Double-pipe countercurrent exchanger

The time required to heat the agitated batch using the double pipe countercurrent exchanger can be determined from Equation 8-170. 

A. Zavala-Rio, R. Femat, and G. Solis-Perales. Countercurrent double-pipe heat exchangers are a special type of positive systems. In First Multidisciplinary International Symposium on Positive Systems Theory and Applications (POSTA 2003), volume IEEE LNCIS 294, pages 385-392, Roma, Italy, August 2003. 

Fig. 1.19 Fluid temperatures t) ] and do in a double-pipe heat exchanger, a countercurrent flow, b cocurrent flow...

A heavy hydrocarbon oil with heat capacity, Cp = 0.55 Btu/(lb °F), is being cooled in a countercurrent double-pipe heat exchanger from Tj = 210°F to T2 = 170°F. The oil flows inside a tube at the rate of 8000 Ib/h and the inside tube surface temperature is maintained at 60°F. The overall heat-transfer coefficient,... 

FIGURE 6.24 Basic double-pipe heat exchanger, with arrows showing countercurrent flow. 

In many systems, energy is exchanged between recycle streams such as the streams and B2 shown in Fig. 7-3. Consider the case where energy is transferred from stream B2 to Bx in a double-pipe heat exchanger with countercurrent flow. 

Aniline is to be cooled from 200 to 150°F in a double-pipe heat exchanger having a total outside area of 70 ft. For cooling, a stream of toluene amounting to 8600 Ib/h at a temperature of 100 F is available. The exchanger consists of l in. Schedule 40 pipe in 2-in. Schedule 40 pipe. The aniline flow rate is 10,000 Ib/h. (a) If flow is countercurrent, what are the toluene outlet temperature, the LMTD, and the overall heat-transfer coefficient (A) What arc they if flow is parallel ... 

A flow of 1 kg/s of an organic liquid of heat capacity 2.0 kJ/kgK is cooled from 350 to 330 K by a stream of water flowing countercurrently through a double-pipe heat exchanger. Estimate the effectiveness of the unit if the water enters the exchanger at 290 K and leaves at 320 K. 

Reactant A is converted irreversibly and exothermically to products in a 2-in.-inner-diameter tubular reactor via first-order chemical kinetics. The reactive mixture in the inner pipe is cooled using a concentric double-pipe heat exchanger. The nonreactive cooling fluid in the annular region flows countercurrently with respect to the reactive fluid. The radius ratio of the double-pipe configuration is If = Rinside/ outside = 0.5, the inlet temperature of the reactive fluid is 340 K,... 

In a typical heat exchanger a hot fluid inside a pipe is cooled from T toTj by a cold fluid which is flowing on the outside in a double pipe countercurrently (in the reverse direction) and is heated from Tj to Z tts shown in Fig. 4.5-3a. The AT shown is varying with distance. Hence, AT in Eq. (4.5-17) varies as the area A goes from 0 at the inlet to A at the outlet of the exchanger. 

Figure 4.5-3. Temperature profiles for one-pass double-pipe heat exchangers (a) countercurrent flow (b) cocurrent or parallel flow.

Show that the dynamic model for a double-pipe, countercurrent heat exchanger can have the same form as the model of a packed absorber. Discuss the assumptions inherent in both the heat exchanger and absorber models which might lead to significant differences in the kinds of equations used to describe each system. 

---