A review on different techniques used for performance enhancement of double pass solar air heaters

Ravi, Ravi Kant; Saini, R.P.

doi:10.1016/j.rser.2015.12.004

Cited by 64 publications

(13 citation statements)

References 50 publications

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“…The roughness geometry was shown to increase both frictional losses and the system's heat removal rate. A double-pass SAH with single glass was suggested for drying applications in a study by the same authors [14]. El-Sebaii and Shalaby [15] built an indirect dual-pass v-corrugated plate SAH for drying thymus and mint leaves.…”

Section: Introductionmentioning

confidence: 99%

Thermal Performance Study of Solar Air Dryers for Cashew Kernel: A Comparative Analysis and Modelling Using Response Surface Methodology (RSM) and Artificial Neural Network (ANN)

Huddar

Kaladgi

Cüce

et al. 2022

International Journal of Photoenergy

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In this study, a new procedure for drying of cashew kernels is proposed. The new methodology involves the use of solar air dryers to remove the dark sticky coating called testa on the surface of the cashew kernel to get the final product. There are several challenges in the new procedures, especially with respect to the moisture level to be retained in the cashew kernel post drying for facilitating the optimal peeling activity. In this regard, thermal performance is carried out through a set of experimental and computational trials. The experiments have revealed that the natural and forced convection solar dryers with drying speeds of 1.0 kg/h and 1.66 kg/h, respectively, showed drying efficiencies of 51.7% and 50.9%, which is within the permissible acceptable limit, thus ascertaining a moisture reduction of 40 to 42% in each of case and keeping the moisture content within the band of approximately 5%, required for effective peeling of the testa from the cashew kernel to obtain the final product. This new method has resulted in batch drying of cashew kernels of up to 30 kg capacity in a time span of 360 minutes of solar irradiation with an average consumption of 255 kJ. The results of the experiments are also validated from the artificial neural network (ANN) and response surface methodology (RSM) modelling, resulting in better prediction and optimization of the performance parameters. The error between the actual and experimental values is well within the permissible limit of +/-5%, thereby correlating the experimental and statistical values for deriving an ANN model for predicting the results for different time duration and solar irradiation. In this way, the thermal analysis of the solar dryers for drying cashew kernels has resulted in findings, which shall be utilized to improve the overall performance efficiency and the methodology adopted for maximum yield.

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Section: Introductionmentioning

confidence: 99%

Thermal Performance Study of Solar Air Dryers for Cashew Kernel: A Comparative Analysis and Modelling Using Response Surface Methodology (RSM) and Artificial Neural Network (ANN)

Huddar

Kaladgi

Cüce

et al. 2022

International Journal of Photoenergy

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“…To improve the efficiency of solar energy, there are extensive studies and efforts have focused on improving the heat efficiency and optimizing the structure of solar air collectors [12][13][14][15]. A more effective approach is to maximize the contact between the circulating air and the absorber plate through forced turbulence in double channel, including V-corrugated or sine-wave absorber plates, with fins, baffles or ribs [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Thermal Characteristics and Parametric Analysis of an Improved Solar Wall

Zhao

Zhu

et al. 2021

Applied Sciences

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Solar air collectors installed on buildings can significantly reduce conventional energy consumption in winter and summer. However, some problems arise in the utilization process, such as overheating, inconvenient operation control and low energy efficiency, etc. This work is a parametric analysis focusing on the automatic control and thermal efficiency improvement of the solar wall. An improved color-changing solar wall integrated with automatic control components, such as a photoelectric fan and temperature-controlled damper, was proposed in this paper. Based on the experimental data, the average daily heat output of the color-changing solar wall is 1.08 MJ per unit floor area on clear days in winter and the average thermal efficiency is 56.8%. Meanwhile, a quantitative analysis was carried out based on monitoring experiments for evaluating the thermal characteristic of automatic control components. Furthermore, in order to improve the thermal performance of the solar wall, parametric analysis was performed by numerical simulation. Results from this paper can provide a theoretical basis for the application of solar air collectors in modern buildings.

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“…Turbulence promoters have the potential to overcome these two restrictions, and should be realized by demolishing the laminar sub-layer to create effective momentum exchange and enlarging the heat transfer area to increase the thermal performance. Configurations of design principles attain augmented heat transfer characteristics [13,14] by using different techniques to obtain a higher turbulent intensity, as documented extensively in the literature, such as an extended heat-transfer area using v-grove flow channels [15], various fin shapes [16], thin ribs [17] and baffles [18], and the destroyed laminar sub-layer using flow turbulence with vortex generators [19,20], surface roughening on the absorber plate [21], packing wire mesh [22] and porous medium materials [23], and recycling operations [24].…”

Section: Introductionmentioning

confidence: 99%

Optimizing Thermal Efficiencies of Double-Pass Cross-Corrugated Solar Air Heaters on Various Configurations with External Recycling

Chang

Hsiao

et al. 2021

Energies

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The effect of external-recycle operations on the thermal performance of double-pass cross-corrugated solar air heaters (SAH) under different operating conditions was investigated experimentally and theoretically. Additionally, the simultaneous ordinary equations were solved analytically for each proposed configuration. Four recycling types are introduced for improving the solar thermal performance with different external recycle processes, which are expected to enhance the heat transfer coefficient with a convective turbulent flow between the air and the absorber in the present study. Using recycling double-pass operations, two processes were conducted sequentially: air first flowed over the sinusoidal corrugated absorber plate and then flowed back later over the transverse sinusoidal corrugated bottom plate. Improved device performance was achieved due to the doubled heat transfer area over and under the corrugated absorber plate, from which both the sinusoidal cross-corrugated absorber plate and bottom plate enhanced turbulent intensity. Theoretical predictions and experimental results both indicated that the recycle ratio increased with the SAH thermal efficiency for all proposed designs. The results show a higher heat transfer efficiency for the proposed four configurations using wavelike corrugated plates compared to those conducted in single-pass and flat-plate absorber plates with up to a maximum 133% (from 0.301 to 0.703) increment. The optimal device performance was examined for all external-recycle configurations under the same working dimensions and operational conditions. The best configuration for optimal thermal performance was the device that lengthened the air flow pathway and increased the air velocity within the collector; thus, a higher heat transfer rate was accomplished. The evaluation of increments in the power consumption and of the heat-transfer efficiency enhancement together determined the optimal design based on an economic consideration across various configurations of cross-corrugated double-pass devices.

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A review on different techniques used for performance enhancement of double pass solar air heaters

Cited by 64 publications

References 50 publications

Thermal Performance Study of Solar Air Dryers for Cashew Kernel: A Comparative Analysis and Modelling Using Response Surface Methodology (RSM) and Artificial Neural Network (ANN)

Thermal Performance Study of Solar Air Dryers for Cashew Kernel: A Comparative Analysis and Modelling Using Response Surface Methodology (RSM) and Artificial Neural Network (ANN)

Thermal Characteristics and Parametric Analysis of an Improved Solar Wall

Optimizing Thermal Efficiencies of Double-Pass Cross-Corrugated Solar Air Heaters on Various Configurations with External Recycling

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