18 May 2017
In order to evaluate heat pump systems adequately, in this paper the framework of the so-called Hardware-in-the-Loop concept is applied to create dynamic and realistic boundary conditions. In particular, this means real components of a heat pump system are installed on a test facility, while the boundary conditions are emulated based on a real-time simulation of a complex building model. A future challenge in terms of evaluating heat pump systems in a fair manner are upcoming intelligent and complex control algorithms like predictive control. Hereby, a pure energetic assessment is insufficient, since these energy management systems often aims to reduce cost or to increase thermal comfort. Therefore, we suggest to involve among others also economical aspects as well as aspects of comfort in the characterization procedure of heat pumps. On the one hand, one advantage of the Hardware-in-the-Loop concept is, e.g. to be able to investigate indoor air temperatures and include this knowledge in the evaluation procedure. On the other hand, issues of creating further interfaces for this evaluation methodology are discussed in the paper.
Hence, we compare a reference experiment of a chosen winter day to the same test day but using an energy management system. This energy manager controls the heat pumps compressor and aims to minimize the operational cost taking a simulated photovoltaic system into account. The investigated heat pump system is an air source heat pump coupled to a combined hot water storage tank. The results show an increase in the day related performance factor but higher deviations between actual and set room air temperatures. In general, the paper clarifies the necessity of enhancing evaluation procedures for heat pump systems with focus on future complex energy management systems.