Improving Heat Exchanger Performance

A novel variation is a cyhndrical model equipped with a tube bundle to resemble a sheU-and-tube heat exchanger with a bloated shell [Chem. Proce.s.s., 20 (Nov. 15, 1968)]. Conical ends provide for redistribution of burden between passes. The improved heat-transfer performance is shown by Fig. 11-61. 

The basic layout and flow arrangement for a gasketed plate heat exchanger is shown in Figure 12.60. Comer ports in the plates direct the flow from plate to plate. The plates are embossed with a pattern of ridges, which increase the rigidity of the plate and improve the heat transfer performance. 

Consider now how the network pinch might be overcome. There are four ways in which the network pinch can be overcome and the performance of the existing heat exchanger network improved beyond that for the pinched condition14. 

The experimental data provided in the last section are a contribution to support the feesibility of developing a compact and stand-alone kilowatt-scale stable ATR reactor capable to work in a stable manner over a wide range of operating conditions. Moreover, in order to improve its performance and increase its compactness, it has been integrated with two heat exchangers for the preheating of the air and liquid water fed to the reactor by the hot exhaust stream. 

The critical technology development areas are advanced materials, manufacturing techniques, and other advancements that will lower costs, increase durability, and improve reliability and performance for all fuel cell systems and applications. These activities need to address not only core fuel cell stack issues but also balance of plant (BOP) subsystems such as fuel processors hydrogen production, delivery, and storage power electronics sensors and controls air handling equipment and heat exchangers. Research and development areas include ... 

The authors briefly discuss some of the problems for air cooled heat exchangers and cooling towers using axial fans. The balance of the paper discusses ways to improve system efficiencies in three areas before the fan system design is finalized, improvements in the physical equipment as installed, and recognition of performance problems caused by adjacent equipment. Results of a full-scale test illustrating fan efficiency contributions of various components are given. 1 ref. cited. 

Experimental measurements yielded only a fivefold extension of the reaction cycle time, a difference largely caused by heat storage effects in the small-scale equipment used, which disproportionately enhanced the cooling effect observed in the inert bed control experiment. Despite this less satisfactory result, the desorptive cooling concept would still seem to offer potential for dramatic improvement in performance for regenerative heat exchange processes. 

The benefits obtained by integrating adsorption into regenerative heat exchange demonstrate the synergies available between these two related processes. Similar advantages accrue when heat regeneration is incorporated into adsorptive reactors, in which concentration profiles are manipulated to improve reactor performance through selective ad- and desorption of components in the reaction medium. 

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