PERFORMANCE OF SOLAR PHOTOVOLTAIC MODULE THROUGH COMBINED AIR AND WATER COOLING IN WARM AND HUMID CLIMATIC CONDITION OF INDIA

A study was conducted to evaluate the performance of solar photovoltaic module through combined air and water cooling arrangements in warm and humid climatic condition i.e. in Odisha in India during winter and summer months. Solar photovoltaic system requires neither fuel nor produces any pollutant resulting into its increased importance in today’s energy sector. The electrical output from a solar panel is a function of its efficiency and some other controlling parameters which affects the same. One of the major parameters controlling the efficiency of the panel is the temperature as it goes on increasing while using the panel in the sun. About 31 % of the incident solar radiation on the panel is converted into the useful energy and the rest part is stored in its back side causing the rise of temperature and adversely affecting its output. The stored thermal energy is of no use and decreases the durability of the in-built components of the panel due to the impact of severe thermal stresses on them resulting into reduction in its life span and conversion capability. The simplest way to enhance the efficiency of the panel is to incorporate the various cooling arrangements such as air cooling, water cooling and combined air and water cooling and assessing their effectiveness without any cooling arrangement. From the studies, it was observed that the efficiencies of solar panel were enhanced in the range of 8-11 %, 12-15% and 16-20% in air, water and combined air and water cooling respectively compared to without cooling in a clear day

Performance Study of Diesel Engine by using Mahua Methyl Ester (biodiesel) and its Blends with Diesel Fuel

The results of the performance of a compression ignition engine (direct injected, 4-stroke 2-cylinder engine) by using mahua methyl ester from non-edible vegetable oil (Madhuca indica) and its blends with diesel fuel have been presented in this paper. Short-term engine performance tests were conducted using four different blends of mahua methyl ester oil with diesel fuel from 20% to 100% by volume at three fuel temperatures (30, 50 and 700-C) and at two injection pressures (17640 kPa and 24010 kPa). The engine performance parameters studied were power output, brake specific fuel consumption (BSFC), brake thermal efficiency (BThE) and exhaust gas temperature (ExGT) by using diesel fuel alone and the above mentioned blend fuels. The performance of engine with blend fuel (20% mahua methyl ester and 80% diesel) was found to be better than the other blend fuels. But the values of power output, BSFC, BThE and ExGT in case of blend fuel B20 (20% mahua methyl ester and 80% diesel) were observed to be respectively 3% more, 9% more, 12%more and 0.5% less than the diesel fuel at 700-C temperature and 24010 kPa pressure. The mahua methyl ester (blends of B20) can be used as an alternative diesel fuel replacement with little sacrifice in brake specific fuel consumption

Uniform Water Distribution From Low Pressure Rotating Sprinklers

Population of India has probably crossed 1150 million marks by the end of 2007 (Survey of Indian Agriculture 2007). The estimated requirement of food grains by 2020 will be 307.75 million tonnes to meet the balanced diet norms prescribed by Indian Council of Medical Research. In 2007, the production of food grains was only 212.62 million tonnes. The gap of 95.13 million tonnes has to be narrowed down by adopting modern scientific approaches for efficient management of scarce land and water resources at a sustainable manner.Sprinkler irrigation is one of the modern scientific approaches which is becoming more and more popular in India in regions of water scarcity where available water is insufficient to irrigate the command area by surface irrigation. Uniformity of water distribution at four different nozzle pressures and three different spacing was studied for both plastic and brass type of sprinklers. The deviation of uniformity coefficient of plastic sprinklers from that of brass sprinklers was found to be from 0 to 2 %. It was also observed that optimum uniformity of water distribution was obtained at a nozzle pressure of 2.0 kgf/cm2 in normal windy condition. The uniformity of water distribution decreased with the increase of nozzle pressure beyond 2.0 kgf/cm2 for small and medium size nozzles.Comparison was made among different sprinklers and lateral spacing of 6.1 m x 6.1 m, 6.1 m x 12.2 m and 12.2 m x 12.2 m. It was observed that the spacing of 6.1 m x 6.1 m gives better distribution for low pressure sprinklers for all combinations of nozzle pressures and sizes. It was recommended to operate the low pressure sprinklers at a sprinkler and lateral spacing of 30 % of the spray diameter. It was also observed that the effect of wind velocity on uniformity of water distribution was less for wind velocities below 4 km/h and moderate for wind velocity below 7 km/h and the distribution pattern gets distorted at high wind velocity of 15 km/h

The Anderson prescription for surfaces and impurities

We test the Anderson prescription [1], a BCS formalism for describing superconductivity in inhomogeneous systems, and compare results with those obtained from the Bogoliubov-de Gennes formalism, using the attractive Hubbard model with surfaces and nonmagnetic impurities. The Anderson approach captures the essential features of the spatial variation of the gap parameter and electron density around a surface or an impurity over a wide range of parameters. It breaks down, however, in the strong-coupling regime for a weak impurity potential. [1] P. W. Anderson, J. Phys. Chem. Solids 11, 26 (1959).Comment: 4 pages, 4 figure

Asymmetric Squares as Standing Waves in Rayleigh-Benard Convection

Possibility of asymmetric square convection is investigated numerically using a few mode Lorenz-like model for thermal convection in Boussinesq fluids confined between two stress free and conducting flat boundaries. For relatively large value of Rayleigh number, the stationary rolls become unstable and asymmetric squares appear as standing waves at the onset of secondary instability. Asymmetric squares, two dimensional rolls and again asymmetric squares with their corners shifted by half a wavelength form a stable limit cycle.Comment: 8 pages, 7 figure

Neutrino masses, cosmological bound and four zero Yukawa textures

Four zero neutrino Yukawa textures in a specified weak basis, combined with $\mu\tau$ symmetry and type-I seesaw, yield a highly constrained and predictive scheme. Two alternately viable $3\times3$ light neutrino Majorana mass matrices $m_{\nu A}/m_{\nu B}$ result with inverted/normal mass ordering. Neutrino masses, Majorana in character and predicted within definite ranges with laboratory and cosmological inputs, will have their sum probed cosmologically. The rate for $0\nu\beta\beta$ decay, though generally below the reach of planned experiments, could approach it in some parameter region. Departure from $\mu\tau$ symmetry due to RG evolution from a high scale and consequent CP violation, with a Jarlskog invariant whose magnitude could almost reach $6\times 10^{-3}$, are explored.Comment: Published versio

A texture of neutrino mass matrix in view of recent neutrino experimental results

In view of recent neutrino experimental results such as SNO, Super-Kamiokande (SK), CHOOZ and neutrinoless double beta decay $(\beta\beta_{0\nu})$, we consider a texture of neutrino mass matrix which contains three parameters in order to explain those neutrino experimental results. We have first fitted parameters in a model independent way with solar and atmospheric neutrino mass squared differences and solar neutrino mixing angle which satisfy LMA solution. The maximal value of atmospheric neutrino mixing angle comes out naturally in the present texture. Most interestingly, fitted parameters of the neutrino mass matrix considered here also marginally satisfy recent limit on effective Majorana neutrino mass obtained from neutrinoless double beta decay experiment. We further demonstrate an explicit model which gives rise to the texture investigated by considering an $SU(2)_L\times U(1)_Y$ gauge group with two extra real scalar singlets and discrete $Z_2\times Z_3$ symmetry. Majorana neutrino masses are generated through higher dimensional operators at the scale $M$. We have estimated the scales at which singlets get VEV's and M by comparing with the best fitted results obtained in the present work.Comment: Journal Ref.: Phys. Rev. D66, 053004 (2002

Critical disorder effects in Josephson-coupled quasi-one-dimensional superconductors

Effects of non-magnetic randomness on the critical temperature T_c and diamagnetism are studied in a class of quasi-one dimensional superconductors. The energy of Josephson-coupling between wires is considered to be random, which is typical for dirty organic superconductors. We show that this randomness destroys phase coherence between the wires and T_c vanishes discontinuously when the randomness reaches a critical value. The parallel and transverse components of the penetration depth are found to diverge at different critical temperatures T_c^{(1)} and T_c, which correspond to pair-breaking and phase-coherence breaking. The interplay between disorder and quantum phase fluctuations results in quantum critical behavior at T=0, manifesting itself as a superconducting-normal metal phase transition of first-order at a critical disorder strength.Comment: 4 pages, 2 figure