Review of Design and Modeling of Regenerative Heat Exchangers

Kilkovský, B.

doi:10.3390/en13030759

Cited by 13 publications

(11 citation statements)

References 41 publications

(52 reference statements)

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“…Due to the multifactor nature of the heat transfer process in regenerators, especially taking into account the significant non-stationarity of the transfer phenomena, special attention should be paid to experimental studies [13]. Additional knowledge is needed about the design features of a soil regenerator, taking into account the heat exchange between the gas flow and solid particles [14]. Particular attention should be paid to the choice of granular material.…”

Section: No 2 (79) 2022mentioning

confidence: 99%

Experimental study of a pilot unit of a ground regenerator for greenhouses

Mukminov

Volgusheva

Georgiesh

et al. 2022

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The object of research: the process of heat exchange in a packing in the form of a dense layer of crushed stone as part of a thermal regenerator designed to utilize the low-grade heat of the air in a greenhouse. Investigated problem: increasing the efficiency of air heat accumulation in the greenhouse during the daytime by a regenerative heat exchanger with a granular packing. Conducting experimental tests of regenerator models with a packing in the form of a dense layer of granular material under natural conditions is necessary to improve the design and optimize technological parameters. The main scientific results: the analysis of temperature curves of air changes at the inlet and outlet of the regenerator installed in the mock-up greenhouse with a volume of 0.25 m3, and the packing material was carried out. During the heating period of the nozzle, the accumulated heat was Q=8•104 J, which can be used when the temperature in the greenhouse decreases. During the pause, the loss from the heat exchange channel to the environment is 48,000 J. The duration of the period was 358 min, while the average heat flux corresponded to 2.2 W. Heat losses during the pause period are significant due to its duration, however, the average heat transfer coefficient has a low value of k=2.3 W/m2K, so strengthening the insulation of the heat exchange channel is irrational. The area of practical use of the results of the study: greenhouses, allowing the possibility of installing additional heat exchange equipment. Innovative technological product: the innovativeness of the technical solution is determined by the possibility of using the heat of the air in the greenhouse and the implementation of contact heat exchange between the air flow and the packing particles. The design of the regenerator, the simplicity of its manufacture and operation, as well as the efficiency of air heat accumulation in the greenhouse during the daytime, allow to recommend it for use in greenhouse farms. The scope of the innovative technological product: regenerative heat exchangers with a dense layer of granular material for the utilization of low-grade air flows generated in food production enterprises, ventilation systems and greenhouses

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Section: No 2 (79) 2022mentioning

confidence: 99%

Experimental study of a pilot unit of a ground regenerator for greenhouses

Mukminov

Volgusheva

Georgiesh

et al. 2022

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“…9 In the hot cycle, thermal energy is transferred from the hot fluid to the corrugated plates and in the cold cycle, the plates are exposed and transfer energy to the cold stream. 10–13…”

Section: Introductionmentioning

confidence: 99%

Modification of rotary air preheater toward achieving extended life-span utilizing porous media approach: A case study

Hajebzadeh¹,

Ansari²

2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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The main goal of this study is to achieve the extended operating life of the rotary regenerative air pre-heater (Ljungström) of Bandar Abbas power plant by modifying operational parameters by decreasing the corrosion. To achieve this goal, a three-dimensional CFD simulation of the Ljungström is carried out, utilizing the thermal non-equilibrium porous media model. Temperatures are validated against measured data from the power plant with a maximum relative error of 5.54% on the Celsius scale, and mass flow rates are validated with a maximum relative error of −5.25%. The effect of the Ljungström key parameters including the rotational speed, cold layer material, inlet air/flue gas temperature, and mass flow rate, are analyzed in presence of leakages and neglecting it, using porous media approach. The leakage effect is investigated considering radial and axial/peripheral clearances. Finally, a simulation is performed by applying feasible improved parameters extracted from the above analyses considering the effect of all parameters together in presence of leakages, which shows a 6.14% improvement in the Ljungström effectiveness, reducing the total leakage to about one-third of the actual model and eliminating any corrosion.

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“…With the development of computational techniques and numerical simulation methods, the approach to the modeling of phenomena occurring in such reactors has been changing [1,2]. An approach comprising of several stages has been used in several studies and seems to set the working standard.…”

Section: Introductionmentioning

confidence: 99%

A Simplified Method for Modeling of Pressure Losses and Heat Transfer in Fixed-Bed Reactors with Low Tube-to-Particle Diameter Ratio

et al. 2021

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This manuscript presents a simplified method of modeling fixed-bed reactors based on the porous medium. The proposed method primarily allows the necessity of precisely mapping the internal structure of the bed—which usually is done using real object imaging techniques (like X-ray tomography) or numerical methods (like discrete element method (DEM))—to be avoided. As a result, problems with generating a good quality numerical mesh at the particles’ contact points using special techniques, such as by flattening spheres or the caps method, are also eliminated. The simplified method presented in the manuscript is based on the porous medium method. Preliminary research has shown that the porous medium method needs modifications. This is because of channeling, wall effects, and local backflows, which are substantial factors in reactors with small values of tube-to-particle-diameter ratio. The anisotropic thermal conductivity coefficient was introduced to properly reproduce heat transfer in the direction perpendicular to the general fluid flow. Since the commonly used fixed-bed reactor models validation method based on comparing the velocity and temperature profiles in the selected bed cross-section is not justified in the case of the porous medium method, an alternative method was proposed. The validation method used in this work is based on the mass-weighted average temperature increase and area-weighted average pressure drop between two control cross-section of the reactor. Thanks to the use of the described method, it is possible to obtain satisfactorily accurate results of the fixed-bed reactor model with no cumbersome mesh preparation and long-term calculations.

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Review of Design and Modeling of Regenerative Heat Exchangers

Cited by 13 publications

References 41 publications

Experimental study of a pilot unit of a ground regenerator for greenhouses

Experimental study of a pilot unit of a ground regenerator for greenhouses

Modification of rotary air preheater toward achieving extended life-span utilizing porous media approach: A case study

A Simplified Method for Modeling of Pressure Losses and Heat Transfer in Fixed-Bed Reactors with Low Tube-to-Particle Diameter Ratio

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