EFFECT OF AMBIENT TEMPERATURE AND AIR FLOW RATE ON THE TEMPERATURE INSIDE THE COMPOST PILE

A heat balance was carried out to predict the compost pile temperature during the maturation stage. The components of the heat generation, solar radiation and heat lost by radiation, evaporation, convection and conduction were the main parts of heat balance at different ambient temperatures. Temperature was predicted at different ambient temperatures (15, 20, 25, 30 and 35°C) and different airflow rates (0.70, 1.10 and 1.50 mg air s⁻¹ kg⁻¹ dry matter). The results indicated that the pile temperature increases with increasing ambient temperature and it decreases with increasing airflow rates, where, as the ambient temperature increased from 15 to 35°C, the pile temperature increased from 33.40 to 43.18°C, and when the airflow rates increased from 0.7 to 1.5 mg air s⁻¹ kg⁻¹ dry matter, the pile temperature decreased from 38.28 to 36.05 °C. The pile temperature increased slightly and reached a maximum value at day 14. It indicates that the net energy gained to the pile increases with increasing ambient temperature, meanwhile, the heat lost decreases with increasing ambient temperature.