An air-cooled pulse tube cryocooler with 50 W cooling capacity at 77 K

Abstract

Abstract.A pulse tube cryocooler with 50 W cooling capacity at 77 K is developed to cool superconducting devices mounted on automobiles. The envisioned cryocooler weight is less than 40 kg, and the input electric power is less than 1 kW. To achieve these requirements, the working frequency is increased to 75 Hz, and the dual-opposed pistons use gas bearings to reduce compressor weight and volume. The heat from the main heat exchanger is rejected by forced convective air instead of water. The compressor and the cold finger are carefully matched to improve the efficiency. The details of these will be presented in this paper. After some adjustment, a no load temperature for the pulse tube cryocooler of 40 K was achieved with 1 kW input electric power in surroundings at 298 K. At 77 K, the cooling capacity is 50 W. If the main heat exchanger is cooled by water at 293 K, the cooling capacity increases to 64 W, corresponding to a relative Carnot efficiency of 18%.

Cross-correlation of the kinematic Sunyaev-Zel’dovich effect and 21 cm intensity mapping with tidal reconstruction

“…[18]. We make slight adjustments as to use all 5 observables in t ij [27] rather than only γ 1 and γ 2 in transverse plane. As for the influence of redshift distortion concerned in [18], linearly, it is just a change of absolute value of δ(k) related to k z , which is easy to correct.…”

Complementary Photocatalytic Toolbox: Control of Intramolecular endo- versus exo-trig Cyclizations of α-Phenyl Olefins to Oxaheterocyclic Products

“…14 Due to their biological activity and effectiveness against a number of diseases, these substances are at the focus of organic syntheses. 15 16 Recently, several groups have synthesized these compounds through cobalt- 17 , indium-, 18 and palladium-catalyzed 19 reactions. Intramolecular cyclizations by photocatalysis complement this synthetic toolbox and provide experimentally very similar but more-sustainable alternatives based on metal-free photoredox catalysis.…”