Assessment of cool thermal storage strategies in Kuwait (2006)

The extensive use of air conditioning for indoor cooling in offices and large\ncommercial buildings in Kuwait represents a major part of the power and electricity\nconsumption in that country. The main objective of this research was to investigate\nice and chilled water cool thermal storage technologies and operating strategies for air\nconditioning. This was motivated by the extreme climatic conditions in Kuwait and\nthe necessity to reduce both maximum power demand and energy consumption whilst\nbeing economically feasible. This work represents the first such study undertaken.\nIn Kuwait approximately 45% of the total annual exported electrical energy is\nconsumed solely by air conditioning systems as a result of the very high ambient\ntemperatures occurring between March and October. Furthermore, it was estimated air\nconditioning systems represent about 62% of the peak electrical load.\nTo assess the potential of cool thermal storage, the air conditioning system for an\nexisting clinic building, representing a typical medium size building in Kuwait, was\ndesigned with and without a cool thermal storage system. The results demonstrate that\ninternal ice-on-coil and chilled water storage systems are suitable storage technologies\nthat can be implemented in Kuwait.\nThe cooling demand of the clinic building was first estimated using the ESP-r\nbuilding energy simulation program, following which the different components in the\nair conditioning systems were sized including chiller, storage tanks, pumps, air\nhandling units for conventional, ice and chilled water storage air conditioning systems\noperating with load levelling, 50% demand limiting and full storage strategies. The\nheat gains by different auxiliary components in the air conditioning systems were\nestimated and the final cooling demand profiles were developed.\nFor each air conditioning design, the power and energy consumption for the design\nday condition and over the whole year were calculated and analysed. Furthermore, the\nlife cycle costs were determined based on the estimated capital, maintenance,\noperating costs and a financial analysis was carried out.\nFor the Kuwaiti climate, the results demonstrate ice and chilled water storage systems\ncan reduced the maximum power consumption during the day time when the electricity demand is high and largest reduction in the maximum power achieved full\nstorage strategy. However, the energy consumption of ice storage system operating\nwith 50% demand limiting and full strategies were found were found to be higher than\nthe conventional air conditioning system. Nevertheless, the energy consumption in the\nice storage system with a load levelling operating strategy was slightly lower. Chilled\nwater storage system was found to be unlike ice storage system, the energy\nconsumption in all operating strategies improved over the conventional system.\nBased on the estimated life cycle cost using the actual operating costs for both the\ngovernment and user, it was established that for the government, ice storage operating\nwith load levelling strategy and all other strategies of the chilled water storage\nsystems would be more economical than conventional systems. However, for the user,\nload levelling ice storage, load levelling chilled water storage, and 50% demand\nlimiting chilled water storage systems would be more cost effective.\nOut of all alternatives, chilled water storage system with a load levelling strategy was\nfound to be the most cost effective for the climate of Kuwait and for similar climates\nof Kuwait. Although, the outcome from this research work can not be generalised\nhowever, the method of sizing and energy and economic analysis, which was\ndiscussed in this thesis can be generalised and followed to evaluate the impact of cool\nthermal storage systems on energy performance and economy of the air conditioning systems.