Design of a new test bench based on the Hardware-in-the Loop methodology for dynamic performance testing of hydronic heat pumps

In this paper, the main features and the operating principle of a new experimental test facility built at the University of Bologna are presented. The energy performance of small- and medium-sized air-source and ground-coupled heat pumps can be evaluated dynamically through experimental measures based on the Hardware-in-the-Loop (HiL) methodology. The main elements of the test bench are a highly-insulated climate chamber, in which the unit under test is placed; a borehole heat exchanger field, composed by 4 boreholes having different lengths, a hydronic circuit and the building emulator, a whole-building simulation software. By means of these last two elements, the operating conditions of the heat pump under test (e.g., ambient temperature, water mass flow rate or the building thermal load) are calculated, reproduced by the hydronic loop and given as inputs to the heat pump. To show the potentiality of the facility, experimental tests have been carried out on an air-source heat pump according to the procedure reported by the standard EN 14511-3. Results point out the reliability of the test bench outcomes, since a good agreement with performance data declared by the heat pump manufacturer has been obtained.