FIRST AND SECOND LAW EFFICIENCIES OF A SOLAR BIOMASS HYBRID DRYER

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 6, June 2018, pp , Article ID: IJMET_09_06_087 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed FIRST AND SECOND LAW EFFICIENCIES OF A SOLAR BIOMASS HYBRID DRYER T. Praveen Kumar PRIST University, Vallam, Thanjavur, Tamilnadu, India S. Dhanushkodi PRIST University, Vallam, Thanjavur, Tamilnadu, India K. Sudhakar Energy Centre, National Institute of Technology, Bhopal, M. P., India; Faculty of Mechanical Engineering, Universiti Malaysia Pahang, Pahang, Malaysia ABSTRACT The paper is concerned with the first and second law analysis of the drying process of the cashew in a solar biomass hybrid dryer operating in two modes. The first law of thermodynamics was carried out to determine the thermal energy gain of the dryer and energy utilization. Second law analysis was applied to investigate the exergy losses during the hybrid drying process. Experiments were performed in natural and forced hybrid mode to evaluate the energy and exergy efficiency at a specific mass flow rate of air. It is observed that the exergy efficiency of the hybrid dryer in natural convection is slightly higher than the forced convection mode. Key words: Solar Energy, First Law Analysis and Second Law Analysis. Cite this Article: T. Praveen Kumar, S. Dhanushkodi and K. Sudhakar, First and Second Law Efficiencies of A Solar Biomass Hybrid Dryer, International Journal of Mechanical Engineering and Technology, 9(6), 2018, pp INTRODUCTION The application of solar energy for drying applications has to turn into a sustainable alternative owing to the free availability and eco-friendly source of energy. Hybrid solar drying is an improved form of direct solar drying with better design and operating condition. It ensures continuous operation during off sunshine hours by using a backup heating source such as biomass. The hybrid dryers are a little bit complex in design, difficult to construct and maintain. However the main advantage is the better rate of heat transfer to the flowing air. Many experimental and theoretical studies [1 4] have been attempted to analyze the exergy performance of the solar systems. Several studies [5 12] have been done on the various application of solar and biomass energy including solar radiation assessment. Researchers have editor@iaeme.com

2 First and Second Law Efficiencies of A Solar Biomass Hybrid Dryer attempted to improve the performance of hybrid dryers by focusing intensive studies on design, fabrication and performance analysis [15 26]. The exergy analysis has proven to more powerful tool to design and optimize the performance of energy system. The second law analysis provides the quantitative and qualitative evaluation of the different losses in the system. The Second law analysis provides useful information on losses during the drying process and suggests measures to improve the appropriate component design and operating procedure. Although a considerable amount of data has been reported in the literature regarding the energy and exergy analysis of drying various crops, very little information is available on hybrid drying of cashew nut. The corresponding exergy utilization data during the drying process is also limited. This paper aims to analyze the first and second law analysis of a solar biomass hybrid dryer for drying cashew. To quantify the exergy gain and losses, the second law analysis is carried out. Some important conclusions from the experimental work have been drawn and summarized in this paper. 2. EXPERIMENTAL SETUP The solar biomass hybrid dryer consists of a biomass heater, a solar collector, a centrifugal blower and a drying chamber with chimney. The schematic view of the solar biomass hybrid dryer is shown in Fig. 1. Experiments were conducted in the solar biomass hybrid dryer at PRIST University, Puducherry campus (11.86 N, 79.77) TN, India in the month of April at an optimum flow rate of Kg/s for drying 40 kg cashew. The three optimum flow rates are used to dry 40kg of cashew per batch. A fan is used to force the air into the system. Fan regulator controls the flow rate. Solar intensity is measured by solar power meter solarimeter (TENMARS). Hotwire anemometer measures wind velocity. K-type thermocouple and RTD measure the temperature. Figure 1 Experimental setup of the hybrid dryer editor@iaeme.com

3 T. Praveen Kumar, S. Dhanushkodi and K. Sudhakar 3. MATHEMATICAL FORMULATION 3.1 First Law Analysis The drying process can be modeled as a steady flow process of heating, cooling and humidification. First law analysis states that the energy entering the thermal system, including fuel, electricity, and flow of matter is conserved and not destroyed. The general equation of energy conservation of the accumulated air is made using a thermal energy balance [22-26]: Ė = Ė (1) The general equation of mass conservation of the drying air is made using a thermal energy balance: ṁ = ṁ (2) The air specific heat is calculated from Eq. (3). The constant is the specific heat of dry air : Cp= W (3) Where W is the humidity ratio of the dry air. The useful heat gain by a collector can be expressed as (Qu) Q = mc ( T T ) (4) The first law efficiency of the solar collectors is defined as the ratio of the useful heat gain to the incident solar radiation on the collector surface η =!(" # $ " % ) (5) &.' where I is the solar radiation incident on the tilted collector surface, A is the solar collector area The drier efficiency is the product of the collector efficiency and drying chamber efficiency. ηd = ηc * ηdc (6) Where, ηd is solar drier efficiency. ηc is average collector efficiency and ηdc is drying chamber efficiency 3.2. Second Law Analysis Second law analysis introduces the useful concept of exergy in the thermal systems. Second law analysis states that the part of the useful energy entering the thermal system including fuel, electricity and flow of matter is destroyed due to the irreversibilities. Exergy is the amount of maximum work obtained theoretically at the end of a reversible process in which equilibrium with the environment should be obtained. It is the measurement of the quality and grade of the energy. The energy and exergy balance of the system can be expressed as (neglecting the kinetic and potential energy change). The exergy analysis was carried out following the equation provided in the reference [27]. Ė( Ė( = Ė( )*+ (7) Ė(,*- Ė(./0 +Ė( 1-++, Ė( 1-++, =Ė( )*+ (8) Or editor@iaeme.com

4 First and Second Law Efficiencies of A Solar Biomass Hybrid Dryer The exergy outflow of the drying chamber (Ex dco) = mc [(T dco -T a)-t aln "3 "4 ] (9) The exergy Inflow of the drying chamber (Ex dci) = mc [(T dci -T a)-t aln "3 "4 ] (10) The exergy loss (Ex loss)= Ex dci- Ex dco (11) Drying chamber Efficiency (η dc)= 56$57 56$5- The second law efficiency is estimated based on the following relations: Exergy efficiency (η EX) = (12) (13) 4. RESULTS AND DISCUSSIONS Figure 2 shows the variations in the ambient temperature and the solar radiation on the experimental day. Figure 2 Variation of solar intensity and ambient temperature The inlet temperature of drying air significantly influenced the drying time. The initial moisture content of the cashew nut shell is 9.29%. The desired final moisture content is in the range of 3.5 to 4.6 %. The final moisture content of 3.5 % is obtained within 7 hours of drying in the forced convection mode, whereas it takes 9 hours of drying in the natural convection mode [22]. Comparing the two modes, it was observed that the cashew nut in the forced mode dried faster than in the natural mode dryer. Figure 3 & 4 shows the hourly variation of exergy input, output and loss for the hybrid dryers. It was observed that the exergy loss increased drastically reaching peak value of 740 KJ between 1.00 to PM in forced convection hybrids dryer. On the other hand, the exergy loss was relatively smaller in natural convection hybrid dryers. There is an indication that hybrid drying system operating on forced mode wasted more energy than the natural convection mode hybrid dryer editor@iaeme.com

5 T. Praveen Kumar, S. Dhanushkodi and K. Sudhakar Figure 3 Variation of exergy inlet, outlet and loss (Natural convection hybrid dryer) Figure 4 Variation of exergy inlet, outlet and loss (Forced convection hybrid dryer) The second law efficiency of the hybrid dryer for each mode of operation of the dryers was calculated and shown in Figure 5. The first law efficiency indicates the drying process in an ideal interpretation, on the other hand, the second law efficiency shows how the inlet energy is used during the drying process. This efficiency is called real efficiency because it allows viewing the irreversibility. Both the efficiency initially increases and later it decreases during the moisture transfer process. A second law analysis of the drying systems was carried out to find out to study the effect of unavailable energy (anergy or exergy losses) on the performance of the systems. The first law efficiency was found to be greater than the second law efficiency owing to heat loss. The major reason for the lower second law efficiency of dryers is due to the wasted exergy in the outlet air as exergy loss editor@iaeme.com

6 First and Second Law Efficiencies of A Solar Biomass Hybrid Dryer Figure 5 Variation of Exergy efficiency (natural and forced) with time Figure 6 shows the second law efficiency of the two drying systems. The overall analysis gave average exergetic efficiencies of 5% and 4% for natural mode and forced mode, respectively. According to the efficiencies analysis, the second law values are not bigger than 5 % while the first law values reach 40 %. Those results allow evaluating the quantity of energy not used in the drying of cashew nut. Figure 6 Variation of exergy efficiency of natural and forced hybrid dryers. 5. CONCLUSION The drying experiment was carried out on consecutive days without much impact of solar radiation and environmental changes in comparing their performance. First and second law efficiency analysis of two modes of hybrid dryers are presented. The analysis is used to find the available useful energy and the quality of energy that is obtainable from the hybrid dryers. The following are the significant outcome of the experiemntal study. The overall exergetic efficiencies of natural mode and forced mode dryers were found to be 5%, and 4%, respectively. The values of second law efficiency varied between 1 % and 9 % with an average of 4.5 %. The second law efficiency initially increases and later it decreases during the moisture transfer process editor@iaeme.com

7 T. Praveen Kumar, S. Dhanushkodi and K. Sudhakar The natural mode hybrid dryer has a slight edge in superiority over forced mode hybrid dryer. The results obtained show that natural mode and forced mode hybrid solar biomass dryers are still incapable of taking advantage of the combined available energy from solar and biomass. REFERENCES [1] Dhanushkodi, S., Wilson, V. H., & Sudhakar, K. Design and performance evaluation of biomass dryer for cashewnut processing. Advances in Applied Science Research, 6, 2015, pp [2] Sreenath Sukumaran, K. Sudhakar, Performance analysis of Solar powered airport based on energy and exergy analysis, Energy, 2018, doi: /j.energy [3] A.K. Shukla, K. Sudhakar, P. Baredar, Exergetic assessment of BIPV module using parametric and photonic energy methods: a review, Energy Build. 119, 2016, pp [4] Dhanushkodi, S., Wilson, V.H, & Sudhakar, K.Energy analysis of cashew nut processing agro industries: a case study. Bulgarian Journal of Agricultural Science, 22, 2016, pp [5] P Kumar, AK Shukla, K Sudhakar, R Mamat. Experimental exergy analysis of water-cooled PV module. International Journal of Exergy 23,2017,pp, [6] Shukla, K.N., Sudhakar, K., Rangnekar, S., A comparative study of exergetic performance of amorphous and polycrystalline solar PV modules. Int. J. Exergy 17,2015,pp [7] K. Sudhakar, M. Premalatha: Characterization of micro algal biomass through FTIR/TGA/CHN analysis: Application to Scenedesmus sp. Energy Sources Part A Recovery Utilization and Environmental Effects 10, 2015, pp 1-8., [8] K Sudhakar, M Premalatha, M Rajesh: Large-scale open pond algae biomass yield analysis in India: A case study. International Journal of Sustainable Energy 08, 2012, pp-., DOI: / [9] Dhanushkodi, S., H Wilson, V., & Sudhakar, K. Life Cycle Cost of Solar Biomass Hybrid Dryer Systems for Cashew Drying of Nuts in India. Environmental and Climate Technologies, 15, 2015, pp, [10] K.Sudhakar, Tulika Srivastava, Guddy Satpathy, M.Premalatha: Modelling and estimation of photosynthetically active incident radiation based on global irradiance in Indian latitudes. International Journal of Energy and Environmental Engineering, 04, 2013; pp 1-19., [11] M.Debbarma,K. Sudhakar, P. Baredar Thermal modeling, exergy analysis, performance of BIPV and BIPVT: A review, Renewable and Sustainable Energy Reviews, 73, 2017, pp, [12] Dhanushkodi, S., Wilson, V. H., & Sudhakar, K. Mathematical modeling of drying behavior of cashew in a solar biomass hybrid dryer. Resource-Efficient Technologies, 3, 2017,pp [13] Rajput, D.S., Sudhakar, K., Effect of dust on the performance of solar PV panel. Int. J. Chem. Technol. Res. 5, 2013, pp [14] Shukla, K.N., Sudhakar, K., Rangnekar, S., A comparative study of exergetic performance of amorphous and polycrystalline solar PV modules. Int. J. Exergy 17, 2015, pp [15] K.Sudhakar, T.Srivastava, Energy and exergy analysis of 36W solar photovoltaic module, Int.J.Ambient Energy 35, 2014, pp [16] A.K. Shukla, K. Sudhakar, P. Baredar, Exergetic assessment of BIPV module using parametric and photonic energy methods: a review, Energy Build. 119, 2016, pp [17] Dhanushkodi, S., Wilson, V. H., & Sudhakar, K. Energy analysis of cashew nut processing agro industries: a case study.bulgarian Journal of Agricultural Science, 22, 2016,pp editor@iaeme.com

8 First and Second Law Efficiencies of A Solar Biomass Hybrid Dryer [18] Shukla, K.N., Rangnekar, S., Sudhakar, K., Mathematical modelling of solar radiation incident on tilted surface for photovoltaic application at Bhopal, M.P., India. Int. J. Amb. Energy. 04,2015,pp [19] Akash Kumar Shukla, K.Sudhakar, Prashant Baredar, Exergetic analysis of building integrated semitransparent photovoltaic module in clear sky condition at Bhopal India, Case Studies in Thermal Engineering 8, 2016, pp [20] Dhanushkodi, S., Wilson, V. H., & Sudhakar, K. Simulation of Solar biomass hybrid dryer for drying cashew kernel.advances in Applied Science Research, 6,2015,pp [21] A.K. Shukla, K. Sudhakar, P. Baredar, Exergetic assessment of BIPV module using parametric and photonic energy methods: a review, Energy Build. 119, 2016, pp [22] Dhanuskodi, S., Wilson, V., & Kumarasamy, S. Design and thermal performance of the solar biomass hybrid dryer for cashew drying. Facta Universitatis, Series: Mechanical Engineering, 12, 2014, pp [23] K Sudhakar, M Rajesh, M Premalatha: A Mathematical Model to Assess the Potential of Algal Bio-fuels in India. Energy Sources Part A Recovery Utilization and Environmental Effects 04, 2012, pp [24] Sreenath Sukumaran, K. Sudhakar, Fully solar powered airport: A case study of Cochin International airport, Journal of Air Transport Management, 62, 2017, pp [25] Dhanushkodi, S., Wilson, V. H., & Sudhakar, K.Thermal Performance evaluation of Indirect forced cabinet solar dryer for cashew drying. American-Eurasian Journal of Agricultural and Environmental Science, 14, 2014, pp [26] Hyder, F., Sudhakar, K., & Mamat, R. Solar PV tree design: A review. Renewable and Sustainable Energy Reviews, 82, 2018, pp [27] Anto Joseph, Nagarajan and Antony Mary, A Multi Converter Based Pure Solar Energy System with High Efficiency Mppt Controller, Volume 4, Issue 4, July-August (2013), pp , International Journal of Electrical Engineering and Technology (IJEET). [28] Srinivasan. V, M. Francis Luther King, Purushothaman T, A Review on Energy Conservation Using Solar Energy and Radiant Cooling, International Journal of Mechanical Engineering and Technology 8(8), 2017, pp [29] M.R. Kolhe and Dr. P.G. Khot. Alternative Energy: A Special Reference to Solar Energy, International Journal of Management, 6(9), 2015, pp [30] Hameed Majeed Saber and Deepak Lal, Assessment of Solar Energy Distribution For Installing Solar Panels Using Remote Sensing & Gis Techniques, Volume 5, Issue 10, October (2014), pp , International Journal of Advanced Research in Engineering and Technology (IJARET) [31] A.S. Meena, P.L. Meena, M. Chandra, R. Meena, shribai and R.C. Meena, Electrochemical Studies of Anionic and Cationic Surfactants In Photogalvanic Cell For Solar Energy Conversion And Storage, Volume 4, Issue 4, July-August (2013), pp , International Journal of Electrical Engineering and Technology (IJEET) [32] A. Fudholi, K. Sopian, M.H. Yazdi, M.H. Ruslan, M. Gabbasa and H.A. Kazem, Performance analysis of solar drying system for red chili, Solar Energy, 99 (2014), editor@iaeme.com