Development of a Cost-effective Adsorption Dryer for High-quality Aerosol Sampling

Due to their affinity to water, physical-chemical properties of aerosol particles depend highly on the ambient relative humidity (RH). Aerosol drying below 40% RH is recommended to minimize measurement artifacts, increase data quality, and make results from different environments comparable. Diffusion dryers (DD) are one of the most frequently used tools to lower RH in sampled air. This work presents a custom-built DD, its design, construction, and application. By using readily available materials and 3D printing, we were able to manufacture a high-quality, cost-effective DD that can be used in various measurement scenarios (e.g., long-term measurements, intensive field campaigns, laboratory studies, and applications with low-cost sensors). The DD is equipped with ports for desiccant regeneration using clean and dry air, eliminating the need for desiccant removal from the dryer. The field tests of the proposed DD showed that it could reduce RH from ambient 65% to < 5 and 15% at flow rates of 2.5 and 8.0 L min⁻¹, respectively. The transmission efficiency (TE) of 10–20 nm and > 20 nm aerosol particles is between 60–80% and > 80%, respectively. The presented DD is easily scalable, thus, can be adapted for multiple applications at a low cost without compromising the data quality.