Thermo-economic Analysis of a Solar Pit Seasonal Thermal Energy Storage for Greenhouse Heating
Author
Term
4. semester
Education
Publication year
2020
Submitted on
2020-05-29
Pages
111
Abstract
Greenhouse farming is rising due to the high demand of fresh diverse produce and given the fossil-fuel paradigm, it is urging the implementation of renewable and sustainable technologies in this industry. This thesis is based on the heat demand of a tomato greenhouse implemented on the region of Aarhus, Denmark, with internal temperature variations from 18 to 22 ℃, using as main energy source a 2000 m^3 pit seasonal thermal energy storage unit, aided by a 3000〖 m〗^2 U-pipe shaped evacuated tube collector field as energy source, having water as medium and with maximum operating temperature of 85 ℃. In order to understand the feasibility of using a pit storage unit to cope the greenhouse’s temperature requirements, a thermo-economic analysis was done, conducting an energetic examination based on the heat balance of all units and economically, by a net present value (NPV) approach. Knowing the greenhouse hourly heat demand pattern on a year-basis, a multi-node approach was taken to predict stratification in the, dependent on in-and-out fluxes from the collector field and greenhouse. The modelling showed that it is possible to cover a 73 % of a 2000 m^2 tomato growth greenhouse’s heat demand for an optimal temperature control, with a solar collector field and pit storage efficiencies of 33.5 % and 80.5 %, respectively. The setup showed a positive NPV of 200,000 € on a 20 years lifetime basis and a payback period of 10 years.
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