Investigation on Optimum Installation of Latent Heat Storage Board in Greenhouse

A greenhouse with latent heat storage boards is proposed as a passive solar system for drying of woody biomass. From the results of wood drying experiments in greenhouse, it is confirmed that the latent heat storage boards are effective in keeping the greenhouse warm at nighttime, which improves drying rates in the falling drying rate period. However, in autumn and winter seasons, the melting point of phase change material (PCM) in the latent heat storage board has to be reduced, because the air temperature in greenhouse is too low to melt the phase change material. The amount of heat storage for low melting point PCM is about one-half that for high melting point PCM. In the present study, to utilize the high melting point PCM in autumn and winter seasons, both effects of improvement of heat transfer coefficient of latent heat storage board and insulation of greenhouse wall on the temperature rise at nighttime are investigated by numerical simulation. Results showed that in autumn, the high melting point PCM can be utilized by circulating the air in the greenhouse or installing the insulation walls. In winter, the high melting point PCM can be utilized by both improvements of heat-transfer coefficient and thermal insulation walls.