Heat counter-flow

Heat exchanger, counter flow or counter current A heat exchanger in which the flow inlet of one fluid is adjacent to the outlet of the second fluid and vice versa the fluids flow in opposite directions. 

Mori, S., M. Kataya, and A. Tanimoto, Performance of Counter-flows, Parallel Plate Heat Exchangers Under Laminar Flow Conditions, Heat Trans. Eng, V. 2, July-Sept. (1980) p. 29. 

Simple heat exchangers. These can be of the parallel flow, cross-flow or counter-flow pattern and constructed of materials to suit the temperature. 

Figure 3.11 Photograph of the multi-plate stack reactor, originally designed as a counter-flow heat exchanger this type of reactor was also used for periodic operation [13].

P 68] No detailed experimental protocol was given [61, 62,142,143]. Two reactant streams, the solution of the reactant in hexane and concentrated sulfuric acid, were fed separately in a specially designed micro reactor by pumping action. There, a bilayer was formed initially, potentially decomposed to a dispersion, and led to rapid mass transfer between the phases. From this point, temperature was controlled by counter-flow heat exchange between the reaction channel and surrounding heat-transfer channel. The reaction was typically carried out at temperatures from 0 to 50 °C and using residence times of only a few seconds. If needed, a delay loop of... 

The EB entering the styrene plant is generally heated to the threshold cracking temperature (about 1100°F) in a heat exchanger The counter flow in the exchanger is the effluent from the second stage reactor, as shown... 

The three commonly used recuperative flow-type heat exchangers in the power and refrigeration industry are parallel-flow, counter-flow, and cross-flow heat exchangers. Consider the case where a fluid is flowing... 

Figure 7.2 Operation of parallel-flow and counter-flow heat exchangers and their associated temperature profiles.

Usually, the counter-flow heat exchanger is smaller than the parallel-flow heat exchanger because the LMTD of the former exchanger is larger than that of the latter exchanger when the inlet and outlet temperatures of the hot fluid and the inlet and outlet temperatures of the cold fluid are identical. The following example illustrates this comparison. 

A counter-flow heater as shown in Fig. 7.3a heats helium at 101 kPa from a temperature of 20°C to 800°C. The temperature of the heating flue gas (air) entering and leaving are 1800°C and 1200°C at 101 kPa. Find (A) the LMTD, rate of helium flow, and heat transfer based on a unit of heating flue gas, and (B) the LMTD, rate of helium flow, and heat transfer for a parallel-flow heat exchanger under these identical operating conditions. 

Analysis (a) Assume that the heat exchangers are isobaric, and turbine and pump are isentropic. (b) Input heat source fluid = water, P5 = 200 bars, V5=lbar, xg = 0, and pg = 200 bars heat sink fluid = water, X7 = 0, p7 = 0.02bar, Xg=l, and pg = 0.02bar heat exchangers are counter-flow type and steam cycle fluid = water, Xi=0, pi = lbar, V3 = 1, p3 = 117.6bars, and mdot= 1 kg/sec, as shown in Fig. 7.21a. 

Figure 8.8. Plate and spiral compact exchangers, (a) Plate heat exchanger with corrugated plates, gaskets, frame, and corner portals to control flow paths, (b) Flow patterns in plate exchangers, (i) parallel-counter flows (ii) countercurrent flows (iii) parallel flows throughout, (c) Spiral exchanger, vertical, and horizontal cross sections.

Figure 17.11. Types of contactors for reacting gases with liquids many of these also are suitable for reacting immiscible liquids. Tanks (a) with a gas entraining impeller (b) with baffled impellers (c) with a draft tube (d) with gas input through a rotating hollow shaft, (e) Venturi mixer for rapid reactions, (f) Self-priming turbine pump as a mixer-reactor, (g) Multispray chamber. Towers (h) parallel flow falling film (i) spray tower with gas as continuous phase (j) parallel flow packed tower (k) counter flow tray tower. (1) A doublepipe heat exchanger used as a tubular reactor.

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