Experimental Study on the Heat Transfer Performance of the Diffusion-Bonded Micro Channel Heat Exchanger in the Pilot-Scale Test Facility

2013 ◽  
Author(s):  
Seok Ho Yoon ◽  
Dong-Wook Oh ◽  
Young Kim ◽  
Jun Seok Choi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Performance Test ◽  
High Efficiency ◽  
Pilot Scale ◽  
Channel Structure ◽  
Test Facility ◽  
Working Fluid ◽  
Micro Channel ◽  
Nitrogen Gas

The heat exchangers using micro channel structure have been studied due to its high efficiency and compactness. If the micro channel heat exchanger is applied to the natural gas liquefaction process, the efficiency of LNG plant can be improved. In this study, the micro channel was fabricated by chemical etching and the heat exchanger core was made by the diffusion bonding method for cryogenic reliability. For applying to the large scale plant such as LNG plant, the pilot-scale thermal performance test setup of the heat exchanger was built. Tests can be performed in the cryogenic environment. The working fluid is cryogenic nitrogen gas. Two different temperature level of nitrogen gas was made by vaporizing from liquid nitrogen. And these fluids exchange the heat through the micro channel heat exchanger. Test rig is an open loop. Therefore nitrogen gas is discharged to the ambient. Temperatures are measured by RTD sensors. Inlet pressures of heat exchanger are measured by the cryogenic pressure transducer and pressure differences of heat exchanger are measured by the differential pressure transmitters. And all the measured data is acquired by DAQ module and saved into PC. The heat transfer coefficients of the micro channel heat exchanger are calculated and the heat transfer characteristics are investigated. And the test result was compared with the existing heat transfer correlations. And the modified heat transfer correlation of the micro channel heat exchanger in the cryogenic environment is suggested.

Experimental Study on the Heat Transfer Characteristics of Cryogenic Micro Channel Heat Exchanger

2010 ◽  
Author(s):  
Seok Ho Yoon ◽  
Duckjong Kim ◽  
Jun Seok Choi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Performance Test ◽  
High Efficiency ◽  
Experimental Studies ◽  
Micro Channel ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Methane Gas ◽  
Transfer Characteristics

In recent years, many researchers investigated micro channel heat exchangers because of its high efficiency and compactness. However, few experimental studies about micro channel heat exchanger in cryogenic environment have been conducted. In this study, micro channel was fabricated by chemical etching and heat exchanger core was made by diffusion bonding method for cryogenic reliability. Performance test was conducted in cryogenic test rig. Working fluids are liquid nitrogen and methane gas. Methane gas was condensed in the micro channel heat exchanger. Heat transfer coefficients and pressure drop were measured and the heat transfer characteristics were investigated. These results can be used to design the heat exchanger of gas liquefaction plant.

Exploration of Phase Change Within a Capillary Flow Driven Square Micro-Channel Using Lattice Boltzmann Method and Experimental Boundary Conditions

2015 ◽  
Author(s):  
E. Borquist ◽  
G. Smith ◽  
L. Weiss
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Boundary Conditions ◽  
Phase Change ◽  
Lattice Boltzmann ◽  
Capillary Flow ◽  
Working Fluid ◽  
Micro Channel ◽  
External Work ◽  
Boltzmann Method

Previously published research examined the overall efficiency of heat transfer through a copper plated micro-channel heat exchanger. However, since the device is sealed and composed entirely of copper, understanding the phase change, temperature field, and density field of the working fluid is difficult empirically. Given that the efficiency was shown to be greatly increased by the working fluid phase change, this understanding within the device is important to designing devices of greater efficiency and different working fluids. One method of determining device and component performance is numerical modeling of the system. Fluids that undergo phase change have long frustrated those attempting to successfully numerically model systems with acceptable stability. Over the past twenty years, the lattice Boltzmann method (LBM) has transformed the simulation of multicomponent and multiphase flows. Particularly with multiphase flows, the LBM “naturally” morphs the phase change interface throughout the model without excessive computational complexity. The relative ease with which LBM has been applied to some multicomponent/multiphase systems inspired the use of LBM to track phase change within the previously recorded experimental boundary conditions for the copper plated heat exchanger. In this paper, the LBM was used to simulate the evaporation and condensation of HFE-7200 within a capillary flow driven square micro-channel heat exchanger (MHE). All initial and boundary conditions for the simulation are exactly those conditions at which the empirical data was measured. These include temperature and heat flux measurements entering and leaving the MHE. Working fluid parameters and characteristics were given by the manufacturer or measured during experimental work. Once the lattice size, initial conditions, and boundary conditions were input into MATLAB®, the simulations indicated that the working fluid was successfully evaporating and condensing which, coupled with the capillary driven flow, allowed the system to provide excellent heat transfer characteristics without the use of any external work mechanism. Results indicated successive instances of stratified flow along the channel length. Micro-channel flow occurring due to capillary action instead of external work mechanisms made differences in flow patterns negligible. Coupled with the experimentally measured thermal characteristics, this allowed simulations to develop a regular pattern of phase interface tracking. The agreement of multiple simulations with previously recorded experimental data has yielded a system where transport properties are understood and recognized as the primary reasons for such excellent energy transport in the device.

Design and Real Fluid Modelling of Micro-Channel Recuperators for a Nominal 100 MW Class Recuperated Recompression Brayton Cycle Using Supercritical Carbon Dioxide

2015 ◽  
Author(s):  
Joshua Schmitt ◽  
David Amos ◽  
Jayanta Kapat
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Micro Channel ◽  
One Dimensional ◽  
Supercritical Carbon

The goal of this study is to design and assess the effectiveness of a micro-channel recuperator using supercritical carbon dioxide as a working fluid. A one-dimensional thermal analysis is performed for a micro-channel recuperator suitable for a Brayton cycle with a nominal 100 MW class turbomachine. The impact of supercritical carbon dioxide properties near the critical point on the thermal performance of the recuperator is studied in detail. The cycle parameters are first obtained from an overall cycle analysis. Two adjacent flow passages with square cross-section in counter-flow configuration are considered for this analysis along with appropriate symmetry. The high pressure of SCO2 is also addressed and the structural stresses on the micro-channel walls are analyzed. Only the axial temperature variations in the hot stream and the cold stream are considered in the one-dimensional analysis. Each channel is discretized in the axial direction. Axial conduction through the wall is included in the energy balance. Of particular interest in this analysis is the variation of transport properties of the CO2 working fluid as thermodynamic conditions approach the critical point. These property variations are provided to the computer code through the REFPROP database. Over the length of the heat exchanger local changes in Reynolds number, Nusselt number, and heat transfer coefficient are charted. From the results of the heat transfer calculations, the log mean temperature difference and heat exchange effectiveness of the heat exchanger is calculated. Using the code to produce multiple results, the optimum heat exchanger design is found. Recommendations on the manufacturing method of a micro-channel recuperator are made.

Heat transfer enhancement of plate heat exchanger utilizing kaolin-including working fluid

2019 ◽  
Vol 233 (5) ◽  
pp. 626-634 ◽  
Author(s):  
Adnan Sözen ◽  
Ataollah Khanları ◽  
Erdem Çiftçi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Plate Heat Exchanger ◽  
Deionized Water ◽  
Working Fluid ◽  
Improvement Rate ◽  
Plate Heat ◽  
Triton X

Plate heat exchangers having high efficiency and small size are one of the mostly used heat exchangers. They are used in many applications ranging from cooling to heating. Heat transfer improvement of plate heat exchangers can be performed using nanoparticle-including working fluids, i.e. nanofluids. Influences of kaolin-including nanofluid utilization as working fluid on heat transfer performance of the plate heat exchanger were experimentally investigated in this study. The prepared nanofluid included 2% (wt/wt) nanoparticle content and Triton X-100 surfactant was added to the prepared mixture at the rate of 0.2% of a final concentration to increase the solubility of nanoparticles. The experiments were performed in various working conditions with changes in mass flow rate and temperature. The obtained results showed that nanofluid usage as the working fluid enhanced the heat transfer rate in plate heat exchanger in comparison to the results acquired from the tests conducted by deionized water. The improvement rate in mean heat transfer coefficient was achieved as 9.3% when kaolin–deionized water nanofluid was used as the working fluid in plate heat exchanger.

Heat Transfer Performance of Lotus-Type Porous Copper Micro-Channel Heat Sink

2013 ◽  
Vol 749 ◽  
pp. 414-420
Author(s):  
Hai Feng Chen ◽  
Yuan Liu ◽  
Liu Tao Chen ◽  
Yan Xiang Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Channel Structure ◽  
Working Fluid ◽  
Transfer Performance ◽  
Micro Channel ◽  
Porous Copper

Lotus-type porous structure is a new kind of micro-channel structure and can be used as heat sink for heat elimination of high powered electronic devices. Numerical analysis based on the simple fin model was used to predict the equivalent heat transfer coefficient of lotus-type porous copper micro-channel heat sink. Compared with the water, GaInSn working fluid could further promote the heat transfer performance of the heat sink. According to the theoretical analysis, a heat transfer coefficient as high as 14W/(cm2K) was attainable when the pressure drop was 50 KPa and an appropriate structure parameters: 0.4 mm in pore diameter, 0.4 in porosity and 4mm in height of porous copper were achieved.

scholarly journals Thermal Characteristics Analysis on Multi- Heat Pipe Induced Heat Exchanger

2019 ◽  
Vol 9 (2S2) ◽  
pp. 143-147 ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pipe ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cold Water ◽  
Hot Water ◽  
Working Fluid ◽  
Physical Parameters

In this investigation of multi heat pipe induced in heat exchanger shows the developments in heat transfer is to improve the efficiency of heat exchangers. Water is used as a heat transfer fluid and acetone is used as a working fluid. Rotameter is set to measure the flow rate of cold water and hot water. To maintain the parameter as experimental setup. Then set the mass flow rate of hot water as 40 LPH, 60LPH, 80 LPH, 100LPH, 120 LPH and mass flow rate of cold water as 20 LPH, 30 LPH, 40 LPH, 50 LPH, and 60 LPH. Then 40 C, 45 ºC, 50 ºC, 55 C, 60 ºC are the temperatures of hot water at inlet are maintained. To find some various physical parameters of Qc , hc , Re ,, Pr , Rth. The maximum effectiveness of the investigation obtained from condition of Thi 60 C, Tci 32 C and 100 LPH mhi, 60 LPH mci the maximum effectiveness attained as 57.25. Then the mhi as 100 LPH, mci as 60 LPH and Thi at 40 C as 37.6%. It shows the effectiveness get increased about 34.3 to the maximum conditions.

Performance Evaluation of a Vertical U-Tube Ground Heat Exchanger Using a Numerical Simulation Approach

2013 ◽  
Vol 724-725 ◽  
pp. 909-915
Author(s):  
Ping Fang Hu ◽  
Zhong Yi Yu ◽  
Fei Lei ◽  
Na Zhu ◽  
Qi Ming Sun ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Transfer Process ◽  
Working Fluid ◽  
Outlet Temperature ◽  
Ground Heat Exchanger ◽  
Ground Source Heat Pump ◽  
Ground Source

A vertical U-tube ground heat exchanger can be utilized to exchange heat with the soil in ground source heat pump systems. The outlet temperature of the working fluid through the U-tube not only accounts for heat transfer capacity of a ground heat exchanger, but also greatly affects the operational efficiency of heat pump units, which is an important characteristic parameter of heat transfer process. It is quantified by defining a thermal effectiveness coefficient. The performance evaluation is performed with a three dimensional numerical model using a finite volume technique. A dynamic simulation was conducted to analyze the thermal effectiveness as a function of soil thermal properties, backfill material properties, separation distance between the two tube legs, borehole depth and flow velocity of the working fluid. The influence of important characteristic parameters on the heat transfer performance of vertical U-tube ground heat exchangers is investigated, which may provide the references for the design of ground source heat pump systems in practice.

scholarly journals Experimental Study of Forced Convective Heat Transfer in a Coiled Flow Inverter Using TiO2–Water Nanofluids

2020 ◽  
Vol 10 (15) ◽  
pp. 5225
Author(s):  
Barbara Arevalo-Torres ◽  
Jose L. Lopez-Salinas ◽  
Alejandro J. García-Cuéllar
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Convective Thermal ◽  
Convective Heat Transfer Coefficients

The curved geometry of a coiled flow inverter (CFI) promotes chaotic mixing through a combination of coils and bends. Besides the heat exchanger geometry, the heat transfer can be enhanced by improving the thermophysical properties of the working fluid. In this work, aqueous solutions of dispersed TiO2 nanometer-sized particles (i.e., nanofluids) were prepared and characterized, and their effects on heat transfer were experimentally investigated in a CFI heat exchanger inserted in a forced convective thermal loop. The physical and transport properties of the nanofluids were measured within the temperature and volume concentration domains. The convective heat transfer coefficients were obtained at Reynolds numbers (NRe) and TiO2 nanoparticle volume concentrations ranging from 1400 to 9500 and 0–1.5 v/v%, respectively. The Nusselt number (NNu) in the CFI containing 1.0 v/v% nanofluid was 41–52% higher than in the CFI containing pure base fluid (i.e., water), while the 1.5 v/v% nanofluid increased the NNu by 4–8% compared to water. Two new correlations to predict the NNu of TiO2–water nanofluids in the CFI at Reynolds numbers of 1400 ≤ NRe ≤ 9500 and nanoparticle volume concentrations ranges of 0.2–1.0 v/v% and 0.2–1.5 v/v% are proposed.

scholarly journals Thermal-Hydraulic Studies on the Shell-and-Tube Heat Exchanger with Minijets

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3276 ◽  
Author(s):  
Jan Wajs ◽  
Michał Bajor ◽  
Dariusz Mikielewicz
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Waste Heat ◽  
Experimental Studies ◽  
Convection Heat Transfer ◽  
Test Facility ◽  
Experimental Investigations ◽  
Transfer Coefficients ◽  
Tube Heat Exchanger ◽  
Shell And Tube

In this paper a patented design of a heat exchanger with minijets, with a cylindrical construction is presented. It is followed by the results of its systematic experimental investigations in the single-phase convection heat transfer mode. Based on these results, validation of selected correlations (coming from the literature) describing the Nusselt number was carried out. An assessment of the heat exchange intensification level in the described heat exchanger was done through the comparison with a shell-and-tube exchanger of a classical design. The thermal-hydraulic characteristics of both units were the subjects of comparison. They were constructed for the identical thermal conditions, i.e., volumetric flow rates of the working media and the media temperatures at the inlets to the heat exchanger. The experimental studies of both heat exchangers were conducted on the same test facility. An increase in the heat transfer coefficients values for the minijets heat exchanger was observed in comparison with the reference one, whereas the generated minijets caused greater hydraulic resistance. Experimentally confirmed intensification of heat transfer on the air side, makes the proposed minijets heat exchanger application more attractive, for the waste heat utilization systems from gas sources.

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