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N.v. Ogueke - One of the best experts on this subject based on the ideXlab platform.

  • Design improvements for a Collector/generator/adsorber of a solid adsorption solar refrigerator
    Renewable Energy, 2008
    Co-Authors: N.v. Ogueke, Emmanuel E. Anyanwu
    Abstract:

    A study of the effects of different Collector design parameters on the performances of a solar powered solid adsorption refrigerator is presented. The refrigerator uses activated carbon/methanol as the adsorbent/refrigerant pair. The study was undertaken using a computer simulation program developed from a transient analysis of the system. The parameters tested are the Collector Plate emissivity/absorptivity combination, adsorbent packing density, tube spacing, outer tube outside diameter, adsorbent thermal conductivity, heat transfer coefficient at adsorbent/tube interface, and adsorbent tube/Collector Plate materials combination. Two performance indicators namely, condensate yield and coefficient of performance (COP) were used in the study as figures of merit. A multiple regression technique was used to correlate the performance indicators with the Collector parameters through a quadratic relation. Consequently an objective function, suitable for selecting optimal values of the parameters is defined, subject to specified constraints. Selecting the COP as the preferred indicator parameter, optimization was then carried out. Improvements in the ranges of 29–38% for COP and 26–35% for condensate yield were obtained with optimal choices of tube spacing, adsorbent packing density and Collector Plate/adsorbent tube material combinations.

  • Transient analysis and performance prediction of a solid adsorption solar refrigerator
    Applied Thermal Engineering, 2007
    Co-Authors: Emmanuel E. Anyanwu, N.v. Ogueke
    Abstract:

    The transient analysis and performance prediction of a solid adsorption solar refrigerator, using activated carbon/methanol adsorbent/adsorbate pair are presented. The mathematical model is based on the thermodynamics of the adsorption process, heat transfer in the Collector Plate/tube arrangement, and heat and mass transfers within the adsorbent/adsorbate pair. Its numerical model developed from finite element transformation of the resulting equations computes the Collector Plate and tube temperatures to within 5 °C. The condensate yield and coefficient of performance, COP, were predicted to within 5% and 9%, respectively. The resulting evaporator water temperature was also predicted to within 5 °C. Thus the model is considered a useful design tool for the refrigerator to avoid costly experimentation.

  • Transient Analysis and Performance Prediction of a Solid Adsorption Solar Refrigerator
    Solar Energy, 2005
    Co-Authors: Emmanuel E. Anyanwu, N.v. Ogueke
    Abstract:

    The transient analysis and performance prediction of a solid adsorption solar refrigerator, using activated carbon/methanol adsorbent/adsorbate pair are presented. The mathematical model is based on the thermodynamics of the adsorption process, heat transfer in the Collector Plate/tube arrangement, and heat and mass transfers within the adsorbent/adsorbate pair. Its numerical model developed from finite element transformation of the resulting equations computes the Collector Plate and tube temperatures to within 5°C. The condensate yield and coefficient of performance, COP were predicted to within 5% and 9%, respectively. The resulting evaporator water temperature was also predicted to within 4%. Thus the model is considered a useful design tool for the refrigerator to avoid costly experimentation.Copyright © 2005 by ASME

Emmanuel E. Anyanwu - One of the best experts on this subject based on the ideXlab platform.

  • Design improvements for a Collector/generator/adsorber of a solid adsorption solar refrigerator
    Renewable Energy, 2008
    Co-Authors: N.v. Ogueke, Emmanuel E. Anyanwu
    Abstract:

    A study of the effects of different Collector design parameters on the performances of a solar powered solid adsorption refrigerator is presented. The refrigerator uses activated carbon/methanol as the adsorbent/refrigerant pair. The study was undertaken using a computer simulation program developed from a transient analysis of the system. The parameters tested are the Collector Plate emissivity/absorptivity combination, adsorbent packing density, tube spacing, outer tube outside diameter, adsorbent thermal conductivity, heat transfer coefficient at adsorbent/tube interface, and adsorbent tube/Collector Plate materials combination. Two performance indicators namely, condensate yield and coefficient of performance (COP) were used in the study as figures of merit. A multiple regression technique was used to correlate the performance indicators with the Collector parameters through a quadratic relation. Consequently an objective function, suitable for selecting optimal values of the parameters is defined, subject to specified constraints. Selecting the COP as the preferred indicator parameter, optimization was then carried out. Improvements in the ranges of 29–38% for COP and 26–35% for condensate yield were obtained with optimal choices of tube spacing, adsorbent packing density and Collector Plate/adsorbent tube material combinations.

  • Transient analysis and performance prediction of a solid adsorption solar refrigerator
    Applied Thermal Engineering, 2007
    Co-Authors: Emmanuel E. Anyanwu, N.v. Ogueke
    Abstract:

    The transient analysis and performance prediction of a solid adsorption solar refrigerator, using activated carbon/methanol adsorbent/adsorbate pair are presented. The mathematical model is based on the thermodynamics of the adsorption process, heat transfer in the Collector Plate/tube arrangement, and heat and mass transfers within the adsorbent/adsorbate pair. Its numerical model developed from finite element transformation of the resulting equations computes the Collector Plate and tube temperatures to within 5 °C. The condensate yield and coefficient of performance, COP, were predicted to within 5% and 9%, respectively. The resulting evaporator water temperature was also predicted to within 5 °C. Thus the model is considered a useful design tool for the refrigerator to avoid costly experimentation.

  • Transient Analysis and Performance Prediction of a Solid Adsorption Solar Refrigerator
    Solar Energy, 2005
    Co-Authors: Emmanuel E. Anyanwu, N.v. Ogueke
    Abstract:

    The transient analysis and performance prediction of a solid adsorption solar refrigerator, using activated carbon/methanol adsorbent/adsorbate pair are presented. The mathematical model is based on the thermodynamics of the adsorption process, heat transfer in the Collector Plate/tube arrangement, and heat and mass transfers within the adsorbent/adsorbate pair. Its numerical model developed from finite element transformation of the resulting equations computes the Collector Plate and tube temperatures to within 5°C. The condensate yield and coefficient of performance, COP were predicted to within 5% and 9%, respectively. The resulting evaporator water temperature was also predicted to within 4%. Thus the model is considered a useful design tool for the refrigerator to avoid costly experimentation.Copyright © 2005 by ASME

A.n. Tikekar - One of the best experts on this subject based on the ideXlab platform.

  • analysis of fluid flow and heat transfer in a rib grit roughened surface solar air heater using cfd
    Solar Energy, 2010
    Co-Authors: S.v. Karmare, A.n. Tikekar
    Abstract:

    Abstract This paper presents the study of fluid flow and heat transfer in a solar air heater by using Computational Fluid Dynamics (CFD) which reduces time and cost. Lower side of Collector Plate is made rough with metal ribs of circular, square and triangular cross-section, having 60° inclinations to the air flow. The grit rib elements are fixed on the surface in staggered manner to form defined grid. The system and operating parameters studied are: e / D h  = 0.044, p / e  = 17.5 and l / s  = 1.72, for the Reynolds number range 3600–17,000. To validate CFD results, experimental investigations were carried out in the laboratory. It is found that experimental and CFD analysis results give the good agreement. The optimization of rib geometry and its angle of attack is also done. The square cross-section ribs with 58° angle of attack give maximum heat transfer. The percentage enhancement in the heat transfer for square Plate over smooth surface is 30%.

  • Experimental investigation of optimum thermohydraulic performance of solar air heaters with metal rib grits roughness
    Solar Energy, 2009
    Co-Authors: S.v. Karmare, A.n. Tikekar
    Abstract:

    Abstract Artificial roughness has been found to enhance the heat transfer from the Collector Plate to the air in a solar air heater. However, it would result in increase in frictional losses and hence, power required by fan or blower. This paper presents the results of an experimental investigation of thermohydraulic performance of roughened solar air heaters with metal rib grits. The range of variation of system and operating parameters is investigated within the limits of, e/Dh: 0.035–0.044, p/e: 15–17.5 and l/s as 1.72, against variation of Reynolds number, Re: 3600–17000. The study shows substantial enhancement in thermal efficiency (10–35%), over solar air heater with smooth Collector Plate. The thermal efficiency enhancement is also accompanied by a considerable increase in the pumping power requirement due to the increase in the friction factor (80–250%). The optimum design and operating conditions have been determined on the basis of thermohydraulic considerations. It has been found that, the systems operating in a specified range of Reynolds number show better thermohydraulic performance depending upon the insolation. A relationship between the system and operating parameters that combine to yield optimum performance has been developed.

  • 2 Experimental investigation of optimum thermohydraulic performance
    2008
    Co-Authors: S.v. Karmare, A.n. Tikekar
    Abstract:

    10 Abstract 11 Artificial roughness has been found to enhance the heat transfer from the Collector Plate to the air in a solar air heater. However, it 12 would result in increase in frictional losses and hence, power required by fan or blower. This paper presents the results of an experimental 13 investigation of thermohydraulic performance of roughened solar air heaters with metal rib grits. The range of variation of system and 14 operating parameters is investigated within the limits of, e/Dh: 0.035-0.044, p/e: 15-17.5 and l/s as 1.72, against variation of Reynolds 15 number, Re: 3600-17000. The study shows substantial enhancement in thermal efficiency (10-35%), over solar air heater with smooth 16 Collector Plate. The thermal efficiency enhancement is also accompanied by a considerable increase in the pumping power requirement 17 due to the increase in the friction factor (80-250%). The optimum design and operating conditions have been determined on the basis of 18 thermohydraulic considerations. It has been found that, the systems operating in a specified range of Reynolds number show better ther- 19 mohydraulic performance depending upon the insolation. A relationship between the system and operating parameters that combine to 20 yield optimum performance has been developed. 21 2008 Published by Elsevier Ltd. 22 Keywords: Heat transfer; Roughness; Metal rib grit; Turbulent; Solar air heater 23

S.v. Karmare - One of the best experts on this subject based on the ideXlab platform.

  • analysis of fluid flow and heat transfer in a rib grit roughened surface solar air heater using cfd
    Solar Energy, 2010
    Co-Authors: S.v. Karmare, A.n. Tikekar
    Abstract:

    Abstract This paper presents the study of fluid flow and heat transfer in a solar air heater by using Computational Fluid Dynamics (CFD) which reduces time and cost. Lower side of Collector Plate is made rough with metal ribs of circular, square and triangular cross-section, having 60° inclinations to the air flow. The grit rib elements are fixed on the surface in staggered manner to form defined grid. The system and operating parameters studied are: e / D h  = 0.044, p / e  = 17.5 and l / s  = 1.72, for the Reynolds number range 3600–17,000. To validate CFD results, experimental investigations were carried out in the laboratory. It is found that experimental and CFD analysis results give the good agreement. The optimization of rib geometry and its angle of attack is also done. The square cross-section ribs with 58° angle of attack give maximum heat transfer. The percentage enhancement in the heat transfer for square Plate over smooth surface is 30%.

  • Experimental investigation of optimum thermohydraulic performance of solar air heaters with metal rib grits roughness
    Solar Energy, 2009
    Co-Authors: S.v. Karmare, A.n. Tikekar
    Abstract:

    Abstract Artificial roughness has been found to enhance the heat transfer from the Collector Plate to the air in a solar air heater. However, it would result in increase in frictional losses and hence, power required by fan or blower. This paper presents the results of an experimental investigation of thermohydraulic performance of roughened solar air heaters with metal rib grits. The range of variation of system and operating parameters is investigated within the limits of, e/Dh: 0.035–0.044, p/e: 15–17.5 and l/s as 1.72, against variation of Reynolds number, Re: 3600–17000. The study shows substantial enhancement in thermal efficiency (10–35%), over solar air heater with smooth Collector Plate. The thermal efficiency enhancement is also accompanied by a considerable increase in the pumping power requirement due to the increase in the friction factor (80–250%). The optimum design and operating conditions have been determined on the basis of thermohydraulic considerations. It has been found that, the systems operating in a specified range of Reynolds number show better thermohydraulic performance depending upon the insolation. A relationship between the system and operating parameters that combine to yield optimum performance has been developed.

  • 2 Experimental investigation of optimum thermohydraulic performance
    2008
    Co-Authors: S.v. Karmare, A.n. Tikekar
    Abstract:

    10 Abstract 11 Artificial roughness has been found to enhance the heat transfer from the Collector Plate to the air in a solar air heater. However, it 12 would result in increase in frictional losses and hence, power required by fan or blower. This paper presents the results of an experimental 13 investigation of thermohydraulic performance of roughened solar air heaters with metal rib grits. The range of variation of system and 14 operating parameters is investigated within the limits of, e/Dh: 0.035-0.044, p/e: 15-17.5 and l/s as 1.72, against variation of Reynolds 15 number, Re: 3600-17000. The study shows substantial enhancement in thermal efficiency (10-35%), over solar air heater with smooth 16 Collector Plate. The thermal efficiency enhancement is also accompanied by a considerable increase in the pumping power requirement 17 due to the increase in the friction factor (80-250%). The optimum design and operating conditions have been determined on the basis of 18 thermohydraulic considerations. It has been found that, the systems operating in a specified range of Reynolds number show better ther- 19 mohydraulic performance depending upon the insolation. A relationship between the system and operating parameters that combine to 20 yield optimum performance has been developed. 21 2008 Published by Elsevier Ltd. 22 Keywords: Heat transfer; Roughness; Metal rib grit; Turbulent; Solar air heater 23

Akihiro Yabuki - One of the best experts on this subject based on the ideXlab platform.

  • One-Step Fabrication of Short Nanofibers by Electrospinning: Effect of Needle Size on Nanofiber Length
    Advanced Materials Research, 2014
    Co-Authors: Indra Wahyudhin Fathona, Khairurrijal, Akihiro Yabuki
    Abstract:

    The effect of needle size on the fiber length was studied and investigated. A polymer solution of cellulose acetate (CA) and organic solvent was ejected from various sizes of needle gauge then the electrospun polymer fibers were adhered on a Collector Plate. The diameter of fibers was ranging from 80 to 570 nm and the length could be controlled from 10 to 240 µm by increasing the needle size. The breakaway to shortened nanofibers occurred due to the imbalance of force from the surface tension of the polymer solution and the longitudinal force of the applied voltage.

  • One-step fabrication of short electrospun fibers using an electric spark
    Journal of Materials Processing Technology, 2013
    Co-Authors: Indra Wahyudhin Fathona, Akihiro Yabuki
    Abstract:

    Abstract The one-step fabrication process that was developed in this study used an electric spark to produce short electrospun fibers. For this process, a polymer solution of cellulose acetate and organic solvent was ejected from a syringe needle then the electrospun polymer fiber was adhered to a Collector Plate after it passed through the gap between the tips of two electrodes that generated an electric spark. Short fibers were recognized on the Collector Plate, although continuous fibers were also observed. The dimensions for the mean lengths and diameters of the prepared short fibers were 230 μm and 1 μm, respectively. The electrospun fiber was stretched by the electric field, and then the thermal energy of the electric spark burned and truncated the short fibers.