On Climatic Control of Wrap-Around Heat Pipe (WAHP) Enhanced Dehumidifier in Outdoor Air Systems

Although wrap-around heat pipes (WAHP) are widely used for enhanced dehumidification systems in tropical and hot-humid climates, very few literature resources have actually reported any control methodology applicable for WAHP dehumidifier systems for an entire year’s operation. In the present work, a methodology is proposed for an outdoor air unit equipped with a WAHP-based dehumidifier along with other auxiliary components. For this, the ambient conditions over an entire year are categorized into six constituent regions based on temperature and humidity levels. The proposed method involves defining specific control sequences corresponding to ambient conditions under each psychrometric region for tandem operation of system components. Fundamentally, this establishes a sort of segregated climatic control protocol for maintaining acceptable levels of humidity and temperature inside the conditioned spaces during a whole year’s operations. An energy simulation study is performed for two DOE prototype office buildings with six representative weather locations ranging from extremely hot and humid to dry and hot as per ASHRAE’s climate classification. Results show that a 100% outdoor unit comprising WAHP-based dehumidifier system equipped with proposed climatic controls saves cooling plant energy in a range of 1.5–19%, when compared with a similar WAHP-based outdoor unit without any climatic controls and auxiliary components. The proposed controls also enable the outdoor air unit in maintaining comparatively better indoor environmental conditions (temperature and relative humidity), resulting in lesser number of building occupied hours drifting away from prescribed indoor temperature and relative humidity limits than its basic counterpart without any climatic controls. This substantiates the intent and applicability of proposed control methodology for WAHP-based dehumidifier systems.