Liquid Desiccant Unit Project for a Museum in Beijing

Project Overview
This museum is located in Beijing, with a total floor area of approximately 80 m² and a ceiling height of 2.7 m. Its primary function is the preservation and safekeeping of various important books and archival documents. Since paper‑based materials are highly sensitive to humidity fluctuations, high ambient humidity can rapidly promote the growth of mould and fungi, directly threatening the safety of the collections. Therefore, efficient and stable dehumidification equipment is an essential requirement for this museum.

Operation Modes
The design employs Aolan’s heat‑pump counter‑flow liquid desiccant dehumidification unit, which is installed in the indoor air‑conditioning equipment room. The unit is connected to the collection storage area via supply and return air duct systems. With gentle indoor air supply and uniform airflow distribution, extremely low fluctuations in indoor temperature and humidity are ensured. For most of the time, full return‑air circulation is adopted to save energy and reduce consumption. When personnel enter or leave the storage area, the fresh‑air damper can be opened to provide necessary outdoor air, and the unit operates in mixed‑air mode. Throughout the year, it automatically runs as needed, including cooling, dehumidification, heating, and humidification modes. Based on variations in outdoor and indoor temperature and humidity, it automatically switches between cooling‑with‑dehumidification and heating‑with‑humidification, among other modes, to maintain essentially constant indoor temperature and humidity.

Performance Results
The project was put into operation in early December 2024 and has been performing well, meeting the design requirements for indoor temperature and humidity. The daily temperature variation is controlled within 2°C to 5°C, and the daily relative humidity fluctuation does not exceed 5%, achieving stable operation with low fluctuations and low power consumption. At the same time, the system effectively removes harmful substances and fine dust from the air during operation, thereby improving the air quality inside the storage area.

On‑site acceptance was carried out in accordance with the acceptance documents/standards/terms agreed by both parties. The acceptance results met all design specifications. Long‑term operational tracking records show that indoor temperature, humidity, and air quality all meet the required standards, with instantaneous power consumption consistently well below the designed value.