scholarly journals Design, simulation, and testing of a novel micro-channel heat exchanger for natural gas cooling in automotive applications

2016 ◽  
Author(s):  
Yibin Deng ◽  
Shyam Menon ◽  
Zoe Lavrich ◽  
Hailei Wang ◽  
Christopher Hagen
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Natural Gas ◽  
Numerical Simulations ◽  
Computational Cost ◽  
Flow Distribution ◽  
Micro Channel ◽  
The Novel ◽  
Ansys Fluent

Micro-channel heat exchangers offer potential for a highly compact solution in heat transfer applications that have space limitations. Mobile applications such as automotive vehicles are one such area. This work presents the design, modeling, simulation and testing of a two-region micro-channel heat exchanger, employing both engine coolant and R134a, for use in an engine that compresses natural gas for on-board refueling at pressures up to 250 bar. The novel design of the micro-channel heat exchanger is presented. Numerical simulations were performed using ANSYS Fluent utilizing extrapolation techniques to estimate the pressure drop as a function of flow rate and symmetry methods to investigate heat transfer. Pressure drop was determined experimentally, and heat transfer was investigated through system tests employing the novel engine. Experimental results showed good comparison with corresponding numerical simulations which demonstrated the validity of the applied extrapolation and symmetry methods, enabling considerable reduction in computational cost. The pressure drop, flow distribution, and heat transfer characteristics of the heat exchanger are discussed.

Analysis of Flow Mal-Distribution in a Cross-Flow Heat Exchanger

2014 ◽  
Vol 592-594 ◽  
pp. 1428-1432 ◽  
Author(s):  
Krishna P. Mohan ◽  
Shekar M. Santosh ◽  
M. Ramakanth ◽  
M.R. Thansekhar ◽  
M. Venkatesan
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Cross Flow ◽  
Flow Distribution ◽  
Ansys Fluent ◽  
Commercial Code ◽  
Uniform Flow Distribution ◽  
Flow Heat ◽  
Channel Assembly ◽  
Uniform Fluid

Flow mal-distribution is defined as the non-uniform fluid flow distribution among the parallel channels having a common header. Flow mal-distribution is present in every header channel assembly. This mal-distribution has a significant effect on the performance of the heat exchanger by increasing the pressure drop and affecting the heat transfer characteristics. However, in designing a heat exchanger, a uniform flow distribution in each channel is assumed. The present work attempts to reduce the flow mal-distribution in a cross flow heat exchanger. A numerical analysis is done using a commercial code ANSYS FLUENT 3D and the results are validated experimentally. A parametric study is done by changing the size of the channels within the heat exchanger so as to reduce the flow mal-distribution. The effect of varying channel size on flow mal-distribution and pressure drop across the heat exchanger is studied and a geometry with reduced flow mal-distribution is found.

Numerical Study on Flow and Heat Transfer Performance of Natural Gas in a Printed Circuit Heat Exchanger During Trans-Critical Liquefaction

2020 ◽  
Author(s):  
Ting Ma ◽  
Pan Zhang ◽  
Jie Lian ◽  
Hanbing Ke ◽  
Wei Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Natural Gas ◽  
Numerical Study ◽  
Local Pressure ◽  
Local Flow ◽  
Printed Circuit ◽  
Minimum Value ◽  
Flow And Heat Transfer

Abstract The main cryogenic heat exchanger is a core piece of equipment in the liquefaction of natural gas. The printed circuit heat exchanger is gradually becoming a primary choice for the main cryogenic heat exchanger, because it has good pressure resistance, high efficiency, and compactness. In this work, a numerical simulation is conducted to examine the local flow and heat transfer characteristics of natural gas in the printed circuit heat exchanger during trans-critical liquefaction. It is found that the heat flux density reaches a minimum value and the heat transfer is the worst when the temperature difference between the hot and cold sides is the smallest. Owing to the large variations in physical properties of trans-critical natural gas, the local pressure drop exhibits an upward parabolic shape along the flow direction, and the pressure drop reaches a minimum value near the pseudo-critical point. Finally, the friction factor and heat transfer correlations for natural gas during trans-critical liquefaction are fitted.

Heat Transfer Experiments of Ethylene Glycol-Water Mixture in Multi-Port Serpentine Meso-Channel Heat Exchanger Slab

2010 ◽  
Author(s):  
Mesbah G. Khan ◽  
Amir Fartaj
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Ethylene Glycol ◽  
Test Fluid ◽  
Water Mixture ◽  
Micro Channel ◽  
Working Fluids ◽  
Micro Channels

In past few years, narrow diameter flow passages (≤3 mm) have attracted huge research attentions due to their several advantageous features over conventional tubes (≥6 mm) especially from the view points of higher heat transfer, lesser weight, and smaller device size. Several classifications of narrow channels, based on sizes, are proposed in the open literature from mini to meso and micro (3 mm to 100 μm). The meso- and micro-channels have not yet entered into the HVAC and automotive heat exchanger industries to the expected potentials to take the above-mentioned advantages. The reasons may be the limited availability of experimental data on pressure drop and heat transfer and the lack of consolidated design correlations as compared to what is established for compact heat exchangers. While a number of studies available on standalone single straight channels, works on multi-channel slab similar to those used as typical thermal heat exchanger core elements are inadequate, especially the research on multichannel serpentine slab are limited in the open literature. The 50% ethylene glycol and water mixture is widely used in heat exchanger industry as a heat transfer fluid. Studies of pressure drop and heat transfer on this commercially important fluid using narrow tube multi-channel slab is scarce and the availability of experimental data is rare in the open literature. Conducting research on various shapes of meso- and micro-channel heat exchanger cores using a variety working fluids are a definite needs as recommended and consistently urged in ongoing research publications in this promising area. Under present long-term project, an automated dynamic single-phase experimental infrastructure has been developed to carryout the fluid flow and heat transfer research in meso- and micro-channel test specimens and prototype microchannel heat exchanger using a variety of working fluids in air-to-liquid crossflow orientation. In the series, experiments have been conducted on 50% ethylene glycol and water solution in a serpentine meso-channel slab having 68 individual channels of 1 mm hydraulic diameter to obtain the heat transfer data and the general pressure drop nature of the test fluid. Current paper presents the heat transfer characteristics of ethylene glycol-water mixture and the Reynolds number effects on pressure drop, heat transfer rate, test specimen NTU and effectiveness, overall thermal resistance, and the Nusselt number.

scholarly journals Air-side performance of a micro-channel heat exchanger in wet surface conditions

2017 ◽  
Vol 21 (1 Part A) ◽  
pp. 375-385 ◽  
Author(s):  
Raviwat Srisomba ◽  
Lazarus Asirvatham ◽  
Omid Mahian ◽  
Ahmet Dalkılıç ◽  
Mohamed Awad ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Relative Humidity ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Micro Channel ◽  
Surface Conditions ◽  
Air Inlet ◽  
Wet Surface

The effects of operating conditions on the air-side heat transfer, and pressure drop of a micro-channel heat exchanger under wet surface conditions were studied experimentally. The test section was an aluminum micro-channel heat exchanger, consisting of a multi-louvered fin and multi-port mini-channels. Experiments were conducted to study the effects of inlet relative humidity, air frontal velocity, air inlet temperature, and refrigerant temperature on air-side performance. The experimental data were analyzed using the mean enthalpy difference method. The test run was performed at relative air humidities ranging between 45% and 80%; air inlet temperature ranges of 27, 30, and 33?C; refrigerant-saturated temperatures ranging from 18 to 22?C; and Reynolds numbers between 128 and 166. The results show that the inlet relative humidity, air inlet temperature, and the refrigerant temperature had significant effects on heat transfer performance and air-side pressure drop. The heat transfer coefficient and pressure drop for the micro-channel heat exchanger under wet surface conditions are proposed in terms of the Colburn j factor and Fanning f factor.

CFD Analysis of a Shell and Tube Heat Exchanger with Single Segmental Baffles

2020 ◽  
Vol 17 (2) ◽  
pp. 7890-7901
Author(s):  
S. Mohanty ◽  
R. Arora
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Turbulence Models ◽  
Working Fluid ◽  
Ansys Fluent ◽  
Tube Heat Exchanger ◽  
Shell And Tube

In this investigation, a comprehensive approach is established in detail to analyse the effectiveness of the shell and tube heat exchanger (STE) with 50% baffle cuts (Bc) with varying number of baffles. CFD simulations were conducted on a single pass and single tube heat exchanger(HE) using water as working fluid. A counterflow technique is implemented for this simulation study. Based on different approaches made on design analysis for a heat exchanger, here, a mini shell and tube exchanger (STE) computational model is developed. Commercial CFD software package ANSYS-Fluent 14.0 was used for computational analysis and comparison with existing literature in the view of certain variables; in particular, baffle cut, baffle spacing, the outcome of shell and tube diameter on the pressure drop and heat transfer coefficient. However, the simulation results are more circumscribed with the applied turbulence models such as Spalart-Allmaras, k-ɛ standard and k-ɛ realizable. For determining the best among the turbulence models, the computational results are validated with the existing literature. The proposed study portrays an in-depth outlook and visualization of heat transfer coefficient and pressure drop along the length of the heat exchanger(HE). The modified design of the heat exchanger yields a maximum of 44% pressure drop reduction and an increment of 60.66% in heat transfer.

Numerical Simulation of Heat Transfer of Liquefied Natural Gas in Horizontal Circular Tubes under Supercritical Pressure

2014 ◽  
Vol 960-961 ◽  
pp. 438-441 ◽  
Author(s):  
Hai Yu Meng ◽  
Shu Zhong Wang ◽  
Lu Zhou ◽  
Zhi Qiang Wu ◽  
Jun Zhao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Pressure Drop ◽  
Natural Gas ◽  
Numerical Simulations ◽  
Supercritical Pressure ◽  
Liquefied Natural Gas ◽  
Design Parameters ◽  
Circular Tubes ◽  
Submerged Combustion

The submerged combustion vaporizer (SCV) is a kind of equipment used for liquefied natural gas (LNG) vaporization. In order to get insights into the heat transfer of supercritical LNG, numerical simulations were carried out in this paper for investigating heat transfer of LNG in horizontal circular tubes under supercritical pressure. Numerical results showed that LNG temperature at the outlet under the design parameters was 276 K which met the demands of application. The velocity of LNG at the outlet was 12 m/s, and the pressure drop along the ducts was 120 kPa.

A CFD-Based Optimization Design of Flow Distribution Device in the Lower Plenum of Intermediate Heat Exchanger of SFR

2017 ◽  
Author(s):  
Xiaolong Zhang ◽  
Peichi Tseng ◽  
Jiyang Yu ◽  
Muhammad Saeed
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Velocity Distribution ◽  
Optimization Design ◽  
Flow Distribution ◽  
Separated Flow ◽  
Ansys Fluent ◽  
Disk Model ◽  
Tube Heat Exchanger ◽  
Intermediate Heat Exchanger

A computational fluid dynamics based simulation is performed to optimize the design of the flow distribution device in the lower plenum of the intermediate heat exchanger (IHX) of a pool-type sodium-cooled fast reactor (SFR) in this work. As a typical shell and tube heat exchanger, hot primary sodium flows in the IHX from the top and flows over the tube bundles, called shell-side. The secondary sodium (tube-side) runs through heat transfer tubes and its inlet plenum is specified at the bottom. The flow distribution device is arranged in the lower plenum of IHX, to change the flow distribution of the secondary sodium before into the heat transfer tubes. The CFD tool used in the work is ANSYS Fluent code. Two separated flow distribution devices have been simulated and compared. First, the orifice plates, three flow distribution orifice plates with different positions in the cylinder of lower plenum are respectively set as the model 1, 2 and 3. Secondly, the conical disk model, which is arranged at the bottom of the lower plenum, is established as model 4. And changing the size of the conical disk, the model 5 is established to predict the influence of the size of the conical disk on flow distribution. The results show that all of these models have similar velocity distributions at the outlet of lower plenum, which can be divided into three separate regions, where the flow velocity is higher at the inner and outer, and the velocity in the middle is lowest. When the orifice plate is set at the higher position, the overall velocity distribution is more uniform at the outlet. And the larger conical disk could make a more uniform velocity distribution as well.

scholarly journals Numerical Investigation of Finned-tube Heat Exchanger with Circular, Elliptical & Rectangular Tubes

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Finned Tube ◽  
Ansys Fluent ◽  
Tube Heat Exchanger ◽  
Circular Tubes ◽  
Finned Tube Heat Exchanger ◽  
Rectangular Tubes

A three dimensional numerical study has been conducted on finned-tube heat exchanger with multiple rows of tubes using ANSYS (Fluent). The objective of this study is to numerically investigate finned tube heat exchanger with different type of tubes such as circular, elliptical and rectangular tubes. As circular tubes has much pressure drop so elliptical and rectangular tubes has been introduced in order to reduce pressure drop. As well as heat transfer has also been examined. The finite volume based CFD code ANSYS Fluent 16.2 is used to calculate the flow and temperature fields and by applying SIMPLEC algorithm. At low velocity of air and water, nothing significant occurred for the combination of tubes. At high velocity in maximum tube combination there was heat transfer (HT) enhancement and pressure drop reduction when compared with circular tubes only in case of air. When the combinations of circular, elliptical and rectangular tubes has been compared with circular tube heat exchanger (CTHX) heat transfer reduces as well as pressure drop (PD) also reduces for air. In case of water vapor HT and PD behaves the same. When those combinations has been compared with elliptical tube HX, for air in some cases heat transfer remains same and on other case it increases. For pressure drop in case of air, in some cases it reduces and on other cases it reduces. For elliptical tube HX for the fluid water vapor HT and PD both remains same or reduces. This work has not been with conducted any numerical simulation on rectangular Heat exchanger reason behind it there isn’t any existence of this kind of heat exchanger. However, it could be numerically conducted to examine the results between those combination and rectangular heat exchanger.

Development and Analysis of Micro-Channel Heat Exchangers for Natural Gas Cooling

2015 ◽  
Author(s):  
S. Menon ◽  
H. Ganti ◽  
H. Wang ◽  
C. Hagen
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Natural Gas ◽  
Heat Exchangers ◽  
System Performance ◽  
Ambient Air ◽  
Micro Channel ◽  
Cfd Models ◽  
Component Design ◽  
Micro Channels

Abundant availability and potential for lower CO2 emissions are drivers for increased utilization of natural gas in automotive engines for transportation applications. However scarce refueling resources for on-road vehicles impose an infrastructure limited barrier on natural gas use in transportation. A novel ‘bimodal’ engine which can operate in a compressor mode has been developed that allows on-board refueling of natural gas where available without the need for any supplemental device. Engine compression of natural gas however results in considerable heating of the gas which is undesirable from a system stand-point. Micro-channel heat exchangers have been developed to absorb heat from the natural gas using engine coolant and compressed air. This work presents the design and development of the micro-channel heat exchangers as well as a preliminary analysis of system performance. Design methodology for the heat exchanger was based on trade-off studies that correlated system performance with component design. Energy flows through the system are analyzed as a function of engine compression ratio, operating speed, charge flow rate, and ambient air and natural gas conditions. These results are further used to estimate heat transfer co-efficient and effectiveness of the micro-channel heat exchanger. Future work involves developing CFD models of the heat exchanger to obtain a detailed understanding of the conjugate heat transfer and fluid flow processes within the micro-channels.

Development of a Micro-Channel Evaporator Model for a CO2 Mobile Air-Conditioner

2000 ◽  
Author(s):  
M.-H. Kim ◽  
J. M. Yin ◽  
C. W. Bullard ◽  
P. S. Hrnjak
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Mass Transfer Process ◽  
Micro Channel ◽  
Air Conditioner ◽  
Air Conditioning System ◽  
Side Pressure ◽  
Volume Method ◽  
Energy Balances

Abstract This paper presents the development and verification of a heat exchanger model for evaluating thermal performance of an evaporator for a CO2 mobile air-conditioning system. The model has been developed, based on the finite volume method, with emphasis on the air-side heat and mass transfer process. The governing equations are derived from mass and energy balances using newly developed air-side heat transfer and friction loss correlations for micro-channel heat exchangers under dry and wet conditions. The calculated air-side heat transfer and pressure drop data are in good agreement with measured data. However, the refrigerant-side pressure drop estimation for micro-channel tubes usually underestimates the measured value. The simulation results and importance of selecting appropriate heat transfer and pressure drop correlations for the micro-channel heat exchanger are addressed.

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