Movable Thermal Screen For Saving Energy Inside The Greenhouse

Abstract

In this work, a movable thermal screens was designed and examined for the purpose of decreasing greenhouse heating loss in Baghdad during winter nights. Three types of automatic movable thermal screens were tested to decrease the heat loss inside a greenhouse. The transparent cover area was 29.2   with 4 mm glass cover thickness. The mathematical model was formulated in four parts which are the inside air, transparent cover, soil surface, and subsoil layer. The results of the thermal curtains showed that the average temperature of the inside air during the night for the polyethylene, polypropylene, and bubble films was 8.1 ̊C, 10.3 ̊C, and 12.5 ̊C respectively and greenhouse without screens was 5.9 ̊C. These results showed that the bubble film was more effective in a saving energy than polypropylene and polyethylene films. Good agreement was obtained between the mathematical model and the measured values (with relative root mean square errors below 5%). It was shown that the suggested different types of movable thermal curtains were powerful in decreasing heating losses, which is reached about 21.7 % compared with a greenhouse without curtains.