Environmental Engineering Reference
In-Depth Information
dQ
d
γ
p
dv
d
1
v
dp
d
n
θ
=
..
+
.. ,
(25.1)
γ
−
1
θ
γ
−
1
θ
where
g
=C
p
/ C
v
is the ratio of specific heat,
dQ
n
/
d
θ
is the apparent net heat release rate,
dv
/
d
θ is the
rate of volume, and
dp
/
d
θ is the rate of pressure.
25.3.3 c
omBuStion
p
aramEtErS
A single cylinder air-cooled direct injection compression ignition engine developing a power output
of 4.4 kW at the rated speed of 1500 rpm was used for experimental studies. The engine was
coupled to an electrical dynamometer. The engine was fitted with all accessories to measure the
fuel consumption, air consumption, inlet air temperature, and exhaust gas temperature. The engine
was started with neat diesel fuel and warmed up. It was allowed to run for 10 min with biodiesel to
attain a steady condition at its rated speed of 1500 rpm. The engine was gradually loaded to full load
by switching on the load mains. The different biodiesel fuels were tested in a random order. The
speed of the engine was maintained at 1500 rpm, and the time taken for 10 cm
3
of fuel consumption
was measured using a stopwatch. The tests were repeated 5 times, and the average value of the five
readings was taken to eliminate uncertainty.
25.3.3.1
combustion Pressure measurement
Instrument used
A Kistler piezoelectric transducer with a range of 0 -250 bar was used.
Method
• The piezoelectric transducer was mounted on the cylinder head and connected to a charge
amplifier for measuring the pressure inside of the engine cylinder.
• By circulating the cooling water through the inlet opening, the transducer was cooled. The
central opening was used for sending signal to the amplifier.
• The TDC (top dead center) position signal was fed into the computer through the data
acquisition card. In this system, the analogue signal was converted into digital impulses at
fixed crank angles using an analogue-to-digital converter (ADC).
• The digital signal was then transmitted to the computer where it was stored. It was immedi-
ately processed as soon as all of the data for one or any number of cycles had been completed.
• The processing would be in the form of a pressure-crank angle diagram or a pressure-
volume diagram.
The photographic view of the test engine is shown in Figure 25.2 whereas Figure 25.3 depicts the
pressure setup. The schematic of the experimental setup is illustrated in Figure 25.4.
The entire experimental work was performed in the laboratory at room temperature (32°C) and
an atmospheric pressure of 1.01325 bar.
25.4
outPuts and ImPacts
25.4.1 f
uEl
p
ropErtiES
Fuel properties are of foremost importance to the validation of the combustion, performance, and
emissions of a fuel in compression ignition engine. Fuel properties affect the engine combustion
chemistry in many ways; hence, it is essential to study the indispensable properties to realize the
combustion chemistry. Biodiesel fuel combustion chemistry is more complex than that of diesel fuel
because of its complex structure and oxygen content. Biodiesel is composed of several fatty acid
