DOAS with evaporative pre-cooling of exhaust air using rotating contacting device is presented with features like low pressure drop, high effectiveness, noncorrosive plastic construction. Cooling of supply air for ventilation is then accomplished using evaporatively pre-cooled exhaust air.

This enables cooling supply air below the wet bulb temperature of supply air in most of the weather conditions. A counter flow plastic air to air heat exchanger with low pressure drops is deployed for air to air heat exchange. High effectiveness of the heat exchanger having low pressure drops on the supply and exhaust air sides ensures good Indoor Air Quality (IAQ) while keeping the operating costs affordable. This system will be effective in both hot humid as well as hot dry climates.

The paper includes simulation results of achievable effectiveness with such DOAS. Simulation results are compared with experimental data. Case studies indicating the thermal performance, amount of CO2 emission reduction and potential energy savings with such DOAS in Mumbai and five Middle East cities are presented. Typical payback is expected to be in range of 0.25 to 1 year. The effectiveness of the plastic air to air heat exchanger is around 75 to 84% with hydraulic diameter ranging from 5 to 6 mm.