Fin tubes exchangers

In atmospheric air-cooled finned tube exchangers, the air-film coefficient from Eq. (5-64) is sometimes converted to a value based on outside bare surface as follows ... 

Low-fin tubes (Mfi-in-high fins) provide 2.5 times the surface per lineal foot. Surface required should be divided by 2.5 then use Fig. 11-41 to determine basic cost of the heat exchanger. Actual surface times extra costs (from Table 11-14) should then be added to determine cost of fin-tube exchanger. 

The same airflow as in Prob. 10-69 is to be cooled in a finned-tube exchanger with evaporating Freon in the tubes. It may be assumed that the Freon temperature remains constant at 35°F and that the overall heat-transfer coefficient is 125 W/m2 °C. Calculate the exchanger area required in this case. Also calculate the reduction in heat transfer which would result from cutting the air flow rate by one-third. 

Find the increase in the heat transferred for a finned-tube exchanger over a plain-tube exchanger, if c AfJc Ai =1.5 and Af/Ap - 2.0. From the figure, Qf/Qp = 1.25, i.e. an increase of 25%. 

Compact (plate or finned-tube) exchangers have 350 ft of surface area/ft of volirme, and about four times the heat transfer per cubic foot of shell-and-tube imits. 

Petroleum distillate oil (28° API) is to be cooled in a double pipe finned tube exchanger with cooling-tower water under the following conditions ... 

Film coefficient for air film of an air-cooled finned-tube exchanger J/(m sK) Btu/(hft F)... 

Heat Transfer is Finned Tube Exchanger. Air at an average temperature of... 

The double pipe, or fin-tube, exchanger is used when one liquid has a greater resistance to heat flow than anotlier or when the surface area is small. In such cases, the addition of fins to the inner pipe evens out the resistance to heat flow of the two liquids. As shown in Exhibit 6-8, the double pipe exchanger consists of a pipe within a pipe both pipes have a return bend at one end. The inner pipe is fitted with fins the outer pipe acts as the shell. The shell nozzles are mounted venically from the outer pipe, and the tube nozzles are directly welded to the inner pipe ends. The units are generally supponed horizontally by brackets at-... 

An automobile air conditioner has a condenser that removes 60,000 BTU/hr from a refrigerant (auto speed 40 mph ambient temperature of 95°F). Refrigerant temperature is 150°F. U for the finned tube exchanger is 35 BTU/hr ft with an air temperature rise of 10°F. If the U varies as a 0.7 power of velocity and air mass flow directly as velocity, find the percent performance redirection of the condenser a function of velocity (40 mph to 10 mph). Refrigerant (Freon 12) temperature is constant at 150°F. 

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