Operational wind data are used to show that the time-averaged mass flux near the tropopause is downward over the maritime continent (Indonesia) region during both summer and winter. The air descends within a layer above the convective level of neutral buoyancy (despite mean upward motion below and above this layer) and must rise through the mean tropopause elsewhere, contradicting the common vi...

This study suggests using thermoelectric element to generate electric energy from the heat source efficiently. This generator system consists of a Heater, the Lower Heat Transfer Plate to absorb heat from the Heater, Two-Stage Thermoelectric Device module to generate the electric power with the heat transferred from the Lower Heat Transfer Plate, the Upper Heat Transfer Plate to convey the heat...

An analytical simulation model has been developed for predicting and optimizing the thermal performance of bidirectional fin heat sinks in a partiaHy confined configuration. Sample calculations are carried out, and parametric plots are provided, illustrating the effect of various design parameters on the performance of a heat sink. It is observed that the actual convection flow velocity through...

The use of phase change heat transfer in parallel minichannels and microchannels is one of the solutions proposed for cooling high heat flux systems. The increase in pressure drop in a two phase system is one of the problems, that need to be studied in detail before proceeding to any design phase. The pressure drop fluctuations in a network of parallel channels connected by a common head need t...

Flow boiling in microchannels and minichannels has received considerable attention in the past decade. The interest stems from the possibility of achieving the extremely high heat fluxes, over 1 kW/cm, needed for future generation electronics cooling application. The attention has been focused on obtaining experimental heat transfer and pressure drop data, but the fundamental aspects of nucleat...

If a baby starts to cry several hours after drinking his last bottle, his mother knows precisely what he's feeling: He's hungry. But suppose a woman's eyes brim with tears while she watches a DVD. Her husband sinks into the couch: What is she so upset about? She might tell him directly: "This movie is so tragic. It's all about a doomed romance." That may be true. But she could be thinking about...

The present study addresses the problem of ignition of a single sodium droplet, which is an important issue for the nuclear facilities safety. The study follows the approach of previous works and extends the results of those papers to the case of radiative heat loss. The contribution of the thermal radiation is taken into account based on the P-1 approximation for thermal radiation transfer. An...

The dendritic patterns of magnetic flux motion formed during field penetration into an MgB2 film were observed using magneto-optic imaging. To investigate the origin of the dendrites, experiments were performed where the sample was partially covered with an thermally conducting foil serving as an efficient heat sink. We observed that the dendrites are formed only in areas lacking the thermal co...

Two differently-produced open-cell aluminum foams were compared to a commercially available finned heat sink. Further, an aluminum plate and block were tested as a reference. All heat sinks have the same base plate dimensions of four by six inches. The first foam was made by investment casting of a polyurethane preform and has a porosity of 0.946 and a pore density of 10 pores per linear inch. ...

New pressure drop / flow rate measurements coupled with a previously reported heat transfer database have resulted in new friction factor and heat transfer correlation equations for fan-driven impinging flow through square arrays of cylindrical cross-section pin-fins. The correlation equations include the effect of coolant flow rate, pin-fin density and pinfin height. A comparison with a simila...