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In life-cycle costing of thermal energy systems, the basis of costing could be mass or exergy and the approach followed could be deterministic or stochastics. In thermal energy systems with end products/services such as hot air, hot water, steam etc. the value addition is due to higher exergy content; therefore, exergy is a logical basis of costing and stochastics is a practical approach capturing uncertainties of input variables. This paper proposes a novel framework named as stochastic Monte Carlo-based exergy costing (SMXC) for assessment of solar hot water systems. The annual hours of operation, maintenance cost, service life, and capital cost have been identified as highly sensitive input variables. The costs based on mass and exergy content of hot water in deterministic life-cycle costing method are estimated at 0.296 and 0.304 US cent/kg, respectively. The mean values of mass and exergy costs of hot water using Monte Carlo-based stochastics life-cycle costing method are 0.302 and 0.310 US cent/kg. A very low value (i.e. 2.4%) of the exergo-economic factor (f) for the solar water heater indicates the poor exergetic efficiency; therefore, capital investment to improve its efficiency is justified. The methodological approach can be extended to examine the probabilistic exergo-economic cost of array of thermal energy products when the parametric uncertainties play a key role. [ABSTRACT FROM AUTHOR]

The objective of this paper is to study and analyse heat losses from the absorber tube of a parabolic trough solar collector (PTSC) system and development of heat loss correlation. Computational fluid dynamics has been employed to obtain the convective and radiative heat losses. Heat loss model is simulated by employing the discrete ordinate (DO) radiation model to account for the radiation exchange in an enclosure between steel tube and glass cover, which is maintained as vacuum. Heat losses from the glass cover due to forced convection and radiation have been modelled and simulated. The effect of different emissivity on the absorber tube, different diameter ratio between absorber tube and glass cover, different heat transfer coefficients due to wind effects are studied in the considered PTSC system. Results are mentioned in dimensionless numbers for wider applicability. The result indicates that by varying the emissivity of the tube wall from 0.2 to 0.8, Nusselt number increases from 5.66 to 18.6. Similarly, when the heat transfer coefficient is changed from 6.89 to 19.49 W/m2K, Nusselt number increased from 5.66 to 5.81. Effect of vacuum has been studied as well. Finally, the correlation between Nusselt number and its influencing parameters has been obtained for the PTSC. [ABSTRACT FROM AUTHOR]

One of the key barriers to diffusion of domestic solar water heater in India is its high capital cost. Hence, there is a perception among people that it is not economically viable. The objective of this paper is to check the validity of this perception using net present value as a tool. An explicit formula has been developed from first principle to calculate the net present value of a domestic solar water heater which can be used globally. Scenario analysis has been conducted taking three scenarios: current, pessimistic and optimistic, to understand the spread in net present value. Taking probability of each scenario, expected net present value is calculated. The next objective is to go a further step to simulate using Monte Carlo simulation to attach a probability value with the net present value. Monte Carlo simulation model has been developed for risk assessment of solar water heaters. A range of values of all input variables have been considered assuming a normal distribution curve and based upon that a probability distribution curve of net present value is obtained. It was found that solar water heater is a viable option for east-coastal region of India. [ABSTRACT FROM AUTHOR]

This paper focuses on the effects of heat radiation and chemical reactions on naturally occurring convective MHD flow that conducts electricity when there is an induced magnetic field present between two vertical walls having a porous medium between them. An analytical method is adopted to investigate the impacts of all pertinent parameters concerning the presented multi-physics problem. With the aid of relevant conversions, the nonlinear PDEs are remodeled into nonlinear ODEs.The effects of radiation parameters, Hartmann number, Hall current, chemical reaction and porosity parameters are scrutinized on velocity components, induced magnetic field, and current density. The results predict that the temperature profile decreases as the radiation factor rises, whereas the induced magnetic field would exhibit the opposite pattern. The profiles of component velocity get more intense for high rates of the porosity parameter. Additionally, profiles of induced magnetic field surges with elevated chemical reaction parameter values have been noted. The presented approach is very promising for multi-physics phenomena like chemical reactors and solar thermal devices. [ABSTRACT FROM AUTHOR]

This paper presents thermal hydraulic modelling and simulation in the absorber tube of a Linear Fresnel Reflector (LFR) solar thermal system is carried out. The system is modelled using two-phase flow simulation software, RELAP5/MOD3.4. Although, RELAP5 is very commonly used in nuclear engineering design and simulation, it can be used for the simulation of solar thermal systems. Unlike other thermal systems like refrigerators and nuclear industries, there is significant heat loss from the surface of the absorber tube in a solar thermal system, which varies significantly with the temperature of the absorber tube wall. The recently developed temperature dependent heat loss has been incorporated in RELAP5 for variable net heat flux studies. The implementation of the temperature dependent heat losses has been verified by comparing the results obtained from RELAP with those obtained by Homogeneous Equilibrium Model. Parametric studies are carried out using verified RELAP model for different values of heat flux, mass flux, inlet subcooling and inlet pressure. The developed model can be considered as an effective tool for better and effective absorber LFR tube design under designed conditions. [ABSTRACT FROM AUTHOR]

• With an emphasis on the energy-water-food nexus an island in the Indian Ocean is being investigated for solar energy intervention. • A hybrid polygeneration system powered by solar thermal energy with a turbine, VAM, pasteurization unit and membrane distillation is planned. • The energy balance, socio-economic and environmental analysis of the system are done. • To standardize the cost, Levelized expenses for power, water, refrigeration, pasteurization, and heating are computed. • The opportunity cost and social cost benefits of the system are identified. • The environmental cost is added in the cost economics and worked for a better IRR and payback. Rural electrification is constrained by grid extension infrastructural cost, isolated low rural populations, lack of anchor loads, and repayment potential of villagers while decentralized renewable energy power is constrained by high capital cost, low reliability, and non-workable business models. Solar thermal energy can produce electricity, heating, cooling, water, and fuel and has the potential for storage for livelihood applications. Hence solar thermal energy-based cogeneration and polygeneration systems have the potential for intervention in rural livelihoods with a focus on the energy-land–water-food nexus. However, standalone solar thermal systems are capital intensive and shadowed by photovoltaics. In the current work, an island in the Indian Ocean is considered for the study, and a solar thermal energy-based hybrid polygeneration system is designed with end products such as electricity, heating, cooling for food storage, and desalinating to get pure water. The turbine, VAM, pasteurization unit, and membrane distillation unit are the considered components in the present analysis. The thermodynamic properties of the key components of the polygeneration system are identified and the energy and entropy balance of the system is done. The levelised cost of production of polygeneration outputs for 25-year operational life with an accelerated depreciation of 30% of the capital cost, over 8 years is carried out. It is found that the electricity and water pricing are INR 14.71 and INR 14.01 per unit which are not attractive. Normalization is done by adjusting the price of other polygeneration outputs namely refrigeration, hot water, and pasteurizing to make the electricity and water pricing feasible to achieve an IRR of 12.99% and payback of 9 years at a 5% annual escalation. The social cost saved with the benefit of polygeneration outputs is cumulated considering value addition in the supply chain to save agricultural produce and milk, which otherwise would have spoiled. The annual carbon emissions that are curtailed with solar thermal polygeneration outputs are cumulated and found to be 434 tonnes of carbon. The social cost and environmental cost due to carbon are considered as an incentive in the cost economic economics of polygeneration system and it is found that the IRR and payback can be improved to 17.98% and 6.2 years respectively. The work recommends policy interventions to promote decentralized solar thermal polygeneration systems for impact on rural livelihoods with a focus on the energy-water-food nexus. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the analysis of heat losses from the trapezoidal cavity receiver used in linear Fresnel reflector (LFR) system. The experimental studies are conducted under laboratory conditions that are specially designed for this purpose. The effects of parameters such as the temperatures of the tube surface, depth of receiver, number of tubes, and emissivity of tubes are investigated. The loss of heat is taking place from the tube outer surface to glass cover, below the receiver and then glass cover to ambient. As part of this investigation, the system is modelled and simulated using computational fluid dynamics (CFD). After validation, contribution of convection and radiation to the total heat transfer are found out using CFD. Computational predictions are shown to be consistent with the experimental observations which show that the CFD model is a reliable tool for predicting heat loss and overall heat loss coefficient. It was found that losses due to convection are between 5 and 18% of the total heat losses. [Copyright &y& Elsevier]

Abstract: Linear Fresnel Reflector (LFR) solar thermal system is a promising technology in solar thermal applications. In LFR system, parallel absorber tubes (usually 8–16) are located inside a trapezoidal cavity, which receives reflected solar flux from the mirrors situated below it. The fluid (usually water) inside the tubes undergoes phase change due to the incident solar flux. The focus of this paper is to carry out hydrothermal analysis in an absorber tube of a Linear Fresnel Reflector (LFR) solar thermal system. In the present work, a generic methodology to deal with steady state hydrothermal analysis of the absorber tubes has been discussed. The single phase regions as well as the two-phase region of the absorber tube have been analyzed. A one dimensional model has been used for the analysis for both the regions. In the two-phase region analysis is carried out under the assumption that the homogeneous equilibrium model is valid. For this hydrothermal analysis, the radiative and convective heat losses from the surface of the tube to the atmosphere are obviously needed. To obtain the heat losses, the computational analysis of the heat transfer in the trapezoidal cavity is carried out. The present model can be used to predict the variation of bulk fluid temperature, variation of heat transfer coefficient, pressure loss along the length under different mass flux and different solar flux, in single phase region. Similarly, variation of dryness fraction, local boiling two phase flow coefficient, and total pressure drop can be predicted for two phase region. This model can be used to understand and design for a better LFR system. [Copyright &y& Elsevier]

Abstract: A Computational study to investigate the heat loss due to radiation and steady laminar natural convection flow in a trapezoidal cavity having eight absorber tubes for a Linear Fresnel Reflector (LFR) solar thermal system with uniformly heated tubes and adiabatic top wall and side walls has been performed. The losses due to convection and radiation were considered from the bottom glass cover. The results are validated with experimental data. Radiative component of losses from the cavity was found to be dominant which contributes around 80–90%. Heat loss characteristics have been studied for cavities of different depths. Simulations have been carried out for various values of heat transfer coefficient based on the wind speed below the glass surface. Effect of emissivities of the tubes on the heat loss has also been simulated. Flow pattern and isotherms inside the cavity for various depths have been analyzed. Finally, the correlation between the total average Nusselt number and its influencing parameters has been obtained for the proposed cavity. [Copyright &y& Elsevier]

Solar thermal energy-based electricity is capital-intensive, and complex while technically evolving to achieve an optimal design. Global commitments and timelines to increase renewable energy share in the grid have promoted technically mature solar photovoltaics and wind. However, the potential of solar thermal energy for industrial applications, cogeneration and polygeneration is on the back foot for lack of policy, complexity, technical readiness level, cost of components and workable business models. Solar collectors that can generate high-quality steam for power generation is complex and costly; while, modified version of linear Fresnel reflector's (LFR) are prospective for various requirements. The current work looks into the possibility of an LFR and heliostat combination to generate steam at 45 bar, 400C temperature to produce electricity. The levelized cost of electricity (LCOE) and levelized cost of water (LCOW) is found to be INR 5.11 kWh−1 and INR 43.03 m−3, in a 70:30 debt–equity scenario. An IRR of 8.55% is achieved with a payback of 12.5 years, with the sale of electricity at INR 10.11 kWh−1 and water at INR 45 m−3. To reduce the LCOE, LCOW and have an attractive IRR, the viability gap funding (VGF) as an option is tried out. The impact of VGF at, 0%, 10%, 20% and 30% on water generation, electricity generation, IRR, NPV and payback are found. It is found that as the VGF increase, there is a better generation cost for electricity and water, with an improved IRR. However, with the VGF trend and corresponding reduction in electricity and water production cost, it will be ideal to have the VGF close to 15% to keep the electricity sale price at approximately INR 8.5 kWh−1 and water pricing at INR 46 m−3. [ABSTRACT FROM AUTHOR]

A methodology has been presented related to entropy generation due to forced convection boiling in long absorber tubes used in linear Fresnel reflector solar thermal system. Variable heat flux has been applied on the tube which replicates the scenario for aforementioned tubes and local entropy generation has been obtained for various parameters. Mathematical modeling has been made separately for single- phase and two-phase regions in flow boiling conditions encountered in linear Fresnel reflector tubes. Entropy generation in two-phase region has been formulated using homogeneous equilibrium model. The entropy generation at varying mass flux and heat flux cases are calculated. The entropy generation due to heat transfer is found to be more than that of pressure drop. Still, entropy generation due to pressure drop in two-phase region plays a major role of increasing nature of it. Present approach will help researchers and industry to optimize the solar thermal systems where flow related phase change occurs and measures can be taken accordingly to increase energy efficiency of those systems. [ABSTRACT FROM AUTHOR]

• Effect of the tilt angle on the limiting value of heat flux on TEG is established. • Effect of wind direction on the limiting input heat flux for TEGs is investigated. • Sizing of Fresnel lens concentrator is carried out for effective TEG. • Effect of ambient air temperature on the limiting input heat flux for TEG is found. This paper focuses on establishing the dependence of limiting value of input heat flux for solar assisted thermoelectric generators (TEG) on Angle of Attack (AOA) and wind direction of heat sink of TEG. Current study investigates the limiting input heat flux for TEGs with allowable hot side temperature of 150 °C. A fin block with eight fin configuration and fin length of 60 mm is chosen as heat sink configuration for TEG. Computational Fluid Dynamics (CFD) model is developed and analyzed in this work after validation with published experimental results. CFD model consists of four TEGs encapsulated within a target block and a finned block, placed within a domain which simulates low speed wind tunnel. Air flow in the wind tunnel simulates the outdoor wind conditions. Concentrated solar flux is applied on the face of target block. Effect of ambient air temperature on limiting input heat flux is also studied. Dependence of limiting input heat flux on Angle of Attack (AOA) and wind direction, which arises due to the two axis tracking of Sun by Fresnel lens concentrator has been quantified and it is observed that maximum limiting input heat flux occurs at 30 ° AOA. Maximum limiting heat flux reaches 24,000 W/m2 for 30 ° AOA under 5 m/s wind velocity. It is also observed that maximum input heat flux varies by 42.49% with change in wind velocity from 1 to 5 m/s. Maximum limiting input heat flux occurs at 45 ° for horizontal rotation. Area of square array Fresnel lens concentrator varies by 6.29% for 5 m/s wind velocity when AOA is considered to when AOA is not considered for calculation of Fresnel lens area. [ABSTRACT FROM AUTHOR]

In this paper, a three fluid heat exchanger is analytically modeled in order to predict the effects of different design parameters on its thermal performances. The optimum values of these parameters relating to maximum heat transfer and minimum pressure drop are assessed using Taguchi based optimization technique. The present heat exchanger is an improvement of double tube heat exchanger, where a helical coil is inserted in the annular space occupied in between two straight tubes. It is different from other three fluid heat exchangers with respect to construction, flow arrangement and thermal communication point of view, where the hot water is flowing through the helical coil as the heating fluid and continuously transferring thermal energy to normal water and air, which are flowing, in outer annulus and innermost straight tube. The results of the analytical approach are compared and validated against literature and good conformity between them is observed. The temperature distributions of three different fluids along the length of the present heat exchanger are assessed analytically for different flow configurations. Three different non-dimensional design parameters i.e. curvature ratio, non dimensional coil pitch and coil side Reynolds number are selected and their effect on heat transfer and pressure drop characteristics i.e. coil side Nusselt number, effectiveness and friction factor respectively are assessed. It is found that, for tube size 0.0045 m, coil pitch 0.013 m, coil diameter 0.04253 m and hot water flow rate 5 liters per minute, present heat exchanger will perform optimum. It is also resulted that, volumetric flow rate of hot water is the most effective parameter affecting heat transfer with a contribution ratio of 66.82% and tube size is the most effective parameters affecting pressure drop with a contribution ratio of 71.07%. [ABSTRACT FROM AUTHOR]

In the current work parametric studies have been undertaken on a Computational Fluid Dynamics (CFD) model of a Parabolic Trough Solar Collector (PTSC) receiver by varying the inlet temperature of Heat Transfer Fluid (HTF) and wind velocity over the glass cover. The performance of the PTSC receiver has been analyzed by computing circumferential temperature distribution on the absorber tube and the glass cover, and the temperature rise and pressure drop of the HTF. It is found that the circumferential temperature difference (ΔTc) is strongly dependent on the inlet temperature of the HTF. The circumferential temperature difference (ΔTc) decreases from 30.49 K to 17.08 K when the inlet temperature increases from 363 K to 663 K. Simultaneously, the increase in the inlet temperature of the HTF results in a decrease in thermal efficiency of the receiver by 6.45%. The rise in the wind velocity over the glass cover of the receiver from 0.5 m/s to 5 m/s decreases the peak temperature of the glass cover by 8.59%. [ABSTRACT FROM AUTHOR]

Summary: Present work encompasses developing a new methodology to incorporate the heat transfer characteristics of the evacuated space (vacuum) in the annulus region between the absorber tube and glass cover and the effect of selective coatings on the steel absorber tube for a 3‐dimensional computational fluid dynamics model of a parabolic trough solar collector (PTSC) receiver. In the present work, glass cover has been modeled semitransparent to the incoming solar flux, which has been applied on the glass cover. Wavelength‐dependent absorption properties of glass cover material also has been modeled. In the current work, the direct normal irradiation and the mass flow rate of heat transfer fluid (HTF) has been varied to check their individual effect on the performance of PTSC absorber tube. Circumferential temperature distribution of absorber tube and glass cover has been found out; heat transfer to HTF and pressure drop of HTF in the absorber tube have also been calculated. A comparative study has been undertaken to highlight the relative contribution of the vacuum and selective coating on the receiver performance. The value of circumferential temperature difference at mid‐length of absorber tube was found to be 14.78 K for 750 W/m2, which increases to 19.70 K for direct normal irradiation of 1000 W/m2. When vacuum is replaced by air in the annulus region, PTSC absorber performance decreases by 4.82%. Similarly, because of use of selective coating, the thermal efficiency of the receiver increased by 34.59%. Present work encompasses development of a new methodology to incorporate heat transfer characteristics of the evacuated space (vacuum) in the annulus region between the absorber tube and glass cover and selective coatings on the steel absorber tube for a 3‐dimensional computational fluid dynamics model of a parabolic trough solar collector receiver. Glass cover has been modeled semitransparent to the incoming solar flux, which has been applied on the glass cover. [ABSTRACT FROM AUTHOR]

The objective of this paper is to analyze the energy and exergy of a solar thermal based polygenearation process used for rural application in India. Linear Fresnel reflector (LFR) is used as solar thermal energy generation source for polygeneration process. The LFR system design is slightly modified to bring down the cost of the solar field. Electric power, cooling and generation of hot water for process applications are various polygeneric applications discussed in this work. The system is modeled to be experimented for application in rural sector of India, where various processes can function in parallel to cater to livelihood enhancements. Such, stand alone units are useful for community based refrigeration units, especially during the season of harvest. Vapour absorption machine (VAM) and adsorption chiller are selected for consideration in cooling applications, while pasteurizing unit is explained as a hot water utilization method. Molten salt-based storage for short time duration is also investigated in the current study. Thermodynamic analysis and solar field optimization are done for the polygeneration process to identify various operating parameters. Key input parameters are varied to identify the changes in outputs of various components. Energy and exergy analysis shows that there is very less loss in most of the components, while LFR and VAM are found to be high exergy loss equipment. There is a scope of scaling up of such systems which can be operated as standalone units for applications in the rural regions. [ABSTRACT FROM AUTHOR]

The maximum deflection of a Parabolic Trough Solar Collector (PTSC) absorber tube is a result of the circumferential non-uniformity in temperature distribution and self-weight. This non-uniformity in temperature is a factor of incoming solar flux distribution as well as material property of the absorber tube. The present work focuses on structural analysis of absorber tube used in PTSC and the effects of variations of material. Multiphysics platform, namely thermal-fluid analysis and structural analysis has been made in this regard. The computational investigation has been carried out on Schott PTR70 2008 receiver and Therminol VP1 as the Heat Transfer Fluid (HTF). Evacuated annular space along with specular and non-grey nature of glass cover which is semi-transparent to the input flux has been modeled to obtain better accuracy in results. The materials investigated are steel, copper, aluminum and various laminated composites like bimetallic (Cu-Fe) and tetra-layered laminate (Cu-Al-SiC-Fe), which are subjected to different mass flow rate of HTF at the absorber tube inlet with constant heat flux on the absorber tube outer surface. It is found that the change in the material of the absorber tube has a negligible effect on the amount of heat transferred to the HTF, but it has a significant effect on the bending due to thermal expansion as well as due to self-weight. Steel absorber tube is generally used, but its lower thermal conductivity results in poor circumferential temperature distributions. Copper has better thermal characteristics, but higher self-weight and lower mechanical strength compared to steel. So a combined effect of these properties is utilized in bimetallic tube, which results in a decrease in maximum deflection by 7–15% as compared to steel. As the self-weight of the absorber tube plays a vital role in deflection, therefore a tetra-layered laminate absorber tube having lower weight and improved temperature distribution results in a decrease in maximum deflection by 45–49% as compared to steel. [ABSTRACT FROM AUTHOR]

Solar energy is going to play a measure role in the future global energy supply. Its acceptance has already been on rise in developing countries like India, where there is acute shortage of energy due to economic and other climatic reasons. Forecasting or predicting the future output of solar energy is a much needed step to integrate high insolation of solar energy to the nation's power grid. Due to the fluctuating nature of solar energy, an efficient use is possible depending on reliable forecast information and its availability in various time and spatial scales. The current status of forecasting of solar irradiance for energy generation proposes a review of solar radiation prediction and its application in a rapidly increasing economy like India. Various models are developed for analysis which can be developed either by empirical, soft computing or by simulation approach. [ABSTRACT FROM AUTHOR]

In this paper, the forced convective heat transfer enhancement with nanofluids in a 90° pipe bend has been presented. Numerical investigation is carried out for the turbulent flow through the pipe employing finite volume method. The governing differential equations are discretized using hexahedral cells, and the resulting algebraic equations are solved using Commercial solver Fluent 6.3. In order to close the time averaged Navier-Stokes equations, the two-equation κ-ε turbulence model with a standard wall function have been used. The duct Reynolds number is varied in the range of 2,500-6,000. It is observed that the heat transfer is enhanced significantly by varying the volume fraction of the nanofluid. It is also found that the heat transfer is increased with Reynolds number. A strong secondary flow is observed due to the presence of the wall. Turbulent kinetic energy near outer wall is found to be higher than the inner wall of the bend. A comparative assessment for the heat transfer enhancement with different types of nanofluids is also presented. The computed results of area weighted average Nusselt numbers are validated with some of the existing literature. [ABSTRACT FROM AUTHOR]

The current work focuses on magnetohydrodynamic free convective flow mixed with radiation between vertical walls under the consequences of hall current as well as the induced magnetic field and is concerned with panel cooling for the aluminum smelting plant. It has been proposed that the fluid channel has a porous medium. The isothermal transport equations, which primarily concern mass, momentum, energy, and induced magnetic field, are solved analytically. After comparing the model findings with those from the literature, the effect of the different relevant parameters of the current model is gathered and presented. Hartmann number, Hall current on velocity components, current density, induced magnetic field, porosity, and Soret effect are all investigated for their effects. Due to the applied radiation field on plates, the influence of the radiation parameter has also been included. Under the effect of the Hall parameter, the velocity's primary component is observed to increase; nevertheless, the secondary component has been shown to decrease. The Hall effect is observed to be reducing the generated magnetic field, and the Lorentz force Hartmann number decreases the flow. The magnitude of the velocity and current density is decreased because of the radiation parameter. Such methodology should be employed to get first-cut results and to analyze the system in a better way before the prototype development and demonstration. [ABSTRACT FROM AUTHOR]

The influence of microrotational velocity on a fully developed laminar, natural convection flow in vertical concentric annuli in the presence of radial magnetic field between two nonconducting vertical concentric annuli is investigated in the present study. The induced magnetic field is generated due to the motion of an electrically conducting fluid in the annulus; the polar fluid has been considered in the present analysis. Transport equations such as momentum, energy, polar fluid, and induced magnetic field are solved analytically for the isothermal case. The effects of the different pertinent parameters of the present model are obtained and analyzed after verification of present methodology. The effects of the Hartmann number, the gap between two cylinders, and vertex viscosity parameters on velocity profiles, induced magnetic field, induced current density, and microrotational velocity profiles are studied. It is observed that the velocity profile and induced magnetic field decrease due to the vertex viscosity parameter; the Hartmann number accelerates the velocity of the microrotation; the induced current density profile decreases for both the Hartmann number and vertex viscosity parameter. The Hartmann number reduces the magnitude of mass flux and skin frictions at the inner and outer cylinder. [ABSTRACT FROM AUTHOR]

Depletion of fossil fuels, strict pollution rules, and potential generation of waste plastics strive to focus another facet of value addition by conversion of plastic wastes into alternate fuel for a diesel engine. The current study is intended to optimize the combined influences of engine load, fuel blend, and compression ratio on the performance and emission of a normal diesel engine fueled with waste plastic oil diesel (WPO) blend by using response surface methodology (RSM). Optimum engine performance i.e.maximum brake thermal efficiency and minimum NO x emissions are established using the technique of response surface methodology concerning three different engine input parameters engine load, compression ratios, and fuel blend ratio. The compression ratio of 17, 10% of WPO-diesel blending at full load conditions are found to be optimum input parameters. And accordingly, the brake thermal efficiency of 28.8% and NO x emission of 162.45 ppm are obtained under multi-response optimization techniques. A sensitivity analysis has also been accomplished to clarify the significant contribution of different parameters and their orders of importance. The compression ratio has resulted as the most significant factor followed by load and % fuel blend. • Fuel characterization of waste plastic oil obtained as an alternative fuel. • Experiments were carried out to obtain the performance and emission analysis. • Optimization of engine performance parameters using RSM. • Rank identification of engine parameters on performance using sensitivity analysis. • Optimum input parameters are obtained using MRO and DFA. [ABSTRACT FROM AUTHOR]

• A solar polygeneration system is proposed. • It produces three key utilities viz. electricity, hot water, and hot air. • 3E (energy, exergy, economic) analysis is conducted. • The proposed Energy technology is technically feasible and economically viable. • For commercialization this, innovative business model supported by Govt. policy is required. Sustainable development goal 13 emphasizes on climate change, due to which there is an urgent need for a transition towards sustainable energy technologies. There are two key issues on the commercialization of renewable energy technologies viz. performance (efficiency) and economic viability. This paper conducts a 3E (Energy, Exergy, Economic) analysis for a novel off-grid solar polygeneration energy technology producing electricity using the solar PV and hot water along with hot air using the solar thermal system. The analysis has been carried out across four Indian provinces such as Andhra Pradesh (AP), Madhya Pradesh (MP), Uttar Pradesh (UP), and Uttarakhand (UTK) located in four climatic zones. For the solar PV unit, the amount of annual electricity production in kWh are 1748, 1799, 1629, 1434 in mentioned four states, and the annual Levelized Cost of Electricity (LCOE) in ₹/kWh are 9.8, 9.6, 10.5, 12 for AP, MP, UP, and UTK respectively. The values of annual average energy efficiency of the solar thermal system in percentage are 64.6 for AP, 64.5 for MP, 64.2 for UP, and 58.3 for UTK, while exergy efficiency are found to be 1.3, 1.4, 1.2, and 0.7 in percentage for the mentioned states. For the solar thermal unit, the values of payback period in years are obtained to be 5.2, 5.5, 7.5, 9.4 and the values of Benefit-Cost ratio (BCR) are 1.32, 1.25, 0.90, 0.73 for AP, MP, UP, and UTK respectively. An innovative business model coupled with utility policy is required for large-scale deployment of these sustainable energy technologies. [ABSTRACT FROM AUTHOR]