Experimental investigation on flow rate of boil-off gas compressor at low suction temperature

The low suction temperature has a significant effect on the volumetric efficiency of BOG (boil-off gas) compressors. A test rig with temperature sensors was built up to investigate the temperature distribution in the cylinder at various suction temperatures. The suction and discharge flow rates were both measured by the volume flow meter. The heating tape on the pipe before the compressor inlet and the by-pass line were used to adjust the suction temperature. From the test data, the main factors influencing the volumetric efficiency were analyzed, focusing on the temperature coefficient and the suction coefficient. The results show that the suction coefficient, temperature coefficient and volumetric coefficient decreased by 24.4%, 25%, and 23.75%, respectively, when the suction temperature decreased from -54.2°C to -142.2°C. The temperature difference on the cylinder outer surface reached the maximum, 76°C, at the suction temperature of -142.2°C.