Numerical analysis of clogging dynamics in micromachined Joule–Thomson coolers

Cao, Haishan; Vanapalli, Srinivas; Holland, H.J.; Vermeer, C.H.; Brake, H.J.M. ter

doi:10.1016/j.ijrefrig.2017.05.023

Cited by 13 publications

(11 citation statements)

References 21 publications

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“…When this cooler was operated with nitrogen at 8.0 MPa, the cooler could reach a stable temperature of 100 K at 20 mW heat input, and the outlet pressure was 0.6 MPa. Cao et al 17,18 presented two microchannel coolers with the dimensions of 60.0 mm × 9.5 mm × 0.7 mm. The high-pressure channel (HPC) and low-pressure channel (LPC) are all of one layer, in which several pillars with different sizes were arranged using wet etching, and the restriction was composed of 7 etched slits with a size of 2.8 mm × 0.14 mm × 1.1 um, as illustrated in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…The high-pressure channel (HPC) and low-pressure channel (LPC) are all of one layer, in which several pillars with different sizes were arranged using wet etching, and the restriction was composed of 7 etched slits with a size of 2.8 mm × 0.14 mm × 1.1 um, as illustrated in Figure 1. 18 Nitrogen was used between 8.0 and 0.1 MPa and had a cooling power at 99 K of 194 and 187 mW. Several studies have demonstrated that the combination of the microchannel with pillars and the J-T cooler is an effective way to improve the compactness and to enhance the heat transfer rate.…”

Section: Introductionmentioning

confidence: 99%

“…In observational studies, the microchannel J-T coolers mostly adopt the heat exchanger with one or two HPCs and LPCs, maybe due to the limitations of processing technology and manufacturing materials. [11][12][13][16][17][18] The cooling capacity of the J-T coolers is so small that they cannot meet the application requirements of integrated electronic equipment. Therefore, to increase the mass flow rate and cooling capacity by multiple fluids in parallel, the technology that can process laminated microchannels is need to be developed urgently.…”

Section: Introductionmentioning

confidence: 99%

“…In a study conducted by Mylavarapu et al, 27 it showed the flow and heat transfer characteristics of a PCHE with the compactness of 1050 m 2 /m 3 . The PCHE had 12 hot and 6 cold plates diffusion bonded in a single F I G U R E 1 Structure diagram of the microchannel cooler 18 [Colour figure can be viewed at wileyonlinelibrary.com] banking configuration with 11 semi-circular channels on each plate. When operating with supercritical carbon dioxide at 10.5 MPa, the heat transfer coefficient was 300-650 W/(m 2 K).…”

Section: Introductionmentioning

confidence: 99%

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Characterization of a distributed Joule‐Thomson effect cooler with pillars

et al. 2021

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The application of general Joule-Thomson (J-T) coolers in the integrated electronic equipment is limited by its compactness in the heat exchanger and cooling power (a few milliwatts to hundreds of milliwatts). However, the microchannel with pillars has many advantages, such as compact structure, tiny axial thermal conductivity, and large heat transfer area. Besides, when the pressure variation of the fluid is large in the microchannel, the distributed Joule-Thomson effect is generated significantly. Therefore, this study proposed a throttling and heat exchange structure, where heat transfer and throttling coexisted, and fabricated a laminated microchannel distributed J-T cooler with pillars utilizing the processing technology of printed circuit heat exchanger.The refrigeration performance concerning the cold-end temperature, cooling power, and temperature distribution was then investigated through experiments with two refrigerants (argon and nitrogen). The study implies that the temperature difference and cooling power of the cooler both increase with the rise of the inlet pressure with argon, the no-load cold-end temperature is 166.1 K, and the gross cooling power is 3.83 W at 5.20 MPa. The temperature of the cooler increases with the rise of heat load, while the parasitic heat load decreases. The cold-end temperature is 186.0 K, then the parasitic heat load and the gross cooling power are respectively 3.17 W and 7.17 W at 5.20 MPa under the heat load's condition of 4 W. Comparing the refrigeration performance of nitrogen and argon, the cold-end temperature of nitrogen at 5.20 MPa is 235.7 K, which is close to that of argon at 2.98 MPa. Whereas the cooling time of nitrogen is slightly shorter than that of argon, and the cooling power is 3.10 W, higher than that of argon. In addition, this study provides new insight into increasing the cooling power and reducing the application cost of miniature coolers.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of a distributed Joule‐Thomson effect cooler with pillars

et al. 2021

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“…The unique contribution of the present work is to gain insight into the impact of isotropically etched pillars on the thermal and hydrodynamic characteristics of nitrogen gas in microchannels at sub-ambient temperatures, and to develop corresponding correlations of Nusselt number and friction factor. Nitrogen gas is considered as the fluid since the pillar arrays investigated here are used in micromachined Joule-Thomson (JT) cryogenic coolers operate with nitrogen gas ( Cao et al, 2017 ). Section 2 presents the geometry of microchannels with isotropically etched pillars.…”

Section: Introductionmentioning

confidence: 99%

Heat transfer and pressure drop in microchannels with isotropically etched pillars at sub-ambient temperatures

Cao

Vanapalli

Holland

et al. 2019

International Journal of Refrigeration

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Experimental and numerical analysis of the multilayer distributed Joule‐Thomson cooler with pillars

Geng

Cui

She

et al. 2020

Intl J of Energy Research

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The conventional Joule-Thomson cooler is not compact in heat exchanger and insufficient in cooling capacity, which is limited in applying integrated electronics. However, microchannels with pillars are effective in increasing the area to volume ratio and enhancing heat transfer through the presence of vortex. Besides, multilayer microchannels are essential to enlarge the mass-flow rate in the cooler. In this study, a multilayer distributed J-T cooler with pillars is investigated. A new mathematical model of the cooler is developed and validated against the experimental data; the relative errors of the temperature and mass-flow rate are both within 5%. Furthermore, the distribution of temperature and pressure in the microchannel is analyzed by the model calculation. Numerical results show that the temperature of the high-pressure fluid decreased slightly under the influence of the heat exchange and distributed J-T effect. When the inlet pressures are 3.00, 4.00 and 5.40 MPa, the cold-end temperatures are 233.0, 185.8 and 161.2 K, respectively, with the cooling capacity reaching 2.25, 3.40 and 3.87 W, respectively. In addition, the influences of the axial heat conduction and heat leakage on the cooling performance are analyzed by using the models. The temperature rise of the cold end increases by 6.8 and 6.2 K at 5.40 MPa, respectively, considering the above two factors. The simulation model provides a useful tool for the J-T cooler.

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Numerical analysis of clogging dynamics in micromachined Joule–Thomson coolers

Cited by 13 publications

References 21 publications

Characterization of a distributed Joule‐Thomson effect cooler with pillars

Characterization of a distributed Joule‐Thomson effect cooler with pillars

Heat transfer and pressure drop in microchannels with isotropically etched pillars at sub-ambient temperatures

Experimental and numerical analysis of the multilayer distributed Joule‐Thomson cooler with pillars

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