Earth Notes: General Bibliography (rees2014geothermal)

• [rees2014geothermal] Rees, Simon and Curtis, Robin National Deployment of Domestic Geothermal Heat Pump Technology: Observations on the UK Experience 1995–2013 (accessed 2023-04-12), MDPI AG, 2014-08, Energies, volume 7, report/number 8, ISSN 1996-1073, doi:10.3390/en7085460, article/pages 5460–5499 (article) (BibTeX).
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  [Quote: "A further technical issue related to system control is that of dynamic cycling behavior of heat pumps and the application of buffer tanks. ... in the dynamic start-up phases of operation the system operates inefficiently until the proper pressures are established and the compressor runs with less than ideal lubricating conditions. If cycling is excessive (in terms of cycle duration or a high number of cycles per hour) this results in a deterioration of SPF but also some concern as to reduced compressor life. One approach to maximizing cycle times is to include a buffer tank at the outlet of the heat pump from which the heating system draws warm fluid as demanded and to which the heat pump adds heat according to tank temperature. It is evident from the UK trials that industry practice as to the inclusion of buffer tanks varies considerably. The value of configuring the heating system in this way, and the relationship to TRV operation, was investigated following the first phase of the UK field trials in a combined modeling and experimental study. This study showed that operation of TRVs in systems with small numbers of radiators could exacerbate frequent cycling in some situations and that a small buffer tank could be beneficial. Higher frequency cycling was shown to result in modest reductions in system efficiency." Quote: "The predominance of hydronic heating systems using natural gas boilers is also reflected in the national skills and knowledge base. The absence of demand for domestic air conditioning has meant that skills and training in small-scale refrigeration systems is very limited. This is similarly reflected in the education and training that has been demanded by, and delivered to, the domestic heating industry." Quote: "...the EST field trial report concluded that user behavior did have an impact of performance levels and that there was a need for clearer and simpler user advice." Quote: "Revision of the MCS heat pump installation standard (MIS 3005 version 3.1) introduced a requirement to match the heat pump capacity to 100% of the house design heat loss (for mono-energetic systems). This is a rather different approach to that taken in other parts of Europe where common practice is to size to allow the final 10%–20% of peak load to be met by electrical resistance heating. The latter practice can be more optimal in terms of capital cost and not very damaging to running costs if the number of hours in the year when peak loads are approached is small. The relationship between heat pump capacity and design load depends on how loads are calculated and the design temperatures chosen. In the revised UK standard 99th percentile coldest temperatures from typical year climate data are defined and so, arguably, there may be short periods where heat pump capacity is exceeded."]