The design of liquid desiccant dehumidification control system

• Main Author: Wang, Gaige
• Other Authors: Cai Wenjian
• Format: Theses and Dissertations
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10356/72590
• Institution: Nanyang Technological University

A dehumidifier plays a significant role in our lives. To make a dehumidifier run in a more stable, controlled and energy-saving way has been a meaningful research direction and goal. For this reason, a novel control system for dehumidifier, liquid desiccant dehumidification system (LDDS) is developed. In the thesis, we first introduce LDDS working principles, involved technologies, and then we turn to construct the control system, including the design of control circuits and development of control programs based on STM32 microcontroller. After the completion of system design and construction, in order to further enhance system stability and reduce more running power consumption, based on the original control algorithm, we propose an improved edition. Originally, we adopt a passive transfer solution process where desiccant solution is exchanged only when the solution in dehumidification tower has completely lost its dehumidifying capacity, and primary attention is given to the control of solution temperature and flow. As the concentration of desiccant solution is gradually diluted which degrades dehumidifying ability, greater solution flow pumped by dehumidifying pump and lower solution temperature cooled by chiller are needed to ensure that the system is in a steady dehumidifying capacity. This will surely consume large quantity of energy and cause system instability. However, in the new edition, active transfer solution mode is proposed where solution is frequently transferred and exchanged between regeneration tower and dehumidification tower to ensure that dehumidifying process is conducted within an allowable range of solution concentration. The actual measurement result indicates that this control algorithm reduces the system running power consumption by about 20%, and that system stability is also improved.