Thermal Resistance and Pressure Drop of Silicon Based Micro Pin Fin Heat Exchanger Under Cross Flow

2005 ◽  
Author(s):  
Ravi S. Prasher ◽  
John Dirner ◽  
Je-Young Chang ◽  
Alan Myers ◽  
David Chau ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Thermal Resistance ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Temperature Sensors ◽  
Test Chip ◽  
Pin Fin ◽  
Pin Fins ◽  
Silicon Based ◽  
Micro Pin Fins

We have performed a parametric study of the thermal and hydraulic performance of silicon-based micro pin fin heat exchangers with water as the fluid. Circular and square micro pin fins have been fabricated. The pin dimensions ranged from 50 μm to 150 μm. The test chip is unique because it has 20 micro temperature sensors of the size 75 μm × 75 μm to accurately capture the thermal resistance of the micro pin fin heat exchanger. Data shows that there is no difference in the hydraulic and the thermal resistance of circular and square pins. Conventional correlations for friction factor and Nusselt number match well with the data.

Parametrical Study of the Flat-Tube and Pin Fin Heat Exchangers

2007 ◽  
Author(s):  
Maria Pascu ◽  
Naser Sahiti ◽  
Franz Durst
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Automobile Industry ◽  
Heat Exchangers ◽  
Unit Area ◽  
Pin Fin ◽  
Flow Length ◽  
Louvered Fin ◽  
Pin Fins ◽  
Constant Versus

The main objective of the present work was the derivation of heat transfer and pressure drop characteristics for pin fins which could be applied in heat exchangers used in the automobile industry. For this, 34 models of pin fin heat exchangers, characterized by a pin diameter of 0.35 mm, with both inline and staggered arrangements, were numerically investigated. The numerical results were validated through various comparison and validation procedures. The best performing pin fin configuration was determined by employing the performance plot: heat transfer per unit volume (or per unit area, if the pin height is constant) versus the energy input reduced to the same parameter as the heat transfer (volume or area). The heat exchanger performance plot showed that, for the investigated flow length, the staggered pin fin configuration performs better when compared to the inline arrangement. In order to prove the industrial applicability of these results, a louvered fin heat exchanger, commonly used as a car radiator, was experimentally investigated. A comparison of the best performing pin fin heat exchanger with the louvered fin model revealed an enhancement in the heat transfer of the pin fin model of 35%.

Experimental Study on Air Cooling via a Multiport Mesochannel Cross-Flow Heat Exchanger

2011 ◽  
Author(s):  
Sarbadaman Dasgupta ◽  
Faisal A. Siddiqui ◽  
Md. Abdul Quaiyum ◽  
Serena A. Al-Obaidi ◽  
Amir Fartaj
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Exchanger ◽  
Thermal Resistance ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Uniform Temperature ◽  
Flow Channels ◽  
Flow Heat

Researchers are moving forward to provide energy efficient, compact and inexpensive heat exchangers. Main focus is being deployed to the heat exchangers comprising narrow size flow channels such as mesochannels and microchannels for their augmented heat transfer characteristics, compactness and energy efficiency compared to conventional heat exchangers with the same heat exchange duty. Air to water cross-flow heat exchangers are encountered in many engineering applications. While numerous investigations were performed to characterize the heat transfer and fluid flow in mesochannels and microchannels, the literatures examining the air side heat transfer and flow behaviors in the cross-flow mesochannel heat exchangers are inadequate. In the current study air side heat transfer and flow characteristics of cross-flow cooling of air through a multiport slab mesochannel heat exchanger were investigated experimentally. The major components of experimental setup are the closed loop integrated thermal wind tunnel, liquid circulation network with heat add or removal system arrangement, sets of measuring instruments, data acquisition system, and multiport slab mesochannel heat exchanger as the test specimen. The multiport slab mesochannel heat exchanger consists of 15 finned aluminum slabs with 304 mm × 304 mm size frontal area and 100 mm flow length across the direction of air flow. Each slab contains 68 flow channels of 1mm circular diameter. Cold deionized (DI) water at a constant mass flow rate (0.0196 kg/s) was forced to flow through the mesochannels whereas the hot air at different velocities was allowed to pass through the finned passages of the heat exchanger core in cross-flow orientation. The inlet air temperature was changed in three levels (28°C, 33°C and 38°C) while maintaining a constant inlet water temperature of 8° C. The air velocity was varied in four steps (3.5m/s, 5.5m/s, 7.5m/s, and 9.5 m/s) at each temperature level. In the present study heat transfer and fluid flow key parameters such as heat transfer rate (Q˙), number of transfer units (NTU), effectiveness (ε), overall thermal resistance (Rtotal), and the air side Nusselt number (Nua) as well as Reynolds number (Rea) were examined in the region of the air side Reynolds number at the range of 972–2758, with a constant water side Reynolds number of 135. Heat balance performance of the experiment was found to be 4% for all operating conditions. The air side thermal resistance was found to be dominating over the overall thermal resistance ranging from 85% to 91% of the overall thermal resistance. The effect of air side Reynolds number on air side Nusselt number was examined and a general correlation of Nusselt number with Reynolds number was obtained as Nua = 0.3972(Rea)0.3766. The Nusselt number value was found to be higher in comparison with other research works for the corresponding Reynolds number range. The multiport mesochannel flat slab has offered uniform temperature distribution into the core. This uniform temperature distribution leads to higher heat transfer over standalone inline flow tube bank.

Hydoroil-Based Micro Pin Fin Heat Sink

2006 ◽  
Author(s):  
Ali Kosar ◽  
Chih-Jung Kuo ◽  
Yoav Peles
Keyword(s):  
Heat Sink ◽  
Hydraulic Performance ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Nusselt Numbers ◽  
Friction Factors ◽  
Pin Fins ◽  
Micro Pin Fins

An experimental study on thermal-hydraulic performance of de-ionized water over a bank of shrouded NACA 66-021 hydrofoil micro pin fins with wetted perimeter of 1030-μm and chord thickness of 100 μm has been performed. Average heat transfer coefficients have been obtained over effective heat fluxes ranging from 4.0 to 308 W/cm2 and mass velocities from 134 to 6600 kg/m2s. The experimental data is reduced to the Nusselt numbers, Reynolds numbers, total thermal resistances, and friction factors in order to determine the thermal-hydraulic performance of the heat sink. It has been found that prodigious hydrodynamic improvement can be obtained with the hydrofoil-based micro pin fin heat sink compared to the circular pin fin device. Fluid flow over pin fin heat sinks comprised from hydrofoils yielded radically lower thermal resistances than circular pin fins for a similar pressure drop.

Analisis Perbandingan Jenis Material Penukar Kalor Plat Datar Aliran Silang Untuk Proses Pengeringan Kayu

2021 ◽  
Vol 9 (1) ◽  
pp. 60-71
Author(s):  
Abeth Novria Sonjaya ◽  
Marhaenanto Marhaenanto ◽  
Mokhamad Eka Faiq ◽  
La Ode M Firman
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flat Plate ◽  
Heat Exchangers ◽  
Fluid Dynamic ◽  
Cross Flow ◽  
Plate Heat ◽  
Dry Air ◽  
Copper Material ◽  
Plate Type

The processed wood industry urgently needs a dryer to improve the quality of its production. One of the important components in a dryer is a heat exchanger. To support a durable heat transfer process, a superior material is needed. The aim of the study was to analyze the effectiveness of the application of cross-flow flat plate heat exchangers to be used in wood dryers and compare the materials used and simulate heat transfer on cross-flow flat plate heat exchangers using Computational Fluid Dynamic simulations. The results showed that there was a variation in the temperature out of dry air and gas on the flat plate heat exchanger and copper material had a better heat delivery by reaching the temperature out of dry air and gas on the flat plate type heat exchanger of successive cross flow and.   overall heat transfer coefficient value and the effectiveness value of the heat exchanger of the heat transfer characteristics that occur with the cross-flow flat plate type heat exchanger in copper material of 251.74725 W/K and 0.25.

scholarly journals Experimental Study for Counter to Cross Flow Air-cooled Heat Exchangerof Annular Tube having Internal Circular grooving at Different pitches - A Review

2020 ◽  
pp. 268-274
Author(s):  
Suneel Nagar ◽  
Ajay Singh ◽  
Deepak Patel
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Operating Conditions ◽  
Theory And Practice ◽  
Thermal Flow ◽  
Total Cost ◽  
Literature Theory ◽  
Modern Analytical ◽  
Annular Tube

The objective of this study is to provide modern analytical and empirical tools for evaluation of the thermal-flow performance or design of air-cooled heat exchangers (ACHE) and cooling towers. This review consist various factors which effect the performance of ACHE. We introduced systematically to the literature, theory, and practice relevant to the performance evaluation and design of industrial cooling. Its provide better understanding of the performance characteristics of a heat exchanger, effectiveness can be improved in different operating conditions .The total cost of cycle can be reduced by increasing the effectiveness of heat exchanger.

Hydrodynamic and Thermal Characteristics of the Flow Inside a Rectangular Microchannel With Different Cylindrical Micro Pin Fins

2016 ◽  
Author(s):  
Ali Mohammadi ◽  
Ali Koşar
Keyword(s):  
Computational Study ◽  
Thermal Characteristics ◽  
3D Models ◽  
Operating Conditions ◽  
Bottom Surface ◽  
Liquid Form ◽  
Rectangular Microchannel ◽  
Pin Fin ◽  
Pin Fins ◽  
Micro Pin Fins

This article presents a computational study to investigate the hydrodynamic and thermal characteristics of the flow inside a rectangular microchannel with the dimensions of 5000 × 1500 × 100 μm3 (l × w × h’) with different inline arrangements of cylindrical micro pin fins. A parametric study is performed on the effect of different geometrical specifications of micro pin fins on the wake-pin fin interaction. Three values of (50, 100 and 200 μm) are considered for the pin fin diameters (D) while the overall height (H) of the system is set to be constant (100 μm). For the first two cases, two longitudinal and vertical pitch ratios (SL/D and ST/D) of 1.5 and 3 are considered while for H/D ratio of 0.5, only ST/D ratio of 1.5 and SL/D ratios of 1.5 and 3 are considered. As a result, a total number of ten different geometries are analyzed in five different Reynolds numbers of 20, 40, 80, 120 and 160. A constant heat flux is applied through the bottom surface of the microchannel as well as the micro pin fins surfaces. All other surfaces are assumed to be thermally isolated. Thermodynamic properties of water are set to vary with temperature and it is assumed that the working flow remains in the liquid form in all operating conditions. ANSYS commercial package v14.5 with an academic license is utilized to generate the 3D models, applying the appropriate grid networks and simulating the flow fields for each configuration. Results show major dependencies of pressure drops, friction factors, Nusselt numbers and Thermal Performance Index values on ST/D ratio and Reynolds number while minor dependencies of these parameters on SL/D and H/D ratios are observed.

Minimum Irreversibility Criteria for Heat Exchanger Configurations

1999 ◽  
Vol 121 (4) ◽  
pp. 241-246 ◽  
Author(s):  
F. E. M. Saboya ◽  
C. E. S. M. da Costa
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Second Law Of Thermodynamics ◽  
The Other ◽  
Maximum Heat ◽  
Transfer Rates ◽  
Mass Flow Rates ◽  
Flow Heat

From the second law of thermodynamics, the concepts of irreversibility, entropy generation, and availability are applied to counterflow, parallel-flow, and cross-flow heat exchangers. In the case of the Cross-flow configuration, there are four types of heat exchangers: I) both fluids unmixed, 2) both fluids mixed, 3) fluid of maximum heat capacity rate mixed and the other unmixed, 4) fluid of minimum heat capacity rate mixed and the other unmixed. In the analysis, the heat exchangers are assumed to have a negligible pressure drop irreversibility. The Counterflow heat exchanger is compared with the other five heat exchanger types and the comparison will indicate which one has the minimum irreversibility rate. In this comparison, only the exit temperatures and the heat transfer rates of the heat exchangers are different. The other conditions (inlet temperatures, mass flow rates, number of transfer units) and the working fluids are the same in the heat exchangers.

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.

Transient Response of Cross Flow Heat Exchangers Subjected to Simultaneous Temperature and Flow Perturbations

2015 ◽  
Vol 799-800 ◽  
pp. 665-670
Author(s):  
Karthik Silaipillayarputhur
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Convection Heat Transfer ◽  
Cross Flow ◽  
Balance Equations ◽  
Transfer Resistance ◽  
Mass Flow Rates ◽  
Flow Heat ◽  
Transient Thermal ◽  
Central Finite Difference

This paper compares the transient thermal performance between counter and parallel cross flow heat exchangers subjected to time varying inlet mass flow rates and inlet temperatures that hasn’t been previously discussed in the available literature. Specifically the transient performance of 2 pass and 3 pass cross flow heat exchangers is discussed in this paper. In the present study the energy balance equations for the hot and cold fluids and the heat exchanger wall were solved using an implicit central finite difference method. Representative values of NTU were considered, and the NTU’s of the heat exchanger were assumed to be uniformly distributed among the heat exchanger passes. Other physically significant parameters such as the capacity rate ratio and the convection heat transfer resistance ratio were systematically varied. A detailed summary based on the observations has been presented.

Flow Maldistribution Effects on the Temperature Uniformity in Double-Layered Microchannel Heat Sinks

2019 ◽  
Author(s):  
Carlo Nonino ◽  
Stefano Savino
Keyword(s):  
Thermal Resistance ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Total Mass ◽  
Cross Flow ◽  
Heat Sinks ◽  
Temperature Uniformity ◽  
Inlet Velocity ◽  
Microchannel Heat Sinks ◽  
Flow Maldistribution

Abstract A numerical investigation is carried out on the effects of flow maldistribution on the temperature uniformity and overall thermal resistance in double-layered microchannel heat sinks. Different flow maldistribution models accounting for the effects of some typical header designs are considered together with different combinations of the average inlet velocity in the two layers of microchannels for a given total mass flow rate. The numerical simulations are carried out using an in-house FEM procedure previously developed by the authors for the analysis of cross-flow microchannel heat exchangers.

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