Transient seasonal analysis and optimization of integrated solar assisted desiccant indirect evaporative cooling system with dynamic building load under multiple climates

Thermal comfort demand in building sector is increasing remarkably due to population growth, urbanization and global warming, particularly in hot and humid climates like Pakistan. An Integrated Solar Assisted Desiccant Cooling System with Indirect Evaporative Maisotsenko Cycle (SADC-Mc) system is one of the obvious solutions to deal with rapidly growing cooling needs through sustainable, efficient with minimal power consumption. However, the performance of such systems is strongly influenced by the dynamic building load and transient climate conditions like solar irradiance, ambient air temperature and humidity. In this study, a transient seasonal analysis and optimization of SDC-IEM-cycle was performed for multiple climate zones of Pakistan including Humid subtropical (Cwa), Warm semi-arid (BSh), and Warm desert climate (BWh) by considering different cities like Peshawar, Taxila, Lahore, Multan and Karachi. Detailed solar assisted desiccant cooling system model was developed in TRNSYS and M-cycle EES model were integrated to perform the seasonal (April-September) transient simulation analysis under dynamic building load for the selected climates. Afterwards, the system optimization is performed by coupling TRNSYS with optimization tool GenOpt by considering COP, and solar energy gain of the system as cost functions using Hook Jeeves algorithm. The system model validation findings presented good agreement with published experimental data with the mean percentage error of 2.7 %. The SADC-Mc system was found to be 40-60% more efficient than the conventional system in term of COPth for less humid climates of Taxila, Peshawar, and Lahore. The integrated system performed well in terms of cooling capacity (CC) for all cities with the highest value (1694-5407 kWh) in Multan. Moreover, the minimum regeneration heat Qreq of the system was required in Taxila (1451-6603 kWh) and Peshawar (1742-6662 kWh). Solar fraction to meet Qreq was high in Peshawar (0.48 -1) and Taxila (0.47-1). The optimal value of COP was 0.59 along with optimal solar energy gain of 40 MWh. It was concluded that SADC-Mc system offered a sustainable alternative to the conventional system due to its high COPth, CC, and efficient utilization of solar energy with less auxiliary heat requirement to achieve desired thermal comfort.