Experimental investigation on paraffin encapsulated with Silica and Titanium shell in the straight and re-entrant microchannel heat sinks

The encapsulated phase change slurry exhibits excellent heat transfer behaviour in modern high power electronic cooling application due to its unique advantage of latent heat transfer. The present work focuses on the thermal performance of micro-encapsulated paraffin slurry in a straight, segmental, and combined straight-segmental microchannel heat sink. Shell material considered for the encapsulation are Silica (Si) and Titanium (Ti). The in-situ hydrolysis and polycondensation processes were used to synthesise the micro-encapsulation. The micro-encapsulated phase change slurry (MPCMS) was prepared by dispersing the prepared micro-encapsulated particles at a concentration of 1% and 2% in the de-ionized water (DI). The experiments were conducted at different flow rates of 200-400 ml/min under the laminar region of Re. 400-850 with a uniform heat flux of 10, 20, and 30 W/cm(2) and inlet subcooling of 25 degrees C. The thermal and flow behaviour of both the DI and MPCMS is compared by considering the parameters, wall temperature, Nusselt number and pressure drop at the steady state. Furthermore, the effectiveness of the MPCMS were analysed using cost of performance (COP) and compared among the straight, segmental, and combined straight-segmental microchannel heat sink. The experimental results shows that the MPCMS of low concentration (1%) exhibits higher heat transfer than DI in all configurations. At the Reynolds number of 780 and heat flux of 20 W/cm(2), the average Nusselt number in a parallel microchannel heat sink improves by about 13.3% when using MPCMS of low Si concentration (1%). Further, under the same condition, the segmental microchannel heat sink shows higher performance than the combined straight-segmental microchannel and parallel microchannel heat sink by 7.3% and 15.7% respectively. Though, the measurement of COP indicates the lower values with MPCMS, its heat transfer enhancements outweigh its pumping power.

Automated summary

This study investigates the thermal performance of micro-encapsulated paraffin slurry in different shapes and combinations of microchannel heat sinks. The experimental results show that the low concentration micro-encapsulated phase change slurry exhibits higher heat transfer performance than de-ionized water in all configurations.