Development of a 15 K Hydrogen-Based Sorption Cooler

Abstract

At the University of Twente, a 15 K hydrogen-based sorption cooler is under development, which has no moving parts and, therefore, is essentially vibration-free. Moreover, it has the potential of a very long life. Although the cooler may operate standalone, it is designed to precool a helium-based sorption cooler that establishes 5 mW at 4.5 K, requiring a cooling power of 25 mW at the hydrogen stage. Both coolers use microporous activated carbon as the adsorption material. The combination of these two cooler stages needs a total of 5.4 W of input power and is heat sunk at two passive radiators at temperatures of about 50 K and 90 K (1.9 W and 3.5 W, respectively). We developed and built a demonstrator of the helium cooler under a previous ESA-TRP contract, and in 2008 we started a new ESA-sponsored project aiming at the development of the hydrogen stage. In the paper, the preliminary design of this hydrogen-cooler is presented, along with introductory experiments on its Joule-Thomson cold stage.

Present status of developments in physical sorption cooling for space applications

“…JT coolers are known to have a lower efficiency (especially at cooling temperatures >20 K) compared to other cooling cycles, due to the fundamentally irreversible nature of the JT process [4]. The efficiency of the sorption coolers manufactured by the University of Twente varies from 2% of Carnot for a 4.5 K Helium cooler including power consumption of the pre-cooling stage [15] to around 4% of Carnot for a 14.5 K Hydrogen cooler [22]. The 40 K Neon cooler currently under development for a ground-based application is predicted to achieve an efficiency of 1.3% of Carnot.…”

“…This cooler presented several unique challenges not present in the helium cooler [22]. First of all, the pressures in the system required dedicated check valves for the low-and high-pressure lines, each able to cope with the stringent leak rate requirements.…”

Experimental studies on a metal hydride–based single bed sorption cryocooler

“…Bowman et al developed a hydride‐based compressor intended for hydrogen liquefaction through the J‐T expansion valve, and they reported that the requisite lower temperatures were achieved in an evaporator. Burger et al developed a sorption cryocooler for producing 15 K using microporous activated carbon as the metal hydride. Bhandari et al fabricated a ‐based sorption cryocooler using hydrogen as the operational fluid for flight delivery with the Jet Propulsion Laboratory.…”

Optimization of the working fluid for a sorption-based Joule–Thomson cooler

“…Sorption-based Joule-Thomson (JT) coolers have no mechanically actuated parts and, therefore, have many advantages, such as high reliability and long-life, and the absence of vibration and electromagnetic interference [1][2][3]. The required operating temperature depends on the device to be cooled and can extend into the cryogenic range well below 80 K. Usually, for a JT cooler operating at a specific temperature, multiple working fluids can be chosen.…”