Thermal performance enhancement of solar air collector using a novel V-groove absorber plate with pin-fins for drying agricultural products: an experimental study

2019 ◽  
Vol 140 (5) ◽  
pp. 2397-2408 ◽  
Author(s):  
P. Sudhakar ◽  
M. Cheralathan
2019 ◽  
Vol 29 (8) ◽  
pp. 2545-2565
Author(s):  
Safeer Hussain ◽  
Jian Liu ◽  
Lei Wang ◽  
Bengt Ake Sunden

Purpose The purpose of this paper is to enhance the heat transfer and thermal performance in the trailing edge region of the vane with vortex generators (VGs). Design/methodology/approach This numerical study presents the enhancement of thermal performance in the trailing part of a gas turbine blade. In the trailing part, generally, pin fins are used either in staggered or in-line arrangements to enhance the heat transfer. In this study, based on the idea from heat exchangers, pin fins are combined with VGs. A pair of VGs is embedded in the boundary layer upstream of each pin fin in the first row of the pin fin array having an in-line configuration. The effects of the VG angle relative to the streamwise direction and streamwise distance between the pin fin and VGs are investigated at various Reynolds numbers. Findings The results indicated that the endwall heat transfer is enhanced with the addition of VGs and the heat transfer from the surfaces of the pin fins. The level of heat transfer enhancement compared to the case without VGs is more significant at high Reynolds number. The surfaces of the VGs also show a significant amount of heat transfer. Study of the angle of the attack suggested that a high angle of attack is more appropriate for pin fin cooling enhancement whereas an intermediate gap between the VGs and pin fins shows considerable improvement of thermal performance compared to the small and large gaps. The phenomenon of heat transfer augmentation with the VGs is demonstrated by the flow field. It shows that the enhancement of heat transfer is governed by the mixing of the flow as a result of the interaction of vortices generated by the VGs and pin fins. Originality/value VGs are used to disturb the thermal boundary layer. It shows that heat transfer is augmented as a result of the interaction of vortices associated with VGs and pin fins.


Author(s):  
Akhilesh Gupta ◽  
Ravi Kumar ◽  
Bharat Ramani

Solar collector is a type of heat exchanger which transfers solar radiation energy into the heat energy. Conventional solar air collectors have poor thermal efficiency primarily due to high heat losses and low convective heat transfer coefficient between the absorber plate and flowing air stream, leading to higher absorber plate temperature and greater thermal losses. Attempts have been made to improve the thermal performance of conventional solar air collectors by employing various design and flow arrangements. Double pass counter flow solar air collector with porous material in the second air passage is one of the important and effective design improvement that has been proposed to improve the thermal performance. This paper presents the performance and economic analysis of double pass solar air collector with and without porous material. Effects of various parameters on the thermal performance and pressure drop characteristics have been studied experimentally. The study concludes that double pass arrangement with porous material is economical and having short payback period. Also, the thermal performance of double pass solar air collector with porous material is significantly higher compared to double pass solar air collector without porous material and single pass arrangement.


2020 ◽  
pp. 98-117
Author(s):  
Mohammed Fahmi ◽  
Wissam Khalil ◽  
Amer Shareef

In this research, an experimental study has been performed in order to enhance the thermal performance of a double-pass solar air collector by employing extended surfaces. In order to increase the heat transfer area, triangular-shaped fins were mounted on the longitudinal direction of the absorber plate. Four models of the solar air collectors were made of aluminum with different fin configurations. The experiments were carried out at the winter season in the climate of Iraq - Ramadi city with longitude 43.268 and latitude (33.43). The used range of mass flow rate in the experiments was from 0.027 kg/s to 0.037 kg/s. The comparison with previous studies in terms of thermal efficiency showed good agreement where the percentage of error does not exceed 1% between them. The results also provided that the existing of fins was a good technique for enhancing the thermal performance of double-pass solar air collector with a marginal increase in pressure drop. Consequently, it is possible to adopt this kind of solar air collectors for many agricultural applications such as solar dryer.


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