Mathematical Modeling and Performance Analysis of a New Hybrid Solar Dryer of Lemon Slices for Controlling Drying Temperature

Wengang Hao,Baoqi Mi,Yanhua Lai,Shuonan Liu

doi:10.3390/en13020350

Abstract

A new hybrid solar dryer was designed and constructed in this study, which consisted of a flat-plate solar collector with dual-function (DF-FPSC), drying chamber with glass, fan etc. The DF-FPSC was firstly applied in drying agricultural products. The innovative application of hybrid solar dryer can control the drying chamber air temperature within a suitable range by different operation strategies. Drying experiments for lemon slices in the hybrid solar dryer were conducted by comparing open sun drying (OSD). Eight mathematical models of drying characteristics were employed to select the most suitable model for describing the drying curves of lemon slices. Furthermore, energy, exergy economic and environment (4E) analysis were also adopted to analyze the drying process of lemon slices. The results show that under the same experimental condition, the drying capability of the hybrid solar dryer was stronger than that of OSD. Meanwhile, it was found that the Two term and Wang and Singh models were the most suitable for fitting the lemon slices’ drying characteristics inside the hybrid solar dryer. The drying chamber air temperature can be controlled under about 60 °C during the process of lemon slices’ drying. The experimental results show the feasibility and validity of the proposed hybrid solar dryer.

Highlights

Due to the energy crisis and environmental pollution issues, many governments are working on developing green energy to alleviate these problems
The solar radiation intensity increased gradually to the maximum value and decreased equal during tothe theperiod experiments set value. These results show that the operation parameters can meet design of the drying experiment
The maximum temperature of drying chamber was almost equal to the experiments set value. These results show that the operation parameters can meet design requirement in terms of controlling the drying temperature of the drying chamber

Summary

Introduction

Due to the energy crisis and environmental pollution issues, many governments are working on developing green energy to alleviate these problems. Hot air convection drying using a traditional energy source is not a sustainable way of drying due to environmental pollution, high investment and operating costs [2]. Solar drying has the advantages of being a renewable, free, and abundant energy source, the low-temperature utilization of solar energy just matches the suitable material drying temperature [3]. The practical application of solar drying generally needs to be supplemented by other forms of energy due to the influence of solar energy instability, periodic change, low heat collection efficiency, and so on [4,5,6]. Numerous research works concerning solar drying have been conducted over the past few decades

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