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...

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...

A numerical approach was implemented, to study a boiling flow in horizontal serpentine tube. NEPTUNE_CFD two-fluid model used, the behavior of refrigerant R141b diabatic cases. The based on Euler–Euler formalism Navier–Stokes equations, which governing equations are solved for both phases fluid at each time step. conjugate heat transfer—between tube wall and fluid—was considered via coupling wi...

Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was us...

An experimental study is conducted to determine the nucleate pool boiling heat transfer performance of a copper-graphite (Cu-Gr) composite surface in Freon 113. The composite medium consists of ultra-high thermal conductivity graphite fibers of 0.0008~.010 mm diameter being consolidated in a copper matrix (50% area fraction). It has high thermal conductivity along the fiber directions, several ...

The success of quenching process during industrial heat treatment mainly depends on the heat transfer characteristics of the quenching medium. In the case of quenching, the scope for redesigning the system or operational parameters for enhancing the heat transfer is very much limited and the emphasis should be on designing quench media with enhanced heat transfer characteristics. Recent studies...

in this paper, experimentally derived correlations of heat transfer and pressure drop are used in a pareto based multi-objective optimization (moo) approach to find the best possible combinations of heat transfer and pressure drop of tio2-water nanofluid flow in tubes fitted with multiple twisted tape inserts in different arrangement. in this study there are four independent design variables: t...

Title of Document Application of Plate Heat Exchanger for Low Temperature Lift Heat Pump Systems Song Li, Master of Science, 2012 Advisor Professor Reinhard Radermacher, Department of Mechanical Engineering In this thesis I investigated the energy saving potential of a low temperature lift heat pump (LTLHP) such as water source heat pump (WSHP), and studied the utilization of a plate heat excha...

Since the mean characteristic of nucleate boiling is bubble formation and collapse near the heating surface, in this study attempts have been made to investigate heat transfer effects due to the bubbles ebullition and collapse cycle. All possible heat transfer mechanisms are studied qualitatively and quantitatively. For quantitative calculation of the heat transfer portion by each of the introd...