Thermal network predictions of the daily temperature fluctuations in a direct gain room

Abstract

This paper studies the daily temperature fluctuations in a direct gain room measuring 6.1 × 4.57 × 2.44 m 3 (20 ft × 15 ft × 8 ft). The room is assumed to have losses on three faces and 8.36 m 2 (90 ft 2) of south glazing. Let r denote the ratio of the surface area of the mass wall to the area of the south facing glazing. The effect of r on mass walls 10.16, 20.32 and 30.48 cm (4, 8 and 12 in.) thick was determined for values of r equal to 1, 2, 4, 8 and 11.1. The temperature and solar insolation values for a typical January day in Nebraska were duplicated thirty consecutive times and were used for the weather data input to the modeling program. Using thirty consecutive like days has the advantage of damping out the transient solution to the point where it is negligible. It was found that for each thickness of wall, the temperature fluctuations over a day decrease as r increases, and it was also found that for a fixed value of r, the daily temperature fluctuations decrease as the wall thickness is increased. These results are consistent with those reported by Mazria. In addition cloudy day storage was considered for both the 10.16 and 20.32 cm (4 and 8 in.) walls, with r fixed at 4, runs were made with 20, 33, 50 and 100 per cent cloudy days. The results are presented in graphical form and indicate a rapid recovery of the system in most cases.