Melting heat transfer analysis on magnetohydrodynamics buoyancy convection in an enclosure : a numerical study

Therollof melting heat transfer on magnetohydrodynamic natural convection in a square enclosurewithheatingof the bottom wall is examinednumericallyin this article.The dimensionlessgoverning partial differential equations are transformed into vorticity and stream functionformulationand then solved using the finite difference method(FDM). The effects of thermal Rayleigh number(Ra), melting parameter(M) and Hartmann number(Ha) are illustrated graphically.With an increasing melting parameter and Rayleigh number, the rate of fluid flow and temperature gradients are seen to increase. And in the presence of magnetic field, the temperature gradient reduces and hence the conductionmechanism dominated for larger Ha. Greater heat transfer rate is observed in the case of uniform heating compared with non-uniform case. The average Nusselt number reduces with increasing magnetic parameterin the both cases of heating of bottom wall

Effects of ramped wall temperature and concentration on viscoelastic Jeffrey’s fluid flows from a vertical permeable cone

In thermo-fluid dynamics, free convection flows external to different geometries such as cylinders, ellipses, spheres, curved walls, wavy plates, cones etc. play major role in various industrial and process engineering systems. The thermal buoyancy force associated with natural convection flows can exert a critical role in determining skin friction and heat transfer rates at the boundary. In thermal engineering, natural convection flows from cones has gained exceptional interest. A theoretical analysis is developed to investigate the nonlinear, steady-state, laminar, non-isothermal convection boundary layer flows of viscoelastic fluid from a vertical permeable cone with a power-law variation in both temperature and concentration. The Jeffery’s viscoelastic model simulates the non-Newtonian characteristics of polymers, which constitutes the novelty of the present work. The transformed conservation equations for linear momentum, energy and concentration are solved numerically under physically viable boundary conditions using the finite-differences Keller-Box scheme. The impact of Deborah number (De), ratio of relaxation to retardation time (λ), surface suction/injection parameter (fw), power-law exponent (n), buoyancy ratio parameter (N) and dimensionless tangential coordinate (Ѯ) on velocity, surface temperature, concentration, local skin friction, heat transfer rate and mass transfer rate in the boundary layer regime are presented graphically. It is observed that increasing values of De reduces velocity whereas the temperature and concentration are increased slightly. Increasing λ enhance velocity however reduces temperature and concentration slightly. The heat and mass transfer rate are found to decrease with increasing De and increase with increasing values of λ. The skin friction is found to decrease with a rise in De whereas it is elevated with increasing values of λ. Increasing values of fw and n, decelerates the flow and also cools the boundary layer i.e. reduces temperature and also concentration. The study is relevant to chemical engineering systems, solvent and polymeric processes

Radiative and magnetohydrodynamics flow of third grade viscoelastic fluid past an isothermal inverted cone in the presence of heat generation/absorption

A mathematical analysis is presented to investigate the nonlinear, isothermal, steady-state, free convection boundary layer flow of an incompressible third grade viscoelastic fluid past an isothermal inverted cone in the presence of magnetohydrodynamic, thermal radiation and heat generation/absorption. The transformed conservation equations for linear momentum, heat and mass are solved numerically subject to the realistic boundary conditions using the second-order accurate implicit finite-difference Keller Box Method. The numerical code is validated with previous studies. Detailed interpretation of the computations is included. The present simulations are of interest in chemical engineering systems and solvent and low-density polymer materials processing

EXPERIMENTAL STUDY OF HYBRID LIQUID DESICCANT BASED VAPOR COMPRESSION COOLING SYSTEM

In the kingdom of Saudi Arabia, a vast amount of energy is used for air-conditioning and this paper describes a new approach to air conditioning. In the proposed hybrid cooling system, liquid desiccant is used to remove the latent load and the conventional vapor-compression system is used to provide sensible cooling only. In this experimental study, calcium chloride solution is used as the desiccant to dehumidify the air. Gauze-type structured packing towers are used for the dehumidification of air and also for regeneration of the weak desiccant. The designed packed bed dehumidifier and the regenerator are combined with a 5-ton capacity vapor compression system along with the heat recovery units. This paper presents results from a detailed experimental investigation of the heat and mass transfer in a structured packing dehumidifier and regenerator under a variety of operating conditions. In the present study, for the sake of comparison between hybrid and conventional cooling systems, the COP for the cooling system is defined as the heat removed from the space to be cooled divided by energy input for the cooling system. Three different modes of regeneration are considered for the hybrid cooling system and the COP values are compared with conventional vapor compression system. Results show that the ratio of the outlet-to-inlet absolute humidity reaches a steady state value of about 0.6 and the temperature of air decreased from 48 to 38o C in the dehumidifier of the hybrid system. Moreover, it is found that hybrid cooling system provides higher COP compared with conventional system

Colour reduction and anti-microbial evaluation of pre-treated cashew leaves extract

Cashew leaves are used traditionally for various health promoting effects includingj wound healing and diarrhea and could be orally consumed for its effectiveness. Previous research shows that cashew leaves and its bark extracts is rich in tannin and is a potential antimicrobial agent. Extended from these properties, we selected cashew leaves extract as a candidate for potential natural preservative. The extraction method especially using ethanol or other solvent extraction will result in intense colour that will limit its application. The intense green colour of the leaves is due to chlorophyll and become a problem to end product. Various treatments could be used to reduce chlorophyll in the leaves. This study focused on the pretreatment of the cashew leaves in order to minimize the green colour intensity of the extract. Our study shows that pretreatment 3 reduced the green colour intensity significantly. Pretreatment 3: cashew leaves heated in boiling water for 1 minute, immediately cooled in ice-cold water then blotted to dry. The dried leaves then cut into small pieces and floated on the surface of 0.05 M EDTA-2Na, pH 7.0 for 24 hours exposure to the light (5000 lux). The antimicrobial activity of all the extracts was almost similar and was shown to be as effective as methylpareban at concentration as low as 2.5g (v/v). The extract could control the growth of all five main microorganisms as recommended by FDA for cosmetic and bodycare products

The Green Library Initiative in Indian perspective: A Study

Abstract Purpose - The present study was to research instances of green library construction and recognition to raise awareness of green libraries for users. The researcher has explored, this paper highlights the role of a librarian, features of the green library, and initiatives of a green library in India

Kamus konsercasi sumber daya alam : dilengkapi dengan daftar padanan kata Inggris-Indonesia

viii, 158p; 21 cm

KEHIDUPAN MASYARAKAT PULAU GEBE Studi Tentang Kondisi Masyarakat Pasca Berakhirnya Kontrak Kerja PT. Aneka Tambang di Kabupaten Halmahera Tengah

The community live of Gebe Island that experiences bad situation (after the process of mining project), constitutes a description about the failure of state and the regent of Halmahera Tengah ( central Halmahera) in providing public goods for community in Gebe island. By this problem, the writer interested in to do researching and analyzing about the condition of Gebe island people after finality of work contract in P.T. Aneka Tambang in Gebe island. In this research, the writer wish to see and enlarge the state existence and the state failure as the high institution that take responsibility to provide and serve to the people of Gebe island. One of the base question that become main reference for the writer in enlarging the problem in Gebe island is the causal factor of state failure in giving public service in that region (Gebe island) after the finality of mining process in the island, or the causal factor in presenting the existence in people lives of that island after the process of mining. By the sorts of phenomenon that happen before, and as the sorts of datum in the field research, the writer find that: one of the main thing that become the root of failure in giving public service in Gebe island is sub-ordinate process which become problem during mining process. The sub-ordinate process which happen, in writer�s opinion, constitute one of the main thing that causes state has not capability and capacity to provide public service and fall the state down into the failure. Sub-ordinate process which happens during the mining process has given direct impact to the descent of quantity and quality or capability and capacity of the regent of Halmahera Tengah in giving public service. Commonly, this descent of quantity and quality can be known clearly during the transition period of the finality of work contract in P.T. Antam, Tbk persero. When this company leaves Gebe island, it happens chaos in that island. All sorts of public service such as: education, health, electricity, and watering become left unfinished and sorts of infrastructure had been destroyed totally. The regent government or the state has not capability to provide health service for 24 hours, no charge education, no more doctor and teacher. The government also could not provide the opportunities for the people of Gebe island, after the finality of mining process. Because of that, by the problem above, the state failure in providing public service to the Gebe island people, the writer�s conclusion that, this thing has relatedness with subordinate process which happen during the mining process go on. The state�s incapability in giving public service constitute a concrete description about the impact of the subordinate process of state�s role, that cause descent of capacity and capability of the regent government to serve to the people of Gebe island

MHD free convection flow of Eyring–Powell fluid from vertical surface in porous media with Hall/ionslip currents and ohmic dissipation

A mathematical study is presented to analyze the nonlinear, non-isothermal, magnetohydrodynamic (MHD) free convection boundary layer flow, heat and mass transfer of non-Newtonian Eyring–Powell fluid from a vertical surface in a non-Darcy, isotropic, homogenous porous medium, in the presence of Hall currents and ionslip currents. The governing nonlinear coupled partial differential equations for momentum conservation in the x, and z directions, heat and mass conservation, in the flow regime are transformed from an (x, y, z) coordinate system to a (ξ, η) coordinate system in terms of dimensionless x-direction velocity (f′) and z-direction velocity (G), dimensionless temperature and concentration functions (θ and ϕ) under appropriate boundary conditions. Both Darcian and Forchheimer porous impedances are incorporated in both momentum equations. Computations are also provided for the variation of the x and z direction shear stress components and also heat and mass transfer rates. It is observed that with increasing ɛ, primary velocity, secondary velocity, heat and mass transfer rates are decreased whereas, the temperature, concentration and skin friction are increased. An increasing δ is found to increase primary and secondary velocities, skin friction, heat and mass transfer rates. But the temperature and concentration decrease. Increasing βe and βi are seen to increase primary velocity, skin friction, heat and mass transfer rates whereas secondary velocity, temperature and concentration are decreased. Excellent correlation is achieved with a Nakamura tridiagonal finite difference scheme (NTM). The model finds applications in magnetic materials processing, MHD power generators and purification of crude oils