Impact of integrating desiccant dehumidification processes to conventional AC system on urban microclimate and energy use in Beirut city

Abstract

This study investigates the anthropogenic heating of the urban environment of Beirut city due to air conditioning (AC) when integrating a desiccant dehumidification wheel into the conventional vapor compression (VC) system to reduce the high electricity consumption during the summer. Two hybrid system configurations with integrated heat exchanger (HE) and indirect evaporative cooler (IEC) are studied. The hot humid microclimate of Beirut is simulated assuming the use of conventional VC systems. The results were validated by comparing measured and predicted temperatures in four locations of the city. Simulations were then performed using the proposed interventions of the two hybrid systems.The results show that conventional VC systems resulted in an average increase in the ambient temperature in Beirut of 1.3 °C in day-time and 2.2 °C in night-time in the simulated period in the month of August. The electrical energy consumption of hybrid systems with IEC and HE systems was lower by 53% and 38% than VC systems, respectively. Compared to VC, HE systems increased the sensible waste heat by 10% while IEC systems decreased it by 2%. Compared to VC systems, IEC systems resulted in decrease of ambient temperature by 0.1–0.3 °C and HE systems increased the ambient temperature by 0.1–0.3 °C. The IEC system is recommended due to its high electricity savings and lower impact on the urban heat island compared to the conventional system.