Growing concerns related to the environmental impacts of rising global energy consumption compel the continued development of low-emission technologies for the building sector. In the United States, space conditioning and domestic hot water generation account for over half of residential energy end use, with natural gas as the predominant fuel source for heating in much of the country. Solar-assisted heat pump (SAHP) systems offer a promising alternative to meet these demands more sustainably. In combination with thermal storage, these systems utilize renewable solar energy to enhance the performance and range of application of heat pump technologies. SAHP systems include a variety of design configurations and functionalities.In this paper, a concept for a multifunction, indirect, solar-assisted heat pump (MISAHP) system is presented which relies on the utilization of the solar collector array both to absorb and reject thermal energy to deliver both heating and cooling functions for a residential structure. An experimental apparatus is designed and built to facilitate the study of this concept using a hardware-in-loop (HIL) methodology, which combines major advantages of computer simulation and field testing.The apparatus includes an 11.6kW (3.3ton) capacity water-to-water heat pump, 409L (108gal) thermal storage tank, 288L (76gal) domestic hot water tank, two variable speed circulation pumps, and emulation hardware representing a solar collector array and conditioned building space. Each emulator utilizes a pair of brazed-plate heat exchangers, connected to plant heating and chilled water loops, to provide a thermal source and sink for laboratory testing. The salient feature of this design lies in its flexibility. A complex network of piping and electronic diverting valves is used to create various energy flow paths to support fifteen different operational modes for space heating, space cooling, domestic hot water generation, and energy storage charging. This design is intended not only as a platform for research of the MISAHP system concept, but also allow for similar testing of less-complex related SAHP configurations. The apparatus is heavily instrumented for temperature and flow measurement, including thermocouple probes installed at the inlets and outlets of all major components, specialized thermocouple probes used to monitor thermal stratification in both tanks, and induction-style flow meters to accompany both circulator pumps and at the discharge outlet on the domestic hot water tank. Control and data acquisition are predominantly managed using National Instruments hardware and LabVIEW software.The experimental apparatus has been installed, commissioned, and tested. Basic functionality of control and operation has been verified for significant elements of the laboratory setup. As demonstrated through testing of four different operational modes and domestic hot water withdrawal emulation, the experimental apparatus is ready to support future research of SAHP systems.

Design and Development of an Experimental Apparatus for Hardware-in-Loop Testing of Solar Assisted Heat Pump Systems

Paper Proceedings: https://asmedigitalcollection.asme.org/ES/ES2021/volume/84881

ASME 2021 Energy Sustainability (ES2021)

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