Experimental analysis of indoor air quality improvement achieved by using a Clean-Air Heat Pump (CAHP) air-cleaner in a ventilation system

This study investigated the air purification effect of a Clean-Air Heat Pump (CAHP) air-cleaner which combined a silica gel rotor with a heat pump to achieve air cleaning, heating and ventilation in buildings. The experiments were conducted in a field laboratory and compared a low outdoor air supply rate with CAHP air purification of recirculated air with three different outdoor air supply rates without recirculation or air cleaning. Sensory assessments of perceived air quality and chemical measurements of TVOC concentration were used to evaluate the air-cleaning performance of the CAHP. The results of the experiment showed that the operation of the CAHP significantly improved the perceived air quality in a room polluted by both human bio-effluents and building materials. At the outdoor airflow rate of 2 L/s per person, the indoor air quality with CAHP was equivalent to what was achieved in the same room with 10 L/s per person of outdoor air ventilation without air cleaning. The percentage dissatisfied was as low as 5.2% with the CAHP in operation, based on adapted perception assessment. The outdoor air supply rate can be reduced by 76% by using CAHP, as the Clean Air Delivery Rate (CADR) was over three times the outdoor air supply rate when the CAHP was in operation. The chemical measurements indicated a single-pass efficiency of over 92% for the removal of indoor air pollutants when the regeneration temperature was 60 °C. No VOC accumulation on the desiccant wheel was observed.