scholarly journals Investigation of Counterflow Microchannel Heat Exchanger with Hybrid Nanoparticles and PCM Suspension as a Coolant

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Mushtaq I. Hasan ◽  
Mohammad J. Khafeef ◽  
Omid Mohammadi ◽  
Suvanjan Bhattacharyya ◽  
Alibek Issakhov
Keyword(s):  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Pure Water ◽  
Thermal Characteristics ◽  
Hybrid Nanoparticles ◽  
Working Fluid ◽  
Microchannel Heat Exchanger ◽  
Noticeable Increase ◽  
Nanoparticles Concentration

The effect of the hybrid suspension on the intrinsic characteristics of microencapsulated phase change material (MEPCM) slurry used as a coolant in counterflow microchannel heat exchanger (CFMCHE) with different velocities is investigated numerically. The working fluid used in this paper is a hybrid suspension consisting of nanoparticles and MEPCM particles, in which the particles are suspended in pure water as a base fluid. Two types of hybrid suspension are used (Al2O3 + MEPCM and Cu + MEPCM), and the hydrodynamic and thermal characteristics of these suspensions flowing in a CFMCHE are numerically investigated. The results indicated that using hybrid suspension with high flow velocities improves the performance of the microchannel heat exchanger while resulting in a noticeable increase in pressure drop. Thereupon, it causes a decrease in the performance index. Moreover, it was found that the increment of the nanoparticles’ concentration can rise the low thermal conductivity of the MEPCM slurry, but it also leads to a noticeable increase in pressure drop. Furthermore, it was found that as the thermal conductivity of Cu is higher than that for Al2O3, the enhancement in heat transfer is higher in case of adding Cu particles compared with Al2O3 particles. Therefore, the effectiveness of these materials depends strongly on the application at which CFMCHE is employed.

scholarly journals Impact of Employing Hybrid Nanofluids as Heat Carrier Fluid on the Thermal Performance of a Borehole Heat Exchanger

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2892
Author(s):  
Hossein Javadi ◽  
Javier F. Urchueguia ◽  
Seyed Soheil Mousavi Ajarostaghi ◽  
Borja Badenes
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Carrier ◽  
Pure Water ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Borehole Heat Exchanger ◽  
Carrier Fluid ◽  
Hybrid Nanofluids

In this numerical study, 4 types of hybrid nanofluid, including Ag-MgO/water, TiO2-Cu/water, Al2O3-CuO/water, and Fe3O4-multi-wall carbon nanotube/water, have been considered potential working fluid in a single U-tube borehole heat exchanger. The selected hybrid nanofluid is then analyzed by changing the volume fraction and the Reynolds number. Based on the numerical results, Ag-MgO/water hybrid nanofluid is chosen as the most favorable heat carrier fluid, among others, considering its superior effectiveness, minor pressure drop, and appropriate thermal resistance compared to the pure water. Moreover, it was indicated that all cases of Ag-MgO/water hybrid nanofluid at various volume fractions (from 0.05 to 0.20) and Reynolds numbers (from 3200 to 6200) could achieve better effectiveness and lower thermal resistances, but higher pressure drops compared to the corresponding cases of pure water. Nevertheless, all the evaluated hybrid nanofluids present lower coefficient of performance (COP)-improvement than unity which means that applying them as working fluid is not economically viable because of having higher pressure drop than the heat transfer enhancement.

EXPERIMENTAL STUDY ON THERMAL TRANSPORT PHENOMENON OF NANOFLUIDS AS WORKING FLUID IN HEAT EXCHANGER

2014 ◽  
Vol 22 (01) ◽  
pp. 1450005 ◽  
Author(s):  
SHUICHI TORII
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Horizontal Tube ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Transfer Performance ◽  
Nanoparticles Concentration ◽  
Transfer Behavior

This paper aims to study the convective heat transfer behavior of aqueous suspensions of nanoparticles flowing through a horizontal tube heated under constant heat flux condition. Consideration is given to the effects of particle concentration and Reynolds number on heat transfer enhancement and the possibility of nanofluids as the working fluid in various heat exchangers. It is found that (i) significant enhancement of heat transfer performance due to suspension of nanoparticles in the circular tube flow is observed in comparison with pure water as the working fluid, (ii) enhancement is intensified with an increase in the Reynolds number and the nanoparticles concentration, and (iii) substantial amplification of heat transfer performance is not attributed purely to the enhancement of thermal conductivity due to suspension of nanoparticles.

scholarly journals NUMERICAL INVESTIGATION OF ROUGNESS EFFECTS ON HYDERDYNMIC AND THERMAL PERFORMANCE OF COUNTER FLOW MICROCHANNEL HEAT EXCHANGER

2019 ◽  
Vol 11 (4) ◽  
pp. 426-445
Author(s):  
Ahmed A. Ali ◽  
Mushtaq I. Hasan ◽  
Ghassan Adnan
Keyword(s):  
Surface Roughness ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Substrate Material ◽  
Hydraulic Diameter ◽  
Working Fluid ◽  
Counter Flow ◽  
Roughness Effect ◽  
Microchannel Heat Exchanger ◽  
Effect Of Surface

In this paper the effect of surface roughness on the performance of counter flow microchannel heat exchanger has been numerically investigated. The studied Microchannel heat exchanger is a square shape and made of aluminum as substrate material with different values of hydraulic diameters (20, 50, 110, 150 ) μm. The working fluid used is water  at constant properties. Roughness- viscosity model has been used to study the roughness effect with 0.14 ratio of roughness to hydraulic diameter.  The results obtained indicate that pressure drop of (CFMCHX) increased with increasing surface roughness and decrease hydraulic diameter also the results showed that there is a slight increasing in thermal performance with increasing the surface roughness.

Hydrodynamic and Thermal Performance of a Vapor-Venting Microchannel Copper Heat Exchanger

2008 ◽  
Author(s):  
Milnes P. David ◽  
Amy Marconnet ◽  
Kenneth E. Goodson
Keyword(s):  
Heat Exchanger ◽  
Carbon Fiber ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Heat Exchangers ◽  
Single Phase ◽  
Two Phase ◽  
Microchannel Heat Exchanger ◽  
Large Pressure ◽  
Dry Out

Two-phase microfluidic cooling has the potential to achieve low thermal resistances with relatively small pumping power requirements compared to single-phase heat exchanger technology. Two-phase cooling systems face practical challenges however, due to the instabilities, large pressure drop, and dry-out potential associated with the vapor phase. Our past work demonstrated that a novel vapor-venting membrane attached to a silicon microchannel heat exchanger can reduce the pressure drop for two-phase convection. This work develops two different types of vapor-venting copper heat exchangers with integrated hydrophobic PTFE membranes and attached thermocouples to quantify the thermal resistance and pressure-drop improvement over a non-venting control. The first type of heat exchanger, consisting of a PTFE phase separation membrane and a 170 micron thick carbon-fiber support membrane, shows no improvement in the thermal resistance and pressure drop. The results suggest that condensation and leakage into the carbon-fiber membrane suppresses venting and results in poor device performance. The second type of heat exchanger, which evacuates any liquid water on the vapor side of the PTFE membrane using 200 ml/min of air, reduces the thermal resistance by almost 35% in the single-phase regime in comparison. This work shows that water management, mechanical and surface properties of the membrane as well as its attachment and support within the heat exchanger are all key elements of the design of vapor-venting heat exchangers.

Experimental Investigation of Heat Transfer Enhancement of Shell and Tube Heat Exchanger Using SnO2-Water and Ag-Water Nanofluids

2019 ◽  
Vol 12 (4) ◽  
Author(s):  
S. V. Sridhar ◽  
R. Karuppasamy ◽  
G. D. Sivakumar
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Convective Heat Transfer Coefficient ◽  
Two Phase ◽  
Tube Heat Exchanger ◽  
Shell And Tube

Abstract In this investigation, the performance of the shell and tube heat exchanger operated with tin nanoparticles-water (SnO2-W) and silver nanoparticles-water (Ag-W) nanofluids was experimentally analyzed. SnO2-W and Ag-W nanofluids were prepared without any surface medication of nanoparticles. The effects of volume concentrations of nanoparticles on thermal conductivity, viscosity, heat transfer coefficient, fiction factor, Nusselt number, and pressure drop were analyzed. The results showed that thermal conductivity of nanofluids increased by 29% and 39% while adding 0.1 wt% of SnO2 and Ag nanoparticles, respectively, due to the unique intrinsic property of the nanoparticles. Further, the convective heat transfer coefficient was enhanced because of improvement of thermal conductivity of the two phase mixture and friction factor increased due to the increases of viscosity and density of nanofluids. Moreover, Ag nanofluid showed superior pressure drop compared to SnO2 nanofluid owing to the improvement of thermophysical properties of nanofluid.

Statistical Determination of the Experimental Channels Clogging Rates in Mini- and Microchannel Heat Exchangers

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Witold Rybiński ◽  
Jarosław Mikielewicz
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Theoretical Model ◽  
Pressure Drop ◽  
Cold Water ◽  
Nondestructive Method ◽  
Microchannel Heat Exchanger ◽  
Statistical Determination ◽  
Experimental Values

Abstract This paper presents a new statistical, nondestructive method for determination of the experimental channels clogging rate in a mini- or microchannel heat exchanger. Channels clogging may be caused by inaccurate fabrication of the heat exchanger or by fouling of microchannels during exploitation. The theoretical model, used in this method, predicts a significant increase of the pressure drop as the number of clogged microchannels increases. However, the exchanger’s heat transfer rate decreases moderately. It may partly be caused by the additional heat transfer in metal walls, bypassing the inactive, clogged microchannels. The presented method was tested on the prototype of a microchannel heat exchanger. The experimental values of the pressure drop of the hot and cold water flows are 2–5 times higher than the values predicted for clean microchannels. The experimental values for the pressure drop and heat transfer are in good agreement with the values calculated by the use of the theoretical model. The presented statistical method gives two channels clogging rates (for the “hot” and “cold” channels) obtained during normal exploitation without cutting (destroying) the heat exchanger.

Copper Plated Microchannel Heat Exchanger for MEMS Application

2014 ◽  
Author(s):  
E. Borquist ◽  
E. Ogbonnaya ◽  
S. Thapa ◽  
D. Wood ◽  
L. Weiss
Keyword(s):  
Heat Exchanger ◽  
Closed System ◽  
Storage System ◽  
Energy Storage System ◽  
Transport Processes ◽  
Working Fluid ◽  
Microchannel Heat Exchanger ◽  
Thermal Energy Storage System ◽  
Temperature Ranges ◽  
Thermal Absorption

Demand for increased density circuit architecture, micro- and nano-scale devices, and the overall down-scaling of system components has driven research into understanding transport phenomena at reduced scales. One method to enhance transport processes is the utilization of mini-, micro-, or nano-channels which drive uniform temperature and velocity profiles throughout the system. This work specifically examines a unique heat exchanger. The exchanger is developed as a closed system, with 300μm width channels, fabricated entirely with copper. The heat exchanger has been designed for widespread use in varied environments. Further, the exchanger is working fluid non-specific, allowing for different fluids to be specified for various temperature ranges. The system design can be used equally well as a standalone heat exchanger or coupled with another device to provide a thermal energy storage system. Fabricating the heat exchanger with copper for the substrate as well as the channels themselves allows the exchanger to maintain a high thermal conductivity which aides in the fluid energy transference. The exchanger was fabricated to be a closed system removing any excess equipment such as pumps. In testing, the exchanger showed thermal absorption of 2.2kW/m2 given input of 2.63kW/m2 and working fluid amounts of 37μL. The general design and use of copper in the exchanger allowed maximum absorption of 84% of the input with operation below the boiling point of the working fluid.

scholarly journals FIBERGLASS CIRCULAR TURBULATOR IN COUNTER FLOW DOUBLE PIPE HEAT EXCHANGER: A STUDY OF HEAT TRANSFER RATE AND PRESSURE DROP

SINERGI ◽  
2020 ◽  
Vol 25 (1) ◽  
pp. 51
Author(s):  
Sudiono Sudiono ◽  
Rita Sundari ◽  
Rini Anggraini
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Preliminary Investigation ◽  
Working Fluid ◽  
Geometrical Shape ◽  
Double Pipe ◽  
Pipe Heat

This preliminary investigation studied the effect of circular turbulator vortex generator on heat transfer rate and pressure drop in a circular channel countercurrent double pipe heat exchanger with water working fluid. Increasing the number of circular turbulator yielded increasing heat transfer rate and pressure drop. The problem generated when increased pressure drop occurred in relation to more energy consumption of the water pumping system. Therefore, optimization in circular turbulator number is necessary to minimize the pressure drop about distance length between circular turbulator, tube diameter and thickness, type of material and crystal lattice, as well as the geometrical shape of fluid passage (circular or square). This study applied PVC outer tube and copper alloy inner tube, as well as fiberglass circular turbulator. The optimum results showed that seven parts of circular turbulator increasing heat transfer rate by 30% and pressure drop by 80% compared to that passage in the absence of circular turbulator at cool water debit of 7 L/min.

scholarly journals Investigation of heat transfer enhancement in an annular conduit with angled fins using functionalized GNP colloidal suspension

2021 ◽  
Vol 945 (1) ◽  
pp. 012058
Author(s):  
Sayshar Ram Nair ◽  
Cheen Sean Oon ◽  
Ming Kwang Tan ◽  
S.N. Kazi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Power Plants ◽  
Colloidal Suspension ◽  
Industrial Applications ◽  
Point Of View ◽  
Solid Particles ◽  
Working Fluid

Abstract Heat exchangers are important equipment with various industrial applications such as power plants, HVAC industry and chemical industries. Various fluids that are used as working fluid in the heat exchangers such as water, oil, and ethylene glycol. Researchers have conducted various studies and investigations to improve the heat exchanger be it from material or heat transfer point of view. There have been attempts to create mixtures with solid particles suspended. This invention had some drawbacks since the pressure drop was compromised, on top of the occurrence of sedimentation or even erosion, which incurs higher maintenance costs. A new class of colloidal suspension fluid that met the demands and characteristics of a heat exchanger was then created. This novel colloidal suspension mixture was then and now addressed as “nanofluid”. In this study, the usage of functionalized graphene nanoplatelet (GNP) nanofluids will be studied for its thermal conductivity within an annular conduit with angled fins, which encourage swirling flows. The simulation results for the chosen GNP nanofluid concentrations have shown an enhancement in thermal conductivity and heat transfer coefficient compared to the corresponding base fluid thermal properties. The data from this research is useful in industrial applications which involve heat exchangers with finned tubes.

The Effect of Using Nanofluids on Triangular Microchannel Heat Exchanger Performance

2010 ◽  
Author(s):  
G. Bhaskaran ◽  
H. A. Mohammed ◽  
N. H. Shuaib
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Volume Fraction ◽  
Numerical Study ◽  
Particle Volume Fraction ◽  
Three Dimensional ◽  
Hydrodynamic Performance ◽  
Particle Volume ◽  
Microchannel Heat Exchanger

A numerical study is performed to study the effects of using various types of nanofluids on a triangular shaped microchannel heat exchanger (MCHE). The performance of an aluminum MCHE with various types of nanofluids such as Al2O3, CuO, SiO2, Ag and TiO2 and diamond particles with particle volume fraction of 2% using water as base fluid is comprehensively analyzed. The three-dimensional steady, laminar developing flow and conjugate heat transfer of a balanced MCHE were solved using finite volume method. In order to maintain laminar flow in the microchannels, Re number was ranged from 100 to 800. The other parameters tested in this study include the effects of Reynolds number towards the temperature, effectiveness and pressure drop of the MCHE. It is found that nanofluids have improved the temperature profile and heat transfer rate of the MCHE. The increase in pressure drop was minimal while the thermal and hydrodynamic performance of the heat exchanger was enhanced.

Sign in / Sign up

Export Citation Format

Share Document