Experimental investigation of heat transfer in bio-based building block with microencapsulated PCM

The paper presents the investigation of heat transfer in hemp shives and magnesia binder composite with microencapsulated phase change material (PCM) to increase the building material’s thermal mass. The investigated sample was prepared as a three-layer block of dimensions 600×400×480 mm. The external layers of the block had a density of approximately 400-450 kg/m3 and a thickness of 50-60 mm, while the inner layer had a density of approximately 200-250 kg/m3 and a thickness of 290 mm. The study was performed with a block placed between two specially designed climatic chambers. Conditions in chambers were fully stabilized. Additionally, 50 mm wide channels with fans in both chambers were added close to the sample surfaces to force uniform airflow along both sample surfaces. For parameters control in the chambers, dedicated software was developed. Inside the sample nine temperature sensors were placed. During measurements, the temperature of 30°C and relative humidity of 40% was maintained in one chamber, while in the second one, after stabilization in temperature of 20°C and relative humidity of 50%, the temperature was decreased to 15°C without humidity control. During measurement insulating properties of PCM in dynamic conditions were analyzed.