The Thermal Response Test (TRT) is a worldwide adopted in-situ
thermal behaviour of the borehole can differ from the result obtained by means of a heat injection TRT. This issue is of peculiar interest for water-filled boreholes, where the BHE thermal resistance is related to the water temperature and density gradient in the borehole filling-space. In this operating mode a heat pump is usually employed and the constant heat transfer rate condition required by the models can be difficult to be respected since the efficiency of the cooling-machine is dependent on the inlet carrier-fluid temperature to the evaporator.In this paper a methodology to perform a heat extraction DTRT with constant heat transfer rate to the ground is presented. The approach described has been applied in a real water-filled borehole installed in Stockholm, Sweden. Data analysis results are presented and the outcomes regarding the evaluation of the local borehole thermal resistance are discussed and compared with those from an erlier heat injection test performed in the same borehole.
The Thermal Response Test (TRT) is a well known experimental technique for estimating both the ground thermal conductivity and the effective borehole heat exchangers (BHE) resistance in ground coupled heat pump (GCHP) applications. The usual experimental approach for the TRT measurements is to inject (and even extract) a constant heat rate in the ground while the carrier fluid is circulated inside a reference heat exchanger. In this paper the TRT approach is applied with reference to non constant heat rate condition during a several day measuring session at the SEB building site of the University of Genova, Italy. A constant heat injection has been operated for the first 100 hours of the experiment and then a series of 8 hour square pulses (on/off mode) have applied for about 11 days. The ground and BHE thermal properties have been here estimated according to different algorithms developed either at the University of Genova and Polytech Montreal, where either the ILS and FLS (Infinite and Finite Line Source) theories or a Resistance/Capacitance approach are implemented to reconstruct the measured temperature evolution from parameter estimation.
Abstract. This research has been devoted to the selection of the most favourable plant solutions for ventilation, heating and cooling, thermo-hygrometric control of a greenhouse, in the framework of the energy saving and the environmental protection. The identified plant solutions include shading of glazing surfaces, natural ventilation by means of controlled opening windows, forced convection of external air and forced convection of air treated by the HVAC system for both heating and cooling. The selected solution combines HVAC system to a Ground Coupled Heat Pump (GCHP), which is an innovative renewable technology applied to greenhouse buildings. The energy demand and thermal loads of the greenhouse to fulfil the requested internal design conditions have been evaluated through an hourly numerical simulation, using the Energy Plus (E-plus) software. The overall heat balance of the greenhouse also includes the latent heat exchange due to crop evapotranspiration, accounted through an original iterative calculation procedure that combines the E-plus dynamic simulations and the FAO Penman-Monteith method. The obtained hourly thermal loads have been used to size the borehole field for the geothermal heat pump by using a dedicated GCHP hourly simulation tool.
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