Stability chemical heat pump applications

Stability Considerations of AB5 Hydrides in Chemical Heat Pump Applications with Reference to the New LaNi5 xAlx Ternary System... 

PPO forms one of a group of rigid, heat-resistant, more-or-less selfextinguishing polymers with a good electrical and chemical resistance, low water absorption and very good dimensional stability. This has led to a number of applications in television such as tuner strips, microwave insulation components and transformer housings. The excellent hydrolytic stability has also led to applications in water distribution and water treatment applications such as in pumps, water meters, sprinkler systems and hot water tanks. It is also used in valves of drink vending machines. 

PPO is a thermoplastic with excellent heat and dimensional stability, and satisfactory chemical resistance. The material may be found primarily in pump parts and certain other applications where impact strength, good modulus, and reasonable abrasion resistance are required. The chemical resistance of the material is good and the allowable temperature limit of 120°C, under appropriate conditions, extends the attractiveness for use of the product. The cost requires specific need for an identifiable application before choosing the product over many less costly thermoplastics. 

Diffusion pump fluids are high molecular weight materials, such as many oils and mercury, which vaporize at a reasonable temperature. A concern is the thermal and chemical stability of the fluid. Hydrocarbon oils tend to break down under heat to form low molecular weight fractions, or they may oxidize and polymerize into a vamish-like material, and therefore are not desirable for many applications. Silicone oils are much more stable with respect to temperature and oxidation and are the fluids most often used in DPs for vacuum deposition processes. 

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