Study on Phase Change Material in Grooved Bricks for Energy Efficiency of the Buildings

Phase change materials(PCMs)are an interesting technology due to their high density and isothermal behavior during phase change.Phase change material plays a major role in the energy saving of the buildings,which is greatly aided by the incorporation of phase change material into building products such as bricks,cement,gypsum board,etc.In this study,an experiment has been conducted with three identical small chambers made up of normal,grooved and PCM-treated grooved bricks.Before the inclusion of PCM in grooved bricks,PCM material behavior has been studied by different techniques such as DSC,TG/DTA,SEM,and XRD.Thermal properties and thermal stability were investigated by differential scanning calorimeter(DSC)and thermogravimetric analyzer(TGA)respectively.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)were used to determine the microstructure and crystalloid phase of the PCM before and after the accelerated thermal cycling test(0,60,120).These three identical model rooms built were exposed at a temperature just above 40°C with a heater.When the maximum outdoor temperature was 40-41°C,then the temperature of the PCM-treated grooved chamber was 32-33°C.The PCM-treated wall was tested and compared with a conventional and grooved wall.The difference between the PCM-treated grooved chamber and the untreated one was 8-9°C.PCM-treated bricks provided more efficient internal heat retention in summer when the outside temperature increased.

Distributed Real-time Temperature and Energy Control of Energy Efficient Buildings via Geothermal Heat Pumps

Geothermal heat pumps(GHPs)are a type of heating ventilation and air conditioning(HVAC)systems that use low-temperature resources from soil and groundwater for heating/cooling.In recent years,there has been an increasing interest in GHP systems due to their high energy efficiency and abundant geothermal resources.Thus,the optimization and control design of the GHP system has become a hot topic.On the other hand,as the GHP system is an ideal respon-sive load,mechanism design for the GHP system to realize demand response(DR)in a virtual power plant(VPP)without affecting user comfort is particularly essential.In this paper,we propose a distributed real-time temperature and energy management method via GHP systems for multi-buildings,where both floor and radiator heating/cooling distribution subsystems in multiple thermal zones are considered.We design an energy demand response mechanism for a single GHP to track the given energy consumption command for participating in VPP aggregation/disaggregation.Besides,a coordination mechanism for multiple GHPs is designed for the community-level oper-ator in joining VPP aggregation/disaggregation.Both designed schemes are scalable and do not need to measure or predict any exogenous disturbances such as outdoor temperature and heating disturbances from external sources,e.g.,user activity and device operation.Finally,four numerical examples for the simulation of two different scenarios demonstrate the effectiveness of the proposed methods.