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Vol 111, No 2 (2022)
Reviews
Cold storage systems: present and future applications (a view from the Middle East region)
Abstract
The aim of this article is to review the existing types of cold storage systems (СSS) based on known technologies and recommendations for their improvement. The article combines research, thermodynamic analysis, economic aspects and comparison of the quality of known СSS designs. The article is of interest for government officials, manufacturers, engineers, inventors and developers to determine the advantages and disadvantages of existing СSSs. The reasons constraining the use of СSS in Israel are given. Taking into account modern foreign experience in developing “cold” low-temperature energy tank designs and achievements of the ice-slurry production technology of pumped ice slurries, the CSS is proposed, a software is developed and technical and economic analysis of its operation is carried out.
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Development of Air Conditioning Systems
Abstract
This paper presents information on the global production and energy consumption of climate equipment. Information is provided on refrigerants used in air conditioning systems, in particular about R22, which was practically abandoned by many countries in the early 2000s, however, in 2018, about half of air conditioners owned by the population worked on R22. According to a number of estimates, 600 to 800 million units are operated in the world, and about 60% of air conditioners are used refrigerants of the hydrofluorocarbon (HFC) group. Many mixed refrigerants based on the hydrofluoroolefin group are considered potentially possible refrigerants to replace the refrigerants of the HFC group (e.g., R407C, R404A, and R410A). Japan and South Korea suggest using the R32 refrigerant. In India, the production of split systems using the R290 refrigerant has been organized. Various types of air conditioners and their production in the world are presented, working mainly on refrigerants of the HFC group, e.g., R407C, R404A, and R410A. The bactericidal treatment of the air environment using electroconvection and low-temperature nonequilibrium plasma is also described, with the results of processing several cultures and metal surfaces obtained by the authors.
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Original Study Articles
Thin-Film Steam Generators of Binary Geothermal Power Plants
Abstract
BACKGROUND: The cost of electricity generated by a geothermal power plant is twice as low as that of energy sources. However, at present, geothermal power plants mainly use submersible-type apparatus, and the most promising thin-film steam generators have not been sufficiently investigated.
AIM: The purpose of this work is to show the advantages of a thin–film steam generator in comparison with an immersion type heat exchanger.
MATERIALS AND METHODS: The basis for this publication is the experimental research of the author and the analysis of data cited in the literature on heat exchange during the boiling of a film irrigating a bundle of finned pipes.
CONCLUSIONS: The use of thin-film steam generators will significantly reduce the amount of expensive refrigerant in a geothermal power plant circuit. With a cocurrent flow of steam and liquid, the ingress of large drops onto the surface of a superheater tubes is excluded. The use of finned tubes in a bundle with optimal finning parameters ensures a uniform irrigation. The artificial centers of vaporization of the finned tube repeatedly intensify the heat transfer during film boiling, which ultimately leads to a reduction in the weight and dimensions of the superheater.
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Prospects for Creating a New Generation of Ice banks for Systems with Uneven Heat Loads
Abstract
BACKGROUND: The rational application of thermal energy storages with phase transition for objects of the food industry with significantly uneven heat loads is discussed in this article. The drawbacks of existing ice banks, suppressing their spread, are analyzed. Possible methods of addressing these problems during the designing process are considered.
AIM: Development of a new generation of ice banks with a high intensity of ice melting processes and the ability to adjust the heat load.
MATERIALS AND METHODS: The brand-new discharge method based on the film flow around ice surfaces is proposed. The proposed approach allows us to optimize the heat load and provide the maintenance of the required ice water temperature. The laboratory sample of the coaxial film heat exchanger (FHE) was designed by the authors.
RESULTS: Experimental results in the operating range of the levels of supplied water temperatures 20 ℃, 40 ℃, and 60 ℃ and mass flow rates 15, 30, 45, and 60 kg/min are carried out. The experimental results confirmed that the development construction of the FHE with the film mechanism of the heat transfer provides increasing efficiency in orders of magnitude in comparison with ice banks with bulk melting. The reduced heat load with a mass flow rate of 60 kg/min and medium temperature on 60 ℃ was 220–240 kW/m2, and the maximal reduced heat load of the upper layer of coil reached 1300 kW/m2. The generalization of the results showed the application prospects of film ice banks in the refrigeration systems of various industrial and agricultural objects.
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Development of an Air Electric Compressor for a No-Bleed Environmental Control System of an Advanced Regional Aircraft
Abstract
BACKGROUND: Aircraft designers strive to increase the fuel efficiency of aircrafts, including increasing the efficiency of aviation environmental control systems (ECS) by introducing an autonomous source of compressed air with an electric drive as part of aircraft.
AIM: The present paper aimed to consideration of the results of research work (R&D) of the technologies demonstrator for the electric compressor of the aircraft electric ECS and estimation of the performance and compliance of the simulated and experimental characteristics of this electric compressor.
MATERIALS AND METHODS: Comparison of the simulated and experimental characteristics of the electric compressor of the electric ECS of the aircraft was carried out by confirming the compliance of the operating parameters of the technologies demonstrator for the electric compressor with those specified in the request for proposals (RFP), and by comparing the simulated and experimental values of the compression ratio of the compressor stage, isentropic coefficient of performance (COP), obtained during R&D study.
RESULTS: Information about the technical characteristics and design of the electric compressor is given and discussed. A comparative analysis of the presented simulated and experimental characteristics of the electric compressor has been carried out.
CONCLUSIONS: Conclusions are drawn on the compliance of the compressor characteristics with the characteristics specified in the RFP; on the achieved level of readiness of the technology of the electric compressor for the electric ECS of the aircraft, on the need for experimental design work on the electric compressor, taking account of external influencing factors typical for an application as part of aviation equipment.
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Influence of the Gelatin Amount on the Indicators of a Defrosted Fermented Milk Dessert Texture
Abstract
BACKGROUND: The expansion of the range and improvement of the quality are urgent tasks in the ice cream industry. Fermented milk desserts consumed defrosted and combining the properties of ice cream and fermented products can be considered new products. The selection of stabilizer–gelling agents and determination of their mass fraction are important stages in the development of the fermented milk dessert technology. Among them, gelatin is the most effective and convenient.
AIM: The object of this study is to examine the effect of the gelatin amount on the structure and texture of defrosted fermented milk desserts.
MATERIALS AND METHODS: Samples of desserts with a mass fraction of gelatin from 1,3 to 1,9% are the objects of this study. Rheological research methods for estimating the dynamic viscosity and indicators of consistency were used. The dispersion of the air phase of frozen samples and after storing at the temperature of 4±2°С for 4 hours has been estimated.
RESULTS: The dispersion of the air phase and texture characteristics, such as hardness, adhesiveness, adhesive force, apparent modulus, and recoverable deformation, were examined during the research. The research results show that increasing the gelatin amount did not influence the viscosity but decreased the overrun. Increasing the gelatin amount did not influence the average size of air bubbles after 4 h of storage. The influence of the gelatin amount on the texture indicators of the defrosted dessert was estimated. Adhesiveness and adhesive force with the increase in the gelatin amount by 0.3% were reduced by 16% and 9–12%, respectively. The obtained results have practical importance in the production and sale of defrosted fermented milk desserts.
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News
Scientific and Technical Conference With International Participation «The Askezis Of Natural Refrigerants Under the Conditions Of the Dominant Neoclimate Reality»
Abstract
The scientific and technical conference, “Askesis of natural refrigerants under the conditions of the dominant neoclimatic reality” will be held on January 26, 2023, marking the 30th anniversary of the International Academy of Refrigeration, with international participation. The conference will be held in the full-time format at 191002, St. Petersburg, ul. Lomonosova, 9, ITMO University (Dostoevskaya and Vladimirskaya metro stations) and virtually via Zoom. Applications for participation in the conference should be submitted until January 15, 2023.
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Obituary
Lyudmila D. Akimova (11.08.1929-12.09.2022)
Abstract
The editorial board of the journal “Refrigeration Technology” together with All-Russian Scientific Research Institute of Refrigeration Industry – branch of «V.M. Gorbatov Federal Research Center for Food Systems» of RAS and the Russian National Committee for the International Institute of Refrigeration announce with deep regret that Liudmila D. Akimova passed away at the age of 93. She was a longstanding editor-in-chief (from 1985 to 2020) of the well-known journal “Kholodilnaya Tekhnika”. Moreover, she was renowned as an academician, which put a lot of effort into the International Academy of Refrigeration (IAR).
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Lyudmila D. Akimova
Abstract
It is the change of an era…Some people leave an imprint in everyone’s lives around them.
Lyudmila Dmitrievna Akimova was one of them.
In our (the E-4 department employees) lives, she occupied a very important place, since for several years, she remained the editor-in-chief of the prestigious journal “Refrigeration Technology.” A lecturer at the Bauman Moscow State Technical University is inextricably linked with the publication of his/her thoughts in the form of scientific articles, thus warranting a permanent communication with the journal editors.
The journal “Refrigerating Technology” helped us to share with professionals what we thought were “discoveries” and simultaneously learn from the colleagues in the field of low temperatures. In addition, we were aware of all refrigeration measures not only in Russian Federation, but throughout the world. Lyudmila Dmitrievna Akimova helped us to permanently monitor this pulse for several years for which we are deeply grateful to her.
Her good memories will always be cherished.
The staff of the E-4 department, Bauman Moscow State Technical University.
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In Memoriam Lyudmila D. Akimova, Academician of the International Academy of Refrigeration
Abstract
A wonderful woman has passed away. She was charming, intelligent, highly professional, an outstanding enthusiast of her field, who devoted most of her life to publishing in the refrigeration industry. She was deeply in love with the field of refrigeration.
From 1985 to 2020, Lyudmila Dmitrievna has been the editor-in-chief of the distinguished journal Refrigeration Technology. Since 1996, the founder of the journal has been her Publishing House Kholodilnaya Tekhnika owing to her ceaseless energy, understanding of the role the cooling technology has played in the modern civilization. The journal Refrigeration Technology has become a highly regarded and an extremely popular journal for scientists and engineers in artificial cold technology. Generations of domestic refrigeration specialists have read the publications of this journal.
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