A novel solar-geothermal district heating, cooling and domestic hot water system: Dynamic simulation and energy-economic analysis. (15th December 2017)

• Record Type: Journal Article
• Authors: Carotenuto, Alberto; Figaj, Rafal Damian; Vanoli, Laura
• Is Part Of: Energy. Volume 141(2017)
• Page Start: 2652
• Page End: 2669
• Publication Date: 2017-12-15
• Subjects: Evacuated collectors -- Adsorption chiller -- Building retrofit -- Feasibility study -- Parametric analysis; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2017.08.084
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: In this paper a novel low temperature district heating and cooling system based on renewable energy sources is investigated by means of a dynamic simulation model and an energy-economic analysis. A novel solution consisting of geothermal, solar and biomass energy sources integration is considered. Low enthalpy geothermal well, evacuated solar collectors and auxiliary wood-chip boiler are used to supply the district heating system during the winter season. During summer, an adsorption chiller is activated in order to provide district cooling, while during all year, the system produces domestic hot water for the district users. The case study is developed for the district area of Monterusciello, near the city of Pozzuoli, in Southern Italy. For the case study under investigation, a geothermal source is available at about 55 °C with typical irradiance conditions of Mediterranean climate. A rehabilitation of the buildings located in the considered district area is considered. The proposed system is modelled in TRNSYS environment, where a novel and detailed control strategy is implemented in order to manage the system operation and to match the thermal energy demand of the district users. A comprehensive model of the district network and a detailed heating and cooling demand of network users are considered in the dynamic simulation model of the system. A 1-year simulation is performed and the system performance is analyzed with daily, weekly and yearly time bases. The system analysis is completed with a sensitivity analysis, performed in order to evaluate the system energy and economic profitability as a function of the solar collector field area. The results outline that geothermal and solar energy are only used to match the thermal demand of the district users during winter, while only during summer the activation of the auxiliary biomass boiler is mandatory to match the space cooling demand. The novel system achieves a satisfactory yearly performance in terms of solar collector field efficiency (above 40%) and adsorption chiller Coefficient of Performance (0.5). The system is not economically feasible without any public funding (Simple Pay Back of 20.9 years), while a significant primary energy ratio is achieved (above 75%). In case of public funding policies, the Simple Pay Back period can be halved. Highlights: A district system for a council housing area is presented. System includes solar, geothermal and biomass energy sources. The system provides heating/cooling and domestic hot water for a district area. The thermal demand is matched mainly by solar collectors and geothermal well. The system simple pay back period is about 20 years, with incentive 10 years.