The purpose of the article is to evaluate the cooling performance efficiency of a
Compressed Natural Gas (CNG) medium commercial vehicle with a viscous fan, fresh
air cleaner, and choked air cleaner in comparison with limits prescribed in the
Indian Standard (IS) 14557. Due to the increase in CNG availability, a shift is
observed in the market demand for CNG vehicles. The earlier CNG vehicle duty
cycle was limited to plain roads and some limited cities, but now vehicles are
being used for a short trip to nearby hilly routes thereby shifting the
application of the use of a CNG vehicle. CNG vehicles can now be operated in
hilly areas where power and torque demand is maximum and operates at lower
vehicle speeds and in lower gears. The subjected vehicles are designed for
haulage applications to operate with conventional fixed fans, which are
permanently engaged, and smaller radiators. The subjected vehicle was previously
designed as per the requirements of the existing road application with a fixed
fan and small radiator. Vehicle configuration was modified to the viscous fan
and bigger radiator available as off-the-shelf components from the component
suppliers. Viscous fans operate only when the coolant temperature goes beyond
certain limits for better cooling performance of the engine, lower cabin noise,
and higher fuel efficiencies.
The main objective of this article is to compare the thermal behavior in
different vehicle configurations by data acquisition and thereby establish the
fact that subjected CNG vehicles can be used in difficult terrains due to broad
CNG availability with maximum performance. The results obtained during the
experiment with a smaller fixed fan and bigger viscous fan are at an ambient
temperature above 35°C and, for a time, more than 5 minutes as specified in IS
14557. Base data is collected with the existing configuration of a vehicle with
a small fixed fan and small radiator. Afterward vehicle configuration is changed
to the viscous fan and bigger radiator and tested at conditions worse than as
specified in the test standard, i.e., ambient temperature more than 35°C and,
for a time, more than 5 minutes to ensure driveability in all terrains. Then the
experiment is conducted at maximum power condition with fresh air cleaner and
choked air cleaner. Another experiment is conducted to check the worst-case
running in maximum torque condition with fresh air cleaner and choked air
cleaner. After establishing the results in the first and second experiments,
another two experiments were conducted to check the actual performance of the
vehicle in plains and hilly route simulation as well.
