Session: 11-10-01 Single/ Two-Phase Heat Transfer in Active and Passive Systems

Paper Number: 72040

Start Time: Tuesday, 07:00 PM

72040 - Micro Fin Array Configuration in Heat Transfer Enhancement in Mini-Channels 

Flow boiling in mini channels is an effective mechanism for high rate heat dissipation from heated surfaces. Minichannels are applied in many cooling systems, such as electronic cooling devices. The phase change process allows significant energy transport from a heated surface toward the bulk fluid flow while keeping an even surface temperature distribution.  An experimental study was conducted on a novel cooling device that consists of a rectangular micro-fins array placed inside the cooling device. A unique cover was designed and fabricated to allow the mass flow rate in and out and for measuring the temperature and pressure of the fluid. The presence of a fin array increases the solid surface area and distorts the fluid velocity inside the thermal device; therefore, it increases the local convection heat transfer and the overall rate of cooling.  The array of rectangular micro-fins can also prevent dry out on the solid surface caused by any unexpected excess of heat transfer. Scanning electronic microscope measurements showed that the rectangular fin's average thickness was 175 microns and the separation between two fins is 79 microns, respectively. The average hydraulic diameter of the mini channel is 155 microns, the distribution of the rectangular fin array is parallel to the direction of the flow. The narrow passage between the fin array increases the pressure drop of the working fluid and also increases the capillary pumping effects from the cold fluid towards the hot solid surface. The novel mini channels were tested with different volume flow rates and heat inputs to determine the cooling's maximum performance. In order to assess the effect of the fluid properties on the rate of cooling, two fluids were used: distilled water and an engineering fluid. Two thermocouples and two pressure transducer sensors installed at the inlet and outlet recorded the pressure drop and temperature difference for the different flow conditions. In order to compare the performance of the novel device, similar experiments were conducted dummy finless cooling device.  The experimental results showed an improvement in the heat transfer rate of the novel device compared with the dummy device. The experimental results suggest that the surface tension played an essential role the rewetting the heating surface, thus creating a relatively passive pumping mechanism.  According to preliminary results, this study revealed an improvement in the cooling process by having the rectangular array of micro-fins inside the device. It is expected that this novel device may increase the heat transfer rate significantly in aerospace and electronic cooling applications

Presenting Author: Gerardo Carbajal Florida Polytechnic University

Authors:

Gerardo Carbajal Florida Polytechnic University
Colton Frar Florida Polytechnic University
Charisma Clarke Florida Polytechnic University
Edwar Romero-Ramirez Florida Polytechnic University