Evaporator air-side fouling: Effect on performance of room air conditioners and impact on indoor air quality

This study investigated experimentally the effects of real fouling material at the air side of the evaporator's heat exchanger coil on the performance of room air-conditioner units as well as the impact of some fouling material compositions on indoor air quality. At the end of the experiments, examination of the biological contents of the fouling material on the coil was performed; it was found that the coil frontal face had heavy colonies of Aspergillus fungi of different species. This result is important to fill in the knowledge gaps between biological deposition, colonization, and occupant problems of staying in an environment with a fouled evaporator coil. The results of the effect of such fouling materials on the unit performance show that the unit coefficient of performance at the standard air face velocity of 1.53 m/s for a clean evaporator coil was 2.82. It decreased to 1.89 (67%) after injection of 100 g of fouling materials, dropped to 1.79 (63.4%) after injection of 200 g of fouling materials, and fell to 1.23 (43.6%) after injection of 300 g of fouling materials. However, these results demonstrate that the predominant effect of fouling is to cause significant degradation in a room air conditioner's coefficient of performance.