Laboratory evaluation of dual core heat/energy recovery systems

As a component of the NRC's research project launched in 2016 related to air ventilation systems for housing in the arctic, NRC researchers, led by principle investigator Boualem Ouazia, tested and challenged the identified novel dual core technologies using a facility combining two environmental chambers and a heat recovery ventilator (HRV)/energy recovery ventilator (EVR) test rig. The environmental chambers were used to simulate the indoor and outdoor conditions identified by certification standards (Home Ventilating Institute and CSA C-439) and realistic conditions identified in the north. The laboratory evaluation was done under a range of outdoor temperatures of down to -40°C. The laboratory evaluation of Technology 1, a dual core ERV RGSP 300 designed with twin parallel heat exchangers with patented damper, was completed in 2016/2017 and the laboratory evaluation of Technology 2, a dual core H/ERV ARIA 195 ECM designed with a sensible and an enthalpy heat exchangers in serie, was completed in 2017/2018.

Technology 1

The laboratory testing of Technology 1, the dual core ERV RGSP 300 unit, has shown that with the dual core design, the technology was found to be capable of withstanding outdoor temperatures of down to -40°C without deteriorating its thermal performance, and therefore was more frost-tolerant than conventional single core HRVs/ERVs. The calculated apparent sensible and total efficiencies were much higher than values claimed by manufacturers for available single core heat/energy recovery units. The RGSP 300 unit was also found to be able to provide continuous delivery of outdoor air to the space even at very low outdoor temperatures without defrost strategy or pre-heating, showing higher potential to meet the ventilation requirement set by the National Energy Building Code and ventilation standards in extreme cold climates compared to a single heat/energy recovery unit with defrost cycles.

Technology 2

The laboratory testing of dual core Technology 2, the dual core ARIA 195 ECM, was found to not be capable of withstanding outdoor temperatures below -25°C without deteriorating its thermal performance, still more frost-tolerant than conventional single core HRVs/ERVs but much less than Technology 1. The Technology 2 failed after 65 hours continuous testing at an outdoor temperature of -35°C, even with a longer defrost strategy. The calculated apparent sensible and total efficiencies were higher than values claimed for available single core heat/energy recovery technologies at an outdoor temperature of 0°C and even at a colder temperature of -25°C. Technology 2 has shown good thermal and ventilation performance for outdoor temperatures down to -25°C, but underperformed at lower outdoor temperatures when compared with Technology 1.

Additional reading:

• Evaluation of the performance of a dual core air handling unit for use in cold climates. Report # A1-009461.1
• Evaluation of the performance of a dual core heat/energy recovery unit for use in cold climates. Report # A1-009461.3
• Evaluation study of the performance of a dual core energy recovery system for dwellings in the Arctic. Conference paper presented and published at the 9th International Cold Climate HVAC conference 2018.
• Performance of dual core energy recovery ventilation system for use in arctic housing. Conference paper presented and published at the 39th AIVC Conference on smart ventilation for buildings 2018.