Research Outputs

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Now showing 1 - 2 of 2
  • Publication
    System efficiency of pvt collector-driven heat pumps
    (Elsevier, 2020)
    Hengel, Franz 
    ; ;
    The use of standard heat pump (HP) systems offers an efficient option to replace conventional heating systems (e.g. oil and gas boilers) for space heating and domestic hot water. Due to the higher noise emissions and the lower overall energy efficiency of air-to-water heat pumps, the use of ground-coupled heat pump systems is increasingly in demand. The cost-efficient dimensioning of horizontal ground heat exchanger (HGHE) systems, considering possible solar waste heat potentials to improve regeneration behaviour, is particularly challenging. The reason for this is the complex system and control engineering optimisation possibilities resulting from the dynamic heat transport behaviour of the horizontal ground heat exchanger. Essential influencing variables such as the water content of the soil due to the groundwater level, rainwater infiltration and surface evaporation can only be described with massive effort using the model equations of the unsaturated zones. However, these variables are necessary to obtain a better fundamental understanding of the usable storage potential of solar-coupled systems and to be able to derive targeted optimisations at the system level. Therefore, the waste heat utilisation potential of PVT collectors for the regeneration of heat pump coupled horizontal ground heat exchanger systems are analysed employing simulations. For this purpose, a PVT-collector model and a HGHE model based on a single-family were developed and validated by experimental investigations. Based on this, a system simulation model consisting of the components PVT-collector, heat pump, heat delivery system, HGHE and the corresponding control units were built using TRNSYS. With the help of the simulation model, parameter studies were carried out, and the main factors influencing the overall energy efficiency (COP) of the system and the seasonal performance factors (SPF) were identified. Furthermore, the solar waste heat utilisation potential of the PVT collectors was analysed to increase the efficiency of the heat pump system.
      103Scopus© Citations 27
  • Publication
    Measurement data from real operation of a hybrid photovoltaic-thermal solar collectors, used for the development of a data-driven model
    This article presents a measurement dataset from real operation of a hybrid photovoltaic-thermal solar collector. The data is from a summer period, when the collector works at its higher temperature limit, with low thermal efficiency. The dataset characterizes the output of the collector: thermal (heat transfer fluid flowrate, inlet and outlet temperatures) and electrical (raw current and voltage, Hampel filtered power). Further information on the collector are the PV cell temperature and the back surface temperature (in three points). It provides detailed weather information: ambient temperature, solar resource (direct normal, global and diffuse horizontal, global tilted in the collector plane), equivalent radiative sky temperature (calculated from a pyrgeometer), wind speed and direction both horizontal and in the tilted collector plane. The calculated sun position with Duffie and Beckmann method is also given (elevation and azimuth) . The dataset covers 58 summer days from 11th July to 6th September, with a 5 second time step. The data is available as .mat file (MATLAB) and .csv file. A selection of variables from this dataset has already been used in the development of a data-driven model (see related article) [1]. The extended data presented in this article offers mode detailed weather information, opening further investigations opportunities. Further options for data-driven modelling of PVT collectors could be investigated. The correlation of wind related losses to horizontal wind measurements could be compared to a model with wind measurements in the collector plane. The dataset could support the validation of solar models, with direct and diffuse shares on the horizontal or in the tilted plane. [Duck Duck Go](
      43  21