Condensation Heat Gains on Unglazed Solar Collectors in Heat Pump Systems

Abstract

The performance of ground coupled heat pump systems with borehole heat exchangers can be significantly improved by unglazed solar collectors. In this combination, collector operation temperatures below the ambient air level and hence additional condensation heat gains occur. For an investigated and monitored system in Limburg, Germany, the condensation yield was determined to 3.7% or 19 kWh/(a m²). Thereby, condensation shows a significant dependency on the season. During the summer months, only 0.8% of the total collector yield is induced by condensation, while in winter it increases to 13%. The implementation of an established condensation model to the collector model according to EN 12975 is demonstrated. As main result the investigated the heat pump system performance is only marginally improved due to the condensation heat gains.

Seasonal thermal energy storage with heat pumps and low temperatures in building projects—A comparative review

“…Hence, in addition to resulting in a higher COP for the heat pump, i.e. up to 4-5 [24,33], the combination of solar collector with DTES also allows for reducing the borehole depth 4.5 to 7.7 m per square meter of solar collector area [34]. However, for a single family house with a single borehole, the economical aspect of recharging should be considered.…”

High transmittance, low emissivity glass covers for flat plate collectors: Applications and performance

“…Another promising field of application is the renewable support of heat supply systems for hot water production, space heating or cooling, which has been taken anew into consideration within the last years due to growing market of heat pumps. In this case high-quality metallic absorbers are requested, which can replace parts of the building envelope (roofs or façades) and take over the corresponding functions, both in new buildings and building renovation [11,12].…”

Models of Sub-Components and Validation for the IEA SHC Task 44 / HPP Annex 38

“…In Germany, estimated annual condensation heat gains are less than 10% (Pitz-Paal 1988, p.62) whereas first measurements revealed a much smaller fraction of condensation. Measurements on a single family dwelling in Limburg (DE), the condensation yield was determined to be 3.7% of the annual collector yield which corresponds to 19 kWh/(a m²) (Bertram et al 2010). Thereby, condensation shows a significant dependency on the season.…”

“…A TRNSYS simulation study (Bertram et al 2010) revealed a negligible influence on the seasonal performance factor. Here, the maximum calculated difference in the SPF is calculated to be 0.015 or correspondingly about 0.35% of the electricity consumption.…”

“…Two TRNSYS simulation models Type 136 and Type 202 (Bertram et al 2010) have been tested by Citherlet (2012) for different real weather conditions in Yverdon-les-Bains (CH). The results were then compared to the field measurements of unglazed collectors.…”