Model validation and application of the coupled system of pipe-encapsulated PCM wall and nocturnal sky radiator

Highlights: • A coupled system of the pipe-encapsulated PCM wall and nocturnal sky radiator is presented. • The thermal models for the coupled wall system are integrated. • The system experimental platform is setup and the model validation is presented. • Thermal and energy performances of the coupled system in the cooling season are analyzed. With the increasing of the global energy consumption and carbon emissions, the energy decarbonization and sustainable developments are of great urgency. To achieve the carbon peak and carbon neutral in energy utilization of the world, the efficient energy systems by using the natural energy are the popular and important methods. The coupled system of pipe-encapsulated PCM wall and nocturnal sky radiator is a new wall system for improving the performance of the building envelope. It can effectively reduce the building energy consumption with the PCM and the nocturnal natural cooling energy. In this study, the system thermal model coupled by the simplified PCM wall model, the heat-pipe model and the nocturnal radiation model is developed and validated by comparing the model prediction with the coincident experiment measurements. The average temperature difference of the conventional wall internal surface and the wall surface by using the pipe-encapsulated PCM wall is 0.4 °C. The average heat flux difference of the wall internal surface is 2.3 W/m². In addition, the thermal and energy performances of a typical room with the coupled wall system in the cooling season are evaluated. Comparing to the conventional wall system, the internal surface average temperature of the coupled wall system can reduce 0.7 °C. The internal surface heat flow can reduce 53.0% in the cooling season. The required cooling energy consumption of the room in the cooling season can reduce 16.1%. The coupled wall system of pipe-encapsulated PCM wall and nocturnal sky radiator has good application prospects in low energy buildings.