Heat loss from fins

TABLE 4.5 Values of c and b Calculating the Heat Loss From Fin Tips (Eq. 4.68)... 

The heat loss from a finned tube is obtained initially by determining the heat flow into the base of the fin from the tube surface. Thus the heat flow to the root of the fin is ... 

If the fin were such that there was no drop in temperature along its length, then the maximum rate of heat loss from the fin would be ... 

A longitudinal tin on the outside of a circular pipe is 75 mm deep and 3 mm thick. If tire pipe surface is at 400 K. calculate the heat dissipated per metre length from the fin to the atmosphere at 290 K if the coefficient of heat transfer from its surface may be assumed constant at 5 W/m2 K, The thermal conductivity of the material of the fin is 50 W/m K and the heat loss from the extreme edge of the fin may be neglected. It should be assumed that the temperature is uniformly 400 K at the base of the fin. 

All of the heat lost by the fin must be conducted into the base at x = 0. Using the equations for the temperature distribution, we can compute the heat loss from... 

A 2.5-cm-diameter tube has circumferential fins of rectangular profile spaced at 9.5-mm increments along its length. The fins are constructed of aluminum and are 0.8 mm thick and 12.5 mm long. The tube wall temperature is maintained at 200°C, and the environment temperature is 93°C. The heat-transfer coefficient is 110 W/m2 - °C. Calculate the heat loss from the tube per meter of length. 

A circumferential fin of rectangular profile is constructed of aluminum and surrounds a 3-cm-diameter tube. The fin is 2 cm long and I mm thick. The tube wall temperature is 200°C, and the fin is exposed to a fluid at 20°C with a convection heat-transfer coefficient of 80 W/m2 °C. Calculate the heat loss from the fin. 

A total of 10 rectangular aluminum fins k = 203 W/ni K) arc placed on the outside flat surface of an electronic device. Each fin is 100 mm wide, 20 mm high and 4 mm thick. The fins are located parallel to each other at a cenier-to-cenler distance of 8 mm. The temperature at the outside surface of the electronic device is 60°C. The air is at 20°C, and the heal transfer coefficient is 100 W/in K. Determine (a) the rate of heat loss from Uie electronic device to the surrounding air and (b) the fin effectiveness. 

A hot surface at SO C in air at 20°C is to be cooled by attaching 10-em-long and t-cm-diameiei cylindrical fins. Ihe combined heat transfer coefficient is 30 W/m °C, and heat transfer from the fin tip is negligible. If the fin efficiency is 0.75, the rate of heat loss from 100 fins is... 

The total heat loss from the fin, evaluated from conduction at the base of the fin, is... 

The heat loss from the tip of a fin is usually negligible. The ratio of this loss relative to peripheral loss is... 

Heat Loss from Circular Fins. Use the same data and conditions from... 

Example 4.13-2 and calculate the fin efficiency and rate of heat loss from the following different fin materials. 

Heat Loss from Longitudinal Fin. A longitudinal aluminum fin as shown in Fig. 

As the thickness of the lagging is increased, resistance to heat transfer by thermal conduction increases. Although the outside area from which heat is lost to the surroundings also increases, giving rise to the possibility of increased heat loss. It is perhaps easiest to think of the lagging as acting as a fin of very low thermal conductivity. For a cylindrical... 

Figure 14.19 shows some variations of air-type collectors with one covering. These structures can also be made with two coverings. Flow under the absorber reduces the convective heat loss of the air from the covering. There are designs in which air flows on both sides of the absorber. A corrugated or finned absorber surface improves heat transfer between air and absorber. With the latter, flow direction is usually parallel to the fins. 

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