Accepted Manuscript Title: Performance studies on a downdraft biomass gasifier with blends of coconut shell and rubber seed shell as feedstock Author: V Christus Jeya Singh, S Joseph Sekhar PII: DOI: Reference: S1359-4311(15)01026-1 http://dx.doi.org/doi: 10.1016/j.applthermaleng.2015.09.099 ATE 7096 To appear in: Applied Thermal Engineering Received date: Accepted date: 24-4-2015 25-9-2015 Please cite this article as: V Christus Jeya Singh, S Joseph Sekhar, Performance studies on a downdraft biomass gasifier with blends of coconut shell and rubber seed shell as feedstock, Applied Thermal Engineering (2015), http://dx.doi.org/doi: 10.1016/j.applthermaleng.2015.09.099 This is a PDF file of an unedited manuscript that has been accepted for publication As a service to our customers we are providing this early version of the manuscript The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain Performance Studies on a Downdraft Biomass Gasifier with Blends of Coconut Shell and Rubber Seed Shell as Feedstock V Christus Jeya Singh1* and S Joseph Sekhar1 Department of Mechanical Engineering, St Xavier’s Catholic College of Engineering, Nagercoil, Kanyakumari, Tamilnadu, India Corresponding author: *christjsingh@yahoo.co.in Keyword: Coconut shell, Rubber seed shell, Downdraft gasifier, Equivalence ratio, Conversion efficiency Highlights:  Analytical and experimental investigation on the performance of biomass gasifier  Blends of coconut shell and rubber seed shell as feedstock in gasifier instead of wood  Two-zone kinetic model to predict the performance of biomass blends in gasifier  Impact of equivalent ratio on the performance of gasifier with blends of biomasses Abstract The use of biomass gasification system for the generation of combined heat and power has gained importance, because it is considered to be one of the most promising renewable energy technologies Widespread research has been already carried out on downdraft gasifier with single biomass as feedstock However a limited work is available to ascertain the feasibility of utilizing blends of biomasses In this paper, theoretical and experimental studies have been carried out on a 50kWth downdraft gasifier with the blends of coconut shell and rubber seed shell, which are available abundantly in the rural villages of South India Two-Zone kinetic modelling is followed for the theoretical studies Experimental | Paper ID :ICP2015-CP141 Page of 13 study has been carried out to prove the validity of the modelling approach The results show that the mixing of rubber seed shell and coconut shell with various compositions yields the performance which is on par with the woody biomasses Besides, the maximum values of the performance parameters are obtained when the equivalence ratio is maintained between 0.2 and 0.3 Introduction The fossil fuels contribute 80% to world total energy demand, whereas biomass resources cover only 10-15% [1] India has an immense opportunity for energy generation from the available 500 metric tons of biomass per year The rural areas of India depend on conventional biomasses such as firewood, animal dung, agricultural residue and forest products for cooking, heating, lighting and other related applications It is also observed that the biomass energy technology may contribute to one-third of total energy consumption in India [2&3] Biomass gasification process comprises of biochemical reactions inside the gasifier with limited supply of air, and generates combustible gases such as CO, H2 and CH4 The energy content of the combustible gases may be conveniently used for heat and power applications These gases can be effectively utilised in advanced technologies like gas turbines and fuel cells in order to get increased system efficiency [4] The concept of combined heat and power production from biomass is especially useful to agriculture based process industries and rural electrification in developing countries [5&6] The performance of the gasification process depends on the types of feedstock and its characteristics such as moisture content, composition (ultimate analysis), equivalence ratio and so on Inappropriate selection of these parameters may lead to excessive presence of tar and soot in the producer gas These unwanted materials in the producer gas may disturb the continuous and smooth operation of gas engines [7&8] The fixed bed gasifiers are classified depending on the supply of gasifying agent into the reactor They are updraft, downdraft, cross draft and multistage Among the commercially produced gasifiers, downdraft, fluidized bed, updraft and other gasifiers have the share of 75%, 20%, 2.5 % and 2.5% respectively [9] Compared to other gasification technologies, the downdraft gasifier is the most sustainable option for decentralized heat and power generation because the producer gas obtained from it contains very low content of tar and particulates | Paper ID :ICP2015-CP141 Page of 13 Theoretical and experimental studies have been carried out to analyse the behaviour of gasifiers The minimization of Gibbs free energy has been followed [10] to predict the performance of wood waste (saw dust) This approach was found to be good to analyse the gasification process above 1500 K [11] Another model developed based on thermodynamic equilibrium approach by Jarungthammachote and Dutta [12] has considered the equilibrium constant with correction coefficient for predicting the composition of producer gas in a downdraft gasifier It is also suggested that the moisture content and equivalence ratio have to be maintained at 10 to 20% and 0.3 to 0.45 respectively for optimal energy conversion Chemical equilibrium approach has been used to analyse the influence of parameters such as moisture content, equivalence ratio and heating value on the quality of producer gas [11&12] The experimental works have been carried out to predict the influence of various factors on the performance of downdraft biomass gasifier with wood [13, 18], waste wood, wheat straw, coconut shell [14, 18], saw dust [15], cashew nut shell [16], agricultural and forest residues [17], rubber seed kernel, coir-pith [18], etc as feedstock A numerical and experimental study conducted to analyse the behaviour of reduction zone shows that the conversion efficiency of the gasifier decreases as the throat angle increases The optimum length of the reduction zone has been reported as 22 cm for efficient operation of the gasifier [13] The gasifier running with single biomass throughout the year suffers with issues such as risk on transportation, non-availability of a particular biomass throughout the year and incomplete utilization of various biomasses available in a region [19] Therefore blends of biomasses in a gasifier can improve the continuous and steady operation of gasifiers in remote areas A analytical model developed to analyse the performance of saw-dust/cowdung mixture in a downdraft gasifier shows that the mixing of cow dung would reduce the gas production rate and heating value, however, having 40 - 50 % cow dung in the mixture is technologically and economically viable [20] To the further extent of this approach, through this paper, the performance of a 50 kWth downdraft gasifier has been analysed with the blends of coconut shell-rubber seed shell Equilibrium modelling concept has been used in the theoretical studies Experiments were also conducted to investigate the effect of mixture composition and equivalence ratio on the species concentration and heating value of the producer gas Methodology | Paper ID :ICP2015-CP141 Page of 13 The total gasifier model has been simplified into two different zones as shown in Fig.1 The thermodynamic equilibrium approach is followed in the zone-1 while chemical kinetics of reactions has been considered in zone-2 [20] In order to implement the equilibrium analysis, the assumptions used in this analysis are steady state gas flow inside the gasifier, adiabatic wall, infinite residence for the reactions to take place, uniform species temperature at each level of gasification, negligible amount of tar or unburnt hydrocarbon in the exhaust, ideal gas behaviours of gases And major species in the product gas are CO, CO2, H2, CH4 and N2 The blends of two biomasses in various proportions have been used as feedstock in the gasifier instead of single biomass, and the performance parameters like heating value, species concentration, gas production rate and conversion efficiency were studied While using two different biomass energy sources, the global reaction of gasification process for the mixture can be written as [20], 𝐶𝐻𝑙 𝑂𝑝 𝑁𝑞 + 𝑏𝐶𝐻𝑡 𝑂𝑢 𝑁𝑣 + 𝑀𝑤 𝐻2 𝑂 + 𝑋𝑔 𝑂2 + 3.76𝑁2 → 𝑥1 𝐶𝑂 + 𝑥2 𝐻2 + 𝑥3 𝐶𝑂2 + 𝑥4 𝐻2 𝑂 + 𝑥5 𝐶𝐻4 + 𝑥6 𝑁2 + 𝑥7 𝐶 (1) (1) Where l, p, q, t, u, and v are the number of atoms of the respective chemical component in the feedstock The representative chemical formulae (CHlOpNq, CHtOuNv) of different biomasses are derived from their ultimate analysis, using the generalized procedure [21] The equations used for calculating the number of moles of second biomass (b), number of moles of oxygen in air (Xg) and the number of moles of moisture (Mw) have been taken from published literature [20] The ultimate analysis results of feedstock materials are shown in the Table The higher heating value of the biomass is calculated using the Friedl’s equation 𝐻𝐻𝑉 𝑀𝐽 𝑘𝑔 = 3.55𝐶 − 232𝐶 − 2230𝐻 + 51.2𝐶𝐻 + 131𝑁 + 20600 (2) The numbers of moles of respective species, x1 to x7 in the gasification process have been calculated by solving the global reaction [20] A uniform temperature has been assumed to the species at the outlet of zone-1 and the same is determined from the energy balance | Paper ID :ICP2015-CP141 Page of 13 across the zone considering that there is a negligible amount of kinetic and potential energy changes Based on the global reaction given in equation 1, the energy balance equation is expanded as [20], 𝐻𝑓1 + 𝑏𝐻𝑓2 + 𝑋𝑔 𝑇𝑎 𝑇0 𝐶𝑝 𝑂 𝑑𝑇 + 3.76𝑋𝑔 = 𝑇𝑎 𝑇0 𝐶𝑝 𝑁 𝑑𝑇 + 𝑀𝑤 ℎ𝑓 𝐻2𝑂 + 𝑄𝑙𝑜𝑠𝑠 𝑇 𝑥𝑖 ℎ𝑓𝑖 + 𝑖=1 𝑇0 (3) 𝐶𝑝 𝑖 𝑑𝑇 + 𝑥7 𝐶𝑝𝐶 𝑇 − 𝑇0 + 𝑚𝑎𝑠ℎ 𝐶𝑝𝑎𝑠 ℎ 𝑇 − 𝑇0 The energy carried out by individual species (CO, H2, CO2, H2O, CH4, and N2), char and ash are considered separately in the above equation Standard equations are used to find the heat of formation of fuels [22] Specific heat for ash and char is considered as 840 J/kgK and 21.86 J/mol K respectively [20] The species formed in the zone-1 enter the zone-2 and undergo the following endothermic reactions to form the final composition of the producer gas [20] 𝐶 + 𝐶𝑂2 ⇔ 2𝐶𝑂 (4) 𝐶 + 𝐻2 𝑂 ⇔ 𝐶𝑂 + 𝐻2 (5) 𝐶 + 2𝐻2 ⇔ 𝐶𝐻4 (6) 𝐶𝐻4 + 𝐻2 𝑂 ⇔ 𝐶𝑂 + 3𝐻2 (7) The above equations are assumed to be reversible and the rate of reaction is calculated using Arrhenius type kinetic rate equations The mass flow rate of the species (i=1 to 7) at the inlet of the reduction zone depends on the feed rate of biomass The rate of formation of species and the temperature of the species formed in the zone-2 are calculated from the relations used in the previous literature [20] The temperature of the species leaving zone-2 is obtained by applying energy balance across zone-2 The linear and non-linear equations are solved using appropriate tools in the open source software SCILAB The equivalence ratio plays a vital role on the performance of the gasifier [23] If the equivalence ratio is below 0.2, the conversion efficiency and gas production rate reduce | Paper ID :ICP2015-CP141 Page of 13 drastically [24] Therefore in this analysis, the equivalence ratio has been taken between 0.2 and 0.45, and the variations in performance parameters are studied The blends used in this study and their compositions are given in Table Experimental Setup The schematic diagram of the experimental setup consists of an imbert downdraft biomass gasifier (50 kWth), scrubber with cyclone separator and filters is shown in Fig The feedstock to be used in this gasifier as per supplier specification is wood chip A gas analyser, gas chromatograph and a gas flow meter are provided to measure the quality and quantity of the producer gas Calibrated K-type (chromel-alumel) thermocouples are placed in different locations along the axis of the gasifier to measure the temperature at various zones To prevent the leakage of producer gas and to reduce its temperature, a water seal arrangement is made under the reactor A special metering rod is also provided to calculate the flow rate of feedstock To maintain a homogeneous mixture, the biomasses were mixed before being filled in the gasifier Using the special arrangement, the flow rate of feedstock was also recorded A data logger was used to record the temperature in an interval of minutes Samples of the gas were taken every 10 minutes to analyse its composition In addition to that, the quantity of the output gas was also recorded Each blend was studied for a minimum of three times and the average values were taken The equivalence ratio was regulated by controlling the air flow rate and it was measured with an accuracy of ± % HHV and moisture content of feedstock material were checked before each loading Results and Discussion The theoretical work is carried out to study the variation in performance parameters for a wide range of equivalence ratios between 0.2 and 0.45 However, the experimental studies were carried out by maintaining the equivalence ratio between 0.2 and 0.34 The comparison of species concentration obtained from the present model with the previous works [12] shows that the deviation of present result is within 12% Thus the validity of the 2-zone kinetic equilibrium approach to simulate the gasifier has been proved The results obtained from modelling and experimental studies have been analysed, and the influence of the equivalence ratio and composition of biomass blends on the performance parameters are evaluated | Paper ID :ICP2015-CP141 Page of 13 a) Species concentration The variations in species concentration (CO, H2, CO2, CH4 and N2) with equivalence ratio for coconut shell and rubber seed shell are shown in Fig and Fig respectively The results show that the species concentration of CO, H2 and CH4 from the modelling has a close agreement with that of experimental observations It is also observed that the combustible gas composition for both biomasses is high when the equivalence ratio is close to 0.2 However the species concentration of the combustible gases produced using coconut shell is higher than the other one This might be because of the higher carbon content in coconut shell The reduction zone plays a vital role in the performance of the gasifier The endothermic reactions [24] that take place in the reduction zone cause the reduction in the temperature and release CO, H2 and CH4 Since the concentration of CH4 does not vary significantly, the variations of CO and H2 are plotted in Fig and Fig respectively and considered for the discussion A steady increase in CO concentration is observed along the reduction zone whereas the concentration of H2 is almost constant This is due to the difference in the rate of reaction of each reaction The concentration observed for CO and H2 is almost constant when the reduction zone distance is beyond 0.24 m A similar trend has also been observed in previous works [25] The quality of the producer gas leaving the gasifier depends on the concentration of the combustible gases (CO, H2 and CH4) at the exit of the gasifier Even though the theoretical analysis was carried out for all the blends given in Table 2, only the results of the blend D1 is plotted in Fig and considered for discussion It is observed that the species concentration of combustible gases is high when ф is kept at 0.2 Therefore, the airflow rate should be adjusted to maintain the equivalence ratio close to 0.2 for both of the feedstock materials.The trend observed from the experimental study is similar to the prediction from the simulation b) Gas production rate The Fig demonstrates the variation of gas production rate with equivalence ratio for all compositions used in the study It is observed that there is a good agreement between the predicted and measured values Even though the combustible gas composition decreases due to the increase in ф, an increase in gas production rate is observed This is caused by the high concentration of non-combustible gases such as CO2 and N2 in producer gas When the | Paper ID :ICP2015-CP141 Page of 13 equivalence ratio increases, the quantity of O2 increases, and due to the domination of combustion reactions, the production of CO2 increases This causes a reduction in the concentration of CO and H2 c) Higher Heating Value and Conversion Efficiency The heating value depends on the concentration of CO, H2 and CH4 in the producer gas The variation of HHV of producer gas with equivalence ratio (ф), for various feedstock compositions is plotted in Fig It is observed that the HHV reduces with the increase in equivalence ratio (Fig 9) Since the gas production rate is almost constant until the equivalence ratio reaches 0.3(Fig 8), to maintain a high heating value of the producer gas, equivalence ratio may be kept between 0.2 and 0.3 Next to the pure biomass (blend D0), the blend D1 gives better performance at this range The impact of equivalence ratio on conversion efficiency is depicted in Fig 10 The conversion efficiency decreases with the increase in equivalence ratio This is due to the poor quality of producer gas as discussed in the previous section (Fig 9) It is observed that the conversion efficiency is maximum when the biomass blend is rich in coconut shell When rubber seed shell is mixed with coconut shell, the conversion efficiency is reasonably good for the equivalence ratio between 0.2 and 0.3 This prediction shows that the equivalence ratio should be kept in the above said range for the feedstock combinations used in this study Moreover the temperature obtained from the simulation and experimental studies at the reduction zone is matching with the values reported in the literature (26) For instance the temperature at the reduction zone entry for blend D1 is 1285K and 1267K for simulation and experimental observations respectively This proves the validity of energy equations used in this study Conclusion Theoretical and experimental studies were conducted with various binary blends of coconut shell and rubber seed shell as feedstock in a 50kWth downdraft gasifier Based on the present study the following conclusions are made | Paper ID :ICP2015-CP141 Page of 13 The concentration of combustible gases in the producer gas is maximum at equivalence ratio close to 0.2 and a significant reduction in the concentration of CO and H2 is observed when the equivalence ratio is beyond 0.3 Irrespective of the compositions in the blend, to obtain maximum conversion efficiency, the equivalence ratio should be maintained between 0.2 and 0.3 Among the two energy sources, coconut shell shows maximum combustible species concentration and conversion efficiency The present study proves that the coconut shell and rubber seed shell can be used as a single biomass or blends in a biomass gasifier, which is designed for wood Nomenclature ɸ - Equivalence Ratio DAF - Dry Air Free HHV - Higher Heating Value (MJ/kg) D0, D1, D2, D3 - Blends of Coconut Shell and Rubber Seed Shell - Moisture Content of Biomass MC References [1] A Faaij, Modern biomass conversion technologies, Mitigation and Adaptation Strategies for Global Change 11(2006) 343-375 [2] C.C Sreejith, C Muraleedharan, P Arun, Performance prediction of steam gasification of wood using an ASPEN PLUS thermodynamic equilibrium model, International Journal of Sustainable Energy 33(2013) 416-434 [3] A Kumar, D Jones, M.A Hanna, Thermochemical biomass gasification: A Review of the Current Status of the Technology, Energy 2(2009) 556-81 [4] A.P.C Faaji, Bio-energy in Europe: changing technology choices, Energy Policy 34(2006) 322-42 [5] Son Yi, A Study on measurement of the light tar content in the fuel gas produced from small-scale gasification and power generation systems, In: Proceedings of the 15th Annual Meeting of the Japan Institute of Energy; Tokyo: Japan; August 3rd-4th, 2006 [6] B.R Thomas, D Agua, Hand Book of Biomass Downdraft Gasifier Engine System, Golden Colorado: The Biomass Energy Foundation Press, 1998 | Paper ID :ICP2015-CP141 Page of 13 [7] R Singh, A.D Setiawan, Biomass energy policies and strategies: Harvesting potential in India & Indonesia, Renewable and Sustainable Energy Reviews 22(2013) 332-45 [8] R A Gain, Report (Number-IN2081), Biofuels Annual 2012; India, MNRE Biomass Resource Atlas of India; 2009 Biomass data by state 2002-04 [9] N Tippayawong, C Chaichan, A Promwungkwa, P Rerkkriangkrai, Clean Energy from Gasification of Biomass for Sterilization of Mushroom Growing Substrates, International Journal of Energy 5(2011) 96-103 [10] H.A.M Knoef, Inventory of Biomass Gasifier Manufacturers and Installations, Final Report to European Commission, Contract DIS/1734/98-NL, in, Biomass Technology Group B.V.,University of Twente, Enschede; 2000, Netherland [11] A Bhavanam, R.C Sastry, Biomass Gasification Processes in Downdraft Fixed Bed Reactors: A Review, International Journal of Chemical Engineering and Applications 2(2011) 425-433 [12] S Jarungthammachote, A Dutta, Thermodynamic Equilibrium Model and Second Law Analysis of a Downdraft Waste Gasifier, Energy 32(2007)1660-1669 [13] T H Jayah, L Aye, R J Fuller, D F Stewart, Computer Simulation of a Downdraft Wood Gasifier for Tea Drying, Biomass and Bioenergy 25(2003) 459-469 [14] L Fagbemi, L Khezami, R Capart, Pyrolysis products from different biomasses: application to the thermal cracking of tar, Applied Energy 69(2001) 293-306 [15] P R Wander, C R Altafini, R M Barreto, Assessment of a small sawdust gasification unit, Biomass and Bioenergy 27(2004) 467-476 [16] R.N Singh, U Jena, J.B Patel, A.M Sharma, Feasibility study of cashew nut shells as an open core gasifier feedstock, Renewable Energy 31(2006) 481-487 [17] Pengmei Lv, Chuangzhi Wu, Longlong Ma, Zhenhong Yuan, A study on the economic efficiency of hydrogen production from biomass residues in China, Renewable Energy 33(2008) 1874-1879 [18] V C J Singh, S J Sekhar, K Thyagarajan, Performance studies on downdraft gasifier with biomass energy sources available in remote villages, American Journal of Applied Sciences 11(2014) 611-622 [19] B Buragohain, P Mahanta, S Vijayanand, Moholkar, Investigations in gasification of biomass mixtures using thermodynamic equilibrium and semi–equilibrium models, Energy and Environment 2(2011) 551-578 | Paper ID :ICP2015-CP141 Page 10 of 13 [20] P.C Roy, A Dutta, N Chakraborty, Assessment of cow dung as a supplementary fuel in a downdraft biomass gasifier, Renewable Energy 35(2010) 379-386 [21] A Melgar, J.F Perez, H Laget, A Horillo, Thermochemical equilibrium modelling of a gasifying process, Energy Conversion and Management 48(2007) 59-67 [22] Z A Zainal, R Ali, C H Lean, K N Seetharamu, Prediction of Performance of a Downdraft Gasifier using Equilibrium Modeling for Different Biomasses, Energy Conversion and Management 42(2001) 1499-515 [23] P Basu, Biomass Gasification and Pyrolysis Practical Design and Theory, Elsevier, Oxford, UK, 2010 [24] K Sharma, Equilibrium and Kinetic Modeling of Char Reduction Reactions in a Downdraft Biomass Gasifier: a Comparison, Solar Energy 82(2008) 918-28 [25] P.C Roy, A Datta, N Chakraborty, Modelling of a downdraft biomass gasifier with finite rate kinetics in the reduction zone, Energy Research 33(2009) 833-851 [26] A.K Sharma, Experimental study on 75 kWth downdraft (biomass) gasifier system, Renewable Energy 34(2009) 1726–1733 Fig.1 Schematic of downdraft gasifier Fig.2 Schematic of experimental setup Fig.3 Effect of ф on species concentrationfor coconut shell Fig.4 Effect of ф on species concentration for rubber seed shell Fig.5 Concentration of CO along reduction zone with ф of the blend D1 Fig Concentration of H2 along reduction zone with ф of the blend D1 Fig Effect of ф on species concentration for the blend D1 Fig.8 Effect of ф on gas production rate for the blends D0, D1, D2 and D3 Fig Effect of ф on HHV for the blends D0, D1, D2 and D3-Modelling Fig 10 Effect of ф on Conversion Efficiency for the blends D0, D1, D2 and D3-Modelling 10 | Paper ID :ICP2015-CP141 Page 11 of 13 Tables Table Ultimate analysis of biomass (DAF basis) C H O N S MC HHV % Wt % Wt % Wt % Wt % Wt % Wt MJ/kg 50.2 5.7 43.4 0 5.2 19.83 43.21 6.0 50.25 0.55 4.98 17.16 Biomass Coconut shell Rubber seed shell 11 | Paper ID :ICP2015-CP141 Page 12 of 13 Table Different types of blends of biomass materials Feedstock Combination Primary Secondary Energy Energy Source Source Coconut Shell Rubber Seed Shell Mole Blend Fraction Ratio Symbol 100:0 D0 90:10 D1 70:30 D2 60:40 D3 12 | Paper ID :ICP2015-CP141 Page 13 of 13 [...]... Singh, A. D Setiawan, Biomass energy policies and strategies: Harvesting potential in India & Indonesia, Renewable and Sustainable Energy Reviews 22(2013) 332-45 [8] R A Gain, Report (Number-IN2081), Biofuels Annual 2012; India, MNRE Biomass Resource Atlas of India; 2009 Biomass data by state 2002-04 [9] N Tippayawong, C Chaichan, A Promwungkwa, P Rerkkriangkrai, Clean Energy from Gasification of Biomass. .. K Sharma, Equilibrium and Kinetic Modeling of Char Reduction Reactions in a Downdraft Biomass Gasifier: a Comparison, Solar Energy 82(2008) 918-28 [25] P.C Roy, A Datta, N Chakraborty, Modelling of a downdraft biomass gasifier with finite rate kinetics in the reduction zone, Energy Research 33(2009) 833-851 [26] A. K Sharma, Experimental study on 75 kWth downdraft (biomass) gasifier system, Renewable... Khezami, R Capart, Pyrolysis products from different biomasses: application to the thermal cracking of tar, Applied Energy 69(2001) 293-306 [15] P R Wander, C R Altafini, R M Barreto, Assessment of a small sawdust gasification unit, Biomass and Bioenergy 27(2004) 467-476 [16] R.N Singh, U Jena, J.B Patel, A. M Sharma, Feasibility study of cashew nut shells as an open core gasifier feedstock, Renewable... Horillo, Thermochemical equilibrium modelling of a gasifying process, Energy Conversion and Management 48(2007) 59-67 [22] Z A Zainal, R Ali, C H Lean, K N Seetharamu, Prediction of Performance of a Downdraft Gasifier using Equilibrium Modeling for Different Biomasses, Energy Conversion and Management 42(2001) 1499-515 [23] P Basu, Biomass Gasification and Pyrolysis Practical Design and Theory, Elsevier,... Reactors: A Review, International Journal of Chemical Engineering and Applications 2(2011) 425-433 [12] S Jarungthammachote, A Dutta, Thermodynamic Equilibrium Model and Second Law Analysis of a Downdraft Waste Gasifier, Energy 32(2007)1660-1669 [13] T H Jayah, L Aye, R J Fuller, D F Stewart, Computer Simulation of a Downdraft Wood Gasifier for Tea Drying, Biomass and Bioenergy 25(2003) 459-469 [14] L Fagbemi,... Sterilization of Mushroom Growing Substrates, International Journal of Energy 5(2011) 96-103 [10] H .A. M Knoef, Inventory of Biomass Gasifier Manufacturers and Installations, Final Report to European Commission, Contract DIS/1734/98-NL, in, Biomass Technology Group B.V.,University of Twente, Enschede; 2000, Netherland [11] A Bhavanam, R.C Sastry, Biomass Gasification Processes in Downdraft Fixed Bed Reactors:... 1726–1733 Fig.1 Schematic of downdraft gasifier Fig.2 Schematic of experimental setup Fig.3 Effect of ф on species concentrationfor coconut shell Fig.4 Effect of ф on species concentration for rubber seed shell Fig.5 Concentration of CO along reduction zone with ф of the blend D1 Fig 6 Concentration of H2 along reduction zone with ф of the blend D1 Fig 7 Effect of ф on species concentration for the blend... Chuangzhi Wu, Longlong Ma, Zhenhong Yuan, A study on the economic efficiency of hydrogen production from biomass residues in China, Renewable Energy 33(2008) 1874-1879 [18] V C J Singh, S J Sekhar, K Thyagarajan, Performance studies on downdraft gasifier with biomass energy sources available in remote villages, American Journal of Applied Sciences 11(2014) 611-622 [19] B Buragohain, P Mahanta, S Vijayanand,... Vijayanand, Moholkar, Investigations in gasification of biomass mixtures using thermodynamic equilibrium and semi–equilibrium models, Energy and Environment 2(2011) 551-578 9 | Paper ID :ICP2015-CP141 Page 10 of 13 [20] P.C Roy, A Dutta, N Chakraborty, Assessment of cow dung as a supplementary fuel in a downdraft biomass gasifier, Renewable Energy 35(2010) 379-386 [21] A Melgar, J.F Perez, H Laget, A. .. 6.0 50.25 0.55 0 4.98 17.16 Biomass Coconut shell Rubber seed shell 11 | Paper ID :ICP2015-CP141 Page 12 of 13 Table 2 Different types of blends of biomass materials Feedstock Combination Primary Secondary Energy Energy Source Source Coconut Shell Rubber Seed Shell Mole Blend Fraction Ratio Symbol 100:0 D0 90:10 D1 70:30 D2 60:40 D3 12 | Paper ID :ICP2015-CP141 Page 13 of 13