Cryogenic Loop Heat Pipes for the Cooling of Small Particle Detectors at Cern

Abstract

The loop heat pipe (LHP) is among the most effective heat transfer elements. Its principle is based on a continuous evaporation/condensation process and its passive nature does not require any mechanical devices such as pumps to circulate the cooling agent. Instead a porous wick structure in the evaporator provides the capillary pumping forces to drive the fluid [1]. Cryogenic LHP are investigated as potential candidates for the cooling of future small-scale particle detectors and upgrades of existing ones. A large spectrum of cryogenic temperatures can be covered by choosing appropriate working fluids. For high luminosity upgrades of existing experiments installed at the Large Hadron Collider (LHC) (TOTEM) and planned ones (FP420) [2][3] being in the design phase, radiation-hard solutions are studied with noble gases as working fluids to limit the radiolysis effect on molecules detrimental to the functioning of the LHP. The installation compactness requirement of experiments such as the CAST frame-store CCD detector cooling system impels also the design of a compact shaped LHP [4]. This paper reports on the design and experimental results of a general purpose LHP for temperatures as low as 110 K, for which the performances were measured using a Gifford-McMahon (GM) cooler as the cold source, combination envisaged for the cooling of future particle detectors.. CERN-ATS-2010-017January 2010 Abstract CRYOGENIC LOOP HEAT PIPES FOR THE COOLING OF SMALL PARTICLE DETECTORS AT CERNH. Pereira, F. Haug, P. Silva, J. Wu, T. Koettig CERN CH-1211, Geneva, 23, Switzerland ABSTRACTThe loop heat pipe (LHP) is among the most effective heat transfer elements. Its principle is based on a continuous evaporation/condensation process and its passive nature does not require any mechanical devices such as pumps to circulate the cooling agent. Instead a porous wick structure in the evaporator provides the capillary pumping forces to drive the fluid [1]. Cryogenic LHP are investigated as potential candidates for the cooling of future small-scale particle detectors and upgrades of existing ones. A large spectrum of cryogenic temperatures can be covered by choosing appropriate working fluids. For high luminosity upgrades of existing experiments installed at the Large Hadron Collider (LHC) (TOTEM) and planned ones (FP420) [2][3] being in the design phase, radiation-hard solutions are studied with noble gases as working fluids to limit the radiolysis effect on molecules detrimental to the functioning of the LHP. The installation compactness requirement of experiments such as the CAST frame-store CCD detector cooling system impels also the design of a compact shaped LHP [4]. This paper reports on the design and experimental results of a general purpose LHP for temperatures as low as 110 K, for which the performances were measured using a Gifford-McMahon (GM) cooler as the cold source, combination envisaged for the cooling of future particle detectors.

Development of cryogenic loop heat pipes: A review and comparative analysis

“…Pereira et al [22] constructed and experimentally investigated a CLHP as a potential candidate for the cooling of small-scale particle detectors. Noble gases and propane were selected as the cryogenic working fluids.…”

Thermal management and mechanical structures for silicon detector systems

“…Loop heat pipes (LHPs) use capillaries and have recently been studied for use in the CAST experiment. Prototypes have been shown to transfer 30 W over 350 mm at cryogenic temperatures in all orientations [45]. Open evaporative cooling systems using wicks to transport the coolant to the heat sources have been studied for the SSC experiments using Butane as a coolant [46].…”

Experimental study on the supercritical startup of cryogenic loop heat pipes with redundancy design

“…Because the critical temperatures of the cryogenic working fluids are much lower than the ambient temperature, i.e., the critical temperature of nitrogen is about 126 K, and the cryogenic working fluids are in the supercritical state at ambient temperature. In order to start up the CLHP, prior to the application of heat load to the evaporator, the working fluid inside must be first cooled to below its critical temperature until it condenses and saturates the evaporator wick, and an auxiliary measure will be needed to help realize the liquid saturation of the evaporator wick [16]. From the above analysis, a CLHP will inevitably experience a supercritical startup to realize the normal operation.…”

“…So far, several types of CLHPs employing different auxiliary measures to realize the supercritical startup have been developed, such as the gravity-assisted method [16], the secondary evaporator method [17][18][19][20][21][22], the auxiliary loop method [23][24][25][26][27][28] and the capillary pump method [29][30], as reviewed in our previous paper [31]. Because the CLHP employing the auxiliary loop method can realize the supercritical startup in space microgravity environment, and can manage the parasitic heat load effectively with a relatively high heat transport capacity, it is the most suitable for space applications and is selected as the object of study in this work.…”