Modelling cooling down of tubular geometries to cryogenic temperatures

This paper deals with the experimental study of the cooling phenomena of pipes flooded with liquid nitrogen. The heat transfer coefficient required is obtained from a model of the cooling process. Copper, aluminium, high-grade steel and teflon pipes were tested. The pipe lengths were 3.73 m and 34 m (for copper pipe), respectively. The results of the cooling time are illustrated by diagrams that are specific of the respective material. An estimation of the cooling time for copper, aluminium and high-grade steel pipes of considerable lengths is feasible.     

Performance evaluation of cryogenic cooling in reaming titanium alloy

Removal of materials in metal cutting operations through drilling and reaming of hard materials is a difficult process. Wear of the tool and high cutting zone temperature have big effect on it. In this study, experiments have been carried out in a reaming operation on titanium alloy material under flood and cryogenic LN₂ cooling separately. Cutting speed, feed rate, and hole depth (constant) are the three input variable parameters. Torque (M_t), thrust force (F_t), cutting temperature (T), quality of the hole, surface roughness (R_a), and chip morphology are the output parameters. In both cooling conditions, each of the nine experiments based on orthogonal array (OA) L₉ were conducted under both cooling conditions. Based on the results obtained, cutting temperature was reduced by 12–21%, thrust force reduction is 17–32%, and torque reduction is 7–30% in cryogenic LN₂ cooling. Surface roughness is increased by 4–15% and hole quality (circularity and cylindricity) parameters are affected in cryogenic LN₂ cooling with respect to flood cooling. Better chip breaking was found in both flood and cryogenic LN₂ cooling. No drastic changes were observed in microstructure under both cooling conditions.     

Computational method of thermal design of solid state laser quantrons with natural cooling. 2. Parametric optimization

Recipes and results of parametric optimization of a single-tube solid-state laser quantron with natural cooling are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 2, pp. 318–322, August, 1989.     

Thermomechanical response of LNG concrete tank to cryogenic temperatures

The reinforced concrete tanks for liquefied natural gas storage, which have many advantages over steel tanks (high resistance to cryogenic temperatures and thermal shock, fatigue and buckling, fire resistance, etc.), are analyzed. Since the main drawback of concrete tanks is their poor resistance to tensile stresses, in order to investigate the thermally induced tensile stresses, a numerical model of a transient thermal analysis is presented for the evaluation of thermomechanical response of concrete tank to the cryogenic temperature, taking into account the temperature dependence of the thermophysical properties of the concrete tank thermal conductivity and specific heat.     

Numerical evaluation for debonding failure phenomenon of adhesively bonded joints at cryogenic temperatures

In the present study, material characteristics, such as inelastic constitutive behaviour and debonding failure, of an adhesively bonded joint (ABJ) at cryogenic temperature have been evaluated using a computational approach. The modified Bodner-Partom model (BP model) has been introduced to describe the material nonlinearities of ABJ. The Gurson-Tvergaard model (GT model) has also been implemented into the constitutive model in order to analyse the phenomenon of debonding failure. An ABAQUS user-defined subroutine UMAT is developed using a damage-coupled constitutive model based on an implicit formulation. The numerical results are compared with a series of lap shear tests of ABJ at cryogenic temperature in order to verify the proposed method.     

Relating damage evolution of concrete cooled to cryogenic temperatures to permeability

Typically, 9% Ni steel is used for primary containment of liquefied natural gas (LNG). Utilization of concrete in place of 9% Ni steel for primary containment would lead to significant cost savings. Hence, this study investigates changes in the microstructure of concrete due to cryogenic freezing that would affect its relevant engineering properties for containment. The study also evaluates the effect of aggregate type on the damage potential of concrete subjected to cryogenic freezing. The aim is to investigate design methodologies to produce damage-resistant cryogenic concrete. The study employed four concrete mixture designs involving river sand as fine aggregate, and coarse aggregates with different coefficient of thermal expansion (CTE) values. Specifically, the coarse aggregates were limestone, sandstone, trap rock and lightweight aggregate. Concrete cubes were cured under water for at least 28 days and thereafter frozen from ambient (20 °C) to cryogenic temperature (−165 °C). Acoustic emission (AE) sensors were placed on the concrete cubes during freezing. X-ray computed tomography (XRCT) was employed to study the microstructure of concrete cores, before and after cryogenic freezing. The impact of the microstructural evolution thus obtained from AE and XRCT on relevant engineering properties was determined via water and chloride permeability tests. Microcrack propagation determined from AE correlated with changes in permeability. There were no observable cracks in majority of the concrete mixtures after freezing. This implies that microcracks detected via AE and increased permeability was very well distributed and smaller than the XRCT’s resolution. Damage (microcracking) resistance of the concrete with different aggregates was in the order limestone ⩾ trap rock ≫ lightweight aggregate ⩾ sandstone.     

Creep of copper at cryogenic temperatures

The long-term creep behaviour of OFHC copper was investigated at 4.2 K and 77 K. At 77 K, steady-state creep was observed and the creep rates were tens of orders of magnitude higher than would be expected from extrapolations of ambient temperature creep data. The stress exponent obtained at 77 K is 2.2. The apparent activation energy at 77–90 K range is about 0.02 eV. At 4.2 K, transient creep was observed. TEM study of all crept specimens showed cell structures in support of the occurrence of substantial creep at cryogenic temperatures.     

Metrological use of intracavity laser spectroscopy

Measurement Techniques -     

Experimental study with regard to the cooling of cryogenic liquids

Results are shown of an experimental study with regard to the equilibrium or departure from it during the cooling of cryogenic liquids by vapor evacuation or by paddling with bubbles of an uncondensable gas.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 6, pp. 1078–1080, June, 1973.     

一种潜在的激光制冷介质-罗丹明B掺杂PMMA

报道了罗丹明B掺杂PMMA材料制作过程及材料吸收和荧光光谱实验。吸收光谱表明，PMMA样品从紫外到近红外范围存在较小的吸收。罗丹明B／PMMA样品吸收光谱主要反映罗丹明B的吸收特征，其吸收峰中心波长位于550nm。荧光光谱显示，以630nm激发，反斯托克斯荧光峰位于595nm，能量差为0．11eV。该材料辐射反斯托克斯荧光，可用于激光制冷领域的研究。     

Compressional cooling of He3 to millidegree temperatures

A study of adiabatic compressional cooling of a two-phase mixture of solid and liquid He ³ has been made. Details of the experimental arrangement are given. Using a flexible elastic low temperature He ³ cell that is compressed by liquid He ⁴ and precooled by a continuously operating dilution refrigerator, cooling to below 2 m°K was obtained from starting temperatures near 20 m°K. Frictional heating is remarkably low. Calculations are presented which investigate the fraction of solid formed and which suggest rather long thermal equilibrium times in the solid He ³ nuclear spin system. Application of the method to the production of bulk polarized He ³ nuclei is discussed.This research was supported by the U.S. Atomic Energy Commission under contract AT(11-1)-34, P.A. 143.This work is based on the thesis of R. T. Johnson, submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the University of Illinois.     

Behaviour of power MOSFETs at cryogenic temperatures

In this paper an investigation is reported on Siemens-power-metal-oxide-semiconductor (SIPMOS) transistors of both p and n channel types, for their suitability for cryogenic applications. The drain characteristics, temperature dependence of R_ds(on) and switching behaviour have been studied in the temperature range 4.2 – 300 K in BSS91 and BSS92 MOSFETs. The experiments reveal that these types of power transistors are well suited for operations down to ≈ 30 K. However, below 30 K the operating characteristics make them unsuitable for application. This arises because of carrier freeze-out in the n⁻ region on the substrate, which forms a drain.     

New laser materials for diode pumped solid state lasers

Ytterbium (Yb³⁺) doped solid state lasers (e.g. Yb:YAG), pumped with InGaAs laser diodes, have been intensively and successfully developed recently. A search is in progress for novel ytterbium doped crystals possessing properties superior to known Yb doped gain media, or with properties enabling of Yb lasers with new capabilities. Several such materials have been identified and characterized in the past year.     

Relevance of liquid state to solid state properties

We outline in this talk the beginning of a new programme to study physical properties of crystalline solids. It is based on considering the latter, a broken symmetry phase, in terms of the higher symmetry liquid phase. The solid is a calculable perturbation on the fluid. This is exactly opposite to the standard approach which relates mechanical properties to the behaviour of defects (mainly dislocations) etc., in an otherwise perfect crystalline solid. However, most other broken symmetry phases (e.g. ferromagnets) are discussed starting from a symmetric Hamiltonian or a free energy functional, and earlier work by one of the authors shows that the liquid-solid transition is well described, qualitatively and quantitatively, by this approach. On the other hand, defect theories of melting have a long record of nonsuccess. In the first part of the talk, the density wave theory of freezing will be outlined, and it will be shown how properties such as Debye Waller factor, entropy change of freezing etc. can be calculated with no or one free parameter. The problem of calculating shear elastic constants and dislocation core structures as well as energies in terms only of observable liquid state properties will be set up, and results presented. The method will be contrasted with zero temperature ‘atomistic’ models which obscure the essential dependence on structure and flounder in a mass of detail. The concluding part will describe further proposed applications, some suggestive experimental results extant in the literature, and some speculations. Only a summary is presented.