IJIRST –International Journal for Innovative Research in Science & Technology| Volume 1 | Issue 6 | November 2014 ISSN (online): 2349-6010
Design Analysis And Optimization of Double Wall Vacuum Vessel- A Review Paper Jayesh B. Khunt Assistant Professor Mechanical Engineering Department NarnarayanshastriInstitute of Technology, Jetalpur
Kunalkumar M. Jadav ME Student Mechanical Engineering Department NarnarayanshastriInstitute of Technology, Jetalpur
Abstract Present study is aimed towards design and study of cryogenic doubled wall vacuum vessels. A liquid nitrogen storage vessel has been considered for present study. Thermal loading due to temperature differential between low temperature liquid nitrogen and atmospheric temperature is considered as a major factor for designing the vessel. In addition to this, fatigue due to thermal cycling of vessel is considered. Moreover vessel will be subjected to structural loads, e.g. dead weight of the vessel, transportation accelerations and seismic actions. All these structural boundary conditions are applied for present study and accordingly design and optimization of vessel is carried out. Keywords: Vacuum vessel, cryogenic fluids, pressure vessels. _______________________________________________________________________________________________________
I. INTRODUCTION Cryogenics is the science and technology associated with generation of low temperature below 123 K. Cryogenics come from the two words.Kryo means” very cold(frost)” and Genicsmeans “To produce”.So its “Science and art of producing very cold”. Difference between cryogenics and refrigeration fluids are shown in table 1.1. Cryogenic liquids are used for accessing low temperatures. They are extremely cold, with boiling points below 123K. Carbon dioxide and nitrous oxide, which have slightly higher boiling points, are sometimes included in this category. Cryogens have high expansion ratios, which average ~700:1. When they are heated (i. e., exposed to room temperature), they vaporize (turn into a gas) very rapidly. If the volume cannot be expanded (no outlet), the pressure will increase approximately 700-fold or until it blows something out.
123K
300K
Table - 1.1 Cryogen fluids and refrigeration fluids boiling temperature Cryogenics Refrigeration O2 (90.19 K) R134a (246.8 K) Air(78.6 K) R12 (243.3 K) N2 (77.36 K) R22 (233 K) H2 (20.39 K) Propane (231.1 K) He (4.2 K) Ethane (184 K)
The typical container used to store and handle cryogenic fluids is the dewar. The dewar is multi-walled designed with a vacuum jacket for insulation and pressure relief valves to protect against over-pressurization. Cryogens normally are stored at low pressure. All cryogen dewars should be clearly labeled and operated in accordance with the manufacturer's instructions. In table 1.2 some cryogens with its boiling point (K) and Triple points are shown. Table - 1.2 Boiling and triple point of cryogenics fluid Cryogen Boiling Point(K) Triple Point(K) Methane, CH4 111.67 90.69 Oxygen, O2 90.19 54.36 Argon, Ar 87.30 83.81 Air(N2+O2+Ar) 78.6 59.75 Nitrogen, N2 77.36 63.15 Normal H2
20.39
13.96
He4 He3
4.230 3.191
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