BITS Faculty Publications
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Item Improving IAQ and energy efficiency for buildings using vav air conditioning system based on fuzzy logic(AIVC, 2007) Parameshwaran, R.In recent years, in the quest focused about energy conservative building design, as a high efficiencyair conditioning scheme, the variable air volume (VAV) systems owe their growing popularity in heating,ventilation and air conditioning (HVAC) applications. This paper reports the simulation study toinvestigate the inherent operational characteristics of direct expansion (DX) VAV air conditioning (A/C)unit when the supply air fan and compressor speeds are varied based on the thermal load persisting inthe conditioned space. Based on the Matlab-Simulink environment, a new fuzzy based simulationmodel of the DX VAV system has been developed and the energy utilization of the air conditioningsystem is investigated by incorporating the concept of combined economizer cycle (EC) and demandcontrolled ventilation (DCV) techniques into the simulated model. Indoor air quality (IAQ) is addressedunder DCV and combined DCV-EC modes of ventilation. Simulation results obtained for the DX VAVA/C system are compared with the conventional constant air volume (CAV) system. The results inferthat the fuzzy control methodology and algorithm developed are feasible with a proper control of IAQbeing achieved. Variation of refrigerant mass flow rate corresponding to the variation of supply air flowrate is also investigated.Item Thermal Energy Storage Properties of Hybrid Nanocomposite–Embedded Phase Change Material for Sustainable Buildings(Scientific net, 2014) Parameshwaran, R.The thermal properties of the new copper–titania hybrid nanocomposite embedded organic ester phase change material (HNPCM) were analyzed experimentally. The surface functionalized hybrid nanocomposite (HyNC) embedded into the PCM has effectively created the densely packed network of thermal interfaces in the PCM matrix layers. The experimental results suggest that, the incorporation of the HyNC has enabled the HNPCM to exhibit improved thermal conductivity (0.347 W/m K), congruent phase transition temperature (freezing: 33.53ᵒC, melting: 35.32 ᵒC), high latent heat capacity (freezing: 109.05 kJ/kg, melting: 109.14 kJ/kg) and considerable reduction in (freezing time: 21.2%, melting time: 29.2%). The improved thermal properties being achieved facilitate the HNPCM to be considered as a viable thermal storage material for high performance and sustainable building cooling and heating applications.Item 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.Item Experimental Investigation and modeling of hydrogen storage in graphene nanoplatelets incorporated silicon oxycarbide ceramics(Research Square, 2021) Parameshwaran, R.The present work focuses on synthesizing graphene nanoplatelets (GNP) incorporated amorphous silicon oxycarbide ceramic (Si-O-C) for hydrogen adsorption. The changes in the structure of the ceramic upon addition of GNP has been studied using X-ray diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy and Fourier Transform Infrared (FT-IR) spectroscopy. A theoretical framework to quantify these changes is proposed in line with existing structural model. Hydrogen adsorption studies have been carried out at 100K and 2 bar using Sievert’s apparatus. Maximum gravimetric storage density (GD) of 0.16 wt.% was observed after adding 0.3 wt.% of GNP, in comparison to 0.35 wt.% for the non-GNP sample. Pores sized 2–5 nm were found to be critical for hydrogen adsorption. The study finds that GNP addition leads to an increase in the size of the silica nanodomains. This increase in nanodomain size results in increase in the pore sizes of the existing mesopores, thereby reducing the overall hydrogen uptake. Further, the addition of GNP beyond 3 wt.% is found to increase the coordination of mixed bonds (Si-O-C) in the interface which results in agglomeration and subsequent loss of porosity in the composite.Item 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.Item An experimental study on heat power stored by thermal dissipation in electronic components using thermosyphon integrated hybrid nanocomposite phase change material(Elsevier, 2023-11) Parameshwaran, R.This study investigates the heat power stored by the thermal dissipation of electronic components using a thermosyphon integrated hybrid nanocomposite phase change material storage system. The study examines various thermal performances including the percentage of thermal dissipation, thermal resistance and heat transfer coefficient using benzene, deionized water, methanol and methyl acetate as heat transfer fluids, with an intended heat input of 50 – 120 W. The 0.5 wt% copper-titania hybrid nanocomposite particles are dispersed with phase change material (methyl cinnamate) and chosen as hybrid nanocomposite phase change material. The assessment of charging and retrieving characteristics of stored hybrid nanocomposite phase change material has been done by the impact of heat transfer fluids flowing through the copper tube at the different heat inputs. The result findings show that methyl acetate has the maximum percentage of thermal dissipation, low thermal resistance and high heat transfer coefficient of about 99.2 %, 0.311 K/W and 242.36 W/(m2.K) respectively at 120 W. The obtained results are attributed to the low boiling point and enthalpy of vapourization of methyl acetate. The highest heat power stored by hybrid nanocomposite phase change material is discovered as 6.5 W during melting by the impact of vapourized methyl acetate at maximum heat input owing to the higher mass flow rate and lesser time to attain steady state temperature of hybrid nanocomposite phase change material. Also, the developed system promotes thermal management in electronic components along with a minimum power saving of about 5–6 %.Item 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.Item 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.Item Solar thermal energy storage for heating applications — A review(IEEE, 2016) Parameshwaran, R.Rise in energy demands and the need to curb carbon emissions has made proliferation of conventional fuels unviable, leading towards the search for alternative energy sources. With a surplus of sunlight reaching the earth every day, solar energy is an immediate renewable alternative to be considered for satisfying the end-user demand requirements. However, generation using solar energy poses its own challenges such as low energy density, fluctuations in energy generation, and mismatch in supply-demand, making it impracticable. In this paper, recent developments in solar thermal and solar photovoltaic systems utilizing thermal energy storage (TES) for heating applications have been reviewed and presented. A general trend in improvements in performance and efficiencies of the solar thermal systems were observed by integrating them with the TES modules. Furthermore, it is suggested that, research in terms of materials suitable for solar thermal storage and design of thermal storage systems is necessary in achieving cost efficient solar-TES systems with enhanced performance for a variety of heating applications.Item Study on thermal properties of an eco-friendly phase change material for roof cooling application in buildings(Begell House, 2019) Parameshwaran, R.The continuous development of huge and elegant building structures has paved way for the extensive usage of energy sources. Across the spectrum of energy efficient technologies, the concept of thermal energy storage (TES) using the phase change material (PCM) has been constantly receiving huge acclamation from both the scientific and engineering perspectives, worldwide. It is worthwhile to study, in detail, the characteristic aspects of the eco-friendly organic PCMs, which in turn are expected to perform better in terms of achieving passive thermal storage potential as well as energy efficiency, without compromising the structural integrity of the building. The present work is aimed at analysing the thermal properties of an eco-friendly organic PCM (cetyl alcohol: C16H34O) for achieving passive thermal storage, energy efficiency and structural integrity through roof cooling application in buildings. Characterization of the proposed PCM was carried out using the field-emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscope (FTIR), X-ray diffractometer (XRD), thermal conductivity analyzer, viscometer and thermal energy storage experimental facility. The experiments conducted revealed that the PCM has exhibited an onset melting temperature of 48.94 °C and a high latent heat of 237.64 J/g, low thermal conductivity suitable for roof cooling application along with low viscosities at different temperatures indicating the good workability. Characteristic compressive strength of the samples was initially dropped, but it was found to be unaltered with further addition of the PCM. Based on the test results obtained, the cetyl alcohol can be considered as a promising eco-friendly PCM candidate for the passive roof cooling application without sacrificing the energy efficiency in buildings.