**2. Experimental setup**

### **2.1 High-pressure and high-temperature chamber vessel**

The experimental research has been performed by the author [9] using high pressure and high-temperature chamber vessel with four side windows. The experimental setup was described in **Figure 1**. Two transparent quartz windows were placed for visualization purposes. The others were facing each other which are used for an injector and spray, respectively. Three K-type thermocouples were installed close to the wall with the gap of 5 mm. These thermocouples were placed among the nozzle

**Figure 1.** *High-speed video camera setup.*

*Effect of Injection Pressure on Local Temperature and Soot Emission Distribution of Flat-Wall… DOI: http://dx.doi.org/10.5772/intechopen.102867*

tip and wall for injection time purposes. If the ambient temperature was reached of set-point temperature, the diesel fuel will be injected to the chamber. Temperature gradient of these thermocouple was 5K. The injection pulse was defined as injection rate measurement.

**Figure 1** shows the high-speed camera setup and its arrangement. This high-speed video camera was installed to figure out the flame pattern at a frame rate of 20.000 fps (frames per second) with a resolution of 320 x 448 pixels. It indicates that each image has a resolution of 5 pixels per millimeter. Meanwhile, the two-color method was employed to investigate the relation between diesel flame and wall heat loss. Not only is the relation between diesel flame and wall heat loss, but also the distribution of soot and local temperature unable to observe by using the two-color method. The main principle of the two-color method is providing a number of assumptions by using different wavelengths of radiation intensity then the flame temperature and soot formation were found out. The soot concentration is defined from Hotel and Broughton's model which is represent the KL factor. More explanations about KL Factor have already been mentioned in the previous work [9, 10].

The two-color technique was calibrated using a standard light illuminant. Nac Image Technology's "Thermias" two-color pyrometry software was used to analyze the data. As a result, the flame temperature and KL factor were two-dimensional with line-of-sight information.

#### **2.2 Test conditions**

Combusting spray conditions were tested, which is containing the amount of air at high temperature to figure out the local temperature and KL factor under injection pressure. Uniform gas density is set to 16 kg/m3 with keeping the ambient pressure at 4.1 MPa. Measurement conditions on the small-size diesel engines were determined in actual operation to reach the optimum results. Temperature and pressure were adjusted to compression TDC (top dead center) in low load operation for self-ignite


**Table 1.** *Experimental conditions.* the fuel purposes. The impinging distance of 40 mm was decided between the nozzle tip and the wall. Meanwhile, the test conditions were performed by using nozzle with a hole diameter 0.133 mm at three types of injection pressure 80, 120, and 180 MPa. Experimental conditions in detail can be seen in **Table 1**.
