o l . 7, i 2, ma y - o 2017 issn : 2249-5762 (online ... · ijrmet vo l. 7, is s u e 2, ma y - oc t...

IJRMET Vol. 7, IssuE 2, May - ocT 2017 ISSN : 2249-5762 (Online) | ISSN : 2249-5770 (Print)

w w w . i j r m e t . c o m 38 INterNatIONal JOurNal Of reSearch IN MechaNIcal eNgINeerINg & techNOlOgy

A Review on the Performance of Solar Air Heater By Using Different Heat Transfer Enhancement Techniques

1M.Sivaganesh, 2A.Anandaraman, 3Dr. R.Rathnasamy, 4Dr.R.Karthikeyan1,2,3,4Dept. of Mechanical Engineering, Annamalai University, Chidambaram, Tamil Nadu, India

AbstractEnergy from sun can be categorized into two ways in the form of heat and light. We use the solar energy every day in many different ways. There is a variety of products that uses solar energy. These products are called solar thermal collectors. Solar thermal technologies uses the solar heat energy to heat water or air for applications such as space heating, pool heating and water heating for homes and business. Solar air heaters are one of the most promising solar energy applications. It collects solar energy and transfer the heat to passing air which is either stored or used for space heating. It is act as heat exchanger. In the conventional solar air heater, the boundary layer separation is occurred due to the presence of sub laminar layer on the flat plate collector. This leads to poor thermal performance of solar air heater. In order to eliminate or break sub laminar layer, heat transfer enhancement techniques should be manipulated. In this present work, the main aim is to be study the different heat transfer enhancement techniques that are carried out by investigators on solar air heater to improve the thermal efficiency.

KeywordsSolar Energy, Boundary Layer Separation, Sub Laminar Layer, Thermal Performance, Thermal Efficiency.

I. IntroductionSun generates energy at the rate of 3.8 X 1023 KW, earth receives only a small part of it, but that is also considerable. Earth receives 1.7 X 1014 KW or 5.3 X 1024 J/year of solar energy and 8.4 X 1023 J/year reaches the surface of earth. Current world consumption of energy is 4.0 X 1020J/year from all sources. All chemical and radioactive polluting byproducts of the thermonuclear reactions remain behind on the sun, while only pure radiant energy reaches the earth. Energy reaching the earth is incredible. By one calculation, 30 days of sunshine striking the earths have the energy equivalent of total of the entire planet fossil fuels, both used and unused. The key features of solar energy are, it is most promising renewable source of energy, inexhaustible source of energy, potential to meet a significant portion of nations future energy need because of its quantitative abundances and it is a clean & environment friendly sources for energy. The solar energy is widely used in heating of air for residential application, industrial applications and pool heating etc., The conventional solar air heater have been found poor thermal performance. This is due to viscous sub laminar layer formed on smooth plate. It causes the boundary layer separation. So the heat transfer from the absorber plate to air become low & achieves poor thermal efficiency. The lots of researchers have tried to improve the thermal efficiency with the help of heat transfer augmentation techniques.

II. Heat Transfer Improvement Techniques for Solar Air HeaterHeat is the form of energy. It is transferred by conduction, convection and radiation modes. The air is the poor conductor of heat. In solar air collector, air absorbs the heat from the

collector is not satisfy our desired temperature. In order to improve the heat transfer rate from absorber surface to air, some techniques are followed.The Performance of a flat plate solar air collector has been found to depend strongly on the rate of incident solar radiations, the losses from the absorber surfaces and the rate of heat transfer from absorber plate to the air. There are some enhancement techniques are developed. These techniques help to improve the heat transfer performance of the solar air heater. The following are some performance enhancement techniques for solar air heater.

Fig. 1: Heat Transfer Improvement Techniques

III. Effect of Parameters on Performance

A. System ParametersNumber of glass cover1. Glass cover emissivity2. Selectivity of absorber plate3. Plate spacing4. Collector tilt5.

B. Operation ParametersInlet fluid temperature1. Mass flow rate2.

C. Meteorological ParametersIncident solar radiation1. Ambient temperature2. Wind velocity3. Dust on the top glass cover4.

IV. Literature ReviewClara Dhanemozhi A. and Umarani R (2013) (7) had investigated on solar air heater experimentally by using different absorber plate material like glass, polythene and aluminium. It was observed that, solar air heater was constructed with aluminum sheet and of thickness 40mm and area of 0.75m X 0.50m and glass of thickness 5mm and polythene sheet of thickness 0.5mm. The angle of solar air heater was fitted at 20o latitude. All the experiments were conducted in sunny days during the period of 10:00am to 3:00pm.

IJRMET Vol. 7, IssuE 2, May - ocT 2017

w w w . i j r m e t . c o m INterNatIONal JOurNal Of reSearch IN MechaNIcal eNgINeerINg & techNOlOgy 39

ISSN : 2249-5762 (Online) | ISSN : 2249-5770 (Print)

The maximum solar radiation recorded was around 600W/m2. The temperature difference is one of the major factors to determine thermal efficiency. After evaluation, the efficiency of various material based solar air heaters was compared. The result of investigation reveals that glass as absorbing material has higher efficiency of 70-90% efficiency.

Fig. 2: Two Pass Air Heater With Drying Chamber

Fig. 3: Variation Between Time and Efficiency

Mokalla Srinivas and Simon Jayraj (2013) (8) were carried out performance study on hybrid type solar air heater. It was observed that, the absorber plate was designed by slats on bottom side and PV cells on upper side. The different mass flow rate of air was subjected to hybrid solar air heater like 0.005kg/s, 0.007kg/s, 0.01kg/s, 0.0112kg/s and 0.0123kg/s. The maximum thermal efficiency achieved at around 28% with corresponding mass flow rate of 0.0123kg/s and at the same point electrical efficiency was found at around 18%.

Fig. 4: Double Pass Hybrid Solar Air Heater

Fig. 5: Variation Between Mass Flow Rate Vs Efficiency

Anand Patel et al., (2015) (2) had conducted the performance test on the spiral type solar air heater. It was observed that copper tube shaped solar absorber was used in this investigation. This setup was subjected to three different flow velocity like 0.7m/s, 1.8m/s and 2.3 m/s. The thermal efficiency improved at low velocity only while compared with other two velocity. The temperature was increased at around 5.66oC to 7.66oC in low velocity while compared with other.

Fig. 6: Spiral Solar Air Heater

Fig. 7: Variation Between Time and Temperature Chandra Bhushan and S.N.Singh (6) had investigated the thermal performance of the double pass solar air heater experimentally in manner. It was observed that, this investigation was carried out at constant mass flow rate and velocity. The double pass conventional solar air heater gives the efficiency at about min. 23% to max. 58% which is very high compared with single pass solar heater.

Fig. 8: Double Pass Solar Air Heater



Fig. 9: Variation Between Time and Thermal Efficiency

P.Mohamed Shameer and P.Mohamed Nishanth (2013) (9) had investigated experimentally on double pass solar air heater integrated with thermal storage. It was observed that, Aluminium plate was used as the absorber plate and paraffin wax acted as a thermal storage element. The paraffin wax filled tube was fitted on the upper side of the absorber plate. The air entry was below the absorber and exit was above the absorber. The air flow maintained at constant 4.7m/s. The efficiency range was obtained from 30% to 75%.

Fig. 10: Fabricated and Assembled Solar Air Heater Integrated With Thermal Storage


Dr. Bhupendra Gupta et al., (2013) (5)had analysed the thermal performance of solar air heater with and without porous media

under single and double pass flow condition. It was observed that double pass flow condition increases the efficiency by 3-4% than single pass in without porous media. With porous media, glass wool act as porous element of absorber. Under this, the double pass flow condition increases 5% efficient than single pass.

Fig. 12: Porous Media Based Single and Double Pass Solar Air Heater

Fig. 13: Variation Between Mass Flow Rate and Efficiency

D. Bhandari and Dr. S.Singh (2015) (4) had conducted performance analysis on flat plate solar air collectors with and without fins. From the analysis of conventional solar air heater, double glazing single and double pass finned solar air heater, it was concluded that for the same mass flow rate, double pass finned solar air heater shown highest efficiency.

Fig. 14: Double Pass Finned Solar Air Heater




Veena pal et al., (2015) (12) had conducted performance test on solar air heater. It was observed that, daily energy efficiency of solar air heater was increased with increasing mass flow rate of air. Maximum energy efficiency of 56% was obtained at mass flow rate of 0.042kg/s. Energy efficiency increases from 1.21 % to 1.67% for increasing the mass flow rate from 0.036kg/s to 0.042kg/s.

Fig 15: Conventional Solar Air Heater Setup

Fig. 16: Variation Between Time and Energy Efficiency

Nikhil N.Kharbade and R.S. Shelke (2016) (10) had conducted methods of performance of solar air heater using different artificial roughness. It was observed that artificial roughness provided on the absorber plate for turbulency formation on the roughned surfaces. The benefit is

With artificial roughness, thermal performance of absorber • plate increases with minimum friction factor.All passive techniques used to improve thermal performance • of solar air heater have better result 2 to 4 times that of smooth surface (convection type of system)In general nusselt number increases with increase of Reynolds • number. The value of nusselt number substantially higher as compared to smooth absorber plate

The different roughness geometry are as follows:

Fig. 17: Multi ARC Shape RIB

Fig. 18. Delta Shaped Obstacles

Fig. 19: Transverse RIB Grooved

Fig. 20: Metal Grit

Fig. 21: Chamfered RIB

Fig. 22: Wire Rib

Fig. 23: Dimple Shape Roughness



Fig. 24: Inclined and Transverse Rib

Fig. 25: V Rib M.A Amraoui and K. Aliane (2015) (1) had conducted numerical study on three dimensional flow in a flat plate solar collector with baffles. It was observed that, the baffles are placed in the air channel situated between insulator and absorber have the particularity of extending the trajectory of the circulation to keep caloporting air constantly in contact with the absorber and finally to play the role of wings and improving the heat transfer from the absorber to caloporting air.

Fig. 26: Solar Collector With Baffles

Raheleh Nowzari et al.,(11) had studied the thermal performance of double pass solar air heater with mesh layer as absorber plate. It was observed that, absorber plate was replaced by fourteen steel wire mesh layers 0.2 x 0.2cm in cross-section opening and they were fixed in duct parallel to the glazing. The distance between each set of wire mesh layer is 0.5cm to reduce the pressure drop. The wire mesh layer were paint with black before installing them. In this investigation, air flow rate was varied from 0.011kg/s to 0.037kg/s. The result of investigation reveals that, the average efficiency obtained by this proposed solar air heater was 57% at mass flow rate of 0.037kg/s.

It was found that, the increasing the mass flow rate has opposite effect on the temperature difference. The thermal efficiency increased as increase of mass flow rate.

Fig. 27: Mesh Layer Absorber Plate Solar Air Heater


Aravind Nayak et al., (2015) (3) had conducted numerical study on jet plate solar air heater for heat transfer augmentation. It was observed that jet plate with spacing of 15mm and jet plate length ratio less than 0.5 provides improved thermal performance and highest enhancement in nusselt number is found to be about 22% as compared with smooth duct.

Fig. 29: Jet Plate Arrangement on Solar Collector

V. ConclusionThe different heat transfer improvement techniques were studied in this present work. These techniques improves the thermal efficiency & heat transfer rate. This review will give the way for future researchers.




VI. AcknowledgementsThis work was supported by my guide and sub-guide, I express my thanks to us.

References[1] M.A.Amraoui, K.Aliane,“Numerical Study of the Three

dimensional Flow in a Flat Plate Solar Collector with Baffles”, published in Mechanics French Congress, 25thAugust 2015.

[2] Anand Patel, Divyesh Patel and Sadanand Namjoshi,“Thermal performance evaluation of spiral solar air heater”, published in International Journal of Scientific and Research Publications, Vol. 5, Issue 9, September 2015.

[3] Aravind Nayak, Azalea Irani, Manjunath. M.S,“Numerical Study of Jet Plate Solar Air Heater for Heat Transfer Augmentation”, published in International Journal of Indian Research and Technology , Vol. 4, Issue 10, October 2015.

[4] D.Bhandari, Dr. D.Singh,“Performance Analysis of Flat Plate Solar Air Collectors With and Without Fins”, Published in International Journal of Engineering Research and Technology, Vol. 1, Issue 6, August 2012.

[5] Dr. Bhupendra Gupta, Jitendra Kumar Waiker, Gopal Prasad Manikpuri, Brahman Singh Bhalavi,“Experimental analysis of single and double pass smooth plate solar air collector with and without porous media”, Published in American Jounal of Engineering Research, Vol. 2, Issue 12, pp. 144-149, 2013.

[6] Chandra Bhushan, S.N.Singh,“Experimental Investigation of double pass solar air heater”, Published in Asia Pacific Journal.

[7] Clara Dhanemozhi A., Umarani R,“Comparison of the efficiencies of a solar air heater”, published in Internal Journal of Applied Bioengineering, Vol. 7, No. 1, January 2013.

[8] Mokalla Srinivas, Simon Jayaraj,“Performance study of a double pass, hybrid-type solar air heater with slats”, Published in International Journal of Energy Engineering, Vol. 3, Issue 4, pp. 112-121, August 2013.

[9] P. Mohammed Shameer, P.Mohammed Nishath,“Designing and Fabrication of Double Pass Solar Air Heater Integrated with Thermal Storage”, published in International Journal of Science and Research, Vol. 4, Issue 1, on January 2015.

[10] Nikhil N. Kharbade, R.S. Shelke,“Methods of Performance of Solar Air Heater Using Different Artificial Roughness”, published in International Journal of Innovation Research in Science, Engineering and Technology, Vol.5, Issue 1, January 2016.

[11] Raheleh Nowzari, L.B.Y.Aldabagh, Nima Mirzaei, “Experimental Study on Double Pass Solar Air Heater with Mesh layers as Absorber Plate”, Published in International Journal of Electronics, Mechanical, Engineering, Vol. 3, No. 4, pp. 673-682.

[12] Veena Pal, Ajeet Kumar Rai, Vivek sachan,“Performance Study of Solar Air Heater”, Published in International Journal of Mechanical Engineering and Technology, Vol. 6, Issue 7, pp. 01 – 07, July 2015.

M.SIVAGANESH received his B.E in Mechanical from Adhipharasakthi Engineering College, Melmaruvathur, Tamilnadu, India in 2015, the M.E degree in Thermal Power Engineering from Annamalai University, Chidambaram Tamilnadu, India, in 2017.

A.ANANDARAMAN received his B.E in Mechanical from MRK Institute of Technology, Kattumannar Koil, Tamilnadu, India in 2014, the M.E degree in Thermal Power Engineering from Annamalai University, Chidambaram Tamilnadu, India, in 2017.

Dr.R.RATHNASAMY received his B.E in Mechanical from CIT University, Coimbatore, Tamilnadu, India, the M.Tech degree in Thermal Power Engineering from IIT, Madras, Tamilnadu, India, the Ph.D degree in Heat Transfer and Fluid Mechanics from IISC, Bangalore, India. At present , he is a professor at Annamalai University, Chidambaram, Tamilnadu, India.

Dr. R.Karthikeyan received his B.E in Mechanical from Annamalai University,Chidambaram, Tamilnadu, India, the M.E degree in Thermal Power Engineering from Annamalai University, Chidambaram, Tamilnadu, India, the Ph.D degree in Heat Transfer from Annamalai University, Chidambaram, Tamilnadu, India. At present, he is a Associate Professor at Annamalai University, Chidambaram, Tamilnadu, India.

o l . 7, i 2, ma y - o 2017 issn : 2249-5762 (online ... · ijrmet vo l. 7, is s u e 2, ma y - oc t...

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