Per Risberg

Partially pre-mixed auto-ignition of gasoline to attain low smoke and low NOx at high load in a compression ignition engine and comparison with a diesel fuel

A Swedish MK1 diesel fuel and a European gasoline of ∼95 RON have been compared in a single cylinder CI engine operating at 1200 RPM with an intake pressure of 2 bar abs., intake temperature of 40° ...

Advantages of Fuels with High Resistance to Auto-ignition in Late-injection, Low-temperature, Compression Ignition Combustion

Oxides of nitrogen (NOx) and smoke can be simultaneously reduced in compression ignition engines by getting combustion to occur at low temperatures and by delaying the heat release till after the ...

Auto-ignition quality of Diesel-like fuels in HCCI engines

In Homogeneous Charge Compression Ignition (HCCI) engines heat release occurs by auto-ignition and hence the fuel auto-ignition quality is very important. The auto-ignition quality of Diesel fuel ...

A Method of Defining Ignition Quality of Fuels in HCCI Engines

A homogeneous charge compression ignition (HCCI) engine has been run at different operating conditions with fuels of different RON and MON and different chemistries. The ignition quality of the f ...

Auto-ignition Quality of Gasoline-Like Fuels in HCCI Engines

Auto-ignition of fuel mixtures was investigated both theoretically and experimentally to gain further understanding of the fuel chemistry. A homogeneous charge compression ignition (HCCI) engine was run under different operating conditions with fuels of different RON and MON and different chemistries. Fuels considered were primary reference fuels and toluene/n-heptane blends. The experiments were modeled with a single-zone adiabatic model together with detailed chemical kinetic models. In the model validation, co-oxidation reactions between the individual fuel components were found to be important in order to predict HCCI experiments, shock-tube ignition delay time data, and ignition delay times in rapid compression machines. The kinetic models with added co-oxidation reactions further predicted that an n-heptane/toluene fuel with the same RON as the corresponding primary reference fuel had higher resistance to auto-ignition in HCCI combustion for lower intake temperatures and higher intake pressures. However, for higher intake temperatures and lower intake pressures the n-heptane/toluene fuel and the PRF fuel had similar combustion phasing.

The Influence of NO on the Combustion Phasing in an HCCI Engine

In this work the influence of NO on combustion phasing has been studied experimentally in a single cylinder HCCI engine. A isooctane/n-heptane blend (PRF), a toluene/n-heptane mixture (TRF) and a ...

The Influence of EGR on Auto-ignition Quality of Gasoline-like Fuels in HCCI Engines

In previous studies it has been shown that the auto-ignition quality of a fuel at a given engine condition can be described by an octane index defined as, OI=(1-K) RON + K MON, where RON and MON ...

Development of a Heavy Duty Nozzle Coking Test

The diesel engine is still one of the most common and most efficient mobile energy converters. Nevertheless, it is troubled by many problems, one of them being nozzle coking. This is not a new prob ...

In situ biocatalytic synthesis of butyl butyrate in diesel and engine evaluations

Blending petroleum fuels with biofuels is likely to become increasingly important over the years to come. Butyl butyrate has promising characteristics as a blend component in diesel and can be synthesized by lipase‐catalyzed esterification of 1‐butanol and butyric acid, which both can be derived from fermentation technologies. In the current study, the enzyme load and reaction temperature were optimized for the production of butyl butyrate with Novozyme 435 (immobilized Candida antarctica lipase B) directly in diesel at a substrate concentration of 1 m using a molar ratio of 1:1 between n‐butanol and butyric acid. Optimum conditions were found by using a central composite design at an enzyme load of 12 % of substrate weight and a temperature of 57 °C, giving 90 % yield conversion in 30 min, corresponding to a butyl butyrate productivity of 1.8 mol L−1 h−1. Diesel blended with 5, 10, and 30 % butyl butyrate was tested in a heavy‐duty diesel engine under two load cases. The ignition properties of the blended fuels were very similar to pure diesel, making butyl butyrate an interesting diesel substitute. The emission analysis demonstrated lower soot and CO emissions, similar hydrocarbons levels and slightly increased NOx levels compared with using pure diesel. The high activity of lipase in diesel and the compatibility between diesel and butyl butyrate opens up the possibility to develop fuel blending systems where the synthesis of the blend‐in component occurs directly in the fuel.

Nozzle Coking in CNG-Diesel Dual Fuel Engines

Currently there is a large interest in alternative transport fuels. There are two underlying reasons for this interest: the desire to decrease the environmental impact of transports and the need to compensate for the declining availability of petroleum. In the light of both these factors, the CNG-diesel dual fuelengine is an attractive concept. The primary fuel of the dual fuel engine is methane, which can be derived both from renewables and from fossil sources. Methane from organic waste, commonly referred to as biomethane, can provide a reduction in greenhouse gases unmatched by any other fuel. Furthermore, fossil methane, natural gas, is one of the most abundant fossil fuels.Thedual fuelengine is, from a combustion point of view, a hybridof the diesel and theOtto-engineand it shares characteristics with both.From a market standpoint, the dual fuel technology is highly desirable; however, from a technical point of view it has proven difficult to realize. The aim of this project was to identify limitations to engine operation, investigate these challenges, and ,as much as possible, suggest remedies. Investigations have been made into emissions formation, nozzle-hole coking, impact of varying in-cylinder air motion, behavior and root causes of pre-ignitions, and the potential of advanced injection strategies and unconventional combustion modes. The findings from each of these investigations have been summarized, and recommendations for the development of a Euro 6 compliant dual fuel engine have been formulated. Two key challenges must be researched further for this development to succeed: an aftertreatment system which allows for low exhaust temperatures must be available, and the root cause of pre-ignitions must be found and eliminated.