Showing papers in "International journal of ambient energy in 2014"

Energy and exergy analysis of 36 W solar photovoltaic module

Abstract: The solar photovoltaic (PV) system generates both electrical and thermal energy from solar radiation. In this paper, an attempt has been made for evaluating thermal, electrical and exergy output of solar PV panel installed at Energy Centre, NIT Bhopal. Using the first law of thermodynamics, energy analysis was performed and exergy analysis was carried out to determine exergy losses during the PV conversion process by applying the second law of thermodynamics. The operating and electrical parameters of a PV array include PV module temperature, overall heat loss coefficient, open-circuit voltage, short-circuit current, fill factor, etc. were experimentally determined for a typical hazy day of March (10 March 2012) at Bhopal. The experimental data are used for the calculation of the energy and exergy efficiencies of the PV systems. Energy efficiency is seen to vary between 6% and 9% during the day. In contrast, exergy efficiency is lower for electricity generation using the considered PV module, ranging from...

Improving thermodynamic performance parameters of silicon photovoltaic cells via air cooling

Abstract: A numerical and experimental study based on analysing the cooling effect on performance characteristics of silicon solar cells is presented. In the experiments carried out for different cell temperatures, a substantial decrease in power output with increasing cell temperature was observed depending on the decrease in exergy efficiency. In contrast to the remarkable decrease in voltage parameters, a slight increase in current parameters with increasing cell temperature was obtained. A well-known computational fluid dynamics software was utilised to evaluate the effectiveness of cooling applications in terms of enhancement of energy conversion in silicon solar cells. Air was chosen as the cooling fluid in the numerical study. The numerical study was performed for various velocities and temperatures of cooling fluid. Enhancement in energy conversion was determined for each operating condition. The results indicated that cooling applications are quite important to improve the efficiency and the maximum power ...

Experimental investigation to reduce emissions of CI (compression ignition) engine fuelled with methyl ester of cottonseed oil using antioxidant

Abstract: Biodiesel offers cleaner combustion over conventional diesel fuel, including reduced particulate matter, carbon monoxide and unburned hydrocarbon (HC) emissions. However, several studies point to increase in NOx emissions (about 13%) for biodiesel fuel compared with conventional diesel fuel. In this paper, the experimental investigation on the effect of antioxidant additive (l-ascorbic acid) on NOx emissions in a methyl ester of cottonseed oil- (MECSO) fuelled direct injection diesel engine has been reported. The antioxidant additive is mixed in various proportions (100–400 mg) with MECSO and was tested in computerised four-stroke water-cooled single-cylinder diesel engine of 3.5 kW rated power. Results show that the antioxidant additive is effective in controlling the NOx and HC emissions of MECSO-fuelled diesel engines.

Application of artificial neural network for the prediction of jaggery mass during drying inside the natural convection greenhouse dryer

Abstract: In this paper, an attempt is made to predict the hourly mass of jaggery during the process of drying inside greenhouse dryer under the natural convection mode. Jaggery was dried until the constant variation in the mass of jaggery. Artificial neural network (ANN) is used to predict the mass of the dried jaggery on hourly basis. Solar radiation, ambient temperature and relative humidity are input parameters for the prediction of jaggery mass in each hour in the ANN modelling. The results of the ANN model are also validated with experimental drying data of jaggery mass. The statistical parameters such as root mean square error and correlation coefficient (R2) are used to measure the difference between values predicted by the ANN model and the values actually observed from the experimental study. It was found that the results of the ANN model and experimental are shown fairly good agreement.

Multi-criteria decision modelling approach for biodiesel blend selection based on GRA–TOPSIS analysis

Abstract: The aim of this study is to select the best blend between alternative blends of fish oil and diesel using multi-criteria decision making technique The six alternative fuel blends Diesel, B20, B40, B60, B80, and B100 are prepared by varying the amount of diesel in biodiesel Brake thermal efficiency, exhaust gas temperature, oxides of nitrogen, smoke, hydrocarbon, carbon monoxide and carbon dioxide, are considered as evaluation criteria A single-cylinder, constant speed and direct injection diesel engine with a rated output of 44 kW was used for exploratory analysis of evaluation criteria at different load conditions The model fuzzy analytic hierarchy process (FAHP), grey relational analysis (GRA) and technique for order preference by similarity to ideal solution (TOPSIS) are proposed to evaluate the best fuel blend FAHP is used to compute the criteria weights whereas GRA and TOPSIS are combined together and proposed as GRA–TOPSIS for obtaining the final ranking of alternatives The result of the prop

Effect of silt particles on erosion of Turgo impulse turbine blades

Abstract: Silt particles passing through hydro-turbine components cause erosion to the surface which comes in contact. Silt size, silt concentration, velocity of flow, properties of base materials and operating time of the turbine play a vital role in the damage of hydro-turbine components. Several attempts have been carried out to study the effect of these parameters on erosive wear. In this present study, an attempt has been carried out to experimentally investigate the effect of silt size, concentration, jet velocity and operating hours on erosive wear in actual conditions of the Turgo impulse turbine. Based on the experimental data, correlations have also been developed for the estimation of wear rate.

A passive house with seasonal solar energy store: in situ data and numerical modelling

Abstract: This paper presents parametric analysis of solar collector area and solar energy storage volume for a passive house in Galway, Ireland. Using the simulation tool Transient System Simulation Tool (TRNSYS), a model was developed to represent a 215m2 home built to Passivhaus standards and incorporating a 10.6m2 solar thermal collector and a 23m3 solar thermal storage tank. This model was validated through comparison with data collected in situ from the operation of the home over the period of 1 year. Once validated, the model was used to investigate the effect of varying solar collector area and solar energy storagevolume on the fraction of heat demand met by solar energy. Results indicate that increasing collector area from 10.6 to 20m2 could increase total solar fraction from 0.47 to 0.63, decreasing fossil-fuel-derived energy demand at the home under study by a further 30%.

Energy, exergy and entropy analysis of a single-slope floating-cum-tilted wick-type solar still

Abstract: In this article, an attempt has been made to design, fabricate and analyse a single-slope floating-cum-tilted wick-type solar still in terms of energy, exergy and entropies of the still. A new simplified analytical expression for instantaneous exergy efficiency of the proposed still by incorporating the variation of instantaneous energy and entropy of the still has been written and solutions have been found. A comprehensive analysis of the system has been presented by determining the exergy destroyed by internal irreversibility due to the variation of entropy and energy during the working hours of the system.

Grid parity analysis of solar photovoltaic systems in Europe

Abstract: Photovoltaic (PV) power generation plays an important role in future sustainable energy mixes due to its high reliability, yield predictability and capacity for electricity production during peak demand when the electricity price is usually high. But still today, the economic viability of this technology depends on the subsidies usually granted by public authorities and electricity consumers. In the past, some subsidy schemes were inadequately generous, resulting in unsustainable PV growth rates that resulted in high public allowances. This study investigates the actual cost situation of the PV power generation for European countries, giving a perspective of the profitability until 2020 and identifies scenarios for which the technology can be financially self-sufficient without any subsidies. The study showed that the first grid parity was achieved in the Southern European countries. In Northern Europe, the PV cost-effectiveness depends highly on the national electricity price level and solar resources.

Year-round numerical simulation of a parabolic solar collector under Lebanese conditions: Beirut case study

Abstract: A detailed thermal and optical numerical model is developed to simulate the performance of a small-scale parabolic collector having an evacuated receiver line with selective coating, taking into account different energy balances and interactions with the surrounding. An analytical model is developed to estimate the direct, diffuse and global solar radiation intensities on inclined surfaces. The collector performance model was validated using published experimental data. A year-round dynamic simulation for the collector performance under Beirut climatic conditions was carried out with an economic and environmental analysis. The outlet water temperature could reach a maximum of 114°C in July and 52°C in December by employing a collector of about 6 m2 aperture area with 0.01 kg/s water flow rate. The maximum daily thermal energy production is attained in July with 22.267 kWh while January exhibits the lowest thermal energy production with 6.704 kWh per day with a maximum thermal efficiency of 72%.

Stability analysis of power system with doubly fed induction generator-based wind farm connected through series flexible AC transmission SYSTEM device compensated line

Abstract: Wind farm may be remotely located due to the availability of wind. Therefore, series compensation may be required to evacuate large wind power to a distant power system. The impact of series compensation on the stability of power system with wind farm is of concern for transmission and system operation. This paper investigates the stability issues of power system with remote wind farm. The studied power system network is connected to a remote wind farm through a series Flexible AC Transmission System device, Static Synchronous Series Compensator, compensated transmission line. The small signal stability and transient stability issues are studied for uncompensated and compensated system. The results show that damping ratio is increased for most of the oscillatory modes showing increase in small signal stability with series compensation. The eigenvalue sensitivity analysis is performed with the degree of compensation and voltage gain as sensitivity parameters. Transient analysis is performed for a three-pha...

A characteristic evaluation of alumina–zirconia-coated engine fuelled with punnai methyl ester

Abstract: All these years, several studies have been carried out to find feasible, viable and dominant alternate source to fossil fuels, with the primary interest of enhancing engine performance and reducing exhaust tail pipe emissions. The present work enumerates the performance and emission characteristics of low-heat rejection engine (LHRE) coated with the alumina–zirconia (Al2O3–ZrO2) composite. Experimental results proved improvement in brake thermal efficiency, brake-specific fuel consumption and well-to-wheel reduction of carbon monoxide, hydrocarbon and smoke emission for coated engine (CE) in comparison with uncoated engine (UCE). Neat diesel, new high-potential punnai methyl ester and its diesel blends were used as test fuels. However, in the experimental study, oxides of nitrogen increased for CE than UCE.

Combustion of waste chocolate oil biofuel in a diesel engine

Abstract: An experimental study has been carried for almost first time to use methyl esters derived from waste chocolate oil produced from chocolate industry, in an indirect injection diesel engine. Effects of engine speed, engine load output, injection timing of the biofuel and the blend ratio with pure diesel fuel on the engine output torque, combustion noise (maximum pressure rise rate), maximum pressure and maximum heat release rate have been studied. Raw waste oil extracted from the industrial process to produce chocolate has been used to produce the biofuel and its physical and chemical properties have been measured and performance of diesel engine combustion has been evaluated in a Ricardo E6 research engine. It has been found that the biofuel (chocolate oil methyl ester) properties are almost similar to that of diesel and the engine performance was similar to diesel engine running on pure diesel fuel. There is no need to modify the engine when this biofuel is used.

Entropy generation and thermoeconomic analysis of the wire-and-tube condenser

Abstract: In this work, entropy generation analysis of an air-cooled natural draft wire-and-tube condenser commonly used in the domestic refrigerator is carried out to investigate geometrical and operating parameters. The Bejan number formulation is used for the analysis because of its ability to relate the heat transfer to pressure drop entropy generation. The analysis also incorporates thermoeconomics by combining the second law of thermodynamics with economic principles. The analytical study is carried out by varying geometrical parameters of the condenser such as tube outer diameter, wire diameter, number of wire pairs, number of tube rows, tube pitch, wire pitch and refrigerant (R134a) properties such as mass velocity, saturation temperature and dryness fraction. The behaviour of entropy generation due to heat transfer and pressure drop, Bejan number and thermoeconomic variables such as relative cost difference and exergoeconomic factor are analysed. These results are used in obtaining the values of condenser ...

Formulation and validation of a mathematical model for a naturally ventilated greenhouse with shading nets in warm and humid climate of India

Abstract: A thermal model is developed to investigate the suitability of a simple, inexpensive and naturally ventilated greenhouse with shading nets in warm and humid climatic condition for off-season cultivation of vegetables like okra, cucumber, etc. during winter. These vegetables are generally grown during summer and the rainy season. The study was conducted from November 2011 to February 2012 in OUAT, Bhubaneswar, and Odisha where warm and humid climate usually prevails. Air temperatures inside the greenhouse with shading net were only 1–2°C higher during peak sunny hours and considerably 3–5°C more during night hours compared with ambient air temperatures. Lowering of air temperature during peak sunny hours and increasing during the night due to use of shading nets would become favourable for growing off-season vegetables in naturally ventilated greenhouse. Predicted values of air and plant temperatures were found to be in close agreement with experimental values.

The effect of ignition timing and methanol gasoline blends on the performance and emissions of the spark ignition engine

Abstract: The automobile has changed a lot since the first horseless carriage to the gasoline-powered vehicles. The automobile has changed when the roads became paved and the fuel consumption in the gasoline engine forms a major portion of total petroleum consumption in the automobile industry. This work interweaves the study of experiments on the four-cylinder carburettor-type gasoline engine to cue the performance and emission characteristics by advancing the ignition timing from 10° to 30° BTDC using gasoline methanol blends as fuels in the ratios of 5% to 15% at an interval of 5% on volume basis. The effects of varying the engine working parameters such as ignition timing, brake power, brake thermal efficiency are observed and the variation of different engine emission parameters with the exhaust gas analyser is also observed. For M5, the brake-specific fuel consumption values decreased and brake thermal efficiency increased For M15, exhaust emission values decreased.

Solar apricot dryers and drying processes in the high-altitude cold-arid Ladakh region of India

Abstract: Sun drying of apricot fruit (Prunus armeniaca L.) is the oldest form of preservation technique known to the people of Ladakh and is still practiced on a large scale. This is because of the abundance of available sunshine. Export of fresh fruits of apricot and apple outside the region is restricted through quarantine regulations to check the entry of a noxious pest, codling moth to other temperate fruit belts (J&K and HP) of the country. Henceforth, drying is the only possible venture in vogue to receive income from apricot cultivation. Traditional practices followed commonly render the final produce to be unhygienic thereby fetching low returns. The introduction of different types of solar dryers along with other novel drying processes has improved this age-old preservation technique. A perusal of various drying practices followed and the advantages cum utilisation pattern of various driers are discussed in the paper.

Potential emissions reductions from the use of dual-combined heat and power systems in different climate conditions

Abstract: In this paper, the potential carbon dioxide emissions (CDE) reduction from the use of a combined heat and power system with two power generation units (D-CHP) is examined for a restaurant building in nine different climate conditions. The performance of the D-CHP system is evaluated on the basis of CDE and operational cost savings. In addition, the results from the D-CHP optimised scheme are compared with the optimised results of a base-loaded CHP (BL-CHP) system and a CHP system operated following the electric load (CHP-FEL). Results show that the D-CHP system produces greater savings over BL-CHP and CHP-FEL for most of the locations examined, whether optimised based on CDE or based on cost. Moreover, the effect of the emissions and cost spark spreads for each location on the D-CHP system performance is analysed. Results indicate that higher spark spreads are shown to yield greater savings for all CHP configurations.

Experimental investigation of performance and emission characteristics of non-preheated and preheated Karanja oil blend as alternate fuel in the compression-ignition engine

Abstract: In this investigation experimental work had been carried out to analyse the performance and emission characteristics of a single cylinder compression-ignition engine fuelled with diesel and diesel–karanja blend. Diesel–karanja blend was tested with non-preheated and preheated conditions. The effect of temperature on the diesel–karanja blend was also studied in this investigation. The blends, such as non-preheated blend and preheated blend showed specific fuel consumption values which were slightly higher than the diesel operation. The non-preheated blend and preheated blend gave lesser brake thermal efficiency when compared with the diesel operation. The preheated blend gave higher exhaust gas temperature at all loads when compared to diesel operation. Hydrocarbon emission and nitric-oxides emission decreased for both non-preheated blend and preheated blend at all loads when compared with the diesel operation. Carbon-monoxide values increased for both non-preheated blend and preheated blend at all loads w...

Dependence of electrical and structural properties on the thickness of n-type μc-Si thin-film silicon solar cells grown by linear facing target sputtering

Abstract: In this work, the construction of an (Al+Ag)/n+-Si/p-Si/Al thin-film silicon (TF-Si) solar cell is presented. The maximum achievable current density generated by a planar solar cell, with an optimum antireflection coating, for different values of the cell thickness are analysed. Both electrical and optical properties of (Al+Ag)/n+-Si/p-Si/Al TF-Si solar cell have been studied, which assumes the generation of one electron–hole pair per photon and a collection efficiency of unity. A reduction in thickness can lead to an increase in VOC, it can have the opposite effect if surface recombination is not reduced simultaneously. Thin-film solar cell has an absorbed photon flux density about three times higher at each interface, implying that carrier generation at the interfaces of the thinner cell is about three times higher. Finally, for larger grain size, the recombination at the grain boundaries (GBs) of Si will mainly degrade VOC, and not JSC. From the obtained results, it is evident that the larger the grain...

Design and simulation of type II fuzzy logic controller for capturing maximum wind energy

Abstract: The main purpose of this paper is to capture the maximum output power of the wind turbine under various environmental conditions. To achieve this goal, the wind turbine model has been studied and analysed under both low-wind and high-wind circumstances and due to the noisy behaviour of the wind, type II fuzzy logic controller is used for this purpose. Simulations with MATLAB show that type II fuzzy logic controller has better performance than type I.

New energy – new grid

Abstract: The existing energy systems in most industrialised countries are based on a few large centralised power plants delivering electricity to a host of consumers via transmission grids and local distribution networks, with the power plants mostly run as baseload, always on, topped up when needed by fast start-up plants or spinning reserves to meet peak loads and/or supply shortfalls. As the editorial in IJAE Vol. 34 Issue 4 noted, this system is being adjusted to try to accommodate the variable inputs from renewables like wind and solar photovoltaic (PV), with demand management and smart grids seen as new possibilities. In fact what we may see is a shift away from the old model, to one in which large inflexible baseload plants are seen as a problem for grid management and stability, not a solution. In the new system, variable inputs from a range of mostly smaller decentralised renewable energy plants will be balanced by a mixture of backup from plants using stored gas (increasingly green gas rather than fossil gas), electricity storage (e.g. via pumped hydro), energy demand management (delaying demand peaks) and electricity import/export exchanges between regions and countries, using long-distance high voltage direct current (HVDC) supergrid interconnectors. A balancing role can also be played by combined heat and power plants linked to district heating networks and large heat stores (Elliott 2013). Some say this new approach will add excessive costs. However, several studies have now suggested that, when the savings from not having to buy increasingly expensive fossil fuel are included, this may not be the case. For example, the US National Renewable Energy Lab says that wind and solar power generation will be cost competitive with fossil fuels without recourse to federal subsidies by 2025, with solar power costs in western US states falling by 35%, wind by 19%. Even when transmission and integration costs are taken into account, solar and wind could compete with new natural gas fired power plants on cost (NREL 2013a). Moreover, even for large contributions from renewables, up to 35%, NREL’s study of wind and solar grid impacts in the Western USA says operating costs due to the extra cycling needed for backup plants only increase ‘by 2–5% on average for fossil fueled plants’ (NREL 2013b). Some argue that, as the renewable contribution increase even further, these balancing costs will rise disproportionately. That rather depends on how the system is structured and operated. Although there are advantages in local energy storage, it is expensive, and, for balancing, long-distance transmission exchanges may be cheaper, and can reduce the need for backup plants just as effectively. If there is a large wind and solar capacity, occasionally producing surplus electricity in some locations, some of this excess can be sold, via supergrid links, to areas where there is a temporary shortfall, earning valuable income. A paper from Aarhus University in Denmark assess the residual load and excess power generation of 30 European countries, with a 100% penetration of variable renewable energy sources, so as to quantify the benefit of power transmission between countries. They model hourly mismatches between demand and renewable generation from wind and solar PV. For separated countries, they found that balancing, e.g. via backup plants, is required to cover around 24% of the total annual electricity consumption, but only15% of all countries are networked together with unconstrained interconnectors. That would require expanding interconnection link capacity over 11 times. But even it could only be doubled, the balancing requirement would still only be 18% (Rodriguez et al. 2014). It would seem that, although there will be problems with balancing large renewable inputs, they should not be too severe and can be dealt with at reasonable cost, using a range of techniques to make the system more flexible.