Browsing by Author "Parameshwaran, R."

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Analytical and experimental investigations of nanoparticles embedded phase change materials for cooling application in modern buildings
(Elsevier, 2012-03) Parameshwaran, R.
his paper presents the analytical and experimental investigations of the phase change heat transfer characteristics and thermodynamic behavior of spherically enclosed phase change material (PCM) with dispersion of nanoparticles for latent thermal energy storage (LTES) system in buildings. In this study, the heat transfer characteristics in terms of the transient temperature variations, moving interface positions, complete rate of solidification and melting were analyzed for the six different PCMs considered in pure form and with dispersed nanoparticles as well. The heat transfer characteristics of the PCMs considered were analytically modeled and experimentally evaluated for the steady state and transient conditions for various heat generation parameters during freezing and melting cycles of the LTES system. The experimental results infer that for the same thermal load conditions the rate of solidification for the PCMs decreased with the increased mass fractions of nanoparticles while compared to the pure PCMs. For the same operating conditions of the LTES system, similar heat transfer characteristics were observed for the six PCMs considered. In this paper, the analytical model solutions and experimental results for the 60% n-tetradecane: 40% n-hexadecane PCM are presented. The solidification time for the 60% n-tetradecane: 40% n-hexadecane PCM embedded with the aluminium and alumina nanoparticles were expected to reduce by 12.97% and 4.97% than at its pure form respectively. Besides, the test results indicate that by increasing the mass fraction of the nanoparticles beyond the limiting value of 0.07 the rate of solidification was not significant further. Furthermore, the rate of melting was improved significantly for the PCMs embedded with the dispersed nanoparticles than the pure PCMs. The analytical solutions obtained for the pure and dispersed nanoparticles based PCMs were validated using the experimental results. The deviations observed between the analytical solutions and the experimental results were in the range of 10%–13%. Based on the analytical and experimental results the present nanoencapsulated LTES system can be regarded as a potential substitute for the conventional LTES system in buildings for achieving enhanced heat transfer characteristics and energy efficiency.
Applications of Thermal Analysis to the Study of Phase-Change Materials
(Elsevier, 2018) Parameshwaran, R.
To standardize the phase-change materials (PCMs) with regard to their thermophysical and thermal energy storage (TES) properties for achieving better heat storage performance in real-time applications, the greater emphasis being shown on the methods of thermal analysis are increasingly attractive, in recent years. This has paved way for gleaning of the technical revelations from a variety of research studies and is highlighted throughout this chapter. The nucleus of this chapter is focused on exploring the potential PCMs available for the real-time applications as well as on reporting the research studies performed on thermal analysis methods for the PCMs, in recent times. Emphasis is also been laid on the thermal analysis methods on the nanomaterials-based PCMs for the suitable TES applications.
Bio-based hexadecanol impregnated fly-ash aggregate as novel shape stabilized phase change material for solar thermal energy storage
(Elsevier, 2022) Parameshwaran, R.
In light of a variety of latent heat storage materials being available, the concept of utilization of organic PCMs for solar thermal energy storage (STES) is becoming increasingly attractive during the recent past. From this perspective, the present study is aimed at developing a new bio-based shape stabilized phase change material (BSPCM) for achieving passive cooling in buildings through STES. An eco-friendly BSPCM composite, consisting of the hexadecanol as the PCM and the modified porous fly ash-based pebbles as the supporting matrix, was prepared using the vacuum impregnation technique. The prepared BSPCM was then characterized thoroughly with respect to its morphology, crystal and surface structures, phase change properties, thermal stability, leakage stability, thermal conductivity and thermal reliability.
Bio-based phase-change materials
(Elsevier, 2020) Parameshwaran, R.
The development and subsequent incorporation of the advanced materials and technologies in buildings, with a view to target energy savings, and to fulfill the energy requirements have been gaining impetus during the recent years. The inherent vision lying behind the state-of-the-art technological advancements taking place in the construction sector is to sustain the energy efficiency in both existing and newly developed buildings on a long run. Thermal energy storage (TES), achieved through the phase-change materials (PCMs), is one among a few energy-efficient technologies available. The energy demand at the end-user side can be greatly satisfied using the TES technologies. Using bio-based PCMs in buildings is considered to be an ever-growing as well as an emerging field of interest to wider scientific and engineering communities, worldwide. This chapter is devoted to provide an in-depth understanding of a variety of bio-based PCMs for accomplishing thermal storage and energy efficiency in buildings. The nucleus of this chapter is focused on the TES properties enhancement for a variety of bio-based PCMs through the incorporation of different functional materials thereby; energy efficiency in buildings can be achieved.
Biomass-based polymers as effective drag-reducing agents in turbulent flow
(Springer, 2022-01) Parameshwaran, R.
Biopolymers have been used as drag-reducing agents in the recent years. Drag reduction serves a very important role industrially since it enhances the flow rates and hence reduces power consumption. In this study various biopolymers have been used to reduce drag, such as papaya extract, buckwheat flour, and flaxseed, in an aqueous system, using pressure-driven method. The optimum set of parameters for maximum drag reduction were obtained such as the concentration of biopolymer used, pipe diameter, and marine water conditions, and the results were validated using well-known methodologies such as the Toms effect and well-known concepts like the Virk’s maximum drag reduction asymptot
Cryogenic conditioning of microencapsulated phase change material for thermal energy storage
(Springer, 2020-10) Parameshwaran, R.
Microencapsulation is a viable technique to protect and retain the properties of phase change materials (PCMs) that are used in thermal energy storage (TES) applications. In this study, an organic ester as a phase change material was microencapsulated using melamine–formaldehyde as the shell material. This microencapsulated PCM (MPCM) was examined with cyclic cryogenic treatment and combined cyclic cryogenic heat treatment processes. The surface morphology studies showed that the shell surfaces had no distortions or roughness after cryogenic treatment. The cryogenically conditioned microcapsules exhibited diffraction peak intensity shifts and crystal structure changes. The onset of melting for the nonconditioned and conditioned microcapsules were measured to be 8.56–9.56 °C, respectively. Furthermore, after undergoing the cryogenic and heat treatment processes, the PCM microcapsules had appreciable latent heat capacities of 39.8 kJ/kg and 60.7 kJ/kg, respectively. Additionally, the microcapsules were found to have good chemical stability after the cryogenic treatment. In addition, the cryogenically conditioned microcapsules were found to be thermally stable up to 128.9 °C, whereas the nonconditioned microcapsules were stable up to 101.9 °C. Based on the test results, it is obvious that the cryogenically conditioned microcapsules exhibited good thermal properties and are very desirable for cool thermal energy storage applications
Dimethyl Adipate-Based Microencapsulated Phase Change Material with Silica Shell for Cool Thermal Energy Storage
(Springer, 2020-11) Parameshwaran, R.
Phase change materials (PCM) have the ability to store and release thermal energy. Encapsulation of these energy storage materials overcomes the difficulties that can enable them for a broad range of applications. In the present study, microencapsulation of dimethyl adipate into silica shell was carried through interfacial hydrolysis and polycondensation method. The prepared microencapsulated phase change materials (MPCM) were characterised using a field emission scanning electron microscope, have shown good sphericity with an average particle size of 596 nm. The chemical structure of MPCM obtained using Fourier transform infrared spectroscopy has exhibited good chemical stability between shell and core materials. Latent heat of enthalpy measured using differential scanning calorimetry was around 24 kJ/kg with onset melting and end set melting as 7.33 °C and 11.97 °C, respectively. Furthermore, thermo-gravimetric analysis studies have shown that MPCM exhibited end set temperatures as 180 °C. Due to the inorganic shell coating over the PCM droplets, MPCM has shown an increase in thermal stability. These properties make MPCM as a viable candidate for cool thermal energy storage applications.
Effect of aggregation on thermal conductivity and heat transfer in hybrid nanocomposite phase change colloidal suspensions
(AIP, 2013-11) Parameshwaran, R.
his study aims to investigate the role of aggregation of the hybrid nanocomposite particles on thermal conductivity and heat transfer of the phase change colloidal suspensions. It is observed that the incorporation of the hybrid nanocomposite particles substantially enhances thermal conductivity of such suspensions up to 42.4% and effectively reduces their freezing time by 19.5%. The predictions and the experimental results supports the fact that the aggregation of the hybrid nanocomposite particles largely involve in the eventual thermal conductivity enhancements and heat transfer of the phase change colloidal suspensions, with a sufficiently lesser effects realized from the nanoparticles Brownian motion.
Efficient Variable Air Volume Air Conditioning System Based on Fuzzy Logic Control for Buildings
(STA, 2009-03) Parameshwaran, R.
A variable air volume (VAV) system is highly preferred to be an energy efficient airconditioning scheme in modern heating, ventilation and air conditioning (HVAC)applications. Based on the energy consumption characteristics, VAV systems are fastreplacing constant air volume (CAV) systems and are capable of maintaining the thermalcomfort for varying load conditions. Fuzzy logic controllers (FLC) are highly preferred ratherthan conventional controllers since FLC exhibits reduced peak overshoot that is observedunder transient conditions of the system. FLC has the capability of controlling the systemprecisely with the set points defined. This paper describes the thermal comfort and energyconservation potential of the VAV system utilizing a fuzzy logic controller (FLC) thatenhances the system performance substantially. A simple VAV building model wasdeveloped and the energy utilization of the VAV system has been experimentallyinvestigated. Input data for fuzzy logic are zone temperature and duct static pressure and theoutput is supply air fan speed. Experimental results show that the energy saving potential ofthe VAV system was 27% at part load conditions, compared with the CAV system.Experimental results express that the required thermal comfort was achieved using FLC.
Energy conservative air conditioning system using silver nano-based PCM thermal storage for modern buildings
(Elsevier, 2014-02) Parameshwaran, R.
This work aims at improving the thermal performance and energy efficiency of chilled water based variable air volume air conditioning system integrated with the silver nanoparticles embedded latent thermal energy storage system. The latent thermal energy storage air conditioning system incorporated with the demand controlled ventilation and the economizer cycle ventilation schemes were experimentally investigated for the year-round building air conditioning application. Phase change material embedded with silver nanoparticles enabled it to exhibit improved heat transfer mechanisms in charging and discharging cycles. Experimental results suggest that the proposed air conditioning system achieved an on-peak and per day average energy savings potential of 36–58% and 24–51%, respectively, for year round operation while compared to the conventional air conditioning system. Similarly, while compared with a basically similar variable air volume air conditioning system, the proposed air conditioning system yielded 7.5–18.6% and 7.9–17.8% of on-peak and per day average energy conservative potential, respectively. Furthermore, test results infer that the combined effects produced by the silver nanoparticles embedded latent thermal energy storage system with the ventilation techniques augmented the overall thermal performance of the system. In total, the combined air conditioning system would be beneficial in terms of accomplishing good thermal comfort, acceptable indoor air quality and energy redistribution needs in buildings without sacrificing energy efficiency.
Energy conservative building air conditioning system controlled and optimized using fuzzy-genetic algorithm
(Elsevier, 2010-05) Parameshwaran, R.
In this work, the combined effect of the energy conservative variable refrigerant volume (VRV) system and the variable air volume (VAV) system was experimentally investigated using genetic fuzzy optimization method that yielded better thermal comfort, indoor air quality (IAQ) requirements without compromising on the energy savings potential. The proposed system was tested using the demand controlled ventilation (DCV) combined with the economizer cycle ventilation (ECV) techniques and examined for a year-round building air conditioning (A/C) application. The supply air temperature (SAT) set points were varied under three distinct strategies and the optimal solutions obtained for the fuzzy systems designed resulted in an enhanced energy conservative potential. The test results of the proposed system were compared with the conventional fan coil A/C system. Based on the three strategies of the supply air temperature, the proposed system yielded an improved per day energy savings potential of 54% in summer and 61% in winter design conditions. Furthermore, for the strategies considered the proposed system achieved an annual energy conservative potential of 36% and exhibited more possible ways to achieve thermal comfort, IAQ and energy conservation
An Energy Efficient Air Conditioning System using Displacement Ventilation and Chilled Ceiling for Modern Office Buildings
(Taylor & Francis, 2016-03) Parameshwaran, R.
Thermal comfort and indoor air quality (IAQ) play a vital role in creating a pleasant and healthier indoor environment for occupants. The supply air conditions and the concentration of CO2 contaminant present in the supply air can decide the comfort level and purity of air in indoor environments. In this study, an effort was made to investigate the combined effect of a chilled ceiling and displacement ventilation (CC-DV) air conditioning (A/C) system that would possibly achieve good thermal comfort and IAQ in a proposed office building subjected to hot and humid climatic conditions. Simulation model analysis was performed under the MATLAB-Simulink environment to examine the thermal performance of the CC-DV system for different cooling capacities shared by CC and DV. Simulation results for classifying the required supply air conditions and mean contaminant removal efficiency are presented. Experimental results and existing convective correlations for floor level and head level temperatures in the occupied zone were used to validate and compare the simulation results respectively. The deviation observed between the experimental and simulation results for establishing the supply air temperature requirement was approximately ±10%. Similarly, the deviation between the simulation and the correlation results for head level temperature was ±4%. Based on the simulation model and experimental investigation performed on the CC-DV A/C system, the air supplied at 19 °C results in better thermal comfort and IAQ in indoor environments without compromising the energy conservative potential. In total, the overall energy conserved by the CC-DV system was 13.3% higher than a conventional constant air volume (CAV) A/C system operated under the same outdoor and indoor design conditions.
Energy efficient hybrid nanocomposite-based cool thermal storage air conditioning system for sustainable buildings
(Elsevier, 2013-09) Parameshwaran, R.
The quest towards energy conservative building design is increasingly popular in recent years, which has triggered greater interests in developing energy efficient systems for space cooling in buildings. In this work, energy efficient silver–titania HiTES (hybrid nanocomposites-based cool thermal energy storage) system combined with building A/C (air conditioning) system was experimentally investigated for summer and winter design conditions. HiNPCM (hybrid nanocomposite particles embedded PCM) used as the heat storage material has exhibited 7.3–58.4% of improved thermal conductivity than at its purest state. The complete freezing time for HiNPCM was reduced by 15% which was attributed to its improved thermophysical characteristics. Experimental results suggest that the effective energy redistribution capability of HiTES system has contributed for reduction in the chiller nominal cooling capacity by 46.3% and 39.6% respectively, under part load and on-peak load operating conditions. The HiTES A/C system achieved 27.3% and 32.5% of on-peak energy savings potential in summer and winter respectively compared to the conventional A/C system. For the same operating conditions, this system yield 8.3%, 12.2% and 7.2% and 10.2% of per day average and yearly energy conservation respectively. This system can be applied for year-round space conditioning application without sacrificing energy efficiency in buildings.
Energy efficient PCM-based variable air volume air conditioning system for modern buildings
(Elsevier, 2010-08) Parameshwaran, R.
This work aims at achieving enhanced energy conservation for space conditioning with the application of a new combined variable air volume (VAV)-based chilled water air conditioning (A/C) system and thermal energy storage (TES) system. The phase change material (PCM) used in this system exhibited good charging and discharging characteristics that directly helped in conserving the overall energy spent on cooling and ventilation. The present system was experimentally investigated for summer and winter climatic conditions under demand controlled ventilation (DCV) and DCV combined with the economizer cycle ventilation (ECV) to substantiate its energy savings capability. Based on the results, in the DCV and combined DCV–ECV modes, this system achieved 28% and 47% of per day average energy conservative potential, respectively, while compared to the conventional chilled water-based A/C system. Similarly, the VAV–TES system yielded an on-peak total energy savings of 38% and 42%, respectively, for the same operating conditions.
Energy efficient pumpable cement concrete with nanomaterials embedded PCM for passive cooling application in buildings
(Elsevier, 2020) Parameshwaran, R.
The growing energy demand and energy requirements in the construction sector have paved way to the development and incorporation of the energy efficient materials and technologies in building envelopes. This research work is aimed at investigating the suitability of a pumpable cement concrete with nanomaterials embedded phase change material (PCN-PCM) for achieving energy efficiency in buildings through passive cooling application. In this work, an attempt was made to mix the flyash and ground-granulated blast-furnace slag (GGBS) as replacement materials for the cement along with the super plasticisers. To this engineered pumpable concrete, different sequential processes of adding the organic PCM (lauryl alcohol) embedded with nanomaterials (ZnO and hybrid Cu-TiO2) have been carried out. The mixing process was then optimised based on the incorporation of the PCM (0% to 20% with incremental steps of 5%) and the nanomaterials (0.01%–0.05% with incremental steps of 0.01%) into the cement concrete. The as-prepared PCN-PCM was characterized and tested from both thermal and structural aspects. The XRD results suggest that, the nanomaterials prepared were highly crystalline, and the adsorption of the Cu nanoparticles on the surface of the TiO2 nanoparticles were significant as observed from the FESEM images. The FTIR results confirm that the PCN-PCM composite were chemically stable for the mix-design combinations. In addition, the as-prepared composite achieved a characteristic compressive strength of 20 MPa, which confirms its structural stability. Furthermore, the experimental results reveal that, the PCN-PCM composite exhibited good latent heat potential by storing thermal energy and thereby; regulated the indoor air temperature of the test room around 24 °C. Based on the aforementioned attributes, the as-prepared PCN-PCM composite is expected to serve as an energy efficient candidate for achieving good thermal storage capabilities and structural integrity through passive cooling in buildings.
Energy Efficient Variable Refrigerant Flow Systems for Modern Buildings
(Springer, 2023-02) Parameshwaran, R.
The growing demand for the primary energy and the associated environmental issues globally, have led to the progress in energy conservative approaches in the recent years. From the standpoint of confronting the energy challenges in buildings, the development of energy efficient systems and energy conservative technologies is becoming increasingly important for satisfying the end-user requirements. In the class of highly energy efficient systems, the variable refrigerant flow (VRF) or the variable refrigerant volume (VRV) system has been developed to meet out the cooling and heating requirements in buildings. VRF/VRV system, basically operate through the modulation of the refrigerant flow according to the energy demand in buildings. In recent years, the amalgamation of control systems in heating, ventilation, air conditioning and refrigeration (HVAC&R) research has provided the impetus for the development of VRF systems with enhanced energy efficiency and energy savings potential for building applications. This chapter primarily aims at reviewing the potential research studies emphasizing the importance of VRF cooling and heating systems dedicated for achieving enhanced energy efficiency and energy conservation in buildings. In the spectrum of VRF systems, the technical revelations pertaining to the refrigerant flow characteristics, single-loop and multi-loop units and combined/hybrid VRF systems with advanced intelligent controllers have been reviewed from a variety of research studies reported in the literature. Furthermore, the roles of key governing aspects which greatly influences the operational performance and feasibility of the VRF/VRV systems integration for modern buildings have been addressed and signified.
Evaluation of reaction characteristics of Na2S2O3.5H2O for thermochemical energy storage
(Elsevier, 2019) Parameshwaran, R.
In the present study, calorimetric investigations are performed on Na2S2O3.5H2O to determine the dissociation temperature(s), decomposition temperature and reaction enthalpies due to dehydration and hydration, using the DTG-60H instrument. Towards this, heating and single cycle (comprising of sequential dehydration and hydration reactions) tests are performed. The heating tests are performed to measure the dissociation and decomposition temperatures by heating the material’s sample for a temperature up to 600 °C at a heating rate of 5/ 10/ 20 °C/min. The single cycle tests are performed at different hydration temperatures (30 and 50 °C) and durations (30, 60 and 120 min). The results indicate that the dissociation and decomposition temperatures increase with heating rate. The heating tests also helped in determining the material’s reaction enthalpy due to dehydration. Reaction enthalpy due to hydration increases with its duration and decreases as its temperature increases. For the single cycle with 120 min duration and 30 °C temperature of hydration, the calculated energy storage densities are respectively 1.90 and 1.81 GJ/m3. These values are far superior to that of materials used for conventional thermal energy storage methods.
Experimental Analysis of a Genetic-Fuzzy Inverter DX VAV A/C System for Automatically Ventilated Buildings
(Taylor & Francis, 2016-03) Parameshwaran, R.
In recent years, the quest has been focused on energy efficient building design. To achieve this in terms of high efficiency air conditioning schemes for hot climate cooling, the combination of variable refrigerant volume (VRV) with variable air volume (VAV) systems have become popular. In this paper, attention is focused on achieving good thermal comfort and indoor air quality (IAQ) combined with energy savings by using multi-zone VAV air conditioning (A/C) that incorporates a genetic based fuzzy logic controller (FLC). Experimental analysis based on a combined demand controlled ventilation (DCV) with economizer cycle (EC) was performed on an inverter driven multi-zone direct expansion (DX) VAV A/C system integrated with a fuzzy logic controller and optimized by a genetic algorithm (GA). The opening of the VAV box damper was controlled using the fuzzy logic controller. Based on the test results, the proposed fuzzy logic operated system maintained supply air temperature close to 13°C and an occupant zone at a consistent temperature of around 24 °C. In DCV mode, the concentration of CO2 was maintained between 950 ppm and 1040 ppm while, when the system was operated under a combined DCV-EC ventilation scheme, the CO2 concentration was maintained at between 350 ppm and 970 ppm. The experimental results suggested that CO2 concentration obtained experimentally was well within the permissible limit for the varying load conditions. Under the combined DCV-EC mode of ventilation, using a fuzzy-genetic algorithm, the maximum power obtained for the supply air fan and variable speed compressor was 415 W and 3.4 kW respectively. The compressor was totally turned OFF during the economizer cycle thus contributing to total power savings. The energy savings potential of the proposed fuzzy controlled multi-zone DX VAV A/C system yielded 70% and 89% under DCV and combined DCV economizer cycle ventilation modes respectively when compared with a constant air volume (CAV) A/C system operated under the DCV technique. The test results suggested that it was feasible for this fuzzy control methodology, integrated with the developed genetic algorithm, to provide a proper control of IAQ, thermal comfort and energy conservation.
Experimental Analysis of Energy Efficient Building Air Conditioning System Using Fuzzy Logic Controller
(AIT, 2009-06) Parameshwaran, R.
The present work is focused on investigating the thermal comfort and indoor air quality (IAQ) in buildings through the use of energy efficient air conditioning (A/C) system. In this context, a combined variable air volume (VAV) and variable refrigerant volume (VRV) system is developed and tested with different ventilation strategies for summer and winter design conditions. The proposed system is controlled by the intelligent fuzzy logic controller that enhanced the overall system performance. The proposed system is tested under fixed ventilation, demand controlled ventilation (DCV) and combined DCV and economizer cycle (EC) ventilation that ensured better indoor thermal comfort and IAQ without compromising on the energy efficiency. The test results infer that the proposed air conditioning system controlled by fuzzy logic methodology yield a maximum of 34% and 52% of per day energy savings in summer and winter design conditions respectively. The test results for each technique in terms of thermal comfort, IAQ and energy savings potential are presented.
Experimental analysis of hybrid nanocomposite-phase change material embedded cement mortar for thermal energy storage
(Elsevier, 2020-07) Parameshwaran, R.
The present work aims at developing the hybrid nanocomposite-based phase change material (PCM) embedded cement mortar (HNPCM) for thermal energy storage (TES). The microstructural, thermal and structural properties of the as-prepared HNPCM were experimentally analyzed. The microstructural test results reveal that, the copper-titania (Cu–TiO2) hybrid nanocomposite (HN) particles were spherical and highly crystalline. The HN dispersed into the pristine PCM (1-dodecanol) was chemically stable as confirmed through the Fourier-Transform infrared (FTIR) analysis. The HN embedded into the pristine PCM (HNP) in different proportions exhibited good thermal energy storage potential of 190.03 J/g and 195.03 J/g during freezing and melting, respectively. The thermal stability of HNP was appreciable and found higher than the operating temperature range of the pristine PCM. Furthermore, the incorporation of the HN into the pristine PCM has resulted in the enhancement of thermal conductivity of HNP. On the other hand, the compressive strength of the HNPCM specimens was measured to be above 20 MPa. In spite of the marginal drop, observed in compressive strength of HNPCM, when compared with the conventional cement mortar, the HNPCM has exhibited enough strength to be used as internal wall plastering material with good thermal energy storage potential.