Papers by Sukumar Devotta
Fluid Phase Equilibria, 2008
Supplemental material, sj-pdf-2-pie-10.1177_09544089211021274 for CFD simulation of HC-290 leakag... more Supplemental material, sj-pdf-2-pie-10.1177_09544089211021274 for CFD simulation of HC-290 leakage from a split type room air conditioner by C Ram Prakash, MR Gautham, D Mohan Lal Sukumar Devotta and D Colbourne in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering
International Journal of Refrigeration, 1985
No 1 (January/janvier) pp 1-64 No 2 (March/mars) pp 65-128 No 3 (May/real) pp 129-192 No 4 (July/... more No 1 (January/janvier) pp 1-64 No 2 (March/mars) pp 65-128 No 3 (May/real) pp 129-192 No 4 (July/juillet pp 193-256 No 5 (September/saptembre) pp 257-320 No 6 (November/novembre) pp 321-384 Articles (articles written in French are marked Fr) Analysis of solar absorption cooling systems with low generator temperatures P. Kumar and S. Devotta 356 Analytical method for predicting freezing times of rectangular blocks of foodstuffs Q. T. Pham 43 Application of microelectronics to refrigeration and heat pump technology S. Nowotny 209 Blanching and quality of frozen vegetables and fruit. Review. 2. Sensorial aspects J. Philippon and M.-A. Rouet-Mayer (Fr) 48 Blanching and quality of frozen vegetables and fruit. Review. 3. Nutritional and hygienic aspects, conclusions J. Philippon and M.-A. Rouet-Mayer (Fr) 102 Calculation of thermodynamic properties of refrigerants by the Redlich-Kwong-Soave equation of state R. Camporese, G. Bigolaro and L. Rebellato 147 Chilling hot boned meat with solid carbon dioxide A. Gigiel 91 Combined momentum, heat and mass transfer in vertical slug flow absorbers C. A. Infante Ferreira 326 Comparison between fixed and fluidized bed continuous pea freezers R. O. Reynoso and A. Calvelo 109 Cool storage for air conditioning systems in
Supplemental material, sj-pdf-9-pie-10.1177_09544089211021274 for CFD simulation of HC-290 leakag... more Supplemental material, sj-pdf-9-pie-10.1177_09544089211021274 for CFD simulation of HC-290 leakage from a split type room air conditioner by C Ram Prakash, MR Gautham, D Mohan Lal Sukumar Devotta and D Colbourne in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering
Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 2021
HC-290 is one of the alternatives to HCFC22 in room air-conditioners. With the phase-down schedul... more HC-290 is one of the alternatives to HCFC22 in room air-conditioners. With the phase-down schedules in Kigali Amendment, it is imperative to use HC-290. However, there are concerns about its flammability in the event of a leak from the AC indoor unit (IDU). IEC 60335-2-40 has been revised to extend the capacity ranges for A2L refrigerants and is being further revised with a focus on A2 and A3 refrigerants. In real-life situations, furniture and occupants are present inside the room and these may positively or negatively influence the dispersion of any leaked HC-290. CFD simulation of dispersion of leaked HC-290 has been carried out for a variety of scenarios. The variables include leakage rates, IDU installation heights, IDU blower ON or OFF and types of furniture. Furniture, in general, appears to promote mixing, thereby reducing HC-290 stratification. The maximum concentration occurs on the side where the leak is directed by the momentum of the jet from IDU. There is no significan...
Supplemental material, sj-pdf-4-pie-10.1177_09544089211021274 for CFD simulation of HC-290 leakag... more Supplemental material, sj-pdf-4-pie-10.1177_09544089211021274 for CFD simulation of HC-290 leakage from a split type room air conditioner by C Ram Prakash, MR Gautham, D Mohan Lal Sukumar Devotta and D Colbourne in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering
Catalytic control of auto-exhaust emissions is one of the most successful applications of heterog... more Catalytic control of auto-exhaust emissions is one of the most successful applications of heterogeneous catalysis, both in commercial and environmental point of views. Although noble metal-based catalysts have dominated this area, efforts were always put in towards development of low cost non-noble metal-based catalysts. With the recent need of closed-coupled catalytic converter, thermal stability requirements have also become more severe, leading to the search for stable catalytic materials. Mixed oxides, including those perovskite type compounds with ABO 3 structure have been extensively studied, mainly for their catalytic and electrical properties. Low surface area of these catalysts has so far been the most important limitation for their catalytic applications involving high space velocities, e.g. auto-exhaust catalysis. Various synthesis routes have been earlier attempted to improve their surface area, yet this was much inferior than the noble metal catalysts, dispersed on high surface area alumina. The in situ synthesis of these oxides on alumina is often associated with the formation of undesired phases, due to the reactive nature of perovskite precursors. However, alumina washcoat, commonly used for improving the surface area of ceramic and metallic catalyst supports, can be modified for perovskite applications. In situ synthesis of stabilized perovskites on modified alumina-washcoated supports offer high surface area and excellent catalyst adhesion. Although, it is difficult to ascertain the presence of pure perovskite type materials on support, such improved synthesis has resulted in remarkable improvement in their catalytic activity for their applications in auto-exhaust catalytic converters. This review presents our work on synthesis of various improved perovskite-type mixed oxides supported on modified alumina-washcoated cordierite honeycomb, their characterization, and detailed catalytic evaluations for possible application in automobile pollution control.
Heat Recovery Systems and CHP, 1987
Theoretical Rankine coefficients of performance and compression ratios have been presented for he... more Theoretical Rankine coefficients of performance and compression ratios have been presented for heat pump systems operating on RI3BI. These values are listed in tabular form for temperature lifts of 10-75°C and condensing temperatures of 15-50°C in 5°C increments. A composite plot has been drawn to illustrate the feasible operating range of RI3BI heat pump systems
Journal of Environmental Engineering and Science, 2008
Solid waste management systems currently receive wide attention, from both economic and environme... more Solid waste management systems currently receive wide attention, from both economic and environmental planners, because of their complexity during coordination of various management strategies. The efficiency and cost effectiveness of route optimization and disposal site selection depend largely upon the appropriate placement of storage bins and their corresponding command area for waste contribution. The present paper illustrates a geographic information system (GIS) based algorithm for optimal location and number of storage bins, considering p-median constrained model, based on Indian guidelines for Municipal Solid Waste Rules. The algorithm also computes the contributing command area of solid waste to a particular bin, based on the shortest distance, with descending slope for ease in solid waste collection.
Journal of Agricultural and Food Chemistry, 2006
The feasibility of using surfactant-modified zeolite (SMZ) as a carrier for fertilizer and for sl... more The feasibility of using surfactant-modified zeolite (SMZ) as a carrier for fertilizer and for slow release of phosphorus (P) was investigated. Zeolite-A was modified by using hexadecyltrimethylammonium bromide, a cationic surfactant, to modify its surface to increase its capacity to retain anion, namely, phosphate (PO 4 3-). SMZ was thoroughly characterized using X-ray diffraction, Fourier transform infrared, and scanning electron microscopy to study the effect of surfactant modification. Zeolite-A and SMZ were then subjected to P loading by treating them with fertilizer (KH 2 PO 4). It was observed that the P loading on SMZ increased by a factor of 4.9 as compared to the unmodified zeolite-A. A comparative study of the release of P from fertilizer-loaded unmodified zeolite-A and SMZ and from solid KH 2 PO 4 was performed using the constant flow percolation reactor. The results show that the P supply from fertilizer-loaded SMZ was available even after 1080 h of continuous percolation, whereas P from KH 2 PO 4 was exhausted within 264 h. The results indicate that SMZ is a good sorbent for PO 4 3-, and a slow release of P was achievable. These properties suggest that SMZ has a great potential as the fertilizer carrier for slow release of P.
International Journal of Refrigeration, 1985
Closed cycle absorption cooling systems have been analysed using water-lithium bromide and ammoni... more Closed cycle absorption cooling systems have been analysed using water-lithium bromide and ammoniawater as working fluid pairs. An open cycle system using water-lithium bromide has also been analysed and compared with the closed cycle system. A flat plate collector has been considered for heat supply to the generator of the closed cycle systems. The effect of high flow ratios on the overall solar collector area required has been studied. It has been shown that the daily operating time of a cooling system can be increased by employing relatively high flow ratios.
Desalination, 2007
The paper comprises a case study on the implementation of the advance treatment process (ATP) in ... more The paper comprises a case study on the implementation of the advance treatment process (ATP) in seven smallscale textile industries. The ATPs installed and commissioned are in compliance with the Statutory Board directions for recovery and reuse of treated effluent leading to zero effluent discharge. The textile effluents are treated in effluent treatment plants comprising a physicochemical option followed by biological activated sludge process, pressure sand filtration and activated carbon adsorption. The tertiary treated effluents (25-65 m 3 /d) are high in total dissolved solids, chlorides and hardness, and partly reused for washing screens, cloth and ash quenching. The tertiary treated effluent contained suspended solids and total dissolved solids in the range, 4-30 mg/L and 1980-2682 mg/L, respectively, with COD concentrations in the range, 125-410 mg/L and did not meet the stipulated standards for discharge into inland surface waters. A part of the tertiary treated effluent (4.0-9.5 m 3 /d) is routed to ATP for recovery of boiler feed quality water. The ATP comprises a multi-grade filter, ultrafiltration (UF) unit and a reverse osmosis (RO) unit. The multi-grade filter ensured complete removal of suspended solids with a marginal decrease in COD. The fouling index (b) for the feed to the ultrafiltration was estimated to be varying in the range 0.6-2.1× 10 !3 s !1 .The UF operated at 200-300 kcals with 88-95% permeate recovery. This unit achieved 80-90% removal of BOD and COD and 65-90% removal of phosphates. The RO unit at a pressure range of 1270-1670 kPascals produced 68-84% permeate. The permeate characteristics conforms the boiler water quality as prescribed by the Indian Standards Institution for low-pressure drum type boilers. The pH of the recovered water was adjusted with alkali to pH 10-11 and mechanically deaerated for use in boilers. Recycle/reuse of tertiary treated effluents for various purposes and reuse of the recovered water from advance treatment process as boiler water make-up has resulted in a reduction in water requirements by 30-35% in each industry.
Bulletin of Environmental Contamination and Toxicology, 2005
ABSTRACT
Bulletin of Environmental Contamination and Toxicology, 2008
Source apportionment study is carried out to identify the sources of particulate matter of size l... more Source apportionment study is carried out to identify the sources of particulate matter of size less than 10 lm in Mumbai using chemical mass balance model. Various locations representing different activity zones as low activities (control), normal activity including commercial and residential areas and traffic sites (kerbside) are selected for this purpose to represent the city. It is observed that at control sites industrial contributions prevail, the other significant contributions are from marine and vehicular activities. At normal activity sites, vehicular, industrial and soil dust contributions are observed to be dominant. At two of the kerbside sites, marine contributions are observed to be significant which was due to the proximity of the sites to sea. The vehicular and soil dust contributions are observed to be significant at remaining kerbside sites. The study is useful for preparing the particulate matter reduction action plan for Mumbai, which can be extended further to other cities of India.
Atmospheric Environment, 2004
In developing countries like India, urban solid waste (SW) generation is increasing enormously an... more In developing countries like India, urban solid waste (SW) generation is increasing enormously and most of the SWs are disposed off by land filling in low-lying areas, resulting into generation of large quantities of biogas. Methane, the major constituent gas is known to cause global warming due to green house gas (GHG) effect. There is a need to study the ever-increasing contribution of SW to the global GHG effect. To assess the impacts, estimation of GHG emission is must and to avoid misguidance by these emission-data, qualitative assessment of the estimated GHG is a must. In this paper, methane emission is estimated for a particular landfill site, using default methodology and modified triangular methodology. Total methane generation is same for both theoretical methodologies, but the modified triangular method has an upper hand as it provides a time-dependent emission profile that reflects the true pattern of the degradation process. To check the quality of calculated emission-data, extensive sampling is carried out for different seasons in a year. Field results show a different trend as compared to theoretical results, this compels for logical thinking. Each methane emission-data is backed up by the uncertainty associated with it, this further strengthens the quality check of these data. Uncertainty calculation is done using Monte Carlo simulation technique, recommended in IPCC Guideline. In the due course of qualitative assessment of methane emission-data, many site-specific sensitive parameters are discovered and are briefly discussed in this paper.
Ruthenium (Ru)-based catalytic materials show good catalytic properties for oxidation reactions. ... more Ruthenium (Ru)-based catalytic materials show good catalytic properties for oxidation reactions. However, their thermal stability has been a limitation. Ruthenia-based catalysts have been prepared by supporting different amounts on titania by the impregnation method. These ruthenia-based catalysts show good catalytic activity for carbon/soot oxidation, which could be due to the improved surface area of titania-supported materials as well as the synergistic effect. Catalysts also show improved thermal stability, which is probably due to the formation of solid solution. Dissociative adsorption of oxygen on Ru sites appears to be the plausible mechanism for catalytic activity. It appears possible to influence the catalytic properties of RuO 2 through solid solution formation with similar oxides. Such materials show potential for their possible applications in the regeneration of diesel particulate filters.
Applied Energy, 1989
ABSTRACT
Journal of Heat Recovery Systems
The bodmg temperature T~o m a Rankine cycle power plant is largely determmed by the temperature o... more The bodmg temperature T~o m a Rankine cycle power plant is largely determmed by the temperature of the available heat supply. The gross temperature drop (TBo-Too) is largely determined by the temperature of the coolant m the condenser Tlus means that for a given working fired, the theoreUcal Rankme power cycle effiaency q~ and the pressure ratio (PR) are deterrmned automatically. The only way that the values of r/s and (PR) can be vaned is to choose another working fired Of the 24 working flmds for wluch comprehensive thermodynamic data are avmlable, only 18 have critical temperatures high enough to be considered for use m Rankane cycle power plants with a boding temperature of 120°C and only seven can be considered for a boiling temperature of 200°C. Values of r/~ are listed for gross temperature drops of 20, 30, 40, 50, 60 and 70 K for boiling temperatures of 80, 100, 120, 160 and 200°C respect, vely. NOMENCLATURE Hx enthalpy of umt mass of working fluid at stale condition X [kJ kg-~] Pro vapour pressure of boiling working fluid [bar] Pco vapour pressure of condensing working flmd [bar] (PR) pressure raUo = Plo/Pco [dimensionless] Teo temperature of boiling working fluid [°C or K] Tco temperature of condensing working fired [°C or K] theoretical Camot heat engine efficiency [%] ~m theoretical Rankane power cycle effmency [~/o]
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Papers by Sukumar Devotta