Numerical Simulation of a Microencapsulated Phase Change Material Slurry Flowing in a Helical Coil Heat Exchanger

2013 ◽  
Author(s):  
Ehsan M. Languri ◽  
Aly H. Shaaban ◽  
Minsuk Kong ◽  
Jorge L. Alvarado
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Heat Exchangers ◽  
Helical Coil ◽  
Microencapsulated Phase Change Material ◽  
Coil Heat Exchanger ◽  
Change Material ◽  
Coil Heat

Heat transfer analysis of microencapsulated phase change material (MCPM) slurry flowing through a helical coil heat exchanger was carried out numerically. MPCM slurry at different mass fractions with known thermal and physical properties was chosen as heat transfer fluid (HTF). MPCM slurries can carry significantly higher thermal load when the PCM undergoes phase change within a specified temperature range. However, little is known as to how MPCM behave in helical coil heat exchangers. Helical coil heat exchangers are being used widely in many industrial applications including air conditioning systems due to their compactness and high thermal effectiveness. Enhancing the heat transfer rate of coil heat exchanger by using MPCM slurry without altering the existing parameters of coil heat exchangers such as shell diameter should lead to energy savings due to reductions in HTF pumping energy demands at identical heat loads. The ultimate goal of this study is to show a significant enhancement in heat transfer when MPCM slurry is pumped through helical coil heat exchangers. Unlike traditional HTF used in helical coil heat exchangers, the proposed MPCM slurry could alter the flow structure and the internal convection by inducing and enhancing the formation of secondary flows, as a result of phase change in the microencapsulated phase change material. Specifically, a three dimensional numerical study was undertaken to understand the effects of the helical coil heat exchanger geometry and the HTF flow characteristics on heat transfer enhancement. Baseline numerical simulations were conducted using water as HTF in order to compare with MPCM slurry numerical results. The numerical model was solved based on the finite volume method. The temperature-dependent properties of MPCM slurry and boundary conditions were considered. The promising results of this numerical study demonstrate the importance of formulated HTF and the geometry of the heat exchanger on the heat transfer enhancement and energy savings.

Thermal Performance of Microencapsulated Phase Change Material Slurry in a Coil Heat Exchanger

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Min-Suk Kong ◽  
Kun Yu ◽  
Jorge L. Alvarado ◽  
Wilson Terrell
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Phase Change ◽  
Thermal Performance ◽  
Mass Fraction ◽  
Microencapsulated Phase Change Material ◽  
Coil Heat Exchanger ◽  
Change Material ◽  
Coil Heat

An experimental study has been carried out to investigate the convective heat transfer and pressure drop characteristics of microencapsulated phase change material (MPCM) slurry in a coil heat exchanger (CHX). The thermal and fluid properties of the MPCM slurries were determined using a differential scanning calorimeter (DSC) and a rotating drum viscometer, respectively. The overall heat transfer coefficient and pressure drop of slurries at 4.6% and 8.7% mass fractions were measured using an instrumented CHX. A friction factor correlation for MPCM slurry in the CHX has been developed in terms of Dean number and mass fraction of the MPCM. The effects of flow velocity and mass fraction of MPCM slurry on thermal performance have been analyzed by taking into account heat exchanger effectiveness and the performance efficiency coefficient (PEC). The experimental results showed that using MPCM slurry should improve the overall performance of a conventional CHX, even though the MPCM slurries are characterized by having high viscosity.

An Experimental Study of Heat Transfer Characteristics of Microencapsulated Phase Change Material Slurry in a Coil Heat Exchanger

2013 ◽  
Author(s):  
Minsuk Kong ◽  
Jorge L. Alvarado ◽  
Ehsan M. Languri
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Coil Heat Exchanger ◽  
Change Material ◽  
Coil Heat

The use of microencapsulated phase change material (MPCM) slurry as an enhanced heat transfer fluid is considered to be very promising for saving energy in thermal energy systems. However, little is known how MPCM may exhibit enhanced heat transfer performance in coil heat exchanger. Coil heat exchangers are extensively used in industrial applications including heating, ventilating and air conditioning (HVAC) systems because of their superior heat transfer performance and compactness. In this study, the heat transfer characteristics of MPCM slurry in a coil heat exchanger have been investigated experimentally. Thermal properties of MPCM slurry were measured using a differential scanning calorimeter. Pressure drop, overall heat transfer coefficient and heat transfer effectiveness in a coil heat exchanger were determined by considering different flow rates. It was found that heat transfer characteristics were positively affected by the phase change process of the phase change material in MPCM, even though MPCM exhibit reduced turbulence and increased pressure drop. The overall heat transfer coefficient for MPCM slurry is in the range of 5,000 to 9,000 W/m2-K over a Dean number range from 1,600 to 4,000 (equivalent Reynolds number range of 6,000 to 15,000). The enhancement in heat transfer performance is about 17% when compared to that for water. In addition, durability tests of MPCM slurry were conducted to evaluate the MPCM’s ability to withstand continuous pumping conditions, which is critically important in the implementation of MPCM slurry in industrial applications.

scholarly journals Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness

2016 ◽  
Vol 37 (4) ◽  
pp. 137-159 ◽  
Author(s):  
Rafał Andrzejczyk ◽  
Tomasz Muszyński
Keyword(s):  
Heat Transfer ◽  
Surface Modification ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Helical Structure ◽  
Nuclear Industry ◽  
Helical Coil ◽  
Tube Heat Exchanger ◽  
High Heat Transfer ◽  
Coil Heat

Abstract The shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil, centrifugal force is acting on the moving fluid due to the curvature of the tube results in the development. It has been long recognized that the heat transfer in the helical tube is much better than in the straight ones because of the occurrence of secondary flow in planes normal to the main flow inside the helical structure. Helical tubes show good performance in heat transfer enhancement, while the uniform curvature of spiral structure is inconvenient in pipe installation in heat exchangers. Authors have presented their own construction of shell and tube heat exchanger with intensified heat transfer. The purpose of this article is to assess the influence of the surface modification over the performance coefficient and effectiveness. The experiments have been performed for the steady-state heat transfer. Experimental data points were gathered for both laminar and turbulent flow, both for co current- and countercurrent flow arrangement. To find optimal heat transfer intensification on the shell-side authors applied the number of transfer units analysis.

Sign in / Sign up

Export Citation Format

Share Document