PCM thermal energy storage for indoor environments
During the IIR PCM2018 conference which took place on May 21-23 in Orford, Canada, numerous applications of phase-change materials (PCMs) and slurries were presented, including in commercial refrigeration (refrigerated display cabinets), domestic refrigeration (refrigerators and freezers), heat pumps, district cooling, and other applications. The PCM application which has been the target of the highest number of papers is indoor thermal environment of buildings.
- E. Osterman and U. Stritih1 presented a solution using PCMs as a way of storing thermal energy in order to reduce energy consumption in buildings. During summer nights, outdoor cold is stored and delivered during the day to reduce cooling load, whereas in winter, heat from solar air collectors is stored for heating during morning and evening hours.
The proposed latent heat storage system is a stand-alone unit suitable for offices, which consists of plates filled with paraffin RT22HC.
The authors have examined the operation of the system over a year, explored the feasibility of using it for both cooling and heating and carried out a parametrical analysis (influence of melting temperatures, plate’s thickness, width of channels,...) in order to find the best set of parameters for given conditions. Calculations show that for Ljubljana, Slovenia, annual energy savings for a small office could be around 190 kWh.
- Y. Kusama and Y. Ishidoya2 developed a PCM plaster (melting point of 23 °C) composed of microencapsulated PCM and gypsum plaster. Measurements of temperature and relative humidity were made from January to June 2016 in two experimental residences constructed in Hokkaido, Japan (cold climate) with the developed PCM plaster. The indoor environment of the houses, which were airtight with high insulation, showed comfortable temperature and humidity ranges, and the energy saving rate (ratio of heating load and total heat loss) was about 50% on average.
- N. Morovat and A.K. Athienitis3 have investigated different design options for the integration of active PCM in an office zone. The charging and discharging of the PCM, arranged in layers, is managed by a controlled airflow passing through these layers. Two configurations are considered: (a) PCM in a wall in which a PCM layer is in contact with the air in the room and (b) PCM within a duct heat exchanger in a ceiling plenum. Several control strategies are also evaluated. Montreal climate conditions were used to evaluate the annual energy performance of the system. In comparison with a room without PCM, it was found that the annual heating energy use can be reduced by 29% for the first configuration, and 33% for the second. An enhanced control strategy may yield a 38% reduction with the Configuration B. Furthermore, the morning peak load could be reduced by 22% by improving the charging/discharging strategy of the PCM in the ceiling plenum.
1 Osterman. E., Stritih U. Parametrical analysis of PCM thermal storage system for heating and cooling of buildings. Available in Fridoc.
2 Kusama Y., Ishidoya Y., Measurement results of indoor environment and energy-saving experimental residences constructed with PCM plaster in Hokkaido (Japan) Available in Fridoc.
3 Morovat N., Athienitis A. K., Impact of building-integrated PCM on the indoor thermal environment and energy performance of an office zone. Available in Fridoc.