Performance characteristics of a hybrid absorption chiller driven by exhaust gas and cooling water from a gas engine.

In this study, a hybrid absorption chiller was proposed as a part of the energy supply facility for a building with a rooftop greenhouse. Using the exhaust gas and the cooling water from the gas engine, the hybrid absorption chiller supplies the cooling and heating in summer and winter, respectively. Starting from the reference cycle, optimization processes were performed in three steps to maximize the improvements in the cooling capacity and the COP. The COP and the cooling capacity of the finally optimized cycle could be substantially improved compared to those of the initial reference cycle. Additionally, the performance characteristics in off-design conditions were investigated. The hybrid absorption cycle displayed a unique feature, that is, the overall COP decreased with the increasing temperature and the mass flow rate of the hot water due to the crucial role of the single-effect cycle with a low COP. Using the proposed hybrid absorption chiller, a COP of approximately 1.1 can be achieved, which is substantially higher than that of a single-effect absorption chiller. If the present hybrid absorption system is widely applied to places where gas- and liquid-phase waste heat is available, then this system is expected to contribute to energy savings and the reduction of CO2 emissions. [ABSTRACT FROM AUTHOR]