Modelling of improved energy performance of air-cooled chillers with mist pre-cooling

Evaporative cooling technologies for air-cooled chillers for building energy performance improvement

“…A series of experimental and simulation studies by authors (Yang, Chan, Wu, Yang, & Zhang, 2012;Yang, Chan, Wu, Yu, & Yang, 2012;Yu & Chan, 2005, 2006, 2009Yu, Chan, Sit, & Yang, 2013;Yu, Chan, Yang, & Sit, 2015) have confirmed that mist precooling of condenser air brings benefits of energy savings and sustainable use of water, with regard to chillers operating in a warm and humid climate. The benefits would be more appealing for chillers operating in a hot-arid climate.…”

“…This is because any fluctuation in the condenser air temperature (Zhang et al, 2000) • Refrigeration effect increased by 6.1-13.3% and COP rose by 31.7-50.6% (Yu & Chan, 2005) • Energy was saved by 2.4-14.0% (Hao et al, 2013) • COP increased by up to 21.3% or 51.5% • Electricity was saved by 14.1% Advances in Building Energy Research would affect the operation of condenser fans to maintain a given set point of condensing temperature. A previous study by Yu and Chan, 2009 indicated that near-optimum control of the mist system can be achieved simply by interlocking the operation of the chillers under head pressure control with a constant mist generation rate. Yet, to achieve the highest improvement of the chiller COP, floating head pressure control should be implemented under which the set point of condensing temperature is adjusted based on the load and ambient conditions to minimize the total of compressor power and condenser fan power (Yu & Chan, 2006, 2007a, 2007b, 2008a, 2008b, 2009.…”

“…A previous study by Yu and Chan, 2009 indicated that near-optimum control of the mist system can be achieved simply by interlocking the operation of the chillers under head pressure control with a constant mist generation rate. Yet, to achieve the highest improvement of the chiller COP, floating head pressure control should be implemented under which the set point of condensing temperature is adjusted based on the load and ambient conditions to minimize the total of compressor power and condenser fan power (Yu & Chan, 2006, 2007a, 2007b, 2008a, 2008b, 2009. In many operating conditions, the heat rejection airflow rate is kept high to maintain the condensing temperature at a low set point.…”

“…The significances of this study are to illustrate more design and operating criteria to nurture their applications, and to identify potential integration with optimal control of air-cooled chillers. This study is related to a series of research work by authors on the sustainable design and operation of air-cooled chiller systems and the simulation of improved energy performance of air-cooled chillers with mist precooling (Yang, Chan, Wu, Yu, & Yang, 2012;Yu & Chan, 2005, 2006, 2007a, 2007b, 2008a, 2008b, 2009Yu, Chan, Sit, & Yang, 2013;Yu, Chan, Yang, & Sit, 2015). Vakiloroaya et al (2014) summarize two common devices placed in front of air-cooled condensers to cool evaporatively ambient air from the dry bulb temperature down to the wet bulb temperature.…”

Performance Improvement of Air Conditioning System using Applications of Evaporative Cooling: A Review Paper

“…Yu et al [7] investigated how their coefficient of performance (COP) can be improved by using mist to pre-cool ambient air entering the condensers. The benefit of this application rests on the decrease of compressor power resulting from the reduced condenser air temperature with insignificant consumption of water and pump power associated with the mist generation.…”