Performance Characteristics of a Variable Density Pin Array Micro-Heat Exchanger

2011 ◽  
Author(s):  
George Papadopoulos ◽  
Nicholas Tiliakos ◽  
Gabriel Benel
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Variable Density ◽  
Working Fluid ◽  
Maximum Mass ◽  
Deep Reactive Ion Etching ◽  
Flow Rates ◽  
Micro Heat Exchanger ◽  
Mass Flow Rates ◽  
Nominal Feature

The design, fabrication and preliminary performance of a variable density pin array micro heat exchanger for micro-cooling applications is reported. Various pin diameters and density configurations were analyzed for their ability to provide maximum uniform heat transfer over the active area of the micro-heat exchanger using air as the working fluid for maximum mass flow rates through the micro-heat exchanger in the range of 40 mg/sec to 60 mg/sec. Fabrication of the micro-heat exchanger was performed using deep reactive ion etching (DRIE) technique on a 0.5 mm thick silicon wafer with nominal feature sizes in the range of 5 microns to 20 microns. Performance data is presented based on analysis and comparison to a baseline configuration with no pins.

scholarly journals Thermal Behaviour Analysis of Baffled Multi Heat pipe Induced Heat Exchanger

2019 ◽  
Vol 8 (4S2) ◽  
pp. 275-279
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Thermal Behaviour ◽  
Cold Water ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Compact Heat Exchanger ◽  
Improve Performance ◽  
Flow Rates ◽  
Mass Flow Rates

Thermal behaviour of a multi-heat pipe induced in compact heat exchanger has been analysed with the influence of baffles. The heat transfer fluid and working fluid used for the investigation are water and acetone. In this investigation, baffles are used to improve performance. In this research, different parameters like temperature range of hot and cold water were 50ºC, 60ºC, 70ºC and 32ºC throughout the analysis. The mass flow rates of hot and cold water ranges as 40 LPH to 120 LPH and 20 LPH to 60 LPH with an increase of 20 LPH and 10 LPH. The result shows that for an optimum revealed conditions of an angle of 0º with 60ºC and 100 LPH there is an increase in effectiveness occurs as 82.05% while comparing to without baffled conditions.

Performance Analysis of Shell and Tube Heat Exchanger using Different Nanofluids

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
J. Thavamani
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Mass Flow ◽  
Base Fluid ◽  
Particle Diameter ◽  
Flow Rates ◽  
Tube Heat Exchanger ◽  
Cold Fluid ◽  
Mass Flow Rates ◽  
Shell And Tube

Heat exchanger is the most important function in industrial sector for transferring heat energy to useful work. Heat transfer occurs between the cold fluid and hot fluid or from hot fluid to cold fluid in conduction and convection mode of through a heat exchanger wall. If heat transfer medium has very low thermal conductivity, it would have limited the efficiency of heat exchanger. Whenever the system is subjected to increased heat load, cooling is the main technical challenge for industries. The main objective of this work is to evaluate the effectiveness of shell and tube heat exchanger experimentally and analyse the flow behaviours of different nanofluids. In our experimental analysis, various nanofluids which consist of water and one percentage volume concentration of Al2O3, CuO and SiO2 passing through tube side in the shell and tube heat exchanger. The nano particle diameter is 70nm. The three dissimilar mass flow rates are considered for the experiments and their results are continuously monitored. The enhancement of heat transfer performance of CuO, Al2O3, SiO2 is compared with the base fluid water. Reynolds number values are calculated with three different mass flow rates and compared with heat transfer characteristics (LMTD, Nusselt number and overall heat transfer coefficient). SEM analysis, energy dispersive spectroscopy, X-ray diffraction of CuO, Al2O3 and SiO2.are conducted. The heat transfer effectiveness is increased by 22.12%, 19.46% and 1.47% respectively for CuO, Al2O3 and SiO2 when compared to base fluid.

Shell and tube heat exchanger thermal-hydraulic analysis equipped with baffles and corrugated tubes filled with non-Newtonian two-phase nanofluid

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ali Akbar Abbasian Arani ◽  
Reza Moradi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Mass Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Content Type ◽  
Mass Flow Rates ◽  
Shell And Tube

Purpose Using turbulators, obstacles, ribs, corrugations, baffles and different tube geometry, and also various arrangements of these components have a noticeable effect on the shell and tube heat exchangers (STHEs) thermal-hydraulic performance. This study aims to investigate non-Newtonian fluid flow characteristics and heat transfer features of water and carboxyl methyl cellulose (H2O 99.5%:0.5% CMC)-based Al2O3 nanofluid inside the STHE equipped with corrugated tubes and baffles using two-phase mixture model. Design/methodology/approach Five different corrugated tubes and two baffle shapes are studied numerically using finite volume method based on SIMPLEC algorithm using ANSYS-Fluent software. Findings Based on the obtained results, it is shown that for low-mass flow rates, the disk baffle (DB) has more heat transfer coefficient than that of segmental baffle (SB) configuration, while for mass flow rate more than 1 kg/s, using the SB leads to more heat transfer coefficient than that of DB configuration. Using the DB leads to higher thermal-hydraulic performance evaluation criteria (THPEC) than that of SB configuration in heat exchanger. The THPEC values are between 1.32 and 1.45. Originality/value Using inner, outer or inner/outer corrugations (outer circular rib and inner circular rib [OCR+ICR]) tubes for all mass flow rates can increase the THPEC significantly. Based on the present study, STHE with DB and OCR+ICR tubes configuration filled with water/CMC/Al2O3 with f = 1.5% and dnp = 100 nm is the optimum configuration. The value of THPEC in referred case was 1.73, while for outer corrugations and inner smooth, this value is between 1.34 and 1.57, and for outer smooth and inner corrugations, this value is between 1.33 and 1.52.

scholarly journals Numerical and experimental investigation of heat transfer of ZnO/Water nanofluid in the concentric tube and plate heat exchangers

2011 ◽  
Vol 15 (1) ◽  
pp. 183-194 ◽  
Author(s):  
Fard Haghshenas ◽  
Mohammad Talaie ◽  
Somaye Nasr
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Transfer Coefficients ◽  
Flow Rates ◽  
Plate Heat ◽  
Heat Transfer Coefficients ◽  
Mass Flow Rates

The plate and concentric tube heat exchangers are tested by using the water-water and nanofluid-water streams. The ZnO/Water (0.5%v/v) nanofluid has been used as the hot stream. The heat transfer rate omitted of hot stream and overall heat transfer coefficients in both heat exchangers are measured as a function of hot and cold streams mass flow rates. The experimental results show that the heat transfer rate and heat transfer coefficients of the nanofluid in both of the heat exchangers is higher than that of the base liquid (i.e., water) and the efficiency of plate heat exchange is higher than concentric tube heat exchanger. In the plate heat exchanger the heat transfer coefficient of nanofluid at mcold = mhot = 10 gr/sec is about 20% higher than base fluid and under the same conditions in the concentric heat exchanger is 14% higher than base fluid. The heat transfer rate and heat transfer coefficients increases with increase in mass flow rates of hot and cold streams. Also the CFD1 code is used to simulate the performance of the mentioned heat exchangers. The CFD results are compared to the experimental data and showed good agreement. It is shown that the CFD is a reliable tool for investigation of heat transfer of nanofluids in the various heat exchangers.

scholarly journals Experimental and CFD Analysis of GW70 based Cu Nanofluids in a Parallel Flow Heat Exchanger

2021 ◽  
Vol 10 (4) ◽  
pp. 106-110
Author(s):  
M.L.R. Chaitanya Lahari ◽  
◽  
P.H.V. Sesha Talpa Sai ◽  
K.V. Sharma ◽  
K.S. Narayanaswamy ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Mass Flow ◽  
Parallel Flow ◽  
Hot Water ◽  
Cfd Analysis ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Double Pipe ◽  
Pipe Heat

The Nusselt number, overall heat transfer, and convective heat transfer coefficients of glycerol-water-based Cu nanofluids flowing in a parallel flow double pipe heat exchanger are estimated using CFD analysis. Single-phase fluid approach technique is used in the analysis. Ansys 19.0 workbench was used to create the heat exchanger model. Heat transfer tests with nanofluids at three flow rates (680<Re<1900) are carried out in a laminar developing flow zone. For testing, a 500 mm long concentric double pipe heat exchanger with tube dimensions of ID=10.2 mm, OD= 12.7 mm, and annulus dimensions of ID=17.0 mm, OD= 19.5 mm is employed. Copper is utilized for the tube and annulus material. This study employed three-particle volume concentrations of 0.2 percent, 0.6 percent, and 1.0 percent. The mass flow rates of hot water in the tube are 0.2, 0.017, and 0.0085 kg/s, while the mass flow rates of nanofluids in the annulus are 0.03, 0.0255, and 0.017 kg/s. The average temperature of nanofluids is 36°C, whereas hot water is 58°C. In comparison to base liquid, the overall heat transfer coefficient and convective HTC of 1.0 percent copper nanofluids at 0.03 kg/s are raised by 26.2 and 46.2 percent, respectively. The experimental findings are compared to CFD values, and they are in close agreement.

Applications of Performance Tables on Steady State Analysis of Multipass Parallel Cross Flow Heat Exchanger

2017 ◽  
Vol 28 ◽  
pp. 53-72
Author(s):  
Karthik Silaipillayarputhur ◽  
Ali Al-Saif ◽  
Musab Al-Otaibi
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Heat Exchanger ◽  
Mass Flow ◽  
Thermal Performance ◽  
Rate Ratio ◽  
Cross Flow ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Operational Phase

In this paper, steady state sensible performance analysis on multi pass parallel cross flow exchanger was considered. The inputs to the heat exchanger were described through meaningful physically significant parameters such as number of transfer units, capacity rate ratio and dimensionless input temperature. The inputs to the heat exchager were varied systematically and a parametric study was conducted to determine the thermal performance at each individual pass of the heat exchanger. Heat exchanger’s thermal performance was described through the discharge temperatures that were expressed in a dimensionless form. The results from the study were presented in the form of performance tables. The performance tables employed meaningful and industry recognized dimensionless input parameters and the heat exchanger‘s performance was described through dimensionless discharge temperatures at every pass of the heat exchanger. The developed performance tables shall serve two critical aspects. First, it will help the heat exchanger designers to readily choose an optimum heat exchanger. An undersized heat exchanger shall not deliver the requirements and likewise an oversized heat exchanger shall add unnecessary weight and cost. This aspect was clearly observed in this study as indefinetly increasing the number of transfer units (or surface area) beyond a threshold value didn’t enhance the heat transfer. By employing the performance tables as a guide, the heat exchanger designers can quickly ascertain the performance of the heat exchanger without having to perform simulations and/or lengthy calculations. Second, during operational phase of the heat exchanger, the performance tables can be used to understand the performance variation of the heat exchanger with respect to mass flow rates and/or can help the engineers to choose appropriate mass flow rates for the required heat transfer. The highest heat exchanger performance was observed at the lowest capacity rate ratio and likewise the lowest heat exchanger performance was observed at the highest capacity rate ratio. In-addition, during the operational phase, the performance tables can help to detect an underperforming heat exchanger and can help the engineers to schedule maintenance activity on the heat exchanger equipment.

Boiling Heat Transfer Coefficients in a Falling Film Helical Coil Heat Exchanger for the NH3–LiNO3 Mixture

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
J. A. Hernández-Magallanes ◽  
W. Rivera
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Exchanger ◽  
Boiling Heat Transfer ◽  
Helical Coil ◽  
Falling Film ◽  
Transfer Coefficients ◽  
Flow Rates ◽  
Heat Transfer Coefficients ◽  
Mass Flow Rates

This paper reports the experimental data of boiling heat transfer coefficients for the ammonia–lithium nitrate mixture in a laminar falling film. The analyzed heat exchanger consists of a shell with an internal helical coil. More than one hundred test runs were carried out in steady-state conditions to determine the boiling heat transfer coefficients at generation temperatures, concentrations, and mass flow rates typical of absorption cooling systems of capacities between 5 and 10 kW. Ammonia vapor was produced at generation temperatures between 80 °C and 105 °C obtaining boiling heat transfer coefficients between 85 and 340 W/m2K. Semi-empirical correlations were used by diverse authors to correlate the experimental data. A new correlation was proposed with which the best adjustments were obtained. Also, the influence of the heat flux, the refrigerant solution mass flow rates, and the exit vapor qualities were analyzed in the boiling heat transfer coefficients.

Investigating the effect of nanoparticle on thermo-economic optimization of fin and tube heat exchanger

2016 ◽  
Vol 231 (6) ◽  
pp. 1127-1140 ◽  
Author(s):  
Hassan Hajabdollahi ◽  
Zahra Hajabdollahi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Mass Flow ◽  
Annual Cost ◽  
Design Parameters ◽  
Total Annual Cost ◽  
Cold Side ◽  
Flow Rates ◽  
Tube Heat Exchanger ◽  
Mass Flow Rates

In this paper, the effects of Al2O3 nanoparticles suspended in the water-based fluid on the thermo-economic properties of a fin and tube heat exchanger are studied using fast and elitism nondominated sorting genetic algorithm. Nine design parameters are selected as design parameters, and the total annual cost and effectiveness are considered as the two objective functions. First, the effect of nanoparticle on the total annual cost versus effectiveness is obtained at different cold side mass flow rates, and the results are compared with the base fluid. The results show that nanoparticles have a significant influence on the total annual cost and effectiveness in a lower cold side mass flow rates. Next, the heat exchanger volume versus effectiveness for the optimum points is measured at different cold side mass flow rates. It is demonstrated that, adding Al2O3 nanoparticle to the base fluid for the fixed value of effectiveness, decreases the heat exchanger volume, and this reduction is more significant in the lower mass flow rates. The pressure drop and total heat transfer surface area versus effectiveness for the optimum points are also obtained with and without nanoparticle. An increase in the tube side pressure drop is revealed in the nanofluid. In addition, due to the increase in the overall heat transfer coefficient, the lower heat transfer surface area is required for the fixed value of effectiveness. Finally, variations of objective functions versus particle volumetric concentration for five typical optimum points are estimated. It is concluded that an optimal value for the volumetric concentration can be obtained, in which the effectiveness is highest.

Turbulent forced convection in a shell and tube heat exchanger equipped with novel design of wing baffles

2019 ◽  
Vol 29 (6) ◽  
pp. 2103-2127 ◽  
Author(s):  
Ahmed Youcef ◽  
Rachid Saim ◽  
Hakan F. Öztop ◽  
Mohamed Ali
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Flow Rates ◽  
Content Type ◽  
Tube Heat Exchanger ◽  
Mass Flow Rates ◽  
Shell And Tube

Purpose This work presents a numerical study of the dynamic and thermal behavior of a turbulent flow in a shell and tube heat exchanger equipped with a new design of baffle type wing. The implementation of this type of baffle makes it possible to lengthen the path of the fluid in the shell, to increase the heat flux exchanged on the one hand and is to capture the weakness of the shell and tube heat exchanger with segmental baffles on the other hand. Design/methodology/approach This paper aims to analyze numerically the thermo-convective behavior of water using CFD technique by solving the conservation equations of mass, momentum and energy by the finite volume method based on the SIMPLE algorithm for coupling velocity-pressure. To describe the turbulence phenomenon, the Realizable k–ε model is employed. The analysis is done for different mass flow rates. The parameters studied are: the fluid outlet temperature, the average heat transfer coefficient, the pressure drop, the total heat transfer rate, the effect of the geometric shape of the baffle on the thermal behavior. The purpose of this study is to propose a new design of a shell and tube heat exchanger with a high heat transfer coefficient and a lower pressure drop compared to a shell and tube heat exchanger with transverse and segmental baffles. Findings The results showed that the use of the wing baffles enhanced the heat transfer coefficient significantly and reduced the friction coefficient. Compared with segmental baffles, the wing baffles are 11.67, 18.53 and 11.5 per cent lower in the pressure drop and 1.79, 1.9 and 2.39 per cent higher in the Nusselt number for the three mass flow rates 0.5, 1 and 2 kg/s, respectively. Originality/value The originality of this work lies in proposing a three-dimensional analysis for a novel heat exchanger.

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