Heat/Mass Flow Enhancement Design for a Metal Hydride Assembly. Phase II. Final Report

摘要

The development and demonstration of a metal hydride/chemical heat pump (MHHP) is reported. In the design of the MHHP, heat transfer was considered to be the key technical study area. Therefore, the goal of this effort is improved heat transfer and reduced thermal mass in a hydride heat exchanger/containment assembly. Phase II consisted of the experimental verification of the hydride alloy design data, fabrication of the hydride heat exchanger module components, heat transfer testing of a single heat exchanger element and preliminary performance testing of the entire module. In Phase II, two hydride heat exchanger modules were constructed. Each module consists of 14 finned copper tubes in a staggered tube bundle arrangement enclosed in a cylindrical pressure vessel. The hydride powder is stored in the annular spacing between the fins. The heat transfer media, water, flows through the finned tubes. Insulation thermally isolates the tubes and hydride materials from the high mass pressure vessel. A single metallic filter in each vessel prevents hydride migration from one vessel to another. Two of these vessels were connected together as a pair by a hydrogen flow path. One vessel contains hydride LaNi sub 5 packed around the finned copper tubes, while the second vessel contains hydride MmNi sub 4 sub 15 Fe sub 0 sub 85 * in a similar configuration. Preliminary performance testing of the hydride heat exchangers yielded important data for evaluation of cycle time and heat transfer rates. The test results indicate that the hydride heat exchangers functioned as predicted fulfilling developmental goals of increased heat transfer and lowered cycle time and low thermal mass. (ERA citation 09:016713)