Characterisation of efficiency losses in ground source heat pump systems equipped with a double parallel stage: A case study

J. García-Céspedes, G. Arnó, I. Herms and J.J. de Felipe

Renewable Energy, 2020, vol. 147, issue P2, 2761-2773

Abstract: This work focuses on methods to characterise the efficiency losses in existing ground-source heat pump (GSHP) installations under part-load conditions. Efficiency losses were identified and quantified in a GSHP by analysing key parameters measured and recorded by its monitoring system. The heating/cooling production facility comprises a vertical borehole heat exchanger field and a GSHP equipped with a double parallel stage and fixed-speed compressors within. The methodology was based on the EN-14825 standard and other recent works. However, the particularity of having two parallel stages motivated the creation of a modified theoretical approach, since the original methodology was only applicable to single-stage heat pumps. To obtain significant results, minute-resolved data acquired over time periods with almost constant thermal load (quasi-steady state conditions) proved necessary. The study concluded that the coefficient of performance can suffer reductions as high as 9% exclusively due to part-load operation. Most importantly, it demonstrated that the actual capacity of the GSHP as a whole shows an effective reduction ranging between 20% and 24% with respect to the declared capacity of the heat pump alone. Moreover, weekly-averaged data collected during 3 complete cool and warm seasons point to a progressive degradation from the date of commissioning. Finally, Ground Loop Design software (v2016) was used to validate the methodology. Consistent agreement was found between simulated and measured seasonal performance.

Keywords: Ground source heat pump; Partialisation losses; Seasonal performance; Parallel stages; Part-load factor; Part-load ratio (search for similar items in EconPapers)
Date: 2020
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Citations: View citations in EconPapers (3)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:147:y:2020:i:p2:p:2761-2773

DOI: 10.1016/j.renene.2019.01.029

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