Helium liquefier/refrigerator

Sesuai dengan kegunaannya mesin  pendingin terdiri dari beberapa jenis antara lain :
1. Refrigerator untuk keperluan Industri.
2. Lemari es / Kulkas.
3. Freezer (Pembekuan / pendingin makanan dan minuman).
4. Penyejuk ruangan (AC/Air Conditioning).
5. Dispenser (untuk menghasilkan air panas dan dingin).
6. Kipas angin penyejuk.

Mesin pendingin (Refrigerator) ialah suatu rangkaian mesin atau pesawat yang mampu bekerja untuk menghasilkan suhu atau temperatur dingin (temperatur rendah).
Sesuai dengan kegunaannya mesin  pendingin terdiri dari beberapa jenis antara lain :
1. Refrigerator untuk keperluan Industri.
2. Lemari es / Kulkas.
3. Freezer (Pembekuan / pendingin makanan dan minuman).
4. Penyejuk ruangan (AC/Air Conditioning).
5. Dispenser (untuk menghasilkan air panas dan dingin).
6. Kipas angin penyejuk.

Large-scale helium liquefaction/refrigeration plants have thermodynamically more involved configurations than Collins cycle that is the fundamental cycle for liquefaction and are used for cooling superconducting magnets etc. Transient analysis helps in design of such plants through improved understanding of the processes leading to optimal designs and appropriate strategies for mitigating the effects of fluctuating heat loads. Process simulator with appropriate Equation of State for thermodynamic properties of the fluid, appropriate models for transport and thermo-physical properties of helium and the structural materials helps in modeling and simulation of such plants. In this paper, attempt has been made to bring out the features of helium liquefiers, to discuss the peculiarities of the properties of helium fluid and the materials of construction at temperatures near the normal boiling point of helium that need to be addressed in performing steady state and dynamic simulation. Man...

This paper deals with the application of dynamic simulation of helium refrigerators and liquefiers by a general purpose process simulator Aspen Hysys®. A standard helium liquefier for capacities of 100 L/hr and 50 L/hr with and without liquid nitrogen pre-cooling respectively, have been chosen for validation of the code of Aspen Hysys®. To obtain an accurate simulation result we need appropriate equation of state, accurate transport properties of helium and thermal properties of metal, actual equipment specifications and cooldown sequence with appropriate control. In the present work, the limitations of Aspen Hysys® in simulating helium systems have been identified and techniques to overcome these problems have been discussed. The dynamic simulation has been performed following the above techniques in order to obtain cooldown profiles. The cooldown process has been simulated from 300 K to 8 K showing similar trends in the temperature variations at different state points. However, it...

Helium, chemical symbol He, atomic number 2, the second most abundant chemical element in the earth universe after hydrogen (H 76 percent; He 23 percent) is a colorless, orderless, and tasteless gas and liquid at-268 °C. The noble gases or group-18 element of the periodic table, helium formed in the thermonuclear reactions on stars but it present to a very negligible extent in the earth atmosphere due to the lightness of gas. The boiling and freezing point of helium is lower than any known chemical substances of the universe and cannot be solidified by sufficient cooling at normal atmospheric pressure. Helium gas consists of two stable isotopes with chemical formula He and He, He-4 is formed on earth by alpha particle decay of radioactive elements, but He-3 is formed by nuclear reactions induced by cosmic radiations. Prior to 1960 helium, neon, argon, krypton, xenon, and radon were belong to the family of inert or rare gases, now these are named noble gases. The noble gases were not known at Mendeleev's time. Today all the noble gases like helium, neon, argon, xenon, and radon are discovered and characterize and extreme inertness distinct from any other chemical elements of the periodic table. Helium atom (atomic number = 2 and mass number = 4) has two protons and neutrons in the nucleus and two extranuclear electrons surrounded the nucleus of the atom. 4 3