Cross-flow heat exchangers for anti-freezing of liquid nitrogen

Chang, Ho‐Myung; Gwak, Kyung Hyun; Yang, Hyung Suk; Hwang, Si-Dole

doi:10.1016/j.cryogenics.2013.06.003

Cited by 6 publications

(7 citation statements)

References 9 publications

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“…Yoshida et al presented two design ideas to avoid the freeze-out of LN flow, including a tube-in-bath type HX and a two-stage type of plate-fin HX [10]. Chang et al experimentally demonstrated that cross-flow heat exchangers are effective in avoiding the complete clog-up of all passages, mainly because the temperature distribution is two-dimensional [11]. In any case, a control strategy for the cryogenic system is indispensible for preventing the disastrous freeze-out, and this dynamic behavior should provide useful information for the design of the control system.…”

Section: Resultsmentioning

confidence: 99%

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Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

Chang¹,

Park²,

Yang³

et al. 2014

AIP Conference Proceedings

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Abstract. Dynamic simulation of a Brayton cryocooler is presented as a partial effort of a Korean governmental project to develop 1~3 km HTS cable systems at transmission level in Jeju Island. Thermodynamic design of a 10 kW Brayton cryocooler was completed, and a prototype construction is underway with a basis of steady-state operation. This study is the next step to investigate the transient behavior of cryocooler for two purposes. The first is to simulate and design the cool-down process after scheduled or unscheduled stoppage. The second is to predict the transient behavior following the variation of external conditions such as cryogenic load or outdoor temperature. The detailed specifications of key components, including plate-fin heat exchangers and cryogenic turbo-expanders are incorporated into a commercial software (Aspen HYSYS) to estimate the temporal change of temperature and flow rate over the cryocooler. An initial cool-down scenario and some examples on daily variation of cryocooler are presented and discussed, aiming at stable control schemes of a long cable system.

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Section: Resultsmentioning

confidence: 99%

“…5 and 6), and the possibility of freeze-out of LN emerges as a crucial design issue [10,11]. Yoshida et al presented two design ideas to avoid the freeze-out of LN flow, including a tube-in-bath type HX and a two-stage type of plate-fin HX [10].…”

Section: Resultsmentioning

confidence: 99%

Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

Chang¹,

Park²,

Yang³

et al. 2014

AIP Conference Proceedings

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“…Another anti-freezing scheme recently proposed by Chang et al [9] is to employ a cross-flow HX. In typical counterflow HX's, the temperature distribution of two streams is basically one-dimensional so that all flow passages may be clogged-up simultaneously under freezing condition.…”

Section: Anti-freezing Schemes Of Liquid Nitrogenmentioning

confidence: 99%

“…Chang et al [9] proposed and experimentally verified that cross-flow HX's are superior in anti-freezing of LN to typical counterflow HX's, because the temperature distribution in a cross-flow HX is basically two-dimensional. As next step, it is intended in this paper to effectively incorporate the proposed anti-freezing schemes into the practical PFHX's for the cryogenic system under development.…”

mentioning

confidence: 98%

“…well below its boiling temperature) for electrical insulation [8]. Even though the liquid (mean) temperature is above its freezing point (63.3 K), liquid may partially freeze on the HX wall [9], if the temperature of cold refrigerant (He) is lower than 63.3 K. The onset of LN freezing will result in an immediate shrink of flow passages, and may end up with a disastrous blockage of LN circulation. For safety, the cryogenic system should be operational clearly away from the freezing condition under normal load.…”

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Plate-fin Heat-exchangers for a 10 kW Brayton Cryocooler and a 1 km HTS Cable

et al. 2015

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Plate-fin heat exchangers (PFHX) are designed and fabricated for a cryogenic cooling system, serving for a 10 kW Brayton cryocooler and a 1 km HTS transmission cable under development in Korea. To achieve compactness and thermal efficiency at the same time, a recuperative HX for Brayton cycle and a sub-cooling HX of liquid nitrogen for HTS cable are designed as integrated parts. A key design feature is focused on the coldest part of sub-cooling HX, where the streams of liquid nitrogen and refrigerant (helium gas) are arranged as two-pass cross-flow so that the risk of freeze-out of liquid nitrogen can be reduced. Details of hardware PFHX design are presented and discussed towards its immediate application to the HTS cable system. A 10 kW Brayton cryocooler is under development in Korea as partial effort of the governmental project for hightemperature superconductor (HTS) power cable [1][2]. The goal of this project is to install and demonstrate the HTS cable and its cryogenic cooling system over 1 km length of transmission line (at 154 kV) in Jeju Island by 2016. The distributed thermal load is carried by a circulating flow of liquid nitrogen (LN) to the Brayton cooler [2]-[4] which is

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A review of the crosswind effect on the natural draft cooling towers

Gurgenci

Guan

et al. 2019

Applied Thermal Engineering

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Crosswind is a significant concern for the design and operation of a natural draft cooling tower. The negative effects of crosswind on the thermal performance of natural draft cooling towers have been shown in many cases, for a variety of tower types. This paper presents a comprehensive review to synthesize the current research status in this field. At first, three common cooling tower research methods used to quantify the crosswind effect: full-scale/field measurements, lab-scale tests and CFD modelling, are reviewed and discussed. Then, based on the existing literature, the crosswind effect and its working mechanism on different types of natural draft cooling towers are summarized and discussed. Finally, the most current findings and solutions to address the crosswind issue are reported. The main advantages and disadvantages of each solution are presented and discussed. The information collected in this review paper could be a useful guidance for the design and optimization of natural draft cooling tower.

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Cross-flow heat exchangers for anti-freezing of liquid nitrogen

Cited by 6 publications

References 9 publications

Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

Plate-fin Heat-exchangers for a 10 kW Brayton Cryocooler and a 1 km HTS Cable

A review of the crosswind effect on the natural draft cooling towers

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