Optimisation strategies for solar assisted heat pumps coupled to traditional thermal fields

Abstract

The advantages of the solar assisted heat pumps are well-known but their diffusion on the market is still very limited. One of the main causes is associated to their complexity and almost always working under transient regime which can lead to frequent blocks especially when a low level of control and automatization is present. From the point of view of conceptual design, solar assisted heat pumps tend to be more subjected to blocks due to their serial asset. The present work illustrates the case study of the solar assisted heat pump pilot plant at Palacus, Genoa, equipped with a heat pump bypass which can directly connect the solar thermal field to either the domestic hot water or the space heating systems when the temperature in the circuit exceeds a fixed set point. This configuration allows therefore the use of the solar field either independently from the heat pump or interfaced with it, according to the external conditions. A numerical model within TRNSYS environment has been developed basing on the information collected on the pilot plant by the data acquisition system. A simulation of the working of the pilot plant along a typical year has been performed, evaluating its increased performance and optimisation thanks to the bypass.