An area method for visualizing heat-transfer imperfection of a heat exchanger network in terms of temperature–heat-flow-rate diagrams

2016 ◽  
Vol 59 (10) ◽  
pp. 1517-1523 ◽  
Author(s):  
Jing Wu ◽  
XianPei Yang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Flow Rate ◽  
Heat Flow Rate ◽  
Heat Exchanger Network ◽  
Area Method ◽  
Temperature Heat

scholarly journals Energy analysis of heat exchanger in a heat exchanger network

2018 ◽  
Vol 22 (5) ◽  
pp. 1999-2011 ◽  
Author(s):  
Martina Rauch ◽  
Antun Galovic
Keyword(s):  
Mathematical Model ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Flow Rate ◽  
Local Extremum ◽  
Heat Flow Rate ◽  
Fluid Stream ◽  
Heat Exchanger Network ◽  
Maximum Heat ◽  
The Given

For many years now, heat exchanger optimization has been a field of research for a lot of scientists. Aims of optimization are different, having in mind heat exchanger networks with different temperatures of certain streams. In this paper mathematical model in dimensionless form is developed, describing operation of one heat exchanger in a heat exchanger network, with given overall area, based on the maximum heat-flow rate criterion. Under the presumption of heat exchanger being a part of the heat exchanger network, solution for the given task is resting in a possibility of connecting an additional fluid stream with certain temperature on a certain point of observed heat exchanger area. The connection point of additional fluid stream determines the exchanging areas of both heat exchangers and it needs to allow the maximum exchanged heat-flow rate. This needed heat-flow rate achieves higher value than the heat-flow rate acquired by either of streams. In other words, a criterion for the existence of the maximum heat-flow rate, as a local extremum, is obtained within this mathematical model. Results of the research are presented by the adequate diagrams and are interpreted, with emphasis on the cases which fulfill and those which do not fulfill the given condition for achieving the maximum heat-flow rate.

scholarly journals Heat Transfer and Friction Factor Characteristics of Heat Exchanger using Aluminium Oxide and Titanium Oxide

2019 ◽  
Vol 8 (3) ◽  
pp. 2950-2952
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Titanium Oxide ◽  
Flow Rate ◽  
Liquid Flow ◽  
Aluminium Oxide ◽  
Plain Water ◽  
Heat Flow Rate ◽  
Nano Fluids

t A heat flow and fluid flow investigation of double tube heat exchanger by means of warped tape insert under the mixing water based nano fluids. In this article Aluminium oxide and Titanium oxide was used to get better performance heat exchanging device. A different mass flow rate of fluids used to conduct the experiment and gathered various surface temperature for analyses the heat flow augmentation. A heat flow rate Nano fluids 10 to 12% was enhanced compare with the plain base water. A heat flow with liquid flow Aluminum oxide was enhanced with +8% compare with the plain base water. A heat transfer characteristics titanium oxide were augment with raise of Re and 12% was augmented compare with the plain water. However heat flow and liquid flow heat exchanging device was increasing with volume of Nano fluids increased and leading to friction facto

Heat and Mass Transfer to Air in a Cross Flow Heat Exchanger with Surface Deluge Cooling

2016 ◽  
Vol 24 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Andrea Diani ◽  
Luisa Rossetto ◽  
Roberto Dall’Olio ◽  
Daniele De Zen ◽  
Filippo Masetto
Keyword(s):  
Heat Exchanger ◽  
Heat Flow ◽  
Flow Rate ◽  
Data Center ◽  
Heat Dissipation ◽  
Cross Flow ◽  
Critical Conditions ◽  
Heat Flow Rate ◽  
External Temperature ◽  
Flow Heat

Cross flow heat exchangers, when applied to cool data center rooms, use external air (process air) to cool the air stream coming from the data center room (primary air). However, an air–air heat exchanger is not enough to cope with extreme high heat loads in critical conditions (high external temperature). Therefore, water can be sprayed in the process air to increase the heat dissipation capability (wet mode). Water evaporates, and the heat flow rate is transferred to the process air as sensible and latent heat. This paper proposes an analytical approach to predict the behavior of a cross flow heat exchanger in wet mode. The theoretical results are then compared to experimental tests carried out on a real machine in wet mode conditions. Comparisons are given in terms of calculated versus experimental heat flow rate and evaporated water mass flow rate, showing a good match between theoretical and experimental values.

scholarly journals Performance of Air-Cooled Heat Exchanger with Laminar, Transitional, and Turbulent Tube Flow

2018 ◽  
Vol 240 ◽  
pp. 02012
Author(s):  
Dawid Taler
Keyword(s):  
Nusselt Number ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Friction Factor ◽  
Flow Rate ◽  
Empirical Relationship ◽  
Heat Flow Rate ◽  
Transition Flow ◽  
Water Side ◽  
Wide Range

Some air-cooled heat exchangers, especially in air conditioning and heating installations, heat pumps, as well as car radiators, work in a wide range of loads when the liquid flow in the tubes can be laminar, transitional or turbulent. In this paper, a semi-empirical and empirical relationship for the Nusselt number on the liquid-side in the transitional and turbulent range was derived. The friction factor in the transition flow range Rew,trb ≤ Rew ≤ Rew,tre was calculated by linear interpolation between the values of the friction factor for Rew,trb =2,100 and Rew,tre =3,000. Based on experimental data for a car radiator, empirical heat transfer relationships for the air and water-side were found by using the least squares method. The water temperature at the outlet of the heat exchanger was calculated using P-NTU (effectiveness-number of transfer units) method. The heat flow rate from water to air was calculated as a function of the water flow rate to compare it with the experimental results. The theoretical and empirical correlation for the water-side Nusselt number developed in the paper were used when determining the heat flow rate. The calculation results agree very well with the results of the measurements.

Design and Analysis of a Heat Exchanger Network

2012 ◽  
Vol 9 (1) ◽  
pp. 85-91
Author(s):  
Mohammad Azim Aijaz ◽  
T. S. Ravikumar
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Temperature Difference ◽  
Transfer Rate ◽  
Outlet Temperature ◽  
Optimal Temperature ◽  
Heat Exchanger Network ◽  
Cold Fluid ◽  
Temperature Heat

the hot fluid outlet temperature, cold fluid outlet temperature, heat transfer rate and effectiveness at varying hot and cold fluid inlet temperatures using, log mean temperature difference (LMTD) and effectiveness-number of transfer units (ε-NTU) method. The obtained result illustrates how heat transfer rate and effectiveness increases or decreases at varying hot and cold fluid inlet temperatures. The result obtained from both LMTD and å-NTU method gives statistically significant values. The objective of this paper is to find out the optimal temperature at which heat transfer rate and effectiveness are maximum.

Temperature, heat and heat flow rate calibration of scanning calorimeters in the cooling mode

2000 ◽  
Vol 361 (1-2) ◽  
pp. 1-20 ◽  
Author(s):  
Stefan M Sarge ◽  
Günther W.H Höhne ◽  
Heiko K Cammenga ◽  
Walter Eysel ◽  
Eberhard Gmelin
Keyword(s):  
Heat Flow ◽  
Flow Rate ◽  
Heat Flow Rate ◽  
Cooling Mode ◽  
Temperature Heat

Heat Transfer in a Long, Thin Tube Section of an Air Compressor: An Empirical Correlation From CFD and a Thermodynamic Modeling

2012 ◽  
Author(s):  
Chao Zhang ◽  
Mohsen Saadat ◽  
Perry Y. Li ◽  
Terrence W. Simon
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Flow Rate ◽  
Dimensionless Number ◽  
Transfer Model ◽  
Heat Flow Rate ◽  
Air Compressor ◽  
Thin Tube ◽  
Linear Ode ◽  
Liquid Piston

Heat transfer during compression of air in a long, thin tube is studied by CFD. The tube represents one of the many in a honeycomb geometry inserted in a liquid piston air compressor to minimize temperature rise. A dimensionless number for the heat flow rate that includes the changing heat transfer area between the tube wall and air during compression is used. From the CFD results, alinear relation between the inverse of this dimensionless heat flow rate and the Stanton number is found. Using thisrelation, the transient volume-averaged temperature, and heat flow rate from the air can be well predicted by thermodynamic modeling.With the heat transfer model, a non-linear ODE is solved numerically todetermine the average temperature and pressure. The application of this study can be found in liquid piston air compressors for compressed air energy storage systems.

EXPERIMENTAL STUDY OF HEAT EXCHANGE FROM A STEAM-GAS MIXTURE DURING HEAT TRANSFER THROUGH A RIBBED SURFACE

2021 ◽  
Vol 7 (2) ◽  
pp. 60-74
Author(s):  
Vadim E. Zinurov ◽  
Andrey V. Dmitriev ◽  
Ilnar I. Sharipov ◽  
Alsu R. Galimova
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Transfer Coefficient ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Gas Mixture ◽  
Stationary Mode

This article deals with the problem of heat energy transfer from a steam-gas mixture with a constant temperature of 220 °C. An experimental study of the transfer of heat energy from a steam-gas mixture by a recuperative heat exchanger with a ribbed surface at the industrial enterprise “PULP Invest”, located at the production site of the industrial park Technopolis “Khimgrad” in Kazan, is presented. The design of a heat exchanger with a ribbed surface is described. The finned surface of the recuperative heat exchanger allowed intensifying the transfer of heat flow, due to the appearance of turbulent vortices of the vapor-gas medium when it moves between the transversely arranged fins. For a heated heat carrier, water was used, which in the future is planned to be used for technological and economic needs. This paper presents the experimental method and measuring instruments. During the experiments, the initial temperature of the cold coolant (water) varied from 28.8 to 31.9 °C. The series of experiments included 7 experiments with a different volume flow of water from 60 to 120 liters/hour. The initial volume flow rate was 60 l/h, the flow rate change step was 10 l/h. The results of the studies showed that the time of the output of the studied parameters: temperature head, heat flow and heat transfer coefficient to the stationary mode was 265 s. When entering the stationary mode with a volume flow rate of cold coolant in the range from 60 to 120 l/h, the temperature head varied from 32.2 to 63 °C, the heat flow varied from 4.1 to 4.5 kW, the heat transfer coefficient varied in the range of 24.4-27.9 W/(m2 · K). The obtained results allowed establishing that the heat transfer coefficient is inversely proportional to the thermal resistance of the vapor-gas phase.

Effect of heat generation and thermal radiation on heat transfer in porous enclosure having t-shape inner geometry

2020 ◽  
pp. 095440892097311
Author(s):  
Pentyala Srinivasa Rao ◽  
Anil Kumar
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Thermal Radiation ◽  
Viscous Dissipation ◽  
Flow Rate ◽  
Heat Flow Rate ◽  
Radiation Parameter ◽  
Average Heat ◽  
Dissipation Parameter ◽  
Porous Enclosure

The numerical investigation of steady two-dimensional free convection is conducted to analyze the thermal radiation and viscous dissipation effects on heat transfer characteristics in fluid saturated T-shape porous hollow enclosure. The nonlinear partial differential equations in terms of stream function, using Darcy’s law and Boussinesq approximation, are solved numerically using finite difference scheme based on Gauss-Seidel approach. The results of this analysis discussed for the wide range of pertinent parameters such as radiation parameter ([Formula: see text]), viscous dissipation parameter ([Formula: see text]) and Rayleigh number ([Formula: see text]) in terms of local and average heat flow rate, streamlines and isotherms. The obtained results show that the average heat flow rate is enhanced with radiation parameter and reduced with viscous dissipation parameter. The results are graphically depicted to show the implications of the pertinent parameters in heat and flow field inside the hollow porous enclosure.

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