Page 9 of Thermoelectric Handbook by Melcor

® assembly tips the techniques used in the assembly of a thermoelectric t.e system can be as important as the selection of the proper device it is imperative to keep in mind the purpose of the assembly ­ namely to move heat generally a t.e device in the cooling mode moves heat from an object to ambient all of the mechanical interfaces between the objects to be cooled and ambient are also thermal interfaces similarly all thermal interfaces tend to inhibit the flow of heat or add thermal resistance again when considering assembly techniques every reasonable effort should be made to minimize thermal resistance mechanical tolerances for heat exchanger surfaces should not exceed 0.001 in/in with a maximum of 0.003 total indicated reading if it is necessary to use more than one module between common plates then the height variation between modules should not exceed 0.001 request tolerance lapped modules when ordering most t.e assemblies utilize one or more thermal grease interfaces the grease thickness should be held to 0.001 ± 0.0005 a printers ink roller works well for this when these types of tolerances are to be held a certain level of cleanliness must be maintained dirt grit and grime should be minimized this is very important when grease joints are utilized due to their affinity for these types of contaminants once the t.e modules have been assembled between the heat exchangers some form of insulation/seal should be provided between the exchangers surrounding the modules since the area within the module i.e the element matrix is an open dc circuit and a temperature gradient is often present gas flow which may contain water that could condense should be minimized typically a t.e module is about 0.2 thick so any insulation that can be provided will minimize heat leak the presence of the insulation/seal also offers some protection from physical damage the insulation/seal is often most easily provided by inserting sections of closed cell polyurethane foam about the cavity and sealing with either an rtv type substance or for more physical integrity an epoxy coat whatever form is used it should provide the protection outlined above it is often desirable to provide strain relief for the input leads not only to protect the leads themselves but to help maintain the integrity of the seal about the modules we have included an assembly tips drawing fig 6 this drawing shows the details of the recommended construction of a typical assembly the use of a spacer block yields maximum heat transfer while separating the hottest and coldest parts of the system by the maximum amount of insulation the spacer blocks are used on the cold side of the system due to the lower heat flux density in addition the details of a feed thru and vapor sealing system that can be used for maximum protection from the environment are shown if you follow the recommendations shown in these drawings that you will see a significant improvement in performance when testing an assembly of this type it is important to monitor temperature measuring temperature of the cooling fluids inlet and outlet temperatures as well as flow rates is necessary this is true if either gas or liquid fluids are used knowing input power to the t.e device both voltage and current will also help in determining the cause of potential problems in addition we have enclosed step-by-step procedures for assembling cp and optotectm modules solderable or lapped modules to heat-exchangers figure 6 assembly tips drawing if you should require any further assistance please contact one of our engineers our many years of experience in working with customers ensuring reliable and efficient application of our products has proven to be essential to product success figure 7 assembly procedures drawing tel 609-393-4178 · fax 609-393-9461 · web www.melcor.com · email tecooler@melcor.com for a list of global sales offices visit www.melcor.com 7

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