| Abstract: | The present work is a study of reentrainment of a tracer gas formaldehyde via six rotary air-to-air heat exchangers (all enthalpy exchangers) in the northern part of Sweden. Five exchangers installed in office buildings and one in a day-care centre were included in the study. Formaldehyde in indoor was used as a monitor pollutant and was determined in air samples collected in the ducts at four positions around the rotor of the exchanger, in the supply-air duct and in the exhaust-air duct. Air sampling of homogeneous duct air was performed simultaneously at the four positions using 2, 4-dinitrophenylhydrazine-impregnated glass fibre filters. The sample analysis of formaldehyde was made by high-performance liquid chromatography. The reentrainment of formaldehyde was calculated and found to be 1-9%. These results show that a rotary heat exchanger can be used in buildings where activities produce low levels of air pollutants, provided that the exchanger is properly installed and maintained. |
