Shell and tube micro heat exchanger

Besides microstructured heat exchanger/reactors constructed in the form of plates as shown in Figure 5.1, shell and tube micro heat exchangers are available. An example is shown in Figure 5.6. The heat transfer within the reactor tubes can be estimated with the asymptotic Nu or with Equation 5.12 for short channels. The outer heat transfer coefficient depends on the flow regime, the arrangement of the tubes, and the presence of baffles [8, 13]. For small-scale systems, capillaries submerged in constant temperature baths are commonly used. In this case, the main heat transfer resistance is mostly located at the outer side of the reactor. 

Figure 5.6 Shell and tube micro heat exchanger. (Reprinted with permission from Ref. [14]. Copyright (2005) American Chemical Society.)...

Dudfield et al. [88] presented results generated in the scope of the Mercatox program funded by the European Community aimed at a combined methanol steam reformer/combustor with consecutive CO clean-up by PrOx. First, various catalysts were tested for the reaction as micro spheres in a test reactor which was similar to a macroscopic shell-and-tube heat exchanger (Figure 2.57). 

The performance of a micro structured plate and fin heat exchanger (0.25 dm3 reactor volume), wash coated with 2.0 g of catalyst, was assessed in comparison with similar alternative technologies by Dudfield et al. [88], The first was a shell and tube heat exchanger filled with 4.66 g of catalyst microspheres (0.25 dm3 reactor... 

The mass production of ionic liquids has not yet been attained however, when it should, we would be able to replace actual non-biodegradable and environmental harmful heat transfer fluids. In addition, due to their increased heat storage capacity as compared with traditional heat transfer fluids, they have the potential to use in shell and tube heat exchangers, and in other small capacity heat exchangers like micro-channels. 

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