Experimental characterization of thermal-hydraulic performance of a microchannel heat exchanger for waste heat recovery

Yih, James; Wang, Hailei

doi:10.1016/j.enconman.2019.112309

Cited by 28 publications

(4 citation statements)

References 31 publications

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“…Value Air side (mixture of dry air and water vapor) Density at inlet/kgꞏm -3 0.7377 Density at outlet/kgꞏm - 3 1.0466 Thermal conductivity at inlet/Wꞏm -1 ꞏK -1 0.0357 Thermal conductivity at outlet/Wꞏm -1 ꞏK -1 0.0264 Dynamic viscosity at inlet/kgꞏm -1 ꞏs -1 2.2906×10 -5 Dynamic viscosity at inlet/kgꞏm -1 ꞏs - 1 1.8540×10 -5 Liquid water side Density at inlet/kgꞏm -3 994.0 Density at outlet/kgꞏm -3 985.2 Thermal conductivity at inlet/Wꞏm -1 ꞏK -1 0.623 Thermal conductivity at outlet/Wꞏm -1 ꞏK -1 0.649 Dynamic viscosity at inlet/kgꞏm -1 ꞏs - 1 7.20×10 -4 Dynamic viscosity at inlet/kgꞏm -1 ꞏs - 1 5.04×10 -4…”

Section: Resultsmentioning

confidence: 99%

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Evaluation of a counter-flow microchannel heat exchanger performance with air-water vapor mixture to liquid water

et al. 2020

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Given its configuration and operation conditions, the performance of a counter-flow microchannel heat exchanger (MCHX) is evaluated through detailed calculations. The fluids, both liquid water and air, are considered as continuum flow flowing in microchannels. The MCHX has 59 sheets, and each sheet has 48 microchannels. The microchannels for both fluids have the same cross section of 0.8mm×1mm and same length of 200mm. Log mean temperature difference method is adopted for this evaluation. Using appropriate equations, the properties of air-water vapor mixture are calculated based on that of the two components. Given the inlet temperature for liquid water(35℃) and air (170℃),the calculated outlet temperature for both fluids are 55.5℃ and 43.3℃, respectively. The results also show that the air at the outlet is saturated. The overall heat transfer coefficient reaches 100W/m2ꞏK, which is much higher than that of conventional heat exchanger with similar fluid combinations.

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Section: Resultsmentioning

confidence: 99%

“…Heat exchangers are usually critical components in energy systems and more and more MCHXs are used due to their advantages. In a waste heat recovery and energy conversion system [1], a nominal 10.6KW crosscounter MCHX was designed and fabricated. Oil was used to recover the heat of the exhaust gases from a diesel engine in a MCHX.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a counter-flow microchannel heat exchanger performance with air-water vapor mixture to liquid water

et al. 2020

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“…This inevitably leads to designing these crucial components as dense parallel flow systems. Dimensions of such parallelized systems then vary from large scales encountered, e.g., in process and power industries (such as heat recovery boilers [1] or fin-and-tube heat exchanger [2]) to mini-and micro-scale apparatuses (e.g., minichannels [3], or waste heat recovery micro-units [4]) according to the needs of the respective application. Although the operating conditions can be radically different, a common feature is the reported nonuniformity of flow rates, also known as flow (mal)distribution, in individual parts of the complex systems.…”

Section: Introductionmentioning

confidence: 99%

Experimentally Verified Flow Distribution Model for a Composite Modelling System

Fialová

Jegla

2021

Energies

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Requirements of modern process and power technologies for compact and highly efficient equipment for transferring large heat fluxes lead to designing these apparatuses as dense parallel flow systems, ranging from conventional to minichannel dimensions according to the specific industrial application. To avoid operating issues in such complex equipment, it is vital to identify not only the local distribution of heat flux in individual parts of the heat transfer surface but also the uniformity of fluid flow distribution inside individual parallel channels of the flow system. A composite modelling system is currently being developed for accurate design of such complex heat transfer equipment. The modeling approach requires a flow distribution model enabling to yield accurate-enough predictions in reasonable time frames. The paper presents the results of complex experimental and modeling investigation of fluid flow distribution in dividing headers of tubular-type equipment. Different modeling approaches were examined on a set of header geometries. Predictions obtained via analytical and numerical models were validated using data from the experiments conducted on additively manufactured header samples. Two case studies employing parallel flow systems (mini-scale systems and a conventional-size heat exchanger) demonstrated the applicability of the distribution model and the accuracy of the composite modelling system.

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“…Under the initial performance evaluation using heated air, its expected performance data is shown in table 2. More information about the HRU design and thermal-hydraulic performance can be found in [17].…”

Section: Introductionmentioning

confidence: 99%

Geometric measurement and characterization of a microchannel heat exchanger for performance validation

Yih

Wang

2020

Eng. Res. Express

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With substantial size and performance advantages, microchannel heat exchangers have been attracting increasing attention for various energy recovery and conversion processes. While much research and recent studies focus on their applications and performance, few studies have been devoted to the measurement and dimensional accuracy of actual microchannels in use. In this study, in-depth geometric characterization of a microchannel heat exchanger manufactured using standard photochemical etching and diffusion bonding processes is carried out. The measured channel dimensions are then compared with the design values, which can help better interpret experiment data of the heat exchanger for model validation. Two nondestructive methods were developed to measure cross-sectional areas and perimeters of the microchannels. The first method uses a stereoscopic microscope to take images of the exhaust channels at one end of the microchannel heat exchanger. An image processing routine was developed in MATLAB to measure the exhaust channel dimensions. For the second method, an optical profilometer was used to scan both the exhaust and oil channels from sample shims. Two additional MATLAB routines were developed to process the obtained 3D shim images with the capability of accounting for the bow in the shims. As results, both methods have close agreement on the measured channel dimensions. On average, the cross-sectional areas of the exhaust channels vary more significantly between individual shims due to the nature of the batch photochemical etching process; and the produced exhaust and oil channels are 11% and 8% smaller than the design values. These findings help explain the emerged discrepancy between modeling and experimental data.

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Experimental characterization of thermal-hydraulic performance of a microchannel heat exchanger for waste heat recovery

Cited by 28 publications

References 31 publications

Evaluation of a counter-flow microchannel heat exchanger performance with air-water vapor mixture to liquid water

Evaluation of a counter-flow microchannel heat exchanger performance with air-water vapor mixture to liquid water

Experimentally Verified Flow Distribution Model for a Composite Modelling System

Geometric measurement and characterization of a microchannel heat exchanger for performance validation

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