Accurate prediction of critical heat flux (CHF) in microchannels and minichannels is of great interest in estimating the safe operational limits of cooling systems employing flow boiling. Scale analysis is applied to identify the relevant forces leading to the CHF condition. Using these forces, a local parameter model is developed to predict the flow boiling CHF. The theoretical model is an ext...

Uniform silicon nanowires (SiNW) were successfully fabricated on the top, bottom, and sidewall surfaces of silicon microchannels by using a two-step electroless etching process. Different microchannel patterns with the channel width from 100 to 300 lm were first fabricated in a 10 mm 10 mm silicon chip and then covered by SiNW with an average height of 10–20 lm. The effects of the microchannel ...

Phase change through boiling is used in a variety of heat-transfer and chemical reaction applications. The state of the art in nucleate boiling has focused on increasing the density of bubble nucleation using porous structures and microchannels with characteristic sizes of tens of micrometers. Traditionally, it is thought that nanoscale surfaces will not improve boiling heat transfer, since the...

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 first of two companion papers discusses details of the fabrication, construction, and operation of the experimental facility. Test pieces are fabricated from...

Ahstraet--ln many cooling situations, permanent attachment of fins to heat dissipating devices is undesirable yet htrge mechanical loads, important in reduction of thermal contact resistance, are not permitted. This work considers the interface between a low-force pressed-on fin and a heat source in boiling heat transfer; the thermal contact resistance and how the interface region may be used t...

Surface wettability of materials is important in a myriad of HVAC&R processes. This study is focused on how to manipulate wettability by nanofluid boiling nanoparticle deposition on aluminum surfaces. The focus is on aluminum, because it is commonly used as the material for heat transfer in air conditioning and refrigeration systems. The boiling deposition process occurs under atmospheric press...

The paper reports pressure drop data for hydrocarbon fluids boiling in vertical upflow in a 8.68 m long, 25.4 mm i.d. tube, heated by direct electrical heating. These data were recorded simultaneously with the boiling heat transfer measurements. The systematic trends of the measured pressure gradient with respect to vapour quality, mass flux and pressure are examined. This provides useful infor...

Chemical change during boiling of herbal mixture is a puzzle. By using Danggui Buxue Tang (DBT), a herbal decoction that contains Astragali Radix (AR) and Angelicae Sinensis Radix (ASR), we developed a model in analyzing the hydrolysis of flavonoid glycosides during the boiling of herbal mixture in water. A proper preparation of DBT is of great benefit to the complete extraction of bioactive in...

BACKGROUND There is an increase in number of patients with chronic kidney disease (CKD) in Uganda's health facilities looking for different options of preparing matooke (bananas), their staple food. OBJECTIVE To establish and evaluate an effective method of removing potassium from bananas (matooke). METHODS Bananas were sampled from 5 markets in Kampala, Uganda. Deionized water was used to ...

Basic understanding of the process of coolant heat transfer inside an engine is an indispensable prerequisite to devise an infallible cooling strategy. Coolant flow and its heat transfer affect the cooling efficiency, thermal load of heated components, and thermal efficiency of a diesel engine. An efficient approach to studying cooling system for diesel engine is a 3D computational fluid dynami...