Two phase heat transfer & pressure drop with new environment friendly refrigerants in minichannels (completed)

Background and motivation

Rapidly increasing demands (energy, heating/cooling) and limited available reserves always forced researcher to optimse the useage of available sources. The same ambition within the heat transfer field could be realized by designing compact components so that they can sustain high heating/cooling loads. Microchannel heat exchangers in this respect offers many potential advantages for enhancing heat tranfer, by reducing channel size (increasing available surface area and higher surface area to volume ratios) however this is coupled with penalty of increased pressure drop, there are some additional benefits like reduced fluid inventory, higher efficiency etc. 

Heat fluxes upto 80 w/cm² can be handled with by forced convective heat transfer with air for cooling electroinc chips, while heat transfer coefficient of 500,000 w/m²  (correspoinding to heat load of 500 w/cm²) have been reported in the literature (Steinke, 2006) with single phase flow in microchannels.

Previous studies

Flow boiling heat transfer, pressure drop and dryout with different fluids (R134a, R245fa, Ammonia and propane) under different operating conditions were already explored in the earlier studies conducted here at KTH. 

Goals

To investigate parametric effects (heat and mass flux, quality, system pressure, geometry etc) during flow boiling heat transfer and pressure drop in mini/micro channels.

To trace out involved mechanism and to check the applicability of conventional correlations.

Doctoral thesis:

Author: Zahid Anwar, 2014