Feasibility of Energy Recovery from Exhausted Air of HVAC Systems

This paper investigates directly the feasibility of recovering energy from exhaust air from central air conditioning plants experimentally. A mini vertical axis small wind turbine is connected directly with the exhaust air of the condenser fan. The exhaust air energy recovery unit includes air rotor blades and a generator. The electricity produced from the recovery unit is based on the fan speed and its air flow rate (CFM). The exhaust air from different types of central A/C systems is measured experimentally. The results showed that the speed of the air exhausted from a central A/C package unit with a capacity of 5-ton refrigeration (TR) reached 8–15 m/s based on the rotation speed (RPM) of motor. A small vertical wind turbine was installed on the exhaust of air flowing from the condenser fan of the central A/C package unit with 10-ton refrigeration (TR). The proposed exhaust air energy recovery unit produced 35-40% of the total energy consumption in a building having an A/C plant.