The present study investigated the effects of the experimental parameters on the cooling performance of the indirect liquid cooling method using water and paraffin slurry. The experimental parameters were mass fraction of 2.5~7.5%, heat flux of 10~ 40W/cm² for the simulated VLSI chips and Reynolds numbers of 5,300~16,000. The apparatus consisted of test section, paraffin slurry maker, pump, constant temperature baths, flowmeter etc. The test section made with in-line, four-row array of 12 heat sources for simulating 4×3 multichip module which were flush mounted on the top wall of a horizontal, rectangular channel of aspect ratio 0.2. The inlet temperature was 20°C for all experiments. The size of paraffin slurry was 10~40µm and was not changed before and after the experiment.
The chip surface temperatures for paraffin slurry with the mass fraction of 7.5% showed lower by 16°C than those for water when the heat flux is 40W/cm². The dimensionless local average heat transfer coefficients increased up to 15% at the first row and up to 28% at the fourth row as the mass fraction was increased up to 7.5%. The local heat transfer coefficients reached a row-number-independent, thermally fully developed value approximately at the third row. The local average Nusselt numbers at the fourth row for paraffin slurry with the mass fraction of 7.5% were larger by 23~29% than those for water. The liquid cooling method using paraffin slurry can be applied for high heat flux cases over 40W/cm².