How does heat travel horizontally

The configuration has been studied by number of re- searchers. The most commonl y used predictive equation for convection was derived by Barcohen, S. This situation has been considered for free convective heat transfer from a heated horizontal and vertical surface directly exposed to air with a free surface to vertical fins attached to surface that project vertic ally downward into the air has been studied by Smith, H.

The most comprehensive experimental interrogation was performed by Fuji, V. This work compares horizontal plate heat sinks with vertical plate heat sink for natural cooling applica- tion. As shown in Figure 1, three different configurations will be discussed: 1 vertical plate with vertical fins 2 horizontal plate with fins facing up 3 vertical pate with horizontal fins.

Figure 1 gives some quick guideline on the merits of the different configurations. H T is the temperature of the hot wall and is the temperature of the fin. The prime ' denotes a dimensional quality. The mean heat transfer rate across H. Fo r a given heat sink volume, there exits an optimal fin spacing.

The optimum value occurs when two trends are balanced. If the fins are closely spaced, the heat transfer coeffi- cient h is lower because mixing of the boundary layer occurs the fills up with warm air.

The graph if Figure 3 clearly shows that the heat transfer coefficient decreases as the gap between fins decreases. However, if the fins are closely spaced, there is also more dissipating surface area more fins for a given volume.

The additional sur- face area can counteract the reduced heat transfer coeffi- cient. This can be seen by examining the graph of total wattage dissipated in Figure 4. When a horizontal baseplate heat sink is sinks in not square, there will be two possible orientations for the fin channel. As shown in Figure 5, the fins should be oriented to provide the shortest chan- nel depth.

Fin configurations for natural Free cooling Figure 2. Air enters nears the bot- tom of the fin channels and there will be some air flow from the fin tips.

Air is heated within the fin channels and exit at the top. As the Figure 7 illustrates, vertical fin channels are better. The light from them radiates to us. Conduction is another way that heat moves. Heat is a form of energy, and when it comes into contact with matter Anything that you can touch physically it makes the atoms and molecules move. Once atoms or molecules are moving, they collide with other atoms or molecules, making them move too.

These, then bump into other molecules and make them move, too. In this way, the heat is transferred through matter. Conduction is what makes the handle of a pot hot when only the bottom of the pot is touching the stove. The heat from the burner starts the molecules in contact with the burner start to move. Those molecules bump against others in the pot, which bump others, until all the molecules in the pot, including in the handle, are moving.

When someone touches the pot handle, they feel the heat. The heat has moved from the burner to the cook's hand through conduction. Conduction is an important way that heat travels in space, but only within a spacecraft. View Metrics. Accepted Manuscript Alert. New Issue Alert. Cited By Web Of Science Heat Transfer January Heat Transfer November, Energy Eng February, Heat Transfer May, Heat Transfer February, Introduction Thermal Management of Microelectronic Equipment. Radiation Thermal Management of Microelectronic Equipment.

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