Experimental investigation of 2 K JT (Joule-Thomson) cooling system using "distributed JT effect heat exchanger"

Abstract

The simplest cooling method to achieve 2 K is to use a subatmospheric cooling system of liquid helium, which may have high efficiency benefited from a counterflow heat exchanger. This paper describes the design and fabrication a specific heat exchanger with significant pressure drop using a capillary tube. It is called a "distributed JT (Joule-Thomson) effect heat exchanger". The hot and cold stream specifications of the heat exchanger are as follows; 0.4 mm ID (inner diameter), 0.64 mm OD (outer diameter) and 1.7 m length; 2.4 mm ID, 4 mm OD and 1.1 m length. The heat exchanger was operated using liquid helium as the working fluid at a pressure range of 100 kPa to 3 kPa, and a temperature range of 4.2 K to 2 K. Performance of the heat exchanger is analysed by Fanning friction factor and Colburn J-factor. The experimental investigation presents the characteristic of the distributed JT effect heat exchanger using liquid helium for the first time in the world.