Decrement in heat transfer effectiveness due to solid heat conduction for a counter-current spiral heat exchanger

2016 ◽  
Vol 103 ◽  
pp. 821-831 ◽  
Author(s):  
Duc-Khuyen Nguyen ◽  
Jung-Yang San
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Heat Exchanger ◽  
Spiral Heat Exchanger ◽  
Counter Current

A Novel Gas-Water Heat Exchanger With Minichannels

2008 ◽  
Author(s):  
Yang Chen ◽  
Per Lundqvist ◽  
Bjo¨rn Palm
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Low Pressure ◽  
Shell Side ◽  
Hot Air ◽  
Drop Flow ◽  
Counter Current ◽  
Good Heat ◽  
Current Heat

In the current study, a novel gas water heat exchanger with minichannels is designed, built and tested. The heat exchanger is mainly composed of a number of concentric ring shaped plates, which are made up of several heat exchanger tubes. The ring shaped plates are arranged in parallel and placed in a shell. The heat exchanger is designed as a counter current heat exchanger with laminar flow on the heat exchanger’s shell-side (gas side) and therefore has a very low pressure drop on the shell side. The heat exchanger was tested with water and hot air on its tube-side and shell-side respectively. All the necessary parameters like inlet and outlet temperatures on tube-side and shell-side as well as the pressure drop, flow rate of fluids, etc. were measured. Different existing correlations were used to calculate the overall heat transfer coefficient and the results were compared with the measured value. The measured results show that the new designed heat exchanger can achieve a good heat transfer performance and also maintain a low pressure drop on shell-side (gas side).

The Effectiveness-NTU Relationship of Microchannel Counter Flow Heat Exchangers With Axial Heat Conduction

2007 ◽  
Author(s):  
B. Mathew ◽  
H. Hegab
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Microchannel Heat Exchanger ◽  
Axial Temperature ◽  
Axial Heat ◽  
Relationship Of ◽  
End Wall ◽  
Axial Heat Conduction

In this paper the effect of axial heat conduction on the thermal performance of a microchannel heat exchanger with non-adiabatic end walls is studied. The two ends of the wall separating the coolant are assumed to be subjected to boundary condition of the first kind. As the end walls are not insulated heat transfer between the microchannel heat exchanger and its surroundings occur. Analytical equations have been formulated for predicting the axial temperature of the coolants and the wall as well as for determining the effectiveness of both fluids. The effectiveness of the fluids has been found to depend on the NTU, axial heat conduction parameter and end wall temperatures. The heat transfer through the end walls have been expressed in nondimensional terms. The nondimensional heat transfer from both ends of the wall also depends on the axial heat conduction parameter and temperature gradient at the end walls. A new parameter, performance factor, has been proposed for comparing the variation in effectiveness due to axial heat conduction coupled with heat transfer with the effectiveness without axial heat conduction. The effectiveness of both the hot and cold fluid for several cases of end wall temperatures and axial heat conduction parameter are analyzed in this paper for better understanding of heat transfer dynamics of microchannel heat exchangers.

scholarly journals RESEARCH OF THE FUNCTIONING AND OPTIMIZATION PROCESS OF THE STRUCTURAL-TECHNOLOGICAL PARAMETERS

2020 ◽  
pp. 142-150
Author(s):  
Vitaliy Yaropud
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Thermal Power ◽  
Design Parameters ◽  
Theoretical Studies ◽  
Technological Parameters ◽  
Air Flows ◽  
Counter Current ◽  
Pipe Heat

Domestic and foreign scientists in recent years have performed a considerable amount of scientific research on the biological justification of optimal combinations of microclimate parameters required for the normal development of animals. However, the results of the studies do not allow one to specify the optimal parameters for different species of animals, taking into account their age, sex, weight and level of feeding. While it is possible to specify rather wide limits of change of temperature and relative humidity of air at which productivity is maximum, and technical and economic efficiency is approximately the same. Providing microclimate regulations in livestock premises is associated with significant costs of electricity and heat, which is about 17% of the producers' costs. To create a microclimate in livestock premises based on the above technological parameters and the analysis of the design features of the recuperators, two design and technological schemes of the three-pipe recuperator, which differ in the directions of movement of air flows, are proposed. The purpose of the research is to increase the efficiency of the technological process of functioning of the three-pipe recuperator for livestock premises by substantiating its structural and mode parameters. The results of theoretical studies of pneumatic losses in the three-pipe recuperator determined the dependence of pressure and power losses on the length of the air duct of the three-pipe recuperator, the radius of the external duct and the volume flow rate of air. As a result of theoretical studies, a mathematical model of the heat transfer process in a three-pipe heat exchanger was developed, with condensation in it, which allows to determine the temperature distribution of air flows by its length and its thermal capacity. The results of theoretical studies of the process of heat transfer in the design and technological schemes of a three-pipe recirculator with counter-current and direct-current showed that the counter-current variant is more effective. Optimization of the results of theoretical studies allowed us to determine the dependence of the design parameters of the three-pipe heat exchanger on the volumetric flow rate of air, subject to the highest useful thermal power.

Numerical Simulation of Fluid Flow and Heat Transfer in a Counter-Current Reactor System for Nanomaterial Production

2011 ◽  
Vol 6 (2) ◽  
Author(s):  
Cai Y Ma ◽  
Tariq Mahmud ◽  
Xue Z. Wang ◽  
Chris J Tighe ◽  
Robert I Gruar ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Industrial Process ◽  
Process Equipment ◽  
Cfd Modelling ◽  
Tubular Heat Exchanger ◽  
Heat Exchanger Design ◽  
Flow And Heat Transfer ◽  
Counter Current

Continuous hydrothermal flow synthesis (CHFS) systems can provide high quality fine nanoparticles. However, optimisation of the CHFS system including the reactor and heat exchanger design, and their scaling-up for commercial applications have not been studied and cannot be achieved only through laboratory and pilot plant experiments. CFD modelling techniques are being widely used to simulate fluid field, heat and mass transfer in a lot of industrial process equipment. However, the application of CFD to model CHFS systems is still rare. This paper employs CFD methodology to simulate fluid flow and heat transfer in a counter-current reactor and a tubular heat exchanger of a laboratory-scale CHFS system for the production of TiO2 nanoparticles. The distributions of flow and heat transfer variables such as velocity and temperature in both units are obtained using ANSYS Fluent package. The tracer concentration profile is also simulated via solving the species equations to investigate the mixing behaviour in the counter-current reactor. Temperature distributions at different locations in a counter-current reactor and a tubular heat exchanger of a CHFS system were obtained experimentally. The simulated temperatures in both the reactor and the heat exchanger are compared with the available experimental data, which reveals that a good level of agreement is achieved.

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