A 2 kW-class free-piston Stirling heat pump prototype suitable for cold regions for domestic heating.

• A 2 kW-class FPSHP prototype was designed, built and tested. • The analysis of the distribution of acoustic field and exergy loss were carried out. • The influence of key parameters was studied by simulation and experiment. • The prototype can provide 2253 W of heating with a COP h of 2.76. Compared with conventional vapour-compression heat pump technology, the free-piston Stirling heat pump technology attracts wide attention for its high efficiency, reliability, and environmental friendliness. In this work, a free-piston Stirling heat pump prototype with a two-kilowatt capacity, which can operate with an outside ambient temperature ranging from -20 to 10 °C, was designed, built and tested. First, numerical simulations were carried out to explore the distributions of the acoustic field and exergy loss. Second, the effects of several operating parameters on the heating performance were numerically investigated in detail. Finally, to validate the accuracy of the simulation results, verification experiments were conducted on the experimental platform of a free-piston Stirling heat pump driven by a dual-opposed linear compressor. Experimental data show that with a hot-end temperature of 45 °C and outside ambient temperature of 0 °C, the prototype achieved a heating capacity of 2253 W with a corresponding COP h of 2.76 (based on PV power input) and a relative Carnot efficiency of 39.1 %; in particular, the prototype was able to achieve a COP h of 2.5 when pumping heat from -20 °C to 45 °C for 3.25 MPa mean pressure. The simulation and experimental results demonstrated that the free-piston Stirling heat pump system has good potential to achieve high efficiency as a heating supply in a cold region. [ABSTRACT FROM AUTHOR]