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GROUND SOURCE HEAT PUMP AT HIREF FACTORY (ITALY) Mauro Mantovan , Fabio Faro, Rossano Lazzarin , Fabio Poletto , Andrea Quercioli , HiRef S.p.A . Giacomo Benassi , Davide Del Col, University of Padova. Building and Use. Heating & Cooling System. Heat Pump.
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GROUND SOURCE HEAT PUMP AT HIREF FACTORY (ITALY) Mauro Mantovan, Fabio Faro, RossanoLazzarin, Fabio Poletto, Andrea Quercioli, HiRefS.p.A. GiacomoBenassi, Davide Del Col, University of Padova Building and Use Heating & Cooling System Heat Pump • Optimization strategy for electricity consumption Summer mode • desired hygrothermal conditions 25 °C @ R.U. 55 % • dynamic analysis of the thermal load of the building provides the energy distribution versus the thermal power; • Controls : • Geothermal probes : a proportional-integral control is used for the condensing pressure by varying the water flow; • Cooling capacity : a proportional-integral control is used for the water tank (90 L) temperature by varying the speed of the compressor ; • User circuit : the air flow in the fan coil and the water flow in the hydronic circuit are controlled to maximize the evaporation temperature and minimize the electric absorption of compressor+ user pump + fan coil ; • Characteristics of the heat pump • nominal performance in cooling mode • 14.0 kW @ 12 / 6.9 °C; 25.1 / 30.3 °C • nominal performance in heating mode • 14.1 kW @ 40.3 / 45.0 °C; 14.1 / 9.2 °C • refrigerant R410A ; • scroll compressor with asynchronous el. motor driven by inverter ; • polyvalent heat pump: 3 heat exchangers to operate in cooling/heating mode and for DHW production ; • 4 ways valve on user and probes side of hydronic circuit to work always with countercurrent flows ; • electronic expansion valve ; • inverter pumps on user & pipes circuit, constant velocity on DHW side ; • acquisition system for electricity consumption, thermal power/energy supplied and dissipated, parameters of the refrigerant circuit and geothermal heat exchangers . • The thermal system installed provides: • technical office’s cooling demand in summer • peak of 14.0 kW • latent + sensible • technical office’s heating demand in winter • peak of 13.2 kW • domestic hot water demand for the factory . Sensible + latent load @ 8°C inlet water temperature Borehole Heat Exchanger • Four - in parallel - BHEs with bentonite filling • 140 mm borehole diameter ; deep ~ 80 m • two double U BHEs • in. Diameter 26.6 mm • Thickness 2.9 mm • two single U BHEs • in. Diameter 32.6 mm • Thickness 3.7 mm • Thermal response test on BHEs • Infinite line source model analysis • Calculation of the ground thermal conductivity • 1.62 W/mK ± 4.3 % (P 95.5 % ) • a proportional-integral control provides a PI signal based on the deviation of the hygrothermal conditions from setpoint . Experimental measurements Hydronic Circuit Dynamic of the step response of the compressor Fancoil Galletti mod. Flat • the fan is driven by a brushless electric motor driven by inverter ; • a microprocessor is installed with Modbus serial communication : it allows the remote control (open/close the valve, vary the speed of the fan, read the temperature and humidity of the incoming air measured on board ).