الفهرس | Only 14 pages are availabe for public view |
Abstract Thermal energy storage systems offer a significant benefit to heat transfer systems, particularly air conditioning systems, by moving the high amount of electrical power that is consumed by air conditioning for removing cooling loads from the on-peak period’s high power consumption period to the off-peak period’s low power consumption period and having the capability of covering or sharing the cooling loads with more efficiency and energy cost savings. This is a significant advantage for heat transfer systems, especially air conditioning systems.In this work, an experimental investigation is illustrated to study the effect of operation parameters of heat transfer fluid and design parameters of the coil on the time required for complete charging/discharging processes, the average charging/discharging rate, average charging/discharging rate enhancement and charging/discharging time enhancmenet for ice-on-coil system that utilizes bare U-tube without fins and finned copper U-tube as part of a cold thermal energy storage system (CTES).An experimental test rig is made up of a finned U-tube that is immersed in distilled water as a phase change material (PCM) inside an insulated storage tank. In this study, a total of eight alternative U-tube configurations, one of them is bare U-tube without fins and the other seven U-tubes with a unique set of fin design criteria, are used. The results showed that the time necessary for complete charging (solidification) is reduced while the average charging rate is enhanced with the decrease in HTF inlet temperature, the increase in HTF volume flow rate, the increase in Fin length ratio and the decrease in pitch ratio. In addition, the time necessary for complete discharging (melting) is decreased and the average discharging rate is increased with the increase in HTF inlet temperature, HTF volume flow rate, Fin length ratio, and the decrease in pitch ratio. Also, during the charging process, changing HTF volume flow rate from (10 to 20 l/min) on bare U-tube at constant HTF temperature (-10°C) leads to reduce charging time by 17 % and increasing average charging rate by 20 %, increasing Fin length ratio from (0 to ) on finned copper tubes with pitch ratio (s /d =1) leads to reduce charging time by 60 % and increasing average charging rate by 75%, decreasing pitch ratio from (1.5 to 0.75) on finned copper tubes with fin length ratio ( L/d =1) leads to reduce charging time by 20% and increasing average charging rate by 15%. |