2.4. Test bed
Initially, the engine is coupled to a Tecquipment TD 114 dynamometer
for speed and load control to evaluate engine performance
on biogas in terms of engine power output, torque, brake
specific fuel consumption (bsfc), and brake thermal efficiency. Subsequently,
it is coupled to the compressor of the air-conditioning
unit via a magnetic clutch with different speed ratio (SR), ratio between
engine and compressor speeds. This is conducted to identify
that both the biogas engine and the compressor could run at individually
optimum speed. A radiator cooling fan and an alternator
are also connected to the engine to provide necessary power to
auxiliary components. The biogas engine is employed as a prime
mover to drive the refrigeration system. Simplified schematic diagram
of the experimental test rig is shown in Fig. 1. It consists of
the biogas engine, the air-conditioning unit, a test bed, various sensors
to measure flow rates, temperatures, power, speed, and a data
acquisition system.