Effective heat exchange method by a pair of porous radiative converters.

Tanigawa, Akira; Hanamura, Katsunori; Echigo, Ryozo; Tomimura, Toshio

doi:10.1299/kikaib.57.302

Cited by 3 publications

(2 citation statements)

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“…This procedure has been used in HT heat exchangers to enhance the performance of these equipments. 3,4 Echigo et al 5 studied the effect of gaseous radiation, which is not always small if radiant gases such as carbon dioxide or steam exist in the working fluid. Yoshida et al 6 explored the transient heat transfer characteristics of a porous media in an energy saving system, and the integral method was used to calculate the radiative heat flux.…”

Section: Introductionmentioning

confidence: 99%

Thermal analysis of a three-layered radiant porous heat exchanger including fluid flow simulation

Sajedi

Nassab

Javaran

2013

Proceedings of the Institution of Mechanical Engineers, Part C:

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Based on an effective energy conversion method between flowing gas enthalpy and thermal radiation, a three-layered type of porous heat exchanger (PHE) has been proposed. The PHE has one high temperature (HT) and two heat recovery (HR1 and HR2) sections. In HT section, the enthalpy of gas flow converts to thermal radiation and the opposite process happens in HR1 and HR2. In each section, a 2-D rectangular porous medium which is assumed to be absorbing, emitting and scattering is presented. For theoretical analysis of the PHE, the gas and solid phases are considered in non-local thermal equilibrium and separate energy equations are used for these two phases. Besides, in the gas flow simulation, the Fluent code is used to obtain the velocity distribution in the PHE from inlet to outlet section. For thermal analysis of the PHE, the coupled energy equations for gas and porous layer at each section are numerically solved using the finite difference method. In the computation of radiative heat flux distribution, the radiative transfer equation (RTE) is solved by the discrete ordinates method (DOM). The effects of scattering albedo, optical thickness, particle size of porous medium and inlet gas temperature on the efficiency of PHE are explored. Numerical results show that this type of PHE has high efficiency especially when the porous layers have high optical thickness. The present results are compared with those reported theoretically by other investigators and reasonable agreement is found.

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Section: Introductionmentioning

confidence: 99%

Thermal analysis of a three-layered radiant porous heat exchanger including fluid flow simulation

Sajedi

Nassab

Javaran

2013

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…A similar study was carried out by Gandjalikhan Nassab [4], but the computation was based on the two-flux radiation model. Based on energy conversion between gas enthalpy and thermal radiation, Tanigawa et al [5] proposed a new type of gas-to-gas heat exchanger equipped with a pair of circular porous metal plates. From their analytical and experimental results, it was found that this type of heat exchanger has much higher overall heat transfer coefficient than the conventional heat exchangers.…”

Section: Introductionmentioning

confidence: 99%

Heat transfer characteristics of a cylindrical porous radiant air heater under the influence of a two-dimensional axisymmetric radiative field

Keshtkar

Nassab

Nasr

2009

Proceedings of the Institution of Mechanical Engineers, Part A:

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This work presents the heat transfer characteristics of a new type of porous radiant air heater (PRAH) that operates on the basis of an effective energy conversion method between flowing gas enthalpy and thermal radiation. In this system, four porous layers consisting of porous radiant burner (PRB), high-temperature (HT) section, first heat recovery section, and second heat recovery section are considered. These layers are separated from each other by three quartz glass walls. The PRB generates a large amount of thermal radiative energy, which is converted into gas enthalpy in heat recovery layers. In the HT section, the gas enthalpy of the exhaust flow from PRB converts into thermal radiation. At each layer, the gas and solid phases are considered in non-local thermal equilibrium and combustion in the PRB is modelled by considering a non-uniform heat generation zone. The homogeneous porous media, in addition to its convective heat exchange with the gas, may absorb, emit, and scatter thermal radiation. In order to determine the thermal characteristics of the proposed PRAH, a two-dimensional model is used to solve the governing equations for porous medium and gas flow and the discrete ordinates method is used to obtain the distribution of radiative heat flux in the porous media. Computational results show that this type of air heater has much higher efficiency than the conventional ones. In addition, it is clarified that the high optical thickness and low scattering coefficient for porous layers improve the heater efficiency. In order to validate the applied numerical method at the present analysis, the results are compared with some reported theoretical and experimental results by other investigators and good agreement is found.for this purpose. This is due to the extremely high heat transfer coefficient and large heat transfer surface area for the gas flow through porous matrix. For the first time, Echigo [1] studied the problem of recovering energy from hot exhaust gases by placing a porous layer normal to the gas flow in exhaust ducts. In that study, the solid matrix was assumed not to scatter radiant energy. His analysis revealed that a substantial amount of gas enthalpy might be recovered to radiative energy travelling upstream from the porous segment. Wang and Tien [2] extended Echigo's analysis using the two-flux radiation model and the scattering effect of the porous layer was considered in their computations. Another theoretical study on heat recovery (HR)

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Experimental study on multi-layered type of gas-to-gas heat exchanger using porous media

Tomimura

Hamano

Honda

et al. 2004

International Journal of Heat and Mass Transfer

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Effective heat exchange method by a pair of porous radiative converters.

Cited by 3 publications

References 0 publications

Thermal analysis of a three-layered radiant porous heat exchanger including fluid flow simulation

Thermal analysis of a three-layered radiant porous heat exchanger including fluid flow simulation

Heat transfer characteristics of a cylindrical porous radiant air heater under the influence of a two-dimensional axisymmetric radiative field

Experimental study on multi-layered type of gas-to-gas heat exchanger using porous media

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