Heat conductive inserts

The factor of the resulted heat emission of a hydride bed generally is proportional to effective heat conductivity of a bed and inversely proportional to thickness of a bed. The analysis of these equation shows, that factor of a heat transfer less than smaller factor of a heat emission and consequently it is of no used to increase strongly one of them, thus, not changing another. Results of experiments show, that for brazed and diffusion welded connections of the sorber case and heat-conducting insert R=(0.5-1.5) TO 5 (m2 K)/W. At contact of an insert and the case on tight fit R increases in 10-100 times and influence of contact resistance becomes comparable with influence of the resulted heat emission of a hydride bed. 

Metal hydride element is a complex physical item, which can be described by the continuum theory equations. There are three basic processes i) process of hydrogen filtration through a porous hydride matrix and heat-conducting inserting, ii) processes of heat application and heat abstraction from a space of hydrogenation and iii) chemical processes accompanying hydrogen sorption - desorption. 

The important element of a hydride bed is the heat-conducting insert or any other element improving layer thermal conductivity. Such elements can be metal powder, metal felt, grid, cellular body, punched corrugations, plates, finned tubes... 

Figure 1. The MHHP modular sorber diagram 1 - tubular case of the hydride module 2 -corrugated heat-conducting insert 3 - hydrogen ceramic collector-filter 4 - metal hydride 5 - tip of a metal hydride bed 6 - hydrogen manifold 7 - spacer plate 8 - heat exchanger shroud 9 - union 10 - flange-cover of a heat exchanger. Heat exchanger thermal insulation is not shown conditionally.

Concerns to a material of a skeleton of a heat-conducting insert... 

FIGURE 2.96 Temperature control of critical areas using highly heat conductive inserts (e.g., CuBe) [3]... 

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