Department of Mechanical engineering
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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 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.Item Numerical Investigation of Mixed Convection in a Lid-Driven Square Cavity with and Without Fin(Taylor & Francis, 2019) Parameshwaran, R.Mixed convection in a lid-driven square cavity with an adiabatic fin placed at the middle of the left and bottom wall is studied. A two-dimensional (2D), steady, and laminar flow with stable vertical temperature gradient conditions is simulated. Vorticity-stream function formulation is employed to analyze the energy transport and the resulting governing equations are discretized using finite difference method. Grid convergence index method is used to confirm the reliability of results obtained from the adopted grid. Top wall of the cavity moves from left to right and right to left direction alternatively, while the other three walls are stationary. An isothermal hot and cold temperature boundary condition is applied, respectively, at the top and bottom walls, while an adiabatic boundary condition is applied 484to the vertical sidewalls of the cavity and to the fin. Taking the fin width as 2.5% of the cavity’s side, its length is varied from 5 to 20%. Cavity’s thermo-hydraulics is investigated at Richardson number (Ri) equal to 1. Results are presented in terms of streamlines, isotherms, average, and local Nusselt numbers.Item Study on thermal storage properties of microencapsulated organic ester as phase change material for cooling application(Taylor & Francis, 2019-11) Parameshwaran, R.The phase change materials (PCMs) are latent thermal energy storage materials to store and release energy in the form of latent heat with a change in internal energy. The microencapsulation technique overcomes the limitations faced by the PCMs during energy storage and release. In this study, the new ester-based non-paraffin PCM was microencapsulated into an organic shell using in-situ polymerisation technique. The as-prepared MPCMs was characterised using the field emission electron microscope (FESEM), fourier transform Infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. The results show that the MPCM characterised using FESEM has exhibited a good morphology. The chemical stability studies carried using FTIR spectroscopy also confirmed the formation of microcapsules was only by physical interaction. The DSC test results also signify that microcapsules have a latent heat of enthalpy of 65.32 kJ/kg, with onset melting temperature of 8.57°C. Thus, this ensures the MPCM to be considered as a potential candidate for the CTES application.Item 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.Item 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.