Combined cogeneration and liquid-desiccant system applied in a demonstration building

A hybrid HVAC system, consisting of cogenerators, liquid-desiccant system (LDS), vapor compression and absorption chillers, gas boiler and storage tanks, is established in this paper, which is used to match the power and thermal demands of a 20,000 m2 demonstration building in Beijing, China. Both power produced and waste heat exhausted from the cogenerators are fully used in different stages of the building energy demand according to their energy quality levels, where power is used to meet the electrical load and waste heat is used to regenerate desiccant, drive absorption chiller in summer and heat the building in winter. By applying independent humidity control strategy in this system, a higher indoor comfort level would be obtained. Simulation analysis is carried out to analyze the system performance under different operation modes and conditions. It shows that energy storage devices play an important role in the proposed system. Compared with the conventional HVAC system, the hybrid system is found to be more energy efficient and environmental friendly. It needs only 2 years to recover the extra initial cost and CO2 emission is reduced by about 40%.