Optimal Integration Of Solar Energy With District Cooling System: Mathematical Modeling Approach

The outstanding development witnessed in various sectors across the globe caused mankind to increase their need to cooling energy and hence, consume unsustainable energy resources excessively. That raised the fears on the potential presence of these resources and on how to combat global warming caused by fossil fuel energy. Therefore, industries are shifting toward using renewable energy resources as they are widely available and environmentally friendly. This research addresses the integration of solar energy into conventional cooling systems. Three mixed integer linear programming (MILP) models are developed to represent different configurations of solar thermal and electric cooling systems combined with the conventional cooling systems to minimize annual total system cost. The models are fed with actual data collected on the parameters of the models. Moreover, four different case studies which represent low, medium, high and very high cooling demand scenarios are selected and solved using the CPLEX solver. Furthermore, sensitivity analysis are carried out on the different parameters of the models. The results of the research indicated that the solar electric cooling system connected to the grid is the most economical system compared to other system configuration

Perspectives on Dual-Purpose Smart Water Power Infrastructures for Households in Arid Regions

In hot arid climates, freshwater and power are produced simultaneously through seawater desalination since these regions receive little rainfall. This results in a unique urban water/power cycle that often faces sustainability and resilience challenges. Elsewhere, such challenges have been addressed through smart grid technologies. This chapter explores opportunities and initiatives for implementing smart grid technologies at household level for a case study in Qatar. A functional dual-purpose smart water/power nanogrid is developed. The nanogrid includes multiloop systems for on-site water recycling and on-site power generation based on sustainability concepts. A prototype dual-purpose GSM-based smart water/power nanogrid is assembled and tested in a laboratory. Results of case study implementation show that the proposed nanogrid can reduce energy and water consumptions at household level by 25 and 20%, respectively. Economic analysis shows that implementing the nanogrid at household level has a payback period of 10 years. Hence, larger-scale projects may improve investment paybacks. Extension of the nanogrid into a resilient communal microgrid and/or mesogrid is discussed based on the concept of energy semantics. The modularity of the nanogrid allows the design to be adapted for different scale applications. Perspectives on how the nanogrid can be expanded for large scale applications are outlined

Data of the design of solar assisted district cooling systems

The collected datasets are relevant and related to Optimization of Design and Operation of Solar Assisted District Cooling Systems [1] paper. Part of the data is collected on the main and common components of the system. That includes solar collectors unit price ($/m2), type, and efficiency; absorption chiller capacity (kW), type, initial cost ($), and COP; the hot/chilled water thermal energy storage tank type, initial cost ($) and capacity (kWh); and auxiliary boiler initial cost ($), capacity (kW), type and efficiency. The other part of the data is collected on hourly cooling demand over the year for the state of Qatar (kW), hourly global solar irradiance over the year for the state of Qatar (W/m2) and variable cost of producing and storing chilled and hot water ($/kWh,$/kW). The data are collected from different resources such as government websites, commercial websites, government sectors, journals and real-life case studies. The value of this data comes from that most of the data required to conduct such research in this area are available in one resource. Also, some of the data such as the annual hourly cooling demand and global solar radiation are not available online. Moreover, the collected data are already filtered and the units are consistent and ready to be used. Finally, the data considered to be crucial and the core of such research are available in this paper. 2020 The AuthorsThis publication was made possible by the NPRP award [ NPRP 10-0129-170280 ] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the author[s].Scopu

Optimal design and operation of conventional, solar electric, and solar thermal district cooling systems

This research investigates the integration of solar energy with traditional cooling technologies using solar electric cooling systems. A holistic optimization process is introduced to enable the cost-effective design of such technology. Two mixed-integer linear programming (MILP) models are developed, one for a baseline conventional cooling system and the other for a solar electric cooling system. The MILP models determine the optimal system design and the hourly optimal quantities of electricity and cold water that should be produced and stored while satisfying the cooling demand. The models are tested and analyzed using real-world data, and multiple sensitivity analyses are conducted. Finally, an economic comparison of solar thermal and solar electric cooling systems against a baseline conventional cooling system is performed to determine the most cost-effective system. The findings indicate that the photovoltaic panels used in solar electric cooling cover 42% of the chiller demand for electricity. Moreover, the solar electric cooling system is found to be the most cost-effective, achieving ~5.5% and 55% cost savings compared with conventional and solar thermal cooling systems, respectively. A sensitivity analysis shows that the efficiency of photovoltaic panels has the greatest impact on the annual cost of solar electric cooling systems-their annual cost only increases by 10% when the price of electricity increases by 20%, making solar electric the most economical system. 2021 The Authors. Energy Science & Engineering published by Society of Chemical Industry and John Wiley & Sons Ltd.The publication of this article was funded by the Qatar National Library. This publication was made possible by the NPRP award [NPRP 10-0129-170280] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

Optimization of design and operation of solar assisted district cooling systems

The demand for air conditioning and cooling services is rapidly increasing worldwide. As cooling demand has high coincidence to occur in countries with high solar irradiation, the combination of solar thermal energy and cooling appears to be an exciting alternative to replace traditional electricity-driven cooling systems where electricity is generated from fossil fuels. Nevertheless, solar assisted cooling is not yet widely deployed because of many barriers amongst them the presumed high investment cost of solar cooling technology. This research aims at making this technology more affordable by providing a holistic optimization design of solar assisted district cooling systems. Toward this end, a mixed-integer linear programming model (MILP) is proposed that captures the key design and operation variables of a solar-assisted district cooling system. Hence, the proposed model aims at finding the optimal system design (i.e., the system's main components along with their optimal capacities) together with the optimal hourly policies for production and storage of hot and cold water while satisfying the expected cooling demand. The model was validated using collected real data of different case studies. The optimal system design of some cases showed that solar collectors covered about 46% of the chiller's heat demand. Moreover, the existence of the cold-water TES in the system depends on the chosen chiller capacity and the cooling demand of the case study. Furthermore, a sensitivity analysis was carried out to study the model robustness. The sensitivity analysis shows that the chiller COP had the highest impact on the annual total system cost, where increasing COP by 20% of its initial value, will decrease the annual total system cost by 4.4%. 2020 The AuthorsThis publication was made possible by the NPRP award [NPRP 10-0129-170280] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu