تأثير قطر الأنبوب في أداء المبادل الحراري هواء- أرض المستخدم في البيوت المحمية في محافظة طرطوس

Abstract

Earth-to-air heat exchanger technology is a promising technology that has recently begun to be used to control the temperature of greenhouses, therefore, the aim of the current study was to know how increasing the diameter of the tube would affect the operation of the earth-to-air heat exchanger. Two heat exchangers, 22 meters long and 1.5 meters deep, each in the shape of a U, were tested inside two greenhouses with dimensions of (2*3*12)m. Both were made of PVC with a wall thickness of 2.8mm, the air velocity within the pipes was constant at about 2m.s^-1. The experiments were conducted in a coastal area at a depth of one and a half in clayey soil.

             The results showed that the larger diameter resulted in greater heat exchange. The larger diameter heat exchanger raised the temperature by 38.9% and 20.7% during the two heating periods of the same day, while the smaller diameter heat exchanger raised the temperature by 17.38% and 12.56% during the two heating periods of the same day, during the cooling phase, when temperatures was reached their highest levels during the daytime hours, the exchanger with the larger diameter reduced the temperature inside the greenhouse by about 5.6% while this percentage was 3.4% for the small diameter.