Experimental study of a heat recovery ventilator preheated by a Building Integrated Photovoltaic system in a cold climate

Abstract

The use of heat recovery ventilators (HRVs) in cold climate housing is becoming increasingly common, to provide outside air to the occupied space while recovering heat from the exhausted air. However, frosting of the heat exchanger core impedes HRV operation in cold climate conditions. Strategies for defrosting the core include recirculating the exhaust airstream while stopping the supply of the outside air during the defrost cycle. Preheating the air using heating coils is also used, but its application is limited by the increased energy use of the preheater. This study aims to investigate the impact of a building integrated photovoltaic/thermal (BIPV/T) system on the HRV thermal performance by using it to preheat the outside air. In this experimental study, measurements of a heat recovery ventilator preheated by the BIPV/T system are carried out in a test cell of the Future Buildings Laboratory (FBL) at Concordia University in Montreal, Canada. The results are compared to a HRV without BIPV/T preheating. The relative humidity, temperature and airflow rate of the fresh air and exhaust airstreams are monitored at the inlet and outlet of the HRV. The experiments are conducted during two weeks from January 26th, 2023 to February 08th, 2023. The change of the sensible heat recovery effectiveness ∈ sens of the HRV, outside air outlet temperature T 2 from the HRV and outside air flow rate, ṁ1 and exhaust air flow rate ṁ4 are determined. The primary experimental results indicate that preheating the outside air by the BIPV/T system before entering the HRV can help to increase the outside air outlet temperature T 2 by up to 2.7°C at an outdoor temperature of -25 °C, and the sensible heat recovery effectiveness ∈ sens , outside air flow rate, ṁ1 (23L/s) and exhaust air flow rate ṁ4 (43L/s) of the HRV are kept constant at the same level with preheating by BIPV/T on the HRV at -5 °C to -25 °C of outdoor temperature.