• Energy Research

Abstract The quest and interest shown towards developing organic phase change materials (PCMs) for thermal energy storage (TES) applications in buildings are gaining momentum in recent years. From this perspective, the present study aims at developing a novel microencapsulated bio-based phase change material (MbP) integrated in to a micro concrete composite (MbPMC) for thermal energy storage in buildings. The MbP and MbPMC were experimentally characterized in terms of their morphological, thermal and structural properties. The surface morphology results signified that, the as-prepared MbP particles being formed were near-spherical in shape with sizes ranging between 2 μm and 10 μm. The highly crystalline nature of the bio-based PCM chains and the amorphous structure of the shell material were confirmed through the X-ray diffraction analysis. The Fourier transform infrared (FTIR) spectra has further confirmed the chemical stability between the core (PCM) and the shell material. The MbP has exhibited congruent phase change behavior with a good latent heat potential of 47.31 J/g. Besides, the MbP was found to be thermally stable, commencing from the operating temperature of 35 °C up to 150 °C, as confirmed through the leakage and thermogravimetric tests. A unique and optimized sequential operation of mixing the ingredients for preparing MbPMC matrix was established with a view to obtain the best end product. The as-prepared MbPMC has exhibited adequate structural integrity with a compressive strength of 38.78 MPa at a MbP dosage of 0.075% by the weight of cementitious materials added in the mix. Ultrasonic pulse velocities (UPV), along the directions orthogonal to the direction of pour of the concrete specimens , were observed to be very close, thus proving that the densities, across the cross section of the specimen are more or less uniform. For incremental dosages of MbP, the trend observed in the indicative compressive strengths of MbPMC specimens from rebound hammer tests was observed to be similar to the trend observed in the compressive strength values obtained from the compressive testing machine (CTM). In total, these test results have revealed the ability and stability of the MbP incorporated micro concrete composite (MbPMC) for achieving thermal energy storage and passive cooling in buildings without sacrificing its structural integrity.

Abstract The quest and interest shown towards developing organic phase change materials (PCMs) for thermal energy storage (TES) applications in buildings are gaining momentum in recent years. From this perspective, the present study aims at developing a novel microencapsulated bio-based phase change material (MbP) integrated in to a micro concrete composite (MbPMC) for thermal energy storage in buildings. The MbP and MbPMC were experimentally characterized in terms of their morphological, thermal and structural properties. The surface morphology results signified that, the as-prepared MbP particles being formed were near-spherical in shape with sizes ranging between 2 μm and 10 μm. The highly crystalline nature of the bio-based PCM chains and the amorphous structure of the shell material were confirmed through the X-ray diffraction analysis. The Fourier transform infrared (FTIR) spectra has further confirmed the chemical stability between the core (PCM) and the shell material. The MbP has exhibited congruent phase change behavior with a good latent heat potential of 47.31 J/g. Besides, the MbP was found to be thermally stable, commencing from the operating temperature of 35 °C up to 150 °C, as confirmed through the leakage and thermogravimetric tests. A unique and optimized sequential operation of mixing the ingredients for preparing MbPMC matrix was established with a view to obtain the best end product. The as-prepared MbPMC has exhibited adequate structural integrity with a compressive strength of 38.78 MPa at a MbP dosage of 0.075% by the weight of cementitious materials added in the mix. Ultrasonic pulse velocities (UPV), along the directions orthogonal to the direction of pour of the concrete specimens , were observed to be very close, thus proving that the densities, across the cross section of the specimen are more or less uniform. For incremental dosages of MbP, the trend observed in the indicative compressive strengths of MbPMC specimens from rebound hammer tests was observed to be similar to the trend observed in the compressive strength values obtained from the compressive testing machine (CTM). In total, these test results have revealed the ability and stability of the MbP incorporated micro concrete composite (MbPMC) for achieving thermal energy storage and passive cooling in buildings without sacrificing its structural integrity.

In the quest for energy conservative building design, there is now a great opportunity for a flexible and sophisticated air conditioning system capable of addressing better thermal comfort, indoor air quality, and energy efficiency, that are strongly desired. The variable refrigerant volume air conditioning system provides considerable energy savings, cost effectiveness and reduced space requirements. Applications of intelligent control like fuzzy logic controller, especially adapted to variable air volume air conditioning systems, have drawn more interest in recent years than classical control systems. An experimental analysis was performed to investigate the inherent operational characteristics of the combined variable refrigerant volume and variable air volume air conditioning systems under fixed ventilation, demand controlled ventilation, and combined demand controlled ventilation and economizer cycle techniques for two seasonal conditions. The test results of the variable refrigerant volume and variable air volume air conditioning system for each techniques are presented. The test results infer that the system controlled by fuzzy logic methodology and operated under the CO2 based mechanical ventilation scheme, effectively yields 37% and 56% per day of average energy-saving in summer and winter conditions, respectively. Based on the experimental results, the fuzzy based combined system can be considered to be an alternative energy efficient air conditioning scheme, having significant energy-saving potential compared to the conventional constant air volume air conditioning system.

In the quest for energy conservative building design, there is now a great opportunity for a flexible and sophisticated air conditioning system capable of addressing better thermal comfort, indoor air quality, and energy efficiency, that are strongly desired. The variable refrigerant volume air conditioning system provides considerable energy savings, cost effectiveness and reduced space requirements. Applications of intelligent control like fuzzy logic controller, especially adapted to variable air volume air conditioning systems, have drawn more interest in recent years than classical control systems. An experimental analysis was performed to investigate the inherent operational characteristics of the combined variable refrigerant volume and variable air volume air conditioning systems under fixed ventilation, demand controlled ventilation, and combined demand controlled ventilation and economizer cycle techniques for two seasonal conditions. The test results of the variable refrigerant volume and variable air volume air conditioning system for each techniques are presented. The test results infer that the system controlled by fuzzy logic methodology and operated under the CO2 based mechanical ventilation scheme, effectively yields 37% and 56% per day of average energy-saving in summer and winter conditions, respectively. Based on the experimental results, the fuzzy based combined system can be considered to be an alternative energy efficient air conditioning scheme, having significant energy-saving potential compared to the conventional constant air volume air conditioning system.

Abstract In this study, an ester-based phase change material (PCM) was microencapsulated into a melamine formaldehyde shell using in-situ polymerization. The Surface morphology, thermal stability, and phase change properties of the microcapsules were characterized using field-emission scanning electron microscope (FESEM), thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques, respectively. The observed surface morphology reveals that prepared microcapsules shown near-spherical structures with smooth surfaces. The TGA results indicate that the microencapsulated phase change material (MPCM) has on-set and end set degradation temperatures as 110.3 °C and 142 °C, respectively, ensuring good thermal stability of MPCM. The enthalpy of latent heat measured using the DSC technique was around 65 kJ/kg, with onset peak melting at 8.57 °C.

Abstract In this study, an ester-based phase change material (PCM) was microencapsulated into a melamine formaldehyde shell using in-situ polymerization. The Surface morphology, thermal stability, and phase change properties of the microcapsules were characterized using field-emission scanning electron microscope (FESEM), thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques, respectively. The observed surface morphology reveals that prepared microcapsules shown near-spherical structures with smooth surfaces. The TGA results indicate that the microencapsulated phase change material (MPCM) has on-set and end set degradation temperatures as 110.3 °C and 142 °C, respectively, ensuring good thermal stability of MPCM. The enthalpy of latent heat measured using the DSC technique was around 65 kJ/kg, with onset peak melting at 8.57 °C.

In recent times, the thermochemical energy storage (TCES) method is gaining prominence due to its high energy storage density and minimal heat losses compared to the conventional thermal energy sto...

In recent times, the thermochemical energy storage (TCES) method is gaining prominence due to its high energy storage density and minimal heat losses compared to the conventional thermal energy sto...

In the present study, a novel BSPCM was prepared with the n-dodecanoic acid (or) LA phase change material, which was vacuum impregnated into the porous FA pebbles. The surface morphology of the BSPCM has confirmed the presence of the lauric acid in the porous supporting matrix. The XRD analysis of the BSPCM revealed that the crystalline nature of the PCM was unaltered after impregnation. The surface structure study verified the chemical compatibility between the PCM and supporting material. The DSC results showed that, BSPCM has exhibited a good latent heat of fusion of 68.93 kJ/kg with high thermal energy storage capability of 97.62%. The BSPCM was thermally stable up to 150 °C and showed good leakage stability up to 85 °C. Thermal reliability of the BSPCM performed for 1000 thermal cycles revealed excellent thermal reliability index of 96.76%. Further, thermal conductivity of BSPCM was found to be 0.1702 W/mK, which was attributed to the effective impregnation of the PCM into the fly ash pebbles. In total, the developed BSPCM can be a viable candidate for achieving passive thermal energy storage in buildings.