G. Lakshmi Narayana Rao

Feasibility study of crude rice bran oil as a diesel substitute in a DI-CI engine without modifications

Oil extracted from the inner husk of rice, termed rice bran oil (RBO), promises to be a low-cost, renewable substitute for petroleum-derived diesel as a compression ignition (CI) engine fuel. While rice is a major crop in India, RBO is underutilized. This research work concentrates on the study of the prospect of using unrefined RBO as a diesel engine fuel without any modifications. Like other vegetable oils, crude RBO faces the problem of high viscosity and hence blending RBO with diesel is attempted in this work. Tests were conducted in a naturally aspirated direct injection (DI) four-stroke 4.4 kW stationary diesel engine with pure RBO and blends of RBO with diesel. It is observed that specific energy consumption (SEC) of RBO is higher than that of all the fuels at all loads and for 25% RBO, it is very close to that of diesel. As an oxygenated fuel, RBO reduces emission of pollutants like CO and unburnt hydrocarbon (UBHC) by supplying additional oxygen from the fuel. At no-load condition the delay period for RBO and its blends were slightly higher than for diesel. As the load increased the delay periods were shorter than for diesel. The maximum heat release rates of RBO and its blends were lower than that of diesel. The peak pressures for RBO and its blends were slightly higher and occurred earlier than that of diesel. In general blended fuels result in lower viscosity, better combustion and lesser emission than RBO and 25% RBO shows better results than RBO and other blends of RBO.

The comparative analysis of diesel engine combustion and emission parameters fuelled with palm oil methyl esters and its diesel blends

In this work, the combustion and emission characteristics of a direct injection compression ignition engine fuelled with diesel-Palm Oil Methyl Ester (POME) blends are investigated. This study shows that the ignition delay decreases with increase in the POME addition. The maximum rate of pressure rise and maximum rate of heat release decreases with increase in POME addition at all loads. As the percentage of POME in the blend increases, the crank angle at which the maximum rate of heat release takes place advances. The brake thermal efficiency decreases with increase in POME addition. The unburned hydrocarbon, carbon monoxide and soot intensity decreases, while nitrogen oxides (NOx) increase with increase in POME addition. [Received: April 4, 2008; Accepted: November 24, 2008]

Effect of blending crude rice bran oil methyl ester with diesel on properties as CI engine fuel

AbstractIn this study, an attempt was made to investigate the effect of blending a biodiesel derived from high free fatty acid crude rice bran oil (CRBO) with diesel on the properties as a fuel for compression ignition (CI) engine. Biodiesel [crude rice bran oil methyl ester (CRBME)] blend was prepared by mixing 20% CRBME with 80% diesel on a volume basis. As a result of blending CRBME, the flash point and viscosity of diesel increased by 14 and 3·4% respectively and calorific value decreased by 2%. The distillation curve of the CRBME blend was almost similar as that of diesel and an end point temperature of 337°C was obtained during the distillation of CRBME blend. Blending CRBME with diesel increases the specific gravity marginally and its cetane number increased by 2·3%. From this investigation, it was inferred that the properties of CRBME blend were comparable with that of diesel and it can be utilised as a CI engine fuel. As a renewable fuel its role as a partial substitution of diesel fuel can be vital.

Investigation on nonedible vegetable oil as a compression ignition engine fuel in sustaining the energy and environment

In the present investigation, a high free fatty acid (FFA) crude rice bran oil (CRBO), a renewable nonedible vegetable oil was tested on a direct injection compression ignition engine to find its ability to replace diesel oil and reduce the pollutants emitted. Three CRBO samples of different FFAs were tested in blended form to analyze the effects of high FFA with respect to engine performance and emission characteristics. With CRBO blends unburned hydrocarbon emissions were decreased significantly at all loads as a result of enhanced thermal oxidation inside the combustion chamber. The nitrogen oxides (NOx) emissions were reduced at lower loads and particulate emission reduced at higher loads. A marginal increase in carbon monoxide (CO) emission was noticed at all loads relative to diesel. The brake thermal efficiency of the engine was reduced marginally with CRBO blends. The experimental results show that high FFA CRBO can be used to partially replace diesel oil for a more sustainable energy and environment.

Combustion analysis of a direct injection diesel engine when fuelled with sunflower methyl ester and its diesel blends

Uncertainty in the availability of petroleum-based fuels in the near future and stringent pollution norms have triggered a search for renewable and clean-burning fuels. The use of vegetable oil as an alternative fuel has for long been in the pipeline, but its direct use has been limited because of its higher viscosity. In this work, sunflower oil was taken as feedstock and the feasibility of sunflower oil methyl ester (SFME) as an alternative fuel for diesel engines was investigated. Tests were conducted in a 4.4 kW, single cylinder; naturally aspirated direct injection diesel engine. It was observed that the premixed combustion phase of SFME and its blends were less intense compared with diesel oil. In addition, it was observed that SFME and its blends had slightly lower thermal efficiency and lower tailpipe emissions than diesel oil.

Effect of EGR on performance and emission characteristics of diesel engine at advanced injection timing

This work attempts to reduce the smoke density of diesel engine by advancing the fuel injection timing and also the NOx emission of the engine by introducing EGR at the advanced injection timing. A single cylinder 4.4 kW air cooled, naturally aspirated, stationary diesel engine was utilised for the investigation. Engine tests were conducted at different loads at standard injection timing and advanced injection timing with and without EGR and performance and emission parameters were measured. It was observed that the smoke density was decreased by 33% at advanced injection timing with 20% increase in NOx emission. As a result of EGR, NOx emission was decreased by 63% with marginal increase in smoke density. The increase in smoke density resulted from EGR is lower than the smoke density of the engine at standard injection timing. Advanced injection timing with EGR increases the maximum heat releases rate of the engine.

Emission Characteristics of DI CI Engine Fuelled With High FFA CRBO Blend

In this investigation high FFA CRBO a renewable non-edible vegetable oil was tested to find its suitability as a CI engine fuel in its blended form. A dilute blend was prepared by mixing it with petroleum diesel in volume basis [20% CRBO + 80% No.2 petroleum diesel]. The main objective of this investigation is to study the performance and emission characteristics of this high FFA CRBO blend by employing it as a fuel for diesel engine. Tests were conducted on a naturally aspirated DI stationary diesel engine coupled to a swinging field dynamometer. Emissions were measured by using MRU Delta 1600 L gas analyzer. Variations in the emission of UBHC, CO, NOX and smoke density were found for different loads and compared with diesel. It was observed that when operating with CRBO blend, engine emissions levels are reduced significantly than that of diesel. When compared with diesel fuel, NOx emission, UBHC emission and smoke density for CRBO blend were lower with slight increase in CO emissions. It was also observed that the variations in brake thermal efficiency between CRBO blend and diesel were minimum at all operating conditions. From the experimental results it can be concluded that as a dilute blend higher FFA CRBO has an ability to replace petroleum diesel partially as the engine emissions were reduced significantly with minor loss in power.Copyright