The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform

Jincan Chen - One of the best experts on this subject based on the ideXlab platform.

  • Influence of multi-irreversibilities on the performance of a Brayton refrigeration cycle working with an ideal Bose or Fermi gas
    International Journal of Thermal Sciences, 2008
    Co-Authors: Weiqiang Hu, Jincan Chen
    Abstract:

    An irreversible cycle model of the quantum Brayton refrigeration cycle using an ideal Bose or Fermi gas as the working substance is established. Based on the theory of statistical mechanics and thermodynamic properties of ideal quantum gases, expressions for several important performance parameters such as the Cooling Rate, coefficient of performance and power input, are derived. The influence of the degeneracy of quantum gases, the internal irreversibility of the working substance and the finite-Rate heat transfer between the working substance and the heat reservoirs on the optimal performance of the cycle is investigated. By using numerical solutions, the Cooling Rate of the cycle is optimized for a set of given parameters. The Maximum Cooling Rate and the corresponding parameters are calculated numerically. The optimal boundaries of the coefficient of performance and power input are given. The optimally operating region of the cycle is determined. The expressions of some performance parameters for some special cases are derived analytically.

  • Parametric optimum analysis of an irreversible Ericsson cryogenic refrigeration cycle working with an ideal Fermi gas
    Pramana, 2008
    Co-Authors: Yingru Zhao, Jincan Chen
    Abstract:

    An irreversible model of an Ericsson cryogenic refrigeration cycle working with an ideal Fermi gas is established, which is composed of two isothermal and two isobaric processes. The influence of both the quantum degeneracy and the finite-Rate heat transfer between the working fluid and the heat reservoirs on the performance of the cycle is investigated, based on the theory of statistical mechanics and thermodynamic properties of an ideal Fermi gas. The inherent regeneration losses of the cycle are analyzed. Expressions for several important performance parameters such as the coefficient of performance, Cooling Rate and power input are derived. By using numerical solutions, the Cooling Rate of the cycle is optimized for a given power input. The Maximum Cooling Rate and the corresponding parameters are calculated numerically. The optimal regions of the coefficient of performance and power input are determined. Especially, the optimal performance of the cycle in the strong and weak gas degeneracy cases and the high temperature limit is discussed in detail. The analytic expressions of some optimized parameters are derived. Some optimum criteria are given. The distinctions and connections between the Ericsson refrigeration cycles working with the Fermi and classical gases are revealed.

  • Optimum performance analysis of an irreversible quantum cryogenic refrigeration cycle working with an ideal Bose or Fermi gas
    Physica Scripta, 2008
    Co-Authors: Jincan Chen
    Abstract:

    An irreversible model of the Carnot cryogenic refrigeration cycle working with an ideal Bose or Fermi gas is established, which is composed of two irreversible adiabatic and two isothermal processes. The effects of the quantum degeneracy of the working substance, the irreversibility of the finite-Rate heat transfer between the working fluid and the heat reservoirs, and the internal irreversibility in two adiabatic processes on the optimum performance characteristics of the quantum refrigeration cycle are analyzed. The performance characteristics of the cycle in strong and weak gas degeneracy cases are discussed. Expressions for several important performance parameters such as the coefficient of performance, Cooling Rate and power input are derived. By using numerical solutions, the Cooling Rate of the cycle is optimized for a given power input. The Maximum Cooling Rate and the corresponding parameters are calculated numerically. The optimal regions of the coefficient of performance and power input are determined. Some optimum criteria are given.

  • Optimal analysis on the performance of an irreversible harmonic quantum Brayton refrigeration cycle.
    Physical Review E, 2003
    Co-Authors: Jincan Chen
    Abstract:

    : An irreversible model of a quantum refrigeration cycle working with many noninteracting harmonic oscillators is established. The refrigeration cycle consists of two adiabatic and two constant-frequency processes. The general performance characteristics of the cycle are investigated, based on the quantum master equation and the semigroup approach. The expressions for several important performance parameters such as the coefficient of performance, Cooling Rate, power input, and Rate of entropy production are derived. By using numerical solutions, the Cooling Rate of the refrigeration cycle subject to finite cycle duration is optimized. The Maximum Cooling Rate and the corresponding parameters are calculated numerically. The optimal region of the coefficient of performance and the optimal ranges of temperatures of the working substance and times spent on the two constant-frequency processes are determined. Moreover, the optimal performance of the cycle in the high-temperature limit is compared with that of a classical Brayton refrigerator working with an ideal gas. The results obtained here show that in the high-temperature limit a harmonic quantum Brayton cycle may be equivalent to a classical Brayton cycle.

  • Optimization on the Performance Characteristics of a Magnetic Ericsson Refrigeration Cycle Affected by Multi-Irreversibilities
    Journal of Energy Resources Technology-transactions of The Asme, 2003
    Co-Authors: Jizhou He, Jincan Chen, C. Wu
    Abstract:

    A general irreversible cycle model of a magnetic Ericsson refrigerator is established. The irreversibilities in the cycle model result from the finite-Rate heat transfer between the working substance and the external heat reservoirs, the inherent regenerative loss, the additional regenerative loss due to thermal resistances, and the heat leak loss between the external heat reservoirs. The cycle model is used to optimize the performance of the magnetic Ericsson refrigeration cycle. The fundamental optimum relation between the Cooling Rate and the coefficient of performance of the cycle is derived. The Maximum coefficient of performance, Maximum Cooling Rate and other relevant important parameters are calculated. The optimal operating region of the cycle is determined. The results obtained here are very general and will be helpful for the optimal design and operation of the magnetic Ericsson refrigerators.

Sudipto Chakraborty - One of the best experts on this subject based on the ideXlab platform.

  • Application of binary mixed surfactant additives in jet impingement Cooling of a hot steel plate
    Heat and Mass Transfer, 2019
    Co-Authors: Ishita Sarkar, Jay M. Jha, V. Priyanka, Surjya K. Pal, Sudipto Chakraborty
    Abstract:

    The current research aims at investigating role of three different types of surfactants and their binary mixtures in producing high Cooling Rate during jet impingement on a hot steel plate (100 mm × 100 mm × 6 mm) having initial surface temperature above 900 °C. The surfactants used are Sodium dodecyl sulphate (anionic), cetyltrimethylammonium bromide (cationic) and Polysorbate 20 (Tween 20, non-ionic). The surface tension values of the surfactants and their mixed systems have been measured and it has been observed that the binary mixtures at specific compositions show lower surface tension compared to the pure ones mainly due to synergism. The Cooling results reveal that the mixture of cationic and non-ionic surfactants produces the highest Cooling Rate amongst all the systems. The Maximum Cooling Rate achieved is 182 °C/s for the composition of 25 vol% CTAB and 75 vol% Tween 20 and it is 67% more than that of pure water, 23% more compared to pure CTAB and and 7.7% more than that of pure Tween 20. Thus it can be seen that ultrafast Cooling of a 6 mm thick steel plate can be achieved by using optimized concentrations of mixed surfactant additives and this leads to improvement of quality of steel produced.

  • Ultrafast Cooling of a hot steel plate using Cu-Al layered double hydroxide nanofluid jet
    International Journal of Thermal Sciences, 2017
    Co-Authors: Ishita Sarkar, Samarshi Chakraborty, Sudipto Chakraborty
    Abstract:

    The current work contains a detailed experimental investigation on the alteration of heat transfer characteristics during jet impingement Cooling of a hot steel plate using Copper-Aluminium layered double hydroxide (Cu-Al LDH) nanoparticle as an additive. The experiments have been performed on steel plate having initial surface temperature well above the Leidenfrost point. A new breed of nanoparticle named Cu-Al LDH has been prepared via co-precipitation method and the effect of its concentrations on surface tension, thermal conductivity and viscosity have been studied. The results show that the Cooling Rate increases with the increasing concentration of nanoparticle in coolant upto an optimum level beyond which it declines. A Maximum Cooling Rate of 154 °C/s has been achieved at a nanoparticle concentration of 120 ppm which is 41% higher than that obtained with pure water. The study reveals that ultrafast Cooling Rate can be achieved by Cu-Al LDH nanofluid jet which is essential for the production of high strength steel for various industrial applications.

  • Effect of polymer additive on the Cooling Rate of a hot steel plate by using water jet
    Experimental Thermal and Fluid Science, 2015
    Co-Authors: Ishita Sarkar, Dinesh K. Behera, Sudipto Chakraborty
    Abstract:

    Abstract The current research focuses on the enhancement of heat transfer of a hot steel plate by introducing polymer additive, polyvinylpyrrolidone (PVP) in jet Cooling. The characterization of PVP solution has been done in order to understand the reason for increment in heat transfer. The concentration of PVP has been varied at levels ranging from 50 to 150 ppm along with the variation of flow Rate from 13.3 × 10 −5 to 33.33 × 10 −5  m 3 /s (8 to 20 lpm). The results indicate that the addition of PVP in water jet leads to an appreciable increase in Cooling Rate and surface heat flux compared to that of water which leads to lesser coolant consumption. A PVP concentration of 110 ppm in water is found to provide a Maximum Cooling Rate of 231 °C/s and a Maximum critical heat flux of 3.01 MW/m 2 which are higher than that of water by 111.18% and 19% respectively.

  • Ultra fast Cooling of a hot steel plate by using high mass flux air atomized spray
    Steel Research International, 2013
    Co-Authors: Soumya S. Mohapatra, Satya V. Ravikumar, Surjya K. Pal, Sudipto Chakraborty
    Abstract:

    In the current research, the ultra fast Cooling (UFC) of a hot stationary AISI-304 steel plate has been investigated by using air atomized spray at different air and water flow Rates. The initial temperature of the plate, before the Cooling starts, is kept at 900°C or above. The spray was produced from a full cone internal mixing air atomized spray nozzle at a fixed nozzle to plate distance; and the average spray mass flux was varied from 130 to 370 kg m -2 s by selecting different combinations of air and water flow Rates. The surface heat flux and surface temperature calculations have been performed by using INTEMP software and the calculated results have been validated by comparing with the measured thermocouple data. The heat transfer analysis indicates that the Cooling occurs in the transition boiling regime up to surface temperature of 500°C and thereafter it changes to nucleate boiling regime. The superposed flow of air on the hot plate enhances the Cooling in the temperature range of 900-500°C by sweeping the partially evapoRated droplets from the hot surface. However, due to the high percentage of fine water droplets in the resultant spray produced at higher air flow Rates, the Maximum Cooling Rate is achieved at the medium air flow Rate of 30 N m3 h-1. The Cooling Rate (182°C s-1) produced by an air atomized spray is found to be in the UFC regime of a 6 mm thick steel plate. The findings of this research can be considered as the basis for the fabrication of Cooling system in the run-out table of a hot strip mill. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

C. Wu - One of the best experts on this subject based on the ideXlab platform.

  • Optimization on the Performance Characteristics of a Magnetic Ericsson Refrigeration Cycle Affected by Multi-Irreversibilities
    Journal of Energy Resources Technology-transactions of The Asme, 2003
    Co-Authors: Jizhou He, Jincan Chen, C. Wu
    Abstract:

    A general irreversible cycle model of a magnetic Ericsson refrigerator is established. The irreversibilities in the cycle model result from the finite-Rate heat transfer between the working substance and the external heat reservoirs, the inherent regenerative loss, the additional regenerative loss due to thermal resistances, and the heat leak loss between the external heat reservoirs. The cycle model is used to optimize the performance of the magnetic Ericsson refrigeration cycle. The fundamental optimum relation between the Cooling Rate and the coefficient of performance of the cycle is derived. The Maximum coefficient of performance, Maximum Cooling Rate and other relevant important parameters are calculated. The optimal operating region of the cycle is determined. The results obtained here are very general and will be helpful for the optimal design and operation of the magnetic Ericsson refrigerators.

  • Optimization of submarine thermoelectric coolers incorporating finite-time thermodynamics
    International Journal of Power and Energy Systems, 1995
    Co-Authors: M. Brahan, C. Wu
    Abstract:

    Increasing attention has been paid to the research and development of thermoelectric coolers in recent years. Many of the advantages of thermoelectric coolers are only now being discovered. This paper examines from a theoretical standpoint the characteristics of thermoelectric coolers when applied to finite-time thermodynamics. In addition to the thermoelectric cooler, heat exchangers are added which connect it to a source and a sink. Using this setup, three methods of optimization are examined : Maximum coefficient of performance, Maximum Cooling Rate, and Maximum temperature difference.

Nima Shamsaei - One of the best experts on this subject based on the ideXlab platform.

  • Laser powder bed fusion of Ti-6Al-4V parts: Thermal modeling and mechanical implications
    International Journal of Machine Tools and Manufacture, 2017
    Co-Authors: Mohammad Masoomi, Scott M. Thompson, Nima Shamsaei
    Abstract:

    A continuum-scale modeling approach is developed and employed with three-dimensional finite element analysis (FEA), for simulating the temperature response of a Ti-6Al-4V, two-layered parallelepiped with dimensions of 10×5×0.06 mm3during Laser Powder Bed Fusion (L-PBF), a metals additive manufacturing (AM) method. The model has been validated using experimental melt pool measurements from the literature and also accounts for latent heat of fusion and effective, temperature-dependent transport properties. The discretized temperature, temperature time Rate of change (i.e. Cooling Rate) and temperature gradient are investigated for various scan stRategies and number of lasers, i.e. 1, 2 or 4. The thermal response inherent to multi-laser PBF (ML-PBF) is investigated. The number of sub-regional areas of the powder bed dedicated to individual lasers, or ‘islands’, was varied. The average, Maximum Cooling Rate and temperature gradient per layer, as well as the spatial standard deviation, or uniformity, of such metrics, are presented and their implications on microstructure characteristics and mechanical traits of Ti-6Al-4V are discussed. Results demonstRate that increasing the number of lasers will reduce production times, as well as local Cooling Rates and residual stress magnitudes; however, the anisotropy of the residual stress field and microstructure may increase based on the scan stRategy employed. In general, scan stRategies that employ reduced track lengths oriented parallel to the part's shortest edge, with islands ‘stacked’ in a unit-row, proved to be most beneficial for L-PBF.

Li Zhong-jian - One of the best experts on this subject based on the ideXlab platform.