Heat Transfer Engineering

Development of an experimental facility for investigating single-phase liquid flow in microchannels

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An experimental facility has been developed to investigate single-phase liquid heat transfer and pressure drop in a variety of microchannel geometries. The facility is capable of accurately measuring the fluid temperatures, heater surface temperatures, heat transfer rates, and differential pressure in a test section. A microchannel test section with a silicon substrate is used to demonstrate the capability of the experimental facility. A copper resistor is fabricated on the backside of the silicon to provide heat input. Several other small copper resistors are used with a four-point measurement technique to acquire the heater temperature and calculate surface temperatures. A transparent pyrex cover is bonded to the chip to form the microchannel flow passages. The details of the experimental facility are presented here. The experimental facility is intended to support the collection of fundamental data in microchannel flows. It has the capability of optical visualization using a traditional microscope to see dyes and particles. It is also capable of performing micro-particle image velocimetry in the microchannels to detect the flow field occurring in the microchannel geometries. The experimental uncertainties have been carefully evaluated in selecting the equipment used in the experimental facility. The thermohydraulic performance of microchannels will be studied as a function of channel geometry, heat flux, and liquid flow rate. Some preliminary results for a test section with a channel width of 100 micrometers, a depth of 200 micrometers, and a fin thickness of 40 micrometers are presented.