Kazuhisa Igawa, Yuji Higuchi, Daisuke Tanemura, Kazushi Yamada, Hiroyuki Nishimura, Sakiko Fukunishi, Kazufumi Kohno, Hidekazu Honma, Hidekazu Sugimori
Papers # 2014 Chicago
Recently, as awareness about energy-saving is increasing, high-efficiency energy systems have been developed and introduced. In addition, public and private sectors have simultaneously been implementing various efforts aiming to improve their prevalence rates. These initiatives are represented by the Cogeneration Gas System, which features both a power generation function and Central Heating System containing a latent heat recovery function. Both systems boast a total efficiency of 95％, the highest level in the world. In order to recover exhaust heat during power generation, each system consists of a power generating and hot-water storage unit that functions as a latent heat-recovery type heat-source equipment. The systems use plastic pipes as for hot-water supply and heating which be connected to the tap, bath, and the heater terminal. In terms of design service life, the equipment has a 10-year life expectancy (15 years of practical use) while the pipes have a 30-year lifespan. While many material resins used inside the equipment are engineered plastics such as polyphenylene sulfide (PPS), plastic pipes use cross-linked polyethylene. Versatile raw materials are used for items requiring longer service life; this is the reason plastic pipes require high-level, lifeextending techniques. This report intends to clarify the deterioration behavior of piping systems for heating systems made of traditional cross-linked polyethylene (PEX) and furthermore non-cross-linked polyethylene (PERT), which has excellent eco-friendly properties; this report will also discuss possible countermeasures to this deterioration.