scholarly journals Experimental Investigation of the Heat Transfer and Pressure Drop inside Tubes and the Shell of a Minichannel Shell and Tube Type Heat Exchanger

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8563
Author(s):  
Mateusz Prończuk ◽  
Anna Krzanowska
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Inner Diameter ◽  
Shell And Tube

This paper presents an experimental study on a shell and tube mini heat exchanger (STMHE). The STMHE consisted of seven tubes in a triangular arrangement, with an 0.8 mm inner diameter and 1.0 mm outer diameter. The heat exchanger shell had an inner diameter of 11 mm, and the heat exchanger had no baffles. For the adopted operating conditions, the Reynolds number on the tube side varied in the range of 300–3000, and 2000–12,000 on the shell side. The aim of this study was to determine pressure drop values during fluid flow and Nusselt number correlations for the heat transfer. A new method based on optimisation was used to derive the equations for calculating the heat transfer coefficients. It allowed the determine of the correlation equations for the heat transfer coefficients simultaneously for both sides of the heat exchanger. The obtained correlations yielded overall heat transfer coefficient values that, in most cases, did not differ by more than from those determined experimentally. The experimentally determined critical Reynolds number value for the flow inside the tubes was equal to . The Darcy friction factors correlated well with the classical laminar flow correlation and with the Blasius correlation for turbulent flow. The derived correlations for the Nusselt number were best aligned with the Sieder–Tate, Gnielinski, and Kozioł correlations for tube side laminar flow, turbulent flow, and shell flow, respectively. Good agreement between the results obtained using the experimentally derived correlations and the correlations available in the literature confirms the effectiveness of the used optimisation–based method.

Dimensionless Analysis of Heat Transfer and Flow Resistance on Laminar Flow Recuperator

2008 ◽  
Author(s):  
Chunyu Yin ◽  
Xiaoyong Yang ◽  
Jie Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Resistance ◽  
Similarity Theory ◽  
Installation Space ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Dimensionless Analysis

Recuperator is one of the key components in the helium-turbine cycle coupled with High Temperature Gas cooled Reactor (HTGR). Synthetically considering the heat transfer coefficients, the pressure drop and installation space of recuperator, it is obviously a trend to use compact heat exchanger as recuperator in nuclear power plant. Recuperator recovers heat from the turbine exhaust gas. It promotes the cycle efficiency over entire power range and in all typical modes including start up and shut down modes. The recuperator’s heat transfer coefficients, height, pressure drop have effect on the recuperator’s effectiveness. The main purpose of this paper is to present the law of heat transfer and flow resistance in laminar flow compact exchanger. Based on the similarity theory, the dimensionless parameters of the plate-fin heat exchanger is given in this paper; and then the the dimensionless analysis of the over-all heat transfer coefficient, recuperator’s effectiveness and flow resistance is presented. Furthermore, relationship between the pressure drop and length is also developed.

Experimental Study and Genetic-Algorithm-Based Correlation on Shell-Side Heat Transfer and Flow Performance of Three Different Types of Shell-and-Tube Heat Exchangers

2006 ◽  
Vol 129 (9) ◽  
pp. 1277-1285 ◽  
Author(s):  
Qiu-wang Wang ◽  
Gong-nan Xie ◽  
Bo-tao Peng ◽  
Min Zeng
Keyword(s):  
Heat Transfer ◽  
Genetic Algorithm ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Transfer Coefficients ◽  
Shell Side ◽  
Heat Transfer Coefficients ◽  
Friction Factors ◽  
Shell And Tube

The heat transfer and pressure drop of three types of shell-and-tube heat exchangers, one with conventional segmental baffles and the other two with continuous helical baffles, were experimentally measured with water flowing in the tube side and oil flowing in the shell side. The genetic algorithm has been used to determine the coefficients of correlations. It is shown that under the identical mass flow, a heat exchanger with continuous helical baffles offers higher heat transfer coefficients and pressure drop than that of a heat exchanger with segmental baffles, while the shell structure of the side-in-side-out model offers better performance than that of the middle-in-middle-out model. The predicted heat transfer rates and friction factors by means of the genetic algorithm provide a closer fit to experimental data than those determined by regression analysis. The predicted corrections of heat transfer and flow performance in the shell sides may be used in engineering applications and comprehensive study. It is recommended that the genetic algorithm can be used to handle more complicated problems and to obtain the optimal correlations.

Internal, Shellside Heat Transfer and Pressure Drop Characteristics for a Shell and Tube Heat Exchanger

1985 ◽  
Vol 107 (2) ◽  
pp. 345-353 ◽  
Author(s):  
E. M. Sparrow ◽  
J. A. Perez
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Thermal Loading ◽  
Compartment Pressure ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Tube Heat Exchanger ◽  
Heat Transfer Coefficients ◽  
Shell And Tube

Per-tube heat transfer coefficients and per-compartment and intracompartment pressure drops were measured on the shell side of a shell and tube heat exchanger. The main focus of the work was to determine the response of these quantities to variations in the size of the baffle window; the Reynolds number was also varied parametrically. The pressure measurements showed that the fluid flow is fully developed downstream of the first compartment of the heat exchanger and that the per-compartment pressure drop is constant in the fully developed regime. Within a compartment, the pressure drop in the upstream half is much larger than that in the downstream half. The per-tube heat transfer coefficients vary substantially within a given compartment (on the order of a factor of two), giving rise to a nonuniform thermal loading of the tubes. Row-average and compartment-average heat transfer coefficients were also evaluated. The lowest row-average coefficients were those for the first and last rows in a compartment, while the highest coefficient is that for the row just upstream of the baffle edge. It was demonstrated that the per-tube heat transfer coefficients are streamwise periodic for a module consisting of two consecutive compartments.

scholarly journals Heat transfer rates in hot shell, cold tube inclined baffled small shell, and tube heat exchanger using CFD and experimental approach

2021 ◽  
Vol 9 (4B) ◽  
Author(s):  
Devanand D. Chillal ◽  
◽  
Uday C. Kapale ◽  
N.R. Banapurmath ◽  
T. M. Yunus Khan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Liquid Flow ◽  
Cfd Analysis ◽  
Transfer Coefficients ◽  
Transfer Rates ◽  
Tube Heat Exchanger ◽  
Heat Transfer Coefficients ◽  
Shell And Tube ◽  
Cold Liquid

The work presented is an effort to realize the changes occurring for convective coefficients of heat transfer in STHX fitted with inclined baffles. Effort has been undertaken using Fluent, a commercially available CFD code ona CAD model of small STHX with inclined baffles with cold liquid flowing into the tubes and hot liquid flowing in the shell. Four sets of CFD analysis have been carried out. The hot liquid flow rate through shell compartments varied from 0.2 kg/sec to 0.8 kg/sec in steps of 0.2 kg/sec, while keeping the cold liquid flow condition in tube at 0.4 kg/sec constant. Heat transfer rates, compartment temperatures, and overall heat transfer coefficients, for cold liquid and hot liquid, were studied. The results given by the software using CFD approach were appreciable and comparatively in agreement with the results available by the experimental work, which was undertaken for the same set of inlet pressure conditions, liquid flow rates, and inlet temperatures of liquid for both hot and cold liquids. The experimental output results were also used to validate the results given by the CFD software. The results from the CFD analysis were further used to conclude the effect of baffle inclination on heat duty. The process thus followed also helped realize the effects of baffle inclination on convective heat transfer coefficient of the liquid flow through the shell in an inclined baffle shell and tube heat exchanger. The temperature plots for both cold and hot liquid were also generated for understanding the compartmental temperature distributions inclusive of the inlet and outlet compartments. The heat duty for a heat exchanger has been found to increase with the increase in baffle inclinations from zero degree to 20 degrees. Likewise, the convective heat transfer coefficients have also been found to increase with the increase in baffle inclinations.

Measurements of Developing and Fully Developed Heat Transfer Coefficients along a Periodically Interrupted Surface

1979 ◽  
Vol 101 (2) ◽  
pp. 211-216 ◽  
Author(s):  
N. Cur ◽  
E. M. Sparrow
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Plate Thickness ◽  
Turbulent Regime ◽  
Duct Flow ◽  
Rectangular Duct ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Interrupted Surface

The heat transfer and pressure drop characteristics for an array of colinear, equally spaced plates aligned parallel to the flow in a flat rectangular duct have been studied experimentally. The periodic interruptions (i.e., the gaps between the plates) preclude the attainment of hydrodynamic and thermal development of the type that is encountered in conventional duct flows, but a periodic fully developed regime can exist. Measurements of the heat transfer coefficients for the successive plates of the array affirmed the periodically developed regime and demonstrated the developmental pattern leading to its attainment. The thickness of the plates in the array was varied parametrically. In general, the Nusselt number increases with plate thickness. Thickness-related increases in the fully developed Nusselt number of up to 65 percent were encountered. The presence of the interruptions serves to augment the heat transfer coefficients. In the fully turbulent regime, the heat transfer coefficients are on the order of twice those for a conventional duct flow. The pressure drop also increases with the plate thickness.

scholarly journals Determination of Heat Transfer Coefficients Over Ribbed Surfaces With Infrared Thermography

1997 ◽  
Author(s):  
Francisco P. Brójo ◽  
Luís C. Gonçalves ◽  
Pedro D. Silva
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Stanton Number ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The scope of the present work is to characterize the heat transfer between a ribbed surface and an air flow. The convective heat transfer coefficients, the Stanton number and the Nusselt number were calculated in the Reynolds number range, 5.13 × 105 to 1.02 × 106. The tests were performed inside a turbulent wind tunnel with one roughness height (e/Dh = 0.07). The ribs had triangular section with an attack angle of 60°. The surface temperatures were measured using an infrared (IR) thermographic equipment, which allows the measurement of the temperature with a good spatial definition (10.24 × 10−6 m2) and a resolution of 0.1°C. The experimental measures allowed the calculation of the convective heat transfer coefficient, the Stanton number and the Nusselt number. The results obtained suggested a flow pattern that includes both reattachment and recirculation. Low values of the dimensionless Stanton number, i.e. Stx*, are obtained at the recirculation zones and very high values of Stx* at the zones of reattachment. The reattachment is located at a dimensionless distance of 0.38 from the top of the rib. That distance seems to be independent of the Reynolds number. The local dimensionless Stanton number remains constant as the Reynolds number varies. The convective heat transfer coefficient presents an uncertainty in the range of 3 to 6%.

Shell-and-Tube Side Heat Transfer Augmentation by the Use of Wall Radiation in a Crossflow Shell-and-Tube Heat Exchanger

1984 ◽  
Vol 106 (4) ◽  
pp. 735-742 ◽  
Author(s):  
Y. Yamada ◽  
M. Akai ◽  
Y. Mori
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Room Temperature ◽  
Heat Transfer Performance ◽  
Transfer Coefficients ◽  
Tube Heat Exchanger ◽  
Heat Transfer Coefficients ◽  
Heat Transfer Augmentation ◽  
Hot Gas ◽  
Shell And Tube

The heat transfer performance of a crossflow shell-and-tube heat exchanger for high-temperature use in which heat transfer is augmented by the use of wall radiation in both shell and tube sides, is studied. Radiation plates are inserted in the shell side, and twisted cross-tapes in the tube side. Overall heat transfer coefficients are measured to be about a maximum 80 percent larger than those without radiation, where the inlet temperatures of the hot gas range up to 800 °C, while those of the cold gas are about room temperature. Analytical results agree well with experimental results, and an approximate calculation procedure is found to be simple and accurate enough for practical use.

The Correlation of Heat Transfer Coefficients for the Laminar Natural Convection in a Circular Finned-Tube Heat Exchanger

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Hie Chan Kang ◽  
Se-Myong Chang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Nusselt Number ◽  
Natural Convection ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Finned Tube ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Laminar Natural Convection

This study proposes an empirical correlation for laminar natural convection applicable to external circular finned-tube heat exchangers with wide range of configuration parameters. The transient temperature response of the heat exchangers was used to obtain the heat transfer coefficient, and the experimental data with their characteristic lengths are discussed. The data lie in the range from 1 to 1000 for Rayleigh numbers based on the fin spacing: the ratio of fin height to tube diameter ranges from 0.1 to 0.9, and the ratio of fin pitch to height ranges from 0.13 to 2.6. Sixteen sets of finned-tube electroplated with nickel–chrome were tested. The convective heat transfer coefficients on the heat exchangers were measured by elimination of the thermal radiation effect from the heat exchanger surfaces. The Nusselt number was correlated with a newly suggested composite curve formula, which converges to the quarter power of the Rayleigh number for a single cylinder case. The proposed characteristic length for the Rayleigh number is the fin pitch while that for the Nusselt number is mean flow length, defined as half the perimeter of the mean radial position inside the flow region bounded by the tube surface and two adjacent fins. The flow is regarded as laminar, which covers heat exchangers from a single horizontal cylinder to infinite parallel disks. Consequently, the result of curve fitting for the experimental data shows the reasonable physical interpretation as well as the good quantitative agreement with the correction factors.

Cost-Optimal Operation of Heat Exchanger Network Considering Pressure Drop Constraints

2013 ◽  
Vol 634-638 ◽  
pp. 3898-3902
Author(s):  
Liang Zhao ◽  
Zhao Yi Huo ◽  
Lin Mu ◽  
Hong Chao Yin
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Optimal Operation ◽  
Extended Model ◽  
Transfer Coefficients ◽  
Heat Exchanger Network ◽  
Power Cost ◽  
Heat Transfer Coefficients ◽  
Film Heat Transfer

Considerable research effort has been reported in cost-optimal operation of heat exchanger network. However, most of them neglect the pressure drop influence and assume constant film heat transfer coefficients. Pressure drop of streams are important influencing factors for the performance of heat exchanger network operation. In this paper, a general cost-optimal operation model considering pressure drop constraints and removing the assumption of constant film heat transfer coefficients is proposed. It is necessary to determine the pumping power cost required as part of operating cost function. The extended model is applied to one example taken from previous research, and the results prove that the proposed method can obtain more real optimization results for HEN operational optimization problems.

scholarly journals A Novel Generator Design Utilised for Conventional Ejector Refrigeration Systems

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7705
Author(s):  
Anas F. A. Elbarghthi ◽  
Mohammad Yousef Hdaib ◽  
Václav Dvořák
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Working Fluid ◽  
Convection Coefficient ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Heat Transfer Coefficients ◽  
Cold Fluid ◽  
Cold Stream

Ejector refrigeration systems are rapidly evolving and are poised to become one of the most preferred cooling systems in the near future. CO2 transcritical refrigeration systems have inherently high working pressures and discharge temperatures, providing a large volumetric heating capacity. In the current research, the heat ejected from the CO2 gas cooler was proposed as a driving heating source for the compression ejector system, representing the energy supply for the generator in a combined cycle. The local design approach was investigated for the combined plate-type heat exchanger (PHE) via Matlab code integrated with the NIST real gas database. HFO refrigerants (1234ze(E) and 1234yf) were selected to serve as the cold fluid on the generator flowing through three different phases: subcooled liquid, a two-phase mixture, and superheated vapour. The study examines the following: the effectiveness, the heat transfer coefficients, and the pressure drop of the PHE working fluids under variable hot stream pressures, cold stream flow fluxes, and superheated temperatures. The integration revealed that the cold fluid mixture phase dominates the heat transfer coefficients and the pressure drop of the heat exchanger. By increasing the hot stream inlet pressure from 9 MPa to 12 MPa, the cold stream two-phase convection coefficient can be enhanced by 50% and 200% for R1234yf and R1234ze(E), respectively. Conversely, the cold stream two-phase convection coefficient dropped by 17% and 37% for R1234yf and R1234ze(E), respectively. The overall result supports utilising the ejected heat from the CO2 transcritical system, especially at high CO2 inlet pressures and low cold channel flow fluxes. Moreover, R1234ze(E) could be a more suitable working fluid because it possesses a lower pressure drop and bond number.

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