2.5. Experimental procedure
Experimental investigation of the performance of the vapourcompression
air-conditioning system driven by biogas engine is
divided into three sections. Initially, the engine and the air-conditioning
system are tested separately for individual performance.
Afterward, tests are carried out for the integrated unit.
2.5.1. Biogas engine evaluation
A series of tests are conducted to evaluate biogas engine performance
on stand alone mode of operation with varying speeds and
loads. In the test, engine speed is varied between 1500 and
5000 rpm. Measurements on engine power output, torque, and
specific fuel consumption are performed at the throttle valve openings
of 20%, 40%, 60%, 80%, and 100%. The flow rate of the biogas
can be measured by gas meter. Torque and speed are measured
by a Tohnichi 120DB3 instrument and a digital tachometer, respectively.
Efficiency of the biogas engine, defined as the ratio of the engine
power output to input power from the biogas, is derived from
the following expression: