Enhanced boiling heat transfer by nano structured surfaces and nanofluids

Abstract

In order to meet the future energy demands many interesting techniques have been reported in literature for improving boiling heat transfer using nanoparticles and nano-structured surfaces. The mode of heat transfer and efficiency of water cooled reactors, direct steam generators can be substantially modified by this new technology. Boiling heat transfer is an area of increasing interest in many engineered heat transfer and cooling applications. Nucleate boiling is the efficient heat transfer region in pool boiling. The critical heat flux changes boiling mechanism from efficient mode to inefficient mode by forming a vapor film over the heater surface that leads to boiling crisis. The actual mechanism that creates this boiling crisis still remains a grey area. The CHF parameter cannot be avoided in boiling heat transfer applications; instead it can be postponed by adopting fluid and surface modification techniques. This review analyzes the present status of nano-modification for enhancing the pool boiling and critically compares the experimental results with the theoretical predictions. The existing theoretical models are not satisfactorily explaining the experimental investigations. New investigation techniques and better correlation between the modified surface properties to the heat flux is inevitable for further improvement.