Experimental Studies on Influence of Process Variables to the Exergy Losses at the Double Tube Heat Exchanger

1999 ◽  
pp. 641-648 ◽  
Author(s):  
Ahmet Can ◽  
Doğan Eryener ◽  
Ertan Buyruk
Keyword(s):  
Heat Exchanger ◽  
Experimental Studies ◽  
Process Variables ◽  
Tube Heat Exchanger ◽  
Exergy Losses

scholarly journals Thermal-Hydraulic Studies on the Shell-and-Tube Heat Exchanger with Minijets

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3276 ◽  
Author(s):  
Jan Wajs ◽  
Michał Bajor ◽  
Dariusz Mikielewicz
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Waste Heat ◽  
Experimental Studies ◽  
Convection Heat Transfer ◽  
Test Facility ◽  
Experimental Investigations ◽  
Transfer Coefficients ◽  
Tube Heat Exchanger ◽  
Shell And Tube

In this paper a patented design of a heat exchanger with minijets, with a cylindrical construction is presented. It is followed by the results of its systematic experimental investigations in the single-phase convection heat transfer mode. Based on these results, validation of selected correlations (coming from the literature) describing the Nusselt number was carried out. An assessment of the heat exchange intensification level in the described heat exchanger was done through the comparison with a shell-and-tube exchanger of a classical design. The thermal-hydraulic characteristics of both units were the subjects of comparison. They were constructed for the identical thermal conditions, i.e., volumetric flow rates of the working media and the media temperatures at the inlets to the heat exchanger. The experimental studies of both heat exchangers were conducted on the same test facility. An increase in the heat transfer coefficients values for the minijets heat exchanger was observed in comparison with the reference one, whereas the generated minijets caused greater hydraulic resistance. Experimentally confirmed intensification of heat transfer on the air side, makes the proposed minijets heat exchanger application more attractive, for the waste heat utilization systems from gas sources.

scholarly journals Experimental Verification of an Analytical Mathematical Model of a Round or Oval Tube Two-Row Car Radiator

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3399
Author(s):  
Dawid Taler ◽  
Jan Taler ◽  
Marcin Trojan
Keyword(s):  
Mathematical Model ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Heat Exchangers ◽  
Cfd Simulation ◽  
Experimental Studies ◽  
Hot Water ◽  
Heat Flow Rate ◽  
Cfd Modelling ◽  
Tube Heat Exchanger

The paper presents an analytical mathematical model of a car radiator, which takes into account various heat transfer coefficients (HTCs) on each row of pipes. The air-side HTCs in a specific row of pipes in the first and second passes were calculated using equations for the Nusselt number, which were determined by CFD simulation by the ANSYS program (Version 19.1, Ansys Inc., Canonsburg, PA, USA). The liquid flow in the pipes can be laminar, transition, or turbulent. When changing the flow form from laminar to transition and from transition to turbulent, the HTC continuity is maintained. Mathematical models of two radiators were developed, one of which was made of round tubes and the other of oval tubes. The model allows for the calculation of the thermal output of every row of pipes in both passes of the heat exchangers. Small relative differences between the total heat flow transferred in the heat exchanger from hot water to cool air exist for different and uniform HTCs. However, the heat flow rate in the first row is much higher than the heat flow in the second row if the air-side HTCs are different for each row compared to a situation where the HTC is constant throughout the heat exchanger. The thermal capacities of both radiators calculated using the developed mathematical model were compared with the results of experimental studies. The plate-fin and tube heat exchanger (PFTHE) modeling procedure developed in the article does not require the use of empirical correlations to calculate HTCs on both sides of the pipes. The suggested method of calculating plate-fin and tube heat exchangers, taking into account the different air-side HTCs estimated using CFD modelling, may significantly reduce the cost of experimental research for a new design of heat exchangers implemented in manufacturing.

Bayonet Tube Heat Exchanger

1997 ◽  
Vol 50 (8) ◽  
pp. 445-473 ◽  
Author(s):  
G. S. H. Lock ◽  
Harpal Minhas
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Waste Heat ◽  
Thermal Studies ◽  
Experimental Studies ◽  
Return Flow ◽  
Tube Heat Exchanger ◽  
Numerical Predictions

This review article provides an overview and assessment of the bayonet tube heat exchanger in its concentric tube configuration. The article begins with a brief historical sketch of its use in three main contexts: in the process industries, especially in waste heat recovery; in geotechnical engineering, in permafrost stabilization; and in medicine, especially in cryosurgery. A conceptual outline describing the main heat transfer features of the device in counterflow, parallel flow, and cross flow situations follows. Particular attention is paid to the implications of thermal coupling between the inner tube flow, the annular (return) flow and the external fluid flow. The main text is divided into two parts: Experimental studies and Theoretical studies. Each of these is subdivided into two complementary sections: hydraulic studies, in which the emphasis is placed on fluid flow characteristics, especially in the U-bend at the end of the tube; and thermal studies, emphasizing the convective heat transfer characteristics. Each subsection is further divided to permit separate discussion of laminar, transitional and turbulent flow under steady, single-phase conditions. Experimental data are systematically compared with numerical predictions to provide a comprehensive survey of the effect of the independent variables (flow rate, tube geometry, and fluid properties) on the dependent variables (pressure drop, heat transfer rate). Experimental and numerical data are combined to develop empirical correlations for pressure drop and heat transfer. The final section examines the above findings to uncover the limitations of our current knowledge and thereby suggest profitable avenues for future research. There are 47 references listed at the end of the article.

scholarly journals Thermal Analysis and Performance Evaluation of Triple Concentric Tube Heat Exchanger

2019 ◽  
Vol 8 (6) ◽  
pp. 3898-3905
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Rate Variation ◽  
Tube Heat Exchanger

Triple concentric-tube exchanger (TCTHE) is an improved version of double concentric tube heat exchanger (DCTHE). Introducing an intermediate tube to a DCTHE provides TCTHE and enhances the heat transfer performance. Recognizing the need of experimental results, extremely scarce in the literature and essential to validate theoretical analyses, the aim of this work is to investigate thermal behavior of TCTHE. The present study includes design, development and experimental analysis of TCTHE for oil (ISO VG 22) cooling application required for industrial purposes. It comprises of water (cooling fluid) flowing through innermost tube as well as outer annulus and oil (hot fluid) flows through inner annulus. The experimental studies of the temperature distribution for three fluids along the length and heat transfer characteristics for TCTHE under insulated condition for counter current flow mode are carried out and discussed. The effect of change in oil (hot fluid) temperatures is analyzed keeping water inlet temperatures same at various operating conditions. The experiments have been conducted by varying flow rate of one of the fluids at a time and keeping other two fluid flow rates constant. The results are expressed in terms of temperature variation for all three fluids along the length. The effect of change in hot fluid inlet temperature is expressed in terms of heat transfer rate variation with respect to Reynolds number. The variation of non-dimensional parameters as temperature effectiveness and thermal conductance with respect to Reynolds number is also presented in this paper. Theoretical studies are carried out for evaluation of heat transfer rate using empirical correlations. Experimental validation is carried out for degree of cooling at different Reynolds numbers with theoretical analysis

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