Boiling heat transfer rates impact the performance of various processes like quenching, steam generation, desalination, and boiling water reactors. The film boiling regime of the boiling curve has very low heat transfer rates around the Leidenfrost point which corresponds to the formation of a stable and continuous vapor layer at the solid-liquid interface (Leidenfrost effect). This insulating ...

Two-phase heat transfer coefficients for internal flows play a critical role in the design and analysis of evaporators and condensers. Previous studies propose empirical relations that combine the effects of nucleate and convective boiling onto the overall heat transfer coefficient. Although these relatively simple empirical relations offer physical insight on the nucleation, boiling and flow p...

cooling towers are widely used in most industrial units to reject waste heat to the atmosphere. this paper deals with an experimental analysis of heat and mass transfer phenomena between water and air by direct contact in a cooling tower. the tower is filled with 6 type packing. in this study temperature and pressure drop and tower characteristics was used in determining experimentally the ther...

The success of innovative fouling mitigation techniques such as ion implantation depends upon early stage of scale formation on heat transfer surface. This is because the first crystalline nuclei that appear on the surface during the initial period dictate how fouling would develop in latter stages. In this study, the initial period of deposition of calcium sulphate on heat transfer surfaces ha...

The nucleate boiling process is known to be a very efficient mode of heat transfer. It is desirable to operate many engineering applications in this mode since high heat transfer rates and convection coefficients are associated with small values of the excess temperature. Despite its importance, nucleate boiling has not been fully numerically simulated until very recently because of the complex...

The thermal resistance to heat transfer into the evaporator section of heat pipes and vapor chambers plays a dominant role in governing their overall performance. It is therefore critical to quantify this resistance for commonly used sintered copper powder wick surfaces, both under evaporation and boiling conditions. The objective of the current study is to measure the dependence of thermal res...

The characteristics of local heat transfer and pressure drop were investigated experimentally for the vertical up-flow boiling of refrigerant R1234yf in two types of aluminum multi-port extruded tubes having 16 channels with a crosssection of 0.91 × 0.21 mm (tube A) and 40 channels with a cross-section of 0.34 × 0.21 mm (tube B). At an evaporating temperature of 15 °C, the local heat transfer c...

Demand for high-performance cooling systems is one of the most challenging and virtual issues in the industry and Pulsating heat pipes are effective solutions for this concern. In the present study, the best predictor correlations of flow boiling and condensation are taken into account to model a single turn pulsating heat pipe mathematically. These considerations, result in derivation of more ...

in this work, the characteristics of flow and heat transfer of a fluid containing nano particles of aluminum oxide with the water volume fraction (0.1-0.2-0.3)(v/v) percent of the reports. the overall heat transfer coefficient, heat transfer and the average heat transfer fluid containing nano water - aluminum oxide in a horizontal double pipe counter flow heat exchanger under turbulent flow con...