Science Dialectica最新文献

Magnetic Refrigeration: An Environment-friendly Cooling Technology 磁制冷:一种环保制冷技术

Science Dialectica Pub Date : 2023-05-08 DOI: 10.54162/sd01-25231/02

M. Modak

{"title":"Magnetic Refrigeration: An Environment-friendly Cooling Technology","authors":"M. Modak","doi":"10.54162/sd01-25231/02","DOIUrl":"https://doi.org/10.54162/sd01-25231/02","url":null,"abstract":"Since the last few decades, global warming has threatened the sustainable ecology and environment. Its dominance on climate change is well known and largely discussed agenda at most of the international meets. However, the existing conventional vapor compression based refrigeration technology, which typically uses coolant gas like chlorofluorocarbons, tetrafluoroethane, freon, isobutene, etc., has considerable direct/ passive roles in global warming. Hence, the universal technique involved in refrigerators and air conditioners, an essential part of our daily life, is deteriorating the issues. Furthermore, the traditional vapour compression refrigeration technique has its limitation in energy efficiency with the high capital cost of the compressor and the electricity needed to operate the compressor. Magnetic refrigeration (MR) is an emerging technology using solid, non-volatile, non-toxic magnetic materials as the active components and water or alcohol as the medium for heat transport. It is an efficient technique with great potential because of low energy consumption and environment-friendly cooling at a competitive cost [1-2]. The most promising use of MR is that it can be used ‘in reverse’ as a heat pump. Using environment-friendly materials rather than toxic gases enables this technology to zero carbon emissions. Solid-state nature and more energy efficiency with better adaptability are the significant advantages of MR over other colling techniques. This technology functions based on a thermodynamic property of magnetic materials. This is commonly known as the magnetocaloric effect (MCE), which causes a temperature change if the material is subjected to a magnetic field under adiabatic conditions. It should be mentioned that MCE was discovered in 1881 by E. Warburg; later, the fundamental principle of MCE for practical purpose was interpreted individually by Debye (1926) and Giauque (1927). Figure 1 illustrates the working principle of MR consisting of the following steps. In step 1, a magnetic material is exposed to a sufficiently high magnetic field, and the magnetic moments of the constituent atoms become oriented along the magnetic field direction. If the magnetic field is applied adiabatically, in other way, if the material is suddenly placed inside a magnetic field, its magnetic moments become ordered. As a result, the magnetic entropy decreases due to magnetic ordering. Therefore, the crystalline lattice entropy will increase to compensate for the loss of magnetic entropy to keep the total entropy constant in the adiabatic process. Consequently, the temperature of the material rises. In step 2, this increased heat can then be removed by cooling the material, keeping the magnetic field constant. These two steps can be performed simultaneously by magnetizing the material isothermally. In that case, the magnetic moments will get ordered, but the temperature will not enhance. The isothermal magnetization process, however, will take a long ","PeriodicalId":146549,"journal":{"name":"Science Dialectica","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132143985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}