Energy Conversion¶
Chiller¶
Chillers are used to produce chilled water for cooling applications, such as district cooling systems or industrial processes. Chillers can be powered by geothermal energy, providing a sustainable and efficient cooling solution. The following parameters are proposed for the chiller system:
For chilling we assume the ∆T is strongly limited by the return temperature of the heat conversion process which must be a couple of tens of degrees higher than the ambient temperature which can range up to ca 50°C in summer in high temperature conditions. We adopt 60 °C as reinjection temperature in the heat conversion, in line with assumptions for solar assisted chillers (El-Sharkawy et al., 2014; Ayou and Coronas, 2020), for minimum production temperature we assume 70 °C . Capex and Opex parameters are based on the literature and are indicative for a chiller system with a capacity of 0.3 MW or more (DOE, 2017)
| Parameter | Symbol | Value | Unit |
|---|---|---|---|
| Minimum aquifer production temperature | Tminprod | 70 | °C |
| Maximum cooling temperature for reinjection relative to reservoir (ΔT) | ΔTmax | 40-200 | °C |
| Minimum injection temperature (clips cooling) | Tmininj | 15 | °C |
| Injection (return) temperature | Treturn | 60 | °C |
| Conversion efficiency | η | 0.4 | - |
| Parasitic power needs for conversion process (fraction of net power) | epara | 0.1 | - |
| Annual load hours | Hload | 6000 | hour |
| Capex Base expense | CAPEXbase | 0.5 | million€ |
| Capex Variable (including heat exchanger) | CAPEXother,var | 1100 | €/kW |
| base opex | OPEXbase | 10 | k€ |
| annual opex per unit power | OPEXpower | 50 | €/kW |
| Additional opex per unit energy produced | OPEXheat,var | 0 | €/kWh |
References¶
- El-Sharkawi, I., AbdelMeguid, H., Saha, B.B., 2014. Potential application of solar powered adsorption cooling systems in the Middle East., http://dx.doi.org/10.1016/j.apenergy.2014.03.092.
- Ayou, D., Coronas, A., 2020. Solar-assisted adsorption chillers: A review of the state of the art and future prospects. Renewable and Sustainable Energy Reviews 119, 109580. https://doi.org/10.1016/j.rser.2019.109580
- DOE, 2017. U.S. Department of Energy factsheet Combined heat and power. Technology fact sheet series, https://www.energy.gov/eere/amo/downloads/absorption-chillers-chp-systems-doe-chp-technology-fact-sheet-series-fact-sheet