Development of a Semi-dynamic Model of Active Pipe-embedded Building Envelope for Thermal Performance Prediction for Utilizing Low-grade Energy Sources

Active pipe-embedded building envelope is a new kind of building envelope. The pipe is embedded in the wall slab or roof slab of active pipe-embedded building envelope for allowing water circulated in these pipes to transfer heat. The embedded pipe can enlarge the heat transfer surface between the pipe and the structure and allow low temperature difference heat transfer. Then low-grade energy sources can be coupled with this structure. This paper presents a semi-dynamic model of this structure for performance evaluation of this structure for system design or indoor environment control etc. This semi-dynamic model is a coupled model with two parts. The first part is the simplified dynamic RC model (i.e., resistance and capacitance model). The heat transfer along the width of this structure can be predicted by the RC model. The second part is a classical NTU model. The heat transfer along the pipe and total heat transfer on both surfaces of this structure can be evaluated by the NTU model. A CFD model is developed to act as a virtual experimental test rig to simulate the thermal characteristics of this structure. The simulated result is used to validate this simplified model and its performance prediction.