Predicted and Measured Pressure Drop in Parallel Plate Rotary Regenerators

1980 ◽  
Vol 102 (1) ◽  
pp. 59-63 ◽  
Author(s):  
I. L. Maclaine-Cross ◽  
C. W. Ambrose
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Cross Section ◽  
Heat Exchangers ◽  
Parallel Plate ◽  
Sensible Heat ◽  
Pressure Drops ◽  
Flow Acceleration ◽  
Outlet Pressure ◽  
Measured Pressure

The flow in the passages of parallel plate rotary heat exchangers or regenerators is laminar and fully developed. Laminar flow theory should allow an accurate prediction of heat and mass transfer and pressure drop. Previously measured values of pressure drop have been 20 percent higher than predicted. Pressure drop is predicted here by considering the passage cross section rectangular and correcting for flow acceleration, property variations, and inlet and outlet pressure drop. The pressure drops measured on a parallel plate sensible heat regenerator were within 3 percent of theory and on a prototype parallel plate total heat regenerator within 4 percent.

Measurement of Pressure Drop in a Liquid Metal Reactor Fuel Assembly

2002 ◽  
Author(s):  
Seok Ki Choi ◽  
Il Kon Choi ◽  
Kil Yong Lee ◽  
Ho Yun Nam ◽  
Jong Hyeun Choi ◽  
...  
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Liquid Metal ◽  
Fuel Assembly ◽  
Diameter Ratio ◽  
Pressure Drops ◽  
Liquid Metal Reactor ◽  
The Wire ◽  
Measured Pressure ◽  
Reactor Fuel Assembly

An experimental study has been carried out to measure the pressure drop in a 271-pin fuel assembly of a liquid metal reactor. The rod pitch to rod diameter ratio (P/D) of the fuel assembly is 1.2 and the wire lead length to rod diameter ratio (H/D) is 24.84. Measurements are made for five different sections in a fuel assembly; inlet orifice, fuel assembly inlet, wire-wrapped fuel assembly, fuel assembly outlet and fuel assembly upper region. A series of water experiments have been conducted changing flow rate and water temperature. It is shown that the pressure drops in the inlet orifice and in the wire-wrapped fuel assembly are much larger than those in other regions. The measured pressure drop data in a wire-wrapped fuel assembly region is compared with the existing four correlations. It is shown that the correlation proposed by Cheng and Todreas fits the best with the present experimental data among the four correlations considered.

Effect of Viscosity on the Pressure Gradient in 4-Inch Pipe

2014 ◽  
Author(s):  
M. Mudasar Imam ◽  
Mehaboob Basha ◽  
S. M. Shaahid ◽  
Aftab Ahmad ◽  
Luai M. Al-Hadhrami
Keyword(s):  
Pressure Drop ◽  
Liquid Velocity ◽  
Pressure Drops ◽  
Increase With Increase ◽  
Empirical Relations ◽  
Inclination Angles ◽  
The Difference ◽  
Reference Pressure ◽  
Velocity Pressure ◽  
Measured Pressure

The pressure drop of liquids of different viscosities in multiphase flow is still a subject of research. This paper presents pressure drop measurements of water and oil single phase flow in horizontal and inclined 4 inch diameter stainless steel pipe at different flow rates. Potable water and Exxol D80 oil were used in the study. Experiments were carried out for different inclination angles including; 0°, 15°, 30° (upward and downward flows). Inlet liquid velocities were varied from 0.4 to 1.2 m/s and reference pressure was set at 1 bar. Water and Oil viscosities are 0.798 Pa.s and 1.56 Pa.s at 30°C, respectively. Pressure drop has been found to increase with increase in liquid velocity. Pressure drop has been observed to increase asymptotically with pipe inclination. Upward flows are associated with high pressure drop as compared to downward flows. The pressure drop of water is greater than that of oil for all inclinations. This difference can be attributed to the difference in fluid viscosities and densities. Measured pressure drops were compared with existing empirical relations and good agreement was noticed.

scholarly journals Heat Transfer Enhancement by Perforated and Louvred Fin Heat Exchangers

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 400
Author(s):  
Miftah Altwieb ◽  
Rakesh Mishra ◽  
Aliyu M. Aliyu ◽  
Krzysztof J. Kubiak
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Reynolds Numbers ◽  
Transfer Enhancement ◽  
Flow Rates ◽  
Pressure Drops ◽  
Fin Design

Multi-tube multi-fin heat exchangers are extensively used in various industries. In the current work, detailed experimental investigations were carried out to establish the flow/heat transfer characteristics in three distinct heat exchanger geometries. A novel perforated plain fin design was developed, and its performance was evaluated against standard plain and louvred fins designs. Experimental setups were designed, and the tests were carefully carried out which enabled quantification of the heat transfer and pressure drop characteristics. In the experiments the average velocity of air was varied in the range of 0.7 m/s to 4 m/s corresponding to Reynolds numbers of 600 to 2650. The water side flow rates in the tubes were kept at 0.12, 0.18, 0.24, 0.3, and 0.36 m3/h corresponding to Reynolds numbers between 6000 and 30,000. It was found that the louvred fins produced the highest heat transfer rate due to the availability of higher surface area, but it also produced the highest pressure drops. Conversely, while the new perforated design produced a slightly higher pressure drop than the plain fin design, it gave a higher value of heat transfer rate than the plain fin especially at the lower liquid flow rates. Specifically, the louvred fin gave consistently high pressure drops, up to 3 to 4 times more than the plain and perforated models at 4 m/s air flow, however, the heat transfer enhancement was only about 11% and 13% over the perforated and plain fin models, respectively. The mean heat transfer rate and pressure drops were used to calculate the Colburn and Fanning friction factors. Two novel semiempirical relationships were derived for the heat exchanger’s Fanning and Colburn factors as functions of the non-dimensional fin surface area and the Reynolds number. It was demonstrated that the Colburn and Fanning factors were predicted by the new correlations to within ±15% of the experiments.

Drag Reduction for Nanobubble Mixture Flows Through Micro-Apertures

2013 ◽  
Author(s):  
Akiomi Ushida ◽  
Tomiichi Hasegawa ◽  
Takatsune Narumi ◽  
Toshiyuki Nakajima
Keyword(s):  
Pressure Drop ◽  
Drag Reduction ◽  
Double Layer ◽  
Electric Double Layer ◽  
Glycerol Solution ◽  
Interface Behavior ◽  
Pressure Drops ◽  
Electric Interaction ◽  
Reduction Effect ◽  
Measured Pressure

Drag reduction effect for microbubble mixtures flows has been investigated and reported. However, few studies have focused on nanobubble mixtures, which have sub-micron meter size fine bubbles. In the present study, nanobubble mixtures for water and glycerol solution were passed through several sizes of micro-apertures, and the resultant pressure drops, as compared with water and glycerol solution alone, were evaluated. For small apertures, the experimentally measured pressure drop was less than that for water and glycerol alone. This phenomenon is considered in terms of interface behavior and attributed to the electric interaction between an electric double layer and fine bubbles. The results of the present study suggest that the addition of nanobubbles to a liquid results in excellent drag reduction.

Minichannel Heat Transfer: An Overview on Activities in Europe

2003 ◽  
Author(s):  
Manfred Groll ◽  
Rainer Mertz
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Pressure Drop ◽  
Heat And Mass Transfer ◽  
Heat Exchangers ◽  
Flow Boiling ◽  
Pool Boiling ◽  
Current Status ◽  
Narrow Channels ◽  
Evaporation Heat

An overview will be given about investigations on heat and mass transfer in narrow channels and narrow cavities, from work carried out in the last years up to the current status of research of some relevant scientific groups in Europe. The major topics of this report are evaporation heat transfer and the flow boiling pressure drop in narrow channels; microscale heat and mass transfer phenomena in pool boiling from enhanced evaporator tubes with sub-surface channels are also addressed. In the last years a challenging topic has been the enhancement of the efficiency of heat exchangers by employing micro-structured heat transfer surfaces. The need for smaller heat exchangers with higher heat transfer rates and/or smaller thermal approaches is caused by the ongoing miniaturisation of mechanical and electronic components, leading to higher heat fluxes which can damage or even destroy the components. On the other hand, enhanced heat transfer in big equipment, e.g. heat exchangers for the petrochemical and chemical industries, can lead to significant materials and energy savings and thus reduce environmental pollution. Therefore the European Union, European industries and national organisations have supported various projects to develop and to investigate a new generation of heat transfer surfaces, to better understand the related heat transfer phenomena and to model the heat transfer from these micro heat exchanger elements. There is a very extensive research in this scientific field, comprising both flow boiling and pool boiling. The present paper deals with heat transfer in narrow channels and/or cavities and with the flow boiling pressure drop occurring during heat and mass transfer in narrow channels. Investigations of major European institutions, carried out in the past and at the moment will be presented as a contribution to the overview on the current state-of-the-art in Europe, without claim of completeness. Some recent results on microscale pool boiling and flow boiling obtained in our institute will also be presented (Shuai et al., 2002; Kulenovic et al., 2002; Chen et al., 2002a, b).

Inlet and Outlet Pressure-Drop Effects on the Determination of Permeability and Form Coefficient of a Porous Medium

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
C. Naaktgeboren ◽  
P. S. Krueger ◽  
J. L. Lage
Keyword(s):  
Porous Medium ◽  
Pressure Drop ◽  
Parallel Plates ◽  
Pressure Drops ◽  
Outlet Pressure ◽  
Medium Length ◽  
Laminar And Turbulent Flow ◽  
Flow Through ◽  
Definition Of

The determination of permeability K and form coefficient C, defined by the Hazen-Dupuit-Darcy (HDD) equation of flow through a porous medium, requires the measurement of the total pressure drop caused by the porous medium (i.e., inlet, core, and outlet) per unit of porous medium length. The inlet and outlet pressure-drop contributions, however, are not related to the porous medium length. Hence, for situations in which these pressure drops are not negligible, e.g., for short or very permeable porous media core, the definition of K and C via the HDD equation becomes ambiguous. This aspect is investigated analytically and numerically using the flow through a restriction in circular pipe and parallel plates channels. Results show that inlet and outlet pressure-drop effects become increasingly important when the inlet and outlet fluid surface-fraction φ decreases and the Reynolds number Re increases for both laminar and turbulent flow regimes. A conservative estimate of the minimum porous medium length beyond which the core pressure drop predominates over the inlet and outlet pressure drop is obtained by considering a least restrictive porous medium core. Finally, modified K and C are proposed and predictive equations, accurate to within 2.5%, are obtained for both channel configurations with Re ranging from 10−2 to 102 and φ from 6% to 95%.

scholarly journals AN EXPERIMENTAL ASSESSMENT OF THE PLATE HEAT EXCHANGER CHARACTERISTICS BY WILSON PLOT METHOD

2016 ◽  
Vol 56 (5) ◽  
pp. 367-372 ◽  
Author(s):  
Jan Opatřil ◽  
Jan Havlík ◽  
Ondřej Bartoš ◽  
Tomáš Dlouhý
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Evaluation Method ◽  
Plate Heat Exchanger ◽  
Working Fluid ◽  
Plate Heat ◽  
Wilson Plot ◽  
Measured Pressure ◽  
Theoretical Results

An aim of this paper is suggestion of the evaluation method based on the experimental data and the Wilson plot method for the Plate Heat Exchangers (PHE). For the purpose of the project the new experimental loop was built for the testing of PHE to obtain the overhaul heat transfer coefficient and pressure drop between inlet and outlet of the fluid. The measurement were done for three different PHE with the performance range 30-100kW. The working fluid was water on both sides of the PHE. The differences are in number of pates as well as in extrusion profiles. The Wilson plot evaluation method was involved for the processing experimental data. To obtain more accurate correlations between the experimental data and theoretical results yield of the Wilson plot, the method was enhanced by the measured pressure drop involving. This approach could be useful for PHE designing software and for the manufacturing company.

Sign in / Sign up

Export Citation Format

Share Document