Operational performance of a novel heat pump assisted solar façade loop-heat-pipe water heating system

•A novel loop heat pipe (LHP) was integrated into the building façade to convey the façade solar heat into inside building.•A heat pump was implemented into the LHP system to enhance its thermal efficiency.•The model accuracy was validated by experiment giving less than 7% in error.•The thermal efficiency of the LHP module was increased by 22.2%, with the integration of the heat pump. This paper aims to present an investigation into the operational performance of a novel heat pump assisted solar façade loop-heat-pipe (LHP) water heating system using both theoretical and experimental methods. This involved (1) development of a computer numerical model; (2) simulation of the operational performance of the system by using the model; (3) test rig construction; and (4) dedicated experiment for verification of the model. It was found that the established model is able to predict the operational performance of the system at a reasonable accuracy. Analyses of the research results indicated that under the selected testing conditions, the average thermal efficiency of the LHP module was around 71%, much higher than that of the loop heat pipe without heat pump assistance. The thermal efficiency of the LHP module grew when the heat pump was turned-on and fell when the heat pump was turned-off. The water temperature remained a steadily growing trend throughout the heat pump turned-on period. Neglecting the heat loss of the water tank, the highest coefficient of the performance could reach up to 6.14 and its average value was around 4.93. In overall, the system is a new façade integrated, highly efficient and aesthetically appealing solar water heating configuration; wide deployment of the system will help reduce fossil fuel consumption in the building sector and carbon emission to the environment.