scholarly journals Experimental Study of Innovative Indirect Solar Dryers

2021 ◽  
Vol 39 (4) ◽  
pp. 1313-1320
Author(s):  
Tadahmun A. Yassen ◽  
Manar S.M. Al-Jethelah ◽  
Hussam S. Dheyab

The present work experimentally studied two novel solar dryers’ designs, novel indirect solar dryer (NISD) and novel mixed indirect solar dryer (NMISD). The purpose behind this work is to compare the thermal performance of the proposed dryers with that of a traditional indirect solar dryer (TISD). The testing method involved building and thermally testing the three dryers. The NISD is a novel drying chamber with three absorbed surfaces. The NMISD consisted of a flat plate solar collector and NISD. The air temperature at the drying chamber entrance increased by 60% and 68% for the TISD and NMISD, respectively. In the lower space of the drying chamber, the air temperature was decreased by 35% while increased by 39% for the NISD and NMISD, respectively, compared to the TISD. The air temperature in the upper space of the drying chamber increased by 14% and 49% for the NISD and NMISD, respectively, compared to the TISD. The temperature variations through the drying chamber were -26%, 33%, and 3% in the TISD, NISD, and NMISD, respectively. The thermal efficiencies of the NISD and NMISD were 9% and 55%, respectively, higher than the TISD’s.

2017 ◽  
Vol 114 ◽  
pp. 1407-1418 ◽  
Author(s):  
H. Javaniyan Jouybari ◽  
S. Saedodin ◽  
A. Zamzamian ◽  
M. Eshagh Nimvari ◽  
S. Wongwises

2017 ◽  
Author(s):  
Carola Sánchez ◽  
José Macías ◽  
Jonathan León ◽  
Geancarlos Zamora ◽  
Guillermo Soriano

Passive solar water heating (SWH) is a convenient method to meet domestic hot water requirements in rural areas, where electricity may not be available or fuel supply might be limited due to difficult access. In this work, a low-cost thermosiphon flat-plate solar collector alternative is presented. The design was purposely limited to materials and recyclable products widely available in the local market, such as Tetra Pak, plastic bottles, and polypropylene (PP) fittings and pipes. Since PP is a thermoplastic polymer, a poor heat conductor, it was necessary to ensure a suitable system isolation to obtain an optimum thermal performance, comparable to commercial solar collectors. The design was built and tested in Guayaquil, Ecuadorian coastal city. Six inexpensive temperature sensors were placed at the entrance and exit of the collector, on the flat-plate and inside the hot water storage tank. Data was recorded using an Arduino single-board computer and later analyzed with the data gathered via weather station. The implementation costs of the system are approximately US$300, the overall performance during January 2017 fluctuated between 54% and 23%, and the storage tank temperature range varied from to 46°C to 33°C. Due to its reliability and affordable cost, the SWH system is an attractive alternative to an Ecuadorian commercial solar flat plate collector, which price is set between US$600 and US$700, it has an efficiency around 60%, and the average annual storage tank temperature is 62°C.


Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 350 ◽  
Author(s):  
Wengang Hao ◽  
Shuonan Liu ◽  
Baoqi Mi ◽  
Yanhua Lai

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.


Author(s):  
Saeed Moaveni ◽  
Michael C. Watts

During the past few decades, a wide range of studies have been performed to improve the performance of flat plate solar collectors by either reducing the heat loss from a collector or by increasing the amount of solar radiation absorbed by the absorber plate. Examples of these studies include adding transparent honeycomb to fill the air gap between the glazing and absorber plate to reduce convective heat loss, replacing the air in the gap by other gases such as Argon, Krypton, Xenon and Carbon Dioxide, or adding a chemical coating such as Copper Oxide to increase absorbtance and reduce the emittance of the absorber plate. While these methods improve the collector’s efficiency, they focus primarily on limiting the natural convection that occurs in the collector cavity, or on improving the optical properties of the absorber or glazing. None of these studies have addressed the problem of heat loss due to forced convection to the surrounding ambient air in any detail. Yet, research has shown that forced convection will contribute significantly to the heat loss from a collector. Windbreaks have traditionally been used to direct wind to protect farmland, and to direct wind drifts and sand dunes. Windbreaks also have been shown to provide protection for homes from winter winds which result in reduced heating costs for buildings. While windbreaks have been traditionally used for large scale applications, there is reason to believe that similar benefits can be expected for scaled down applications such as adding a windbreak along side of a flat-plate solar collector. In this paper, we examine the feasibility of using a windbreak to provide a flat plate solar collector protection from the wind in order to improve its performance. A series of experiments were performed wherein the thermal performance of two flat-plate collectors — one without a windbreaker and one with a windbreaker — were measured. The results of these experiments are reported in this paper and the need for further studies to explore different windbreak configurations is discussed.


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