## 3 Test Engine and Parameter Measurement  
A single cylinder diesel engine was adopted in these studies. It is water cooled and natural aspired. The main technical specifications are listed in Table 2. A twin cylinder, water cooled and natural aspired diesel engine with the same emission level was applied, too. Its specifications are listed in Table 2. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Oil** & **Alcohol** & **Product** & **Density** & **LHV** & **OC** & **CN** \\ \hline
0\# diesel & / & 0\# diesel & 860 & 42.5 & 0 & 50 \\ \hline Rapeseed & methanol & RCOOCH\({}_{3}\) & 884 & / & 10.9 & 51 \\ Cottonseed & methanol & RCOOCH\({}_{3}\) & 886 & 37.5 & 10 & 52 \\ \hline Rapeseed & & & 910 & 38.7 & / & / \\ Soybean & ethylene glycol methyl ether & RCOOCH\({}_{2}\)CH\({}_{2}\)OCH\({}_{3}\) & 907.2 & 38.5 & / & 66 \\ Peanut & ethylene glycol methyl ether & RCOOCH\({}_{2}\)CH\({}_{2}\)OCH\({}_{3}\) & 939.1 & 37.0 & / & / \\ Cottonseed & & & 901.5 & 38.5 & 14.3 & 70.1 \\ \hline Palm & ethylene glycol ethyl ether & RCOOCH\({}_{2}\)CH\({}_{2}\)OC\({}_{2}\)H\({}_{5}\) & 893.4 & 36.2 & & 80.4 \\ Soybean & & & 902.7 & 38.6 & / & / \\ \hline Palm & ethylene glycol n-propyl ether & RCOOCH\({}_{2}\)CH\({}_{2}\)OC\({}_{3}\)H\({}_{7}\) & / & 37.3 & 16.35 & 72.3 \\ \hline Palm & propylene glycol methyl ether & RCOOCH(CH\({}_{3}\))CH\({}_{2}\)OCH\({}_{3}\) & 889.2 & / & / & / \\ Cottonseed & diethylene glycol methyl ether & RCOOCH\({}_{2}\)CH\({}_{2}\))\({}_{2}\)OCH\({}_{3}\) & 912.0 & 37.0 & 16.88 & 76.9 \\  & triethylene glycol methyl ether & RCO(OCH\({}_{2}\)CH\({}_{2}\))\({}_{3}\)OCH\({}_{3}\) & 935.5 & 35.8 & 18.90 & 80.9 \\ \hline Standard & & & ASTM & ASTM & ASTM & ASTM \\ \hline \end{tabular}
\end{table} 
Table 1: New models of biodiesel and some of their fuel properties [32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Engine Type** & **2102 QB** & **TY1100** \\ \hline Bore \(\times\) Stroke (mm) & 102 \(\times\) 115 & 100 \(\times\) 115 \\ Displacement (cm\({}^{3}\)) & 1880 & 903 \\ Chamber shape & \(\omega\) & \(\omega\) \\ Compression ratio & 17.5:1 & 18:1 \\ Rated power (\(kW\)) @ speed (r-min\({}^{-1}\)) & 23.5/2300 & 11/2300 \\ Injector type & ZCK1548432 & ZCK1548432 \\ Nozzle hole number–diameter (mm) & 4\(\times\)\(\Phi\)0.3 & 4\(\times\)\(\Phi\)0.3 \\ Delivery timing (deg. BTDC) & 25 & 25 \\ Injection pressure (MPa) & 19.0 & 19.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Single and Twine cylinder diesel engine parameters. The biodiesel used in the tests were laboratory produced. They ran the test diesel engines purely or mixed with China 0# petrodiesel of that time in several different ratios. Some of the related fuel properties are listed in Table 1. The blended fuel properties can be referred in the related literatures. During the tests, the engine was kept under warmed up condition at water temperature of 80 \({}^{\circ}\)C and lubricant oil temperature of 60 \({}^{\circ}\)C. The change of fuels followed a standard schedulal in case of mixing with the former fuel. The test conditions were mainly compared at 1400 r\(\cdot\)min\({}^{-1}\) and 2200 r\(\cdot\)min\({}^{-1}\), the max torque speed and the related speed conditions, respectively. The applied equipment in the engine tests were Kistler pressure sensors and DL750 Data Acquisition System, AVL DiGas and DiSmoke, et al. Engine combustion and emissions data were focused here and compared with the results of the pure petrodiesel operation. The experimental setup for engine combustion performance and emissions measurement is shown in Figure 6. An electrical eddy-current dynamometer was applied to determine the engine torque and brake mean effective pressure (BMEP) can be calculated. An AVL DiSmoke4000 opacimeter was used to record smoke number expressed in extinction coefficient. A five-gas analyzer of type AVL DiGas4000 light was utilized to examine NO\({}_{x}\), CO and HC emissions on-line.