Theory of a magnetic cooling system at very low temperatures

1974 ◽  
Vol 17 (3-4) ◽  
pp. 385-401 ◽  
Author(s):  
Louis Goldstein
Keyword(s):  
Low Temperatures ◽  
Cooling System ◽  
Magnetic Cooling

Magnetic heat pumps – Configurable hydraulic distribution for a magnetic cooling system

2014 ◽  
Vol 37 ◽  
pp. 165-175 ◽  
Author(s):  
J.M. Gatti ◽  
C. Muller ◽  
C. Vasile ◽  
G. Brumpter ◽  
P. Haegel ◽  
...  
Keyword(s):  
Cooling System ◽  
Heat Pumps ◽  
Magnetic Cooling

scholarly journals Study on Thermoelectric Cooler Driven by Solar Energy in Medan City

2018 ◽  
Vol 6 (2) ◽  
pp. 317-327
Author(s):  
Tulus Burhanuddin Sitorus ◽  
Zulkifli Lubis ◽  
Farida Ariani ◽  
Ferry Sembiring
Keyword(s):  
Solar Energy ◽  
Low Temperatures ◽  
Cooling System ◽  
Thermoelectric Module ◽  
Weather Conditions ◽  
Experimental Results ◽  
Heat Sinks ◽  
Peltier Effect ◽  
Thermoelectric Cooler ◽  
Cold Side

The primary purpose of this study is to investigate the performance of thermoelectric cooler driven by solar energy in Medan city, Indonesia. This cooler able to use in a remote area where electricity is still not available. The cooler could be used to store beverage that must be stored at low temperatures to maintain the freshness such as drink cup. The solar thermoelectric cooler is based on the principles of a thermoelectric module or Peltier effect to create a hot side and a cold side. The cold side of the thermoelectric module is utilized for cooling purposes to the cooling space. The heat from the hot side of the module is rejected to ambient surroundings by using heat sinks and fans. The solar thermoelectric cooler was experimentally tested for the cooling purpose. Experimental results showed that the solar thermoelectric cooler could reduce the temperature of the drink cup from 26oC to 15oC in approximately 40 min. The maximum COP of the cooling system during the experiment was calculated and found to be about 0.356. The effect of weather conditions on the COP value was about 85.90%.

scholarly journals Time effects in the magnetic cooling method─I

1936 ◽  
Vol 155 (886) ◽  
pp. 629-639 ◽  
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Initial Temperature ◽  
Magnetic Method ◽  
Time Effects ◽  
Magnetic Cooling ◽  
Cooling Method ◽  
Degree Of Orientation ◽  
Paramagnetic Salt ◽  
The Magnetic Field

The recent progress in attaining extremely low temperatures was made possible by the magnetic method of cooling. This method is based on the following principle: Supposing we have a paramagnetic salt, the ions of which carry a magnetic moment (spin) μ. We assume that the interaction of these spins with the lattice and with one another is so small that the spins can be considered as relatively free. These properties are realized in some salts of the rare earths and of the iron group. In the absence of a magnetic field the spins are distributed at random. The crystal has then a comparatively large entropy due to the exchange of spin directions. If we now switch on a magnetic field H isothermally , the spins will be orientated in the direction of the field. The degree of orientation will depend upon the ratio Hμ/ k T i , where T i is the initial temperature. The entropy will decrease according to the degree of orientation produced by the magnetic field. The decrease in entropy is a certain function of Hμ/ k T i .

Experiments with an anisotropic magnetic crystal at temperatures below 1° K

1951 ◽  
Vol 206 (1085) ◽  
pp. 242-257 ◽  
Keyword(s):  
Curie Point ◽  
Low Temperatures ◽  
Absolute Temperature ◽  
Apparent Absence ◽  
Parallel Magnetic Field ◽  
First Order ◽  
Sharp Maximum ◽  
Magnetic Cooling ◽  
First Order Transition ◽  
Dipole Exchange

Magnetic cooling experiments on a spherical single crystal of cobalt ammonium sulphate are described. Measurements were made as functions of the absolute temperature between 1° K and 0·05° K of (i) the specific heat, (ii) the principal magnetic susceptibilities, and (iii) the variations in susceptibility on applying (adiabatically) a steady parallel magnetic field. The measurements in the range from 1° K down to the Curie point are discussed in connexion with the dipole-dipole, exchange and nuclear interactions in the crystal. Below the Curie point, for the K 1 axis only, an interesting effect was found, in that a steady field was observed to produce an increase in a. c. susceptibility instead of the usual decrease. At these temperatures the susceptibility was found to reach a fairly sharp maximum in a field of a few hundred gauss, and reasons are given for supposing that these maxima (more exactly, the minima in the curves of constant magnetization) mark the boundary of the antiferromagnetic region. The experimental results are discussed in connexion with Sauer & Temperley’s model for the antiferromagnetic state at low temperatures. A possible explanation of the apparent absence of a first-order transition at lower temperatures, expected in the theory but not observed in practice, is also given.

scholarly journals Numerical analysis of a near-room-temperature magnetic cooling system

2017 ◽  
Vol 75 ◽  
pp. 262-275 ◽  
Author(s):  
Mehmet Akif Ezan ◽  
Orhan Ekren ◽  
Cagri Metin ◽  
Ahmet Yilanci ◽  
Emrah Biyik ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Room Temperature ◽  
Cooling System ◽  
Magnetic Cooling

A pre-industrial magnetic cooling system for room temperature application

2012 ◽  
Vol 98 ◽  
pp. 556-561 ◽  
Author(s):  
M. Balli ◽  
O. Sari ◽  
C. Mahmed ◽  
Ch. Besson ◽  
Ph. Bonhote ◽  
...  
Keyword(s):  
Room Temperature ◽  
Cooling System ◽  
Magnetic Cooling ◽  
Temperature Application

scholarly journals Implementation of a cooling system to develop experimental fatigue tests below zero grades Celsius

2020 ◽  
Vol 25 (4) ◽  
pp. 519-525
Author(s):  
Carlos Gerardo Cárdenas Arias ◽  
Camilo Leonardo Sandoval Rodríguez ◽  
Arly Darío Rincón Quintero ◽  
Pablo David Díaz Melo
Keyword(s):  
Heat Transfer ◽  
Fatigue Test ◽  
Fatigue Failure ◽  
Low Temperatures ◽  
Initial Temperature ◽  
Cooling System ◽  
Fatigue Tests ◽  
Sample Material ◽  
Industrial Level ◽  
Materials Behavior

Temperature is one of the matter properties with the greatest influence on the materials behavior existing in nature and those man designed. This physical magnitude allows to demonstrate and define behaviors and materials characteristics in the industry in general. Its influence is present in all the places where the materials fulfill functions, however, in some applications its influence is very little, which allows to disregard its effects. In the steels case (one of the most used materials at the industrial level today), the temperature variation produces dilation or contraction, depending on the temperature magnitude and its variation that affects them. Temperature increases generate an expansion phenomenon in the materials, which under load will reach a point where they present thermal fatigue failure. The opposite is that of temperature drops, where the phenomenon that occurs is contraction, often leading to the loss of adjustments and interference that compromise the equipment functionality and integrity. The fatigue failure mentioned is presented as a result of the stresses and deformations present in both cases. It is desired to condition a rotational flex fatigue test equipment with a cooling system to bring the sample material to temperatures below zero degrees Celsius, in order to check how low temperatures, affect the resistance of steel to fatigue. For this, a cooling system was designed and the fatigue equipment was adapted to reduce heat transfer. After carrying out this implementation and determining that the sizes of the devices were suitable for the proposed purposes, the initial temperature tests were carried out and, once this part was achieved, three repetitions of a rotary fatigue test were performed that demonstrated that the equipment can operate normally.

scholarly journals STORABILITY POTENTIAL OF CARROT (Daucuscarota L.) UNDER STEM SPONGE PADDED EVAPORATIVE COOLING STRUCTURES

2021 ◽  
Vol 15 (2) ◽  
pp. 173-183
Author(s):  
Oyebola Olabinjo
Keyword(s):  
Low Temperatures ◽  
Control Structure ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Metabolic Rates ◽  
Zero Energy ◽  
Percentage Loss ◽  
Evaporative Cooling System ◽  
And Control ◽  
Microclimate Conditions

A zero energy stem sponge padded evaporative cooling storage was evaluated using fresh carrots (Daucuscarota L.) with control refrigerator and a similar structure without any cooling pad.  The overall percentage loss in weight (during the period of experiment) of the carrot was much in the refrigerator (53.97%) and control structure (32.80%) compared to those stored in the evaporative cooling structure (25.19%). Similarly, trend of result was recorded in firmness, loss in firmnesss of the carrots stored in the control structure was greater than the ones in the evaporative cooling sytructre. However, the evaluation of the evaporative cooling system shows that the carrots can be stored for an average of twelve (12) days with negligible changes in weight, colour and firmness unlike the refrigerator and the control structure which noticeable changes began to occur from the fifth day. The modification of the microclimate by use of the zero energy evaporative and evapotranspirative cooling principles helps attain the microclimate conditions favourable for longer storage periods. With reference to the developed stem sponge padded cooler in this study, the modified environment helped in reducing respiration and metabolic rates in the stored carrots.  The high relative humidity and low temperatures in the padded evaporative cooling system discouraged microorganism action on the stored carrots leading to a lengthened shelf-life

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