Performance Assessment of a Thermoelectric Heat Recovery Ventilator

Abstract

Heat recovery ventilators (HRVs) provide significant energy savings for heated buildings in wintertime. By routing warm exiting stale air past incoming cold fresh air, the fresh air is heated without mixing with the stale air. This can save more than half of the heating energy needed to bring the entering cold air to room temperature. Reversing this process can also help to keep buildings cool in the summer. Traditional HRVs use a simple fixed-plate metal heat exchanger to conduct heat between the airstreams. Thermoelectric membranes, otherwise known as Peltier tiles, show promise in increasing the efficiency of HRVs by adding an active heat transfer element to the system. If the cold side of the tile is exposed to a warm airstream it will absorb heat. The warm side will accordingly reject heat into a cold airstream like a heat pump. The focus of this study was the evaluation of a prototype HRV, equipped with a thermoelectric heat pump (TEM-HRV). The concept was conceived by Natural Resources Canada (NRCan) to enhance the performance of HRVs. The protype unit was assembled from components supplied by NRCan and performance tested in accordance with Canadian Standards Association (CSA) guidelines. Four configurations of combined TEM-HRV test units were tested, as well as a standalone TEM heat pump and fixed-plate HRV. Tests were conducted at various flow rates and current inputs to the TEMs. The performance tests were compared to a numerical model of the TEM-HRV, to assess its accuracy. From the results of the physical tests and the computer modelling, recommendations are given for integration of thermoelectrics into residential heat-recovery ventilation systems.