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The paper presents a survey of the opportunities to convert compression ignition heavy duty truck engines to work on single or dual fuel modes with CNG. In one popular option, the compression ignition engine is converted to spark ignition with throttle load control and port injection of the CNG. In another option of increasing popularity, the LNG is directly injected and ignited by direct injection of pilot Diesel. This latter option with direct injection of natural gas and diesel through separate injectors that are fully independent in their operation is determined to be the most promising, as it is expected to deliver better power density and similar part load fuel economy to Diesel.

Exhaust heat recovery systems are used to make use of otherwise wasted heat from a car engine. The purpose of exhaust heat recovery systems is to reduce the fuel consumption of the car and consequently reduce CO2 emissions. The unique system design described herein utilises thermoelectric generators (TEGs) and heat pipes with its key advantage being it is a passive solid state design. The use of these components creates a few design constraints. For example, both the TEGs and heat pipes have operating temperature limitations. In this paper, a naphthalene heat pipe preheat exchanger is proposed to deal with this problem. Exhaust conditions measured from a representative spark ignition engine were used in a numerical simulation to predict the performance of the exhaust heat recovery system. If 8 modules are used and the engine is producing 8kW of mechanical power, the system is predicted to produce 53.75W of electrical power.

The air entrainment process of a compressed natural gas transient fuel jet was investigated in a constant-volume chamber using Schlieren and particle image velocimetry (PIV) techniques. A new method of calculating air entrainment around a gaseous fuel jet is proposed using Schlieren and PIV imaging techniques. This method offers an alternative to calculation of an alternative to calculation of entrainment using LIF technique in gaseous fuel jets. Several Jet-ambient pressure ratios were tested. In each test, nitrogen was used to fill the chamber as an air surrogate before the jet of natural gas was injected. Schlieren high speed videography and PIV experiments were performed at the same conditions. Schlieren mask images were used to accurately identify the jet boundary which was then superimposed onto a PIV image. Vectors adjacent to the Schlieren mask in the PIV image were used to calculate the spatial distribution of the air entrainment at the jet boundary.

High pressure ratio (PR) compressed natural gas (CNG) jets are studied using optical diagnostics under quiescent but realistic spark-ignited (SI) engine conditions. CNG jets were issued impulsively from a bespoke direct injector. Observations into the delivery characteristics for a large pressure ratio (PR) range were carried out (8.3

Significant research has been made on traditional pre-mixed charge Spark-Ignition Natural-Gas engines which have seen widespread usage across the automotive sector. Many researchers including those in industry are now exploring the Direct-Injection concept for Natural-Gas Spark-Ignition engines. Direct-Injection has significant performance benefits over port-fuel injection, primarily due to increased volumetric efficiency as a result of injecting the fuel after intake valve closure. This could lead to enhanced driving performance over port-fuel injection comparable to gasoline engines. Furthermore, Direct-Injection with increased compression ratio in conjunction with downsizing concepts has the potential to increase thermal efficiency while exhibiting significantly lower CO2 emissions. Advanced combustion strategies like stratified mixture combustion has been widely studied for gasoline and proven to increase the low load thermal efficiency over homogeneous stoichiometric combustion.