Prof. S Dasappa is a faculty at the Centre for Sustainable Technologies, Indian Institute of Science. He had his education at the Indian Institute of Science and obtained Masters and Ph. D degree in the faculty of engineering. His area of research has been solid, liquid and gaseous fuel combustion science and technology. The work has resulted in the understanding of various processes occurring during gasification and answered several myths in the area of gasification. Research in the area of internal combustion engine using alternate fuels has resulted in addressing impact of fuel properties on engine in-cylinder performance. Some of the specific areas of research are,
He has over 150 publications in various international and national journals, conferences and edited books and 18 patents .Prof. Dasappa has been involved in technology transfer for bioenergy devices in India and abroad. He has been involved in several national and international projects. He has won several awards in the area of Biomass energy at national and international. He has supervised several Master's level thesis and a Ph D thesis in the area of bioenergy, combustion and related areas and is currently supervising 9 research students for Doctoral degree.
Prof. Dasappa has been involved in extramural Research support with Research grants and support from agencies like MNRE, DST, UNIDO, UNDP, Italian MATT, SIDA, Cummins Inc, EKZ Switzerland, DRDO, Tata Motors, GE, either as investigator or co-investigator over the last 6 years with project funding amounting to over 6 million USD. Further both the scientific and technological superiority has resulted in technology transfer to developing and developed nations. These technological interventions in industries have resulted in saving over 1000 tons of oil annually resulting in mitigating over 3000 tons of CO2.
The challenge in using biomass as fuel for gasification has been to generate consistent gas quality with low tar and also accept different types of biomass. This is related to the aero-thermochemistry aspects in the reactor design. Tar can be removed by enhancing the residence time of gas in the reactor maintained at high temperature (1000 – 1200 K) to improve the conversion of higher molecular weight compounds to lower molecular weight compounds. The novel reactor geometry designed earlier has been further researched to establish air mass flux for reactor design and also to accept agro residues whose ash content can vary. the main scientific consideration for such an intervention is the operating air mass flux, which has a dual role to play.
Pyrolysis, a diffusion process depends on the heating rate and thus the surface area of the particle is important. Experimental results on tar content in the raw hot gas were compared with wood flakes and standard wood pieces as fuel. The ratio of surface area to equivalent diameter is two times higher for flakes compared with wood pieces. It is clear that tar is about 80 % higher in the case of wood flakes compared with standard wood pieces. The analysis suggests that the time for pyrolysis is lower with a high surface area particle and is subjected to fast pyrolysis rates resulting high tar fraction. Further, it has also been shown that the fixed bed closed top down draft system, the residence time is insufficient to crack the tar. Experiments and analysis provide scientific basis for the generation of high tar in fixed bed gasification system for small size wood pieces. The quality and quantity of tar generated depends on the heat flux on the exposed particle. Increasing the residence time helps in reducing the hot tar. The open top configuration has a better control on residence time due to the propagation front.
Thermochemical conversion of biomass has potential for producing renewable hydrogen. The research carried out has resulted in establishing the process parameters for generating hydrogen rich fuel gas using oxy-steam as reactants. Experimental investigation was carried out in an open-top downdraft gasifier with facility to use steam and oxygen as reactants with lower contaminants. The critical issues addressed in this study are related to optimizing the oxygen flow rate for ensuring the appropriate thermal conditions, i.e., temperature and residence time inside the reactor and also controlling the higher propagation rate with the use of oxygen compared to air in an open top down draft configuration.
The use of producer gas in an engine whose properties are different poses critical challenges in optimizing engine operating parameters, like carburetion, ignition timing, peak power and turbocharging. In the area of using producer gas as a fuel in engines, contributions made have been towards establishing producer gas engine power capacity from an existing natural gas engine. Research on the turbo-charging of engines using producer gas has suggested that optimization of the compressor and turbine is essential for the new fuel as most of them are designed for natural gas. Continuing the earlier work in the laboratory on adapting natural gas engines for producer gas, the research focus on specific areas in using producer as a fuel in reciprocating engines are highlighted below.
Summarizing, the scientific contributions,
1.    HS Mukunda, PJ Paul, S Dasappa, NKS Rajan, , G Sridhar, HV Sridhar “Biomass Gasifier” Oct 1998 Indian Patent no. 217056.
2.    HS Mukunda, PJ Paul, S Dasappa, NKS Rajan, , G Sridhar, HV Sridhar “Biomass Gasifier” Oct. 2000 9623(P-11) Switzerland 1840/99 Patent no. 693 929.
3.    H.S. Mukunda, PJ Paul, S Dasappa, NKS Rajan, G Sridhar, HV Sridhar, An improved biomass gasifier, , Indian Patent granted No. 217056, Dated 2008.
4.    H.S. Mukunda, S. Dasappa, P.J. Paul, N.K.S. Rajan, G. Sridhar, H.V. Sridhar, Fuel efficient biomass stove and a method of operating the stove, Indian Patent granted No. 229283, Dated 2009.
5.    HS Mukunda, S. Dasappa, P.J. Paul, NKS Rajan, M. Jayamurthy, A process of removing hydrogen sulfide from a gaseous stream containing hydrogen sulfide. Indian Patent Granted no. 193111.
6.    H.S. Mukunda, S. Dasappa, P.J. Paul, NKS Rajan, DN Subbukrishna A novel process and apparatus for the manufacture of precipitated silica from rice husk ash, Indian Patent granted No. 216477, Dated 2008.
7.    H.S. Mukunda, S. Dasappa, P.J. Paul, NKS Rajan, D.N Subbukrishna. A novel process and apparatus for the manufacture of precipitated silica from rice husk ash, Chinese Patent granted No. ZL 200480005829.5, Dated 2008.
8.    S. Dasappa, H.S. Mukunda, P.J. Paul, N.K.S. Rajan, G. Sridhar, HV Sridhar, A process and apparatus for cleaning tar and dust laden gas to highest level of purity using Cn Technology, Indian Patent granted No. 215917, Dated 2008.
9.    H.S. Mukunda, S. Dasappa, P.J. Paul, NKS Rajan, DN Subbukrishna A novel process and apparatus for the manufacture of precipitated silica from rice husk ash, Indonesian Patent granted No. ID P 0024190, Dated 2009.
10.    HS Mukunda, S. Dasappa, P.J. Paul, N.K.S. Rajan, D.N. Subbukrishna, A novel process and apparatus for the manufacture of precipitated silica from rice husk ash, Japan Granted Patent No. 4537379, dated, 2010.
11.    H.S. Mukunda, P.J. Paul, S. Dasappa, N.K.S. Rajan, G. Sridhar, H.V. Sridhar An improved biomass gasifier, Japanese Patent granted No. 4805520, Dated 2011.
12.    HS Mukunda, S. Dasappa, P.J. Paul, N.K.S. Rajan, D.N. Subbukrishna, A novel process and apparatus for the manufacture of precipitated silica from rice husk ash, Vietnam Granted Patent No. 11795, dated, 2013.
1.    HS Mukunda, S. Dasappa, P.J. Paul, N.K.S. Rajan, D.N. Subbukrishna, A novel process and apparatus for the manufacture of precipitated silica from rice husk ash, Thailand patent application No. 088822.
2.    H. S. Mukunda, S. Dasappa, N.K.S. Rajan and P. J. Paul, Biomass stove apparatus and method for its use, H, Indian Patent application No: 1763/CHE/2008.
3.    H. S. Mukunda, S. Dasappa, N.K.S. Rajan and P. J. Paul, IISc Ejector Induced Gasification Stove - n kg/hour Indian Patent application No: 3202/CHE/2008.
4.    S. Dasappa, P. J. Paul and N.K.S. Rajan, Producer gas carburetor, Indian PATENT APPLICATION NO: 2659/CHE/2009.
5.    S. Dasappa, H.S. Mukunda, P.J. Paul, N.K.S. Rajan, G. Sridhar, H.V. Sridhar, A process and apparatus for cleaning Tar and Dust laden gas to highest level of purity using Cn Technology, PCT/IN2010/000713 filed on 1-12-2010.
6.    H.S. Mukunda, S. Dasappa, P.J. Paul, N.K.S. Rajan, , G. Sridhar, H.V .Sridhar, Fuel efficient biomass stove and a method of operating the stove, PCT, application No. 45524-50484).
7.    S. Dasappa, D.N. Subbukrishna, P. J. Paul, N.K.S. Rajan, Charcoal from biomass using gasification, Indian Patent application No. 2246/CHE/2011.
Graduate level courses on Bio energy systems, Renewable energy, Alternate fuels for IC Engines.
Sadhan Mahapatra: Experiments and Analysis on Wood Gasification in an Open Top Downdraft Gasifier [PDF]
Snehesh Shivananda Ail: Combustion synthesized cobalt catalysts for liquid fuel generation via Fischer Tropsch Reaction [PDF]
Anand M Shivapuji: In-cylinder experimental and modeling studies on producer gas fuelled operation of spark ignited gas engines [PDF]