In-cylinder heat transfer characteristics of hydrogen fueled engine: a steady state approach.

Author:Rahman, M.M.
 
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INTRODUCTION

Hydrogen, as an alternative fuel, has the unique properties which provides a significant advantages over other types of fuel. It can be used as a vehicle fuel which is promising in the effects of establishes an environmental friendly mobility system. Extensive studies were performed on hydrogen fueled internal combustion engines (White et al., 2006; Kahraman et al., 2007; Rahman et al., 2009a; 2009b). The increasing concern of energy shortage and environmental protection, research are going on for improving engine fuel economy. Hydrogen engine is being developed into a hydrogen fueled engine with different types of fuel supply method (Kahraman et al., 2007; Rahman et al., 2009a; Bakar et al., 2009). It is particularly suitable for fueling internal combustion engines (Yusaf et al., 2005). The flow field identification inside a cylinder of internal combustion engines during the intake, compression, expansion and exhaust strokes are an important stage for comprehension of physical phenomenon which occurs in the motor cycle. The movement of the inlet air-fuel mixture has a great influence on the performance of the engine. Developments in the engine simulation technology have made the virtual engine model a realistic suggestion (Li et al., 2000). Now-a-day, computational fluid dynamics codes are used to simulate the engine performance and visualize the flow characteristics (Bahram et al., 1994). Application of these codes for engine improvement have saved significant time and cost in the design and development stage of combustion engine system (Shojaeefard and Noorpoor, 2008). Computational modeling and analysis of in-cylinder gas flow is a major part of successful combustion, emission production and engine performance simulation. Realization of the in-cylinder gas flow characteristics for the internal combustion engine is very substantial for advanced understanding and further optimization of the engine. The in-cylinder gas flow characteristics have major influence on combustion process, fuel consumption, emission production and engine performance. The objective of this study is to investigate the variation of in-cylinder heat transfer characteristics of port injection hydrogen fueled internal combustion engine by utilizing steady state method. The effect of engine speed and AFR are also investigated.

MATERIALS AND METHODS

Engine model: A single cylinder port injection hydrogen fuel model was developed utilizing the GT-suite software. The injection of hydrogen was studied in the midway of the intake port. The computational model of single cylinder hydrogen fueled engine is shown in Fig. 1. The engine specifications are listed in Table 1. The intake and exhaust ports of the engine cylinder are modeled geometrically with pipes and the air enters through a bell-mouth orifice to the pipe. The discharge coefficients of the bell-mouth orifice were set to 1 to ensure the smooth transition. The diameter and length of bell-mouth orifice pipe are 0.07 and 0.1 m respectively and it is connected to intake air cleaner with 0.16 m of diameter and 0.25 m of length. A log style manifold was developed from a series of pipes and flow-splits. The total volume of each flow-split was 256 [cm.sup.3]. The flow-splits compose from an intake and two discharges. The intake draws air from the preceding flow-split. One discharge supplies air to adjacent intake runner and other supplies air to the next flow-split. The last discharge pipe was closed with a cup. The flow-splits are connected with each other through pipes with 0.09 m diameter and 0.92 m length. The junctions between the flow-splits and the intake runners were modeled with bell-mouth orifice.

[FIGURE 1 OMITTED]

Table 1: Engine specification...

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