The depletion of conventional fuel source at a fast rate and increasing environmental pollution have motivated extensive research in combustion modeling and energy efficient engine design. In the present work, a computer simulation incorporating progressive combustion model using thermodynamic equations has been carried out using MATLAB to evaluate the performance of a diesel engine. Simulations at constant speed and variable load have been carried out for the experimental engine available in the laboratory. For simulation, speed and Air/Fuel ratios, which are measured during the experiment, have been used as input apart from other geometrical details. A state-of-the-art experimental facility has been developed in-house. The facility comprises of a hundred horsepower water cooled eddy current dynamometer with appropriate electronic controllers. A normal load test has been carried out and the required parameters were measured. A six gas analyzer was used for the measurement of NOx, HC, CO 2 , O 2 , CO and SO x . and a smoke meter was used for smoke opacity. The predicted Pressure-Volume (PV) diagram was compared with measurements and found to match closely. It is concluded that the developed simulation software could be used to get quick results for parametric studies.

This paper reports the results of a study to determine a ternary blend of oxygenated additives for reduction in smoke emissions in diesel engines. Initial studies on binary blends established twenty percent (by volume) n-butanol-diesel blend (B20) as the base fuel. Subsequently observations were taken with Nitromethane (NM)-n-butanol-diesel blends. It was observed that binary blends are not able to reduce smoke and other emissions beyond the optimum blending ratio (B20). Also, Cetane Number of binary blends was found to be lowered due to poor Cetane Number of n-butanol. It is therefore necessary to add another additive which helps in reducing smoke substantially and improve Cetane Number of blend without affecting the other parameters. The study found that blending of one percent of NM by volume gives best results for smoke reduction. The overall effect of this ternary blend is to reduce the smoke and NO x up to 69.76% and 5.4% respectively. It is concluded that NM-n-butanol-diesel blend would be a potential fuel for smoke reduction in diesel engines.

A turbocharged three cylinder automotive common rail diesel engine was modified to operate in the n-butanol diesel dual fuel mode. The quantity of butanol injected by the port fuel injectors and the rail pressure, injection timing and number of injection pulses of diesel were varied using open engine controllers. Experiments were performed in the dual fuel mode at a constant speed of 1800 rpm at varying BMEPs. Butanol to diesel energy share (BDES) was varied and the injection timing of diesel was always set for highest brake thermal efficiency (BTE). Single pulse injection (SPI) and two pulse injection (TPI) of diesel were evaluated. In SPI with increase in butanol diesel energy share (BDES), BTE remained unchanged. At high loads and high BDES the heat release rate variation indicated that butanol auto ignited before diesel with both SPI and TPI of diesel. NO emission always decreased because of reduced temperatures due to evaporation of butanol. Butanol also reduced the smoke levels except at high loads. HC levels were always higher. With optimized injection parameters TPI of diesel resulted in lower NO, similar smoke and BTE with lesser rate of pressure rise as compared to SPI of diesel.

Buoyancy-driven exchange flows of helium-air through inclined a narrow tube was investigated. Exchange flows may occur following the opening of a window for ventilation, as well as when a pipe ruptures in a high temperature gas-cooled reactor. The experiment in this paper was carried out in a test chamber filled with helium and the flow was visualized using the smoke wire method. A high-speed camera recorded the flow behavior. The image of the flow was transferred to digital data, and the slow flow velocity, i.e. micro flow rate was measured by PIV software. Numerical simulation was carried out by the code of moving particle method with Lagrange method.

The operating experience from nuclear installations worldwide has provided a non-negligible number of mostly explosive plant internal fire events due to high energy arcing equipment faults (HEAF). These typically occur at higher voltage electrical components such as switchgears and circuit breakers, or at high cables. In some of the events, the electric arcs have led to partly significant consequences to the environment of the affected components exceeding typical fire effects. In-depth investigations have indicated failures of those fire barriers and protection features not designed against such impacts induced by the rapid pressure increase. The potential safety significance of HEAF events has caused the OECD Nuclear Energy Agency (NEA) to initiate a task on “HEAF” for in-depth investigations on this type of events in member states, their damage mechanisms and root causes as an important part of better understanding fire risk at NPP which is better accomplished by an international group to pool knowledge and research means. Major goal is to develop deterministic correlations to predict damage and to establish a set of input data and boundary conditions for more detailed modeling. The output may directly support development of improved treatment methods in fire PRA for NPP applications. One input into this OECD task is an in-depth analysis of the German operating experience with HEAF in nuclear power plants based on a questionnaire specifically developed for collecting the necessary data and information on these events. This survey has provided more than 30 events. The investigations demonstrate that HEAF only occur at few specific components such as switchgears and transformers, but also at cables and distribution connections on typical voltage levels between 0,4 kV and 400 kV. All high energy arcing faults reported from German nuclear power plants were detected within a short time period and signaled via fault indications. In case of a relevant release of smoke there was a fire alarm by the fire detection system. The separation of redundant trains was ensured in case of all events. Neither the required function of fire protection means nor additional components were impaired by the explosive failure. Technical causes have been found to be the major root causes for the high energy arcing faults. Other causes are human failure, ageing effects and faulty procedures in combination with other root causes. A variety of reasonable preventive measures have already or are to being taken in German nuclear power plants for improving nuclear safety.

While many power companies across the country rely on coal-burning facilities, fires and explosions in coal-handling facilities are of increasing concern. While facility housekeeping by means of controlling dust and preventing spills is very important, a good risk management plan must also include continuous monitoring of toxic and combustible gases. The use of carbon monoxide gas detectors has proved for years to be a very effective early fire detection system. This paper describes a risk-management system that can greatly mitigate the possibility of fire by means of alarming at low levels of CO concentration. The authors present a pro-active approach, focusing not on detecting smoke, which indicates fire, but rather on detecting CO, which indicates the potential for fire. Covered are the benefits of CO monitoring over thermal monitoring and IR scanning, the importance of monitoring for any continual trend upward from background levels, and discussion of how proper alarm setpoints are determined, using case studies.

An experimental study to compare the smoking characteristics of diffusion flames of propylene diluted nitrogen, argon, carbon dioxide and helium was performed. The mass flow rate of propylene at smoke point condition, which was defined as the critical fuel mass flow rate (CFMFR), was first determined. Then, CFMFR was divided into ten different fractions for the study of the mechanism of inert gas dilution on smoke point. The mass flow rate of each different inert gas to achieve the smoke point condition was then determined in the same manner. Flame radiation and the visible flame height for all the diluted fuel flames were measured. The axial soot concentration profiles of nitrogen-diluted smoke point flames were also measured using the laser induced incandescence (LII) method for selective conditions. The inert gas dilution study showed two distinct regions (chemical and momentum controlled regions). The study shows the amount diluent needed to achieve smoke point was in the decreasing order of Ar, CO 2 , N 2 and He on mass basis. The analysis of the results showed that the main reason for this phenomenon was the heat sink capability of the gas. Hence, the specific heat of the gas was an important parameter. In general, nitrogen-diluted flames had higher flame length than other inert gas diluted flames. At higher CFMFR, in helium-diluted flames radiation was higher than in other flames.

Fires can be a major problem when they occur in industrial power generation facilities. The volume, temperature, composition of combustion product species, and location of smoke produced in fires may be calculated. A computer code is described that accomplishes this. Smoke cooling and volume changes are included from radiation heat loss from the fire, cooler air entrainment into the plume (column of smoke products above the fire), and conduction heat loss through the ceiling. Any hydrocarbon fuel, also possibly containing oxygen, is permitted as the fuel, and it burns with a specified equivalence ratio with air or oxygen. If in “air”, the volume fraction of oxygen may be specified. For simplicity and because most applications are to fires burning in air, dissociation is omitted since this is rather minimal at the temperatures encountered. The mathematical basis and algorithms are presented, together with the methodology of the Excel/VBA computer code that permits easy input and output, and results show the versatility of the code.