A review on transient test techniques for obtaining heat transfer design data of compact heat exchanger surfaces

Krishnakumar, K.; John, Anish K.; Venkatarathnam, G.

doi:10.1016/j.expthermflusci.2010.12.006

Cited by 18 publications

(9 citation statements)

References 25 publications

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“…This method was also effectively applied for investigations of heat transfer in compact heat exchangers: Shaji and Das (2010), Krishnakumar et al (2011), Ranganayakulu et al (2017). Heat transfer coefficient is based on the actual surface area of the bed elements and takes into account convective heat transfer between gas and the packed bed element surface.…”

Section: Single Blow Methodsmentioning

confidence: 99%

Measurement Approach of Mean Heat Transfer Coefficient for Packed Bed of Vegetables

Łapiński

Butrymowicz

Kolodziejczyk

2017

Acta Mechanica Et Automatica

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Abstract:The non-invasive measurement approach of the mean heat transfer coefficient for the packed bed of vegetables may be thought as still open issue. There is a clear need for the assessment of heat transfer conditions for various types of fruits and vegetables in order to accurately predict the thermal load that is necessary to select refrigeration equipment for cold storage chamber. Additionally, there is significant development in numerical modelling of heat and mass transfer processes in cold storage chambers for fruits and vegetables which requires precise heat transfer prediction. The theoretical basis for the indirect measurement approach of mean heat transfer coefficient for the packed bed of vegetables that is based on single blow technique is presented and discussed in the paper. The approach based on the modified model of Liang and Yang was presented and discussed. The testing stand consisted of a dedicated experimental tunnel along with auxiliary equipment and measurement system are presented. The geometry of the tested vegetables bed were presented. Selected experimental results of heat transfer are presented and discussed for the packed bed of carrots. These results were presented as dimensionless relationship. The obtained results were compared with the existing dimensionless relationships developed for the packed bed consisting of elements of various regular shapes.

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Section: Single Blow Methodsmentioning

confidence: 99%

Measurement Approach of Mean Heat Transfer Coefficient for Packed Bed of Vegetables

Łapiński

Butrymowicz

Kolodziejczyk

2017

Acta Mechanica Et Automatica

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“…The inlet and outlet stream temperatures are measured continuously over an interval of time and compared to the predictions of a model in order to determine the desired heat transfer information. This so-called single-blow method, and its variations, along with various other transient techniques have been investigated, to some degree, for nearly a century, as explained in a recent review on the subject [35].…”

Section: Introductionmentioning

confidence: 99%

Measuring Transport Coefficients in Heterogeneous and Hierarchical Heat Transfer Devices

Geb¹,

Ge²,

Chu³

et al. 2013

Journal of Heat Transfer

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Experimental determination of transport coefficients, in particular internal heat transfer coefficients, in heterogeneous and hierarchical heat transfer devices such as compact heat exchangers and high surface density heat sinks has posed a persistent challenge for designers. This study presents a unique treatment of the experimental determination of such design data. A new combined experimental and computational method for determining the internal heat transfer coefficient within a heterogeneous and hierarchical heat transfer medium is explored and results are obtained for the case of cross flow of air over staggered cylinders to provide validation of the method. Along with appropriate pressure drop measurements, these measurements allow for thermal-fluid modeling of a heat exchanger by closing the volume averaging theory (VAT)-based equations governing transport phenomena in porous media, which have been rigorously derived from the lower-scale Navier-Stokes and thermal energy equations. To experimentally obtain the internal heat transfer coefficient the solid phase is subjected to a step change in heat generation rate via induction heating, while the fluid flows through under steady flow conditions. The transient fluid phase temperature response is measured. The heat transfer coefficient is then determined by comparing the results of a numerical simulation based on the VAT model with the experimental results. The friction factor is determined through pressure drop measurements, as is usually done. With the lower-scale heat transfer coefficient and friction factor measured, the VAT-based equations governing the transport phenomena in the heat transfer device are closed and readily solved. Several configurations of staggered cylinders in cross flow were selected for this study. Results for the heat transfer coefficient and friction factor are compared to widely accepted correlations and agreement is obseiyed, lending validation to this experimental method and analysis procedure. It is expected that a more convenient and accurate tool for experimental closure of the VAT-based equations modeling transport in heterogeneous and hierarchical media, which comes down to measuring the transport coefficients, will allow for easier modeling and subsequent optimization of high performance compact heat exchangers and heat sinks for which design data does not already exist.

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“…Under the experimental conditions, the steady-state method has a temperature gradient in the channel, and the volumetric heat transfer coefficient mostly depends on the thermal conductivity of the solid phase. For the single-blow method, the temperature of the channel section can be ensured to be uniform by processing the experimental test section, and it becomes a mainstream scheme [22,23]. In this method, the volumetric heat transfer coefficient correlations are determined on foam materials with different geometric structures, such as those described by Dietrich [18] and Xia [19].…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Study on Convective Heat Transfer Characteristics in Foam Materials

Han

Yang

Wu³

et al. 2020

Energies

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Foam materials are widely used in heat exchange because of their high porosity and large specific surface area. Correctly characterizing heat transfer characteristics is the key to ensuring efficient heat transfer. In this paper, single-blow transient test technology is used to experimentally measure the temperature. Silicon carbide ceramics with various thicknesses ranging from 30 to 105 mm and different pore structures were used in the experiments. The test was carried out at the velocity ranging from 0.5 to 1.8 m/s. The air temperature distributions of the inlet and outlet were obtained by processing the experimental data, and the regularity of the average volumetric heat transfer coefficient was obtained and analyzed. Subsequently, the simplified tetrakaidecahedron models with a porosity of 0.85 and 0.75 were used to analyze the heat transfer characteristics. The local thermal equilibrium and local thermal non-equilibrium at the pore scale were analyzed. By comparing the simulation with the experiment, it shows that the larger thickness affects local thermal equilibrium and leads to a decrease in the volumetric heat transfer coefficient. The conclusion can be used to guide the optimization of the design of foam material-mediated heat exchange equipment.

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A review on transient test techniques for obtaining heat transfer design data of compact heat exchanger surfaces

Cited by 18 publications

References 25 publications

Measurement Approach of Mean Heat Transfer Coefficient for Packed Bed of Vegetables

Measurement Approach of Mean Heat Transfer Coefficient for Packed Bed of Vegetables

Measuring Transport Coefficients in Heterogeneous and Hierarchical Heat Transfer Devices

Numerical and Experimental Study on Convective Heat Transfer Characteristics in Foam Materials

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