A novel method for removing noncondensable gas from loop heat pipe. (1st May 2022)

• Record Type: Journal Article
• Authors: Anand, A.R.
• Is Part Of: Thermal science and engineering progress. Volume 30(2022)
• Publication Date: 2022-05-01
• Subjects: Loop heat pipe -- Compensation chamber -- Noncondensable gas -- Thermal management -- Space mission; Heat engineering -- Periodicals; Heat engineering; Thermodynamics; Periodicals; 621.402
• DOI: 10.1016/j.tsep.2022.101198
• Languages: English
• ISSNs: 2451-9049

Abstract

Highlights: Noncondensable gas (NCG) is a serious issue in loop heat pipes (LHPs) for space use. A method of NCG removal from LHPs is proposed for the 1st time to space industries. The method is demonstrated on an acetone-LHP with flat evaporator with air as NCG. The method can completely remove NCG from any LHP with any working fluid. A model to predict NCG mass is also proposed & validated with earlier experiments. Abstract: Noncondensable gas (NCG) is a critical issue in loop heat pipes (LHPs) for space missions and can arise due to plenty of reasons. Compensation chamber (CC) of an LHP, being a nearly stagnant point, accumulates NCG that arises due to any reason. NCG in an LHP intended for space use should be removed before its hermetic sealing itself. In this paper, a novel method is presented for the first time to completely remove NCG from LHPs through a series of attempts using a simple setup consisting of a pressure sensor, a rough vacuum pump and a metering valve connected to the CC. The method is demonstrated on an LHP with flat evaporator with acetone as working fluid and air as NCG. When the LHP operates, a certain amount of NCG is removed from the CC through the vacuum pump by momentarily opening and closing the metering valve in each attempt. Through a series of test runs, based on a decrease in the operating temperature and an increase in the maximum heat transport prior to deprime in each test run with reference to those of the previous test run, it is ascertained that a certain amount of NCG is removed in each attempt. A unique model is also proposed to predict the NCG mass based on the CC pressure and the predicted CC liquid level. Results of the proposed model are validated with those of previous experiments in the LHP containing capacitance gauge for CC liquid level measurement.