continent of Africa. With respect to green teas, the corresponding numbers are ~1 million metric tons (1 9 109 kg) globally

Objectives

Conclusion