The effect of surface roughness on nucleate boiling heat transfer is not clearly understood. This study is devised to conduct detailed heat transfer and bubble measurements during boiling on a heater surface with controlled roughness. This second of two companion papers presents an analysis of heat transfer and bubble ebullition in nucleate boiling with new measures of surface roughness: area r...

In the present work, functionalized 304 stainless steel metallic surfaces were created with the use of a Femtosecond Laser Surface Processing (FLSP) technique. The laser processing technique produces self-organized micro/nanostructures on the surface. The heat transfer performance of various FLSP functionalized surfaces were characterized through pool boiling and Leidenfrost experiments. Enhanc...

the subjects of heat transfer and cooling system are very important topics in the internal combustion engines (ice). in modern cooling systems, low weight, small size and high compactness are the critical designing criteria that requires heat transfer enhancement. boiling phenomenon which is occurred in the water jacket of the ice is one of the methods to increase heat transfer in the coolant s...

This paper presents a new numerical model, called the CAS model, for boiling heat transfer. The CAS model is based on the cellular automata (CA) technique that is integrated into the popular SIMPLER algorithm for CFD problems. In the model, the CA technique deals with the microscopic nonlinear dynamic interactions of bubbles while the traditional CFD algorithm is used to determine macroscopic s...

This thesis consists of an experimental investigation of the effect of surfactants on the boiling curve of water. Via adsorbtion to the boiling surface, surfactants alter the surface energy interaction during bubble formation at nucleation sites. The surfactants initially enhance the heat transfer coefficient at the onset of nucleate boiling due to higher nucleation density and higher bubble de...

Boiling is a common mechanism for liquid-vapor phase transition and is widely exploited in power generation and refrigeration devices and systems. The efficacy of boiling heat transfer is characterized by two parameters: (a) heat transfer coefficient (HTC) or the thermal conductance; (b) the critical heat flux (CHF) limit that demarcates the transition from high HTC to very low HTC. While incre...

Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter a...

Title of Document: CONVECTION AND FLOW BOILING IN MICROGAPS AND POROUS FOAM COOLERS Dae Whan Kim, Doctor of Philosophy, 2007 Directed By: Professor Avram Bar-Cohen Professor Bongtae Han Department of Mechanical Engineering An open and foam-filled microgap cooler, providing direct liquid cooling for a simulated electronic/photonic component and which eliminates the problematic thermal resistance...

Two-phase heat transfer is experimentally examined through vertical small diameter tubes, D =1.45 and 2.8 mm using water under a pressure of 50 to 81 kPa and a natural circulation condition. The pool boiling correlation by Stephan-Abdelsalam and the thermosyphon boiling correlation by Imura, et al. predict the measured experimental data in the 2.8 mm tube with an error of -30%. A large heat tra...