Cooling and desalination account for around half of the total utility consumption in Gulf cooperation council (GCC) countries. As of now in United Arab Emirates (UAE), most of the energy demand is being met with fossil fuel resources but a strong thrive for sustainable future has recently shifted the focus towards renewable energy sources. UAE gains abundant solar irradiation and hence the potential of exploiting solar energy leads to research and development of solar driven polygeneration systems. Polygeneration is one of most efficient ways to maximize the utilization of available energy by integrating different process cycles. Combined heat and power cycles are widely used cogeneration systems and they could be transformed to polygeneration systems by integration of cooling and desalination cycles.
RAK research and innovation center has developed a sustainable and innovative concept to meet these demands along with production of domestic hot. A solar thermal poly-generation (STP) system is designed and developed at SOLAB (Solar Outdoor Laboratory) for production of chilled water for air conditioning using absorption chiller, pure water with membrane distiller and domestic hot water by heat recovery. The STP system has four major components: (i) Evacuated tube collector field (ii) 10TR Absorption chiller (iii) Air-gap membrane distillation (MD) units (iv) Heat exchangers integrated together to operate in four different modes for complete solar cooling, co-generation of pure water and domestic hot water, tri-generation of cooling, pure water and domestic hot water and co-generation of cooling and pure water. Various experiments performed on different modes and the analyzed results show the advantages of combined operation through effective utilization of heat lost in the process operation. In tri-generation mode, heat could be recovered effectively from MD process for DHW production thus reducing overall energy consumption by MD for kg of water production. The schematic sketch below shows the tri-generation system developed at RAK research center. The system could be further extended to Polygeneration for electricity production as well in addition to cooling, pure water and hot water. For more details go through our list of publications.