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Flexible contact gasket is a significant component affecting the sealing performance of the refrigerator. However, few studies were conducted on the permeability characteristics of moist air through refrigerator gaskets. The purpose of this study is to explore the permeability characteristics including permeation paths size, flow type, modeling and temperature-humidity-pressure-structure effect. The characteristic scale of the interface of permeation paths is observed as 10−5 m in the free-state by atomic force microscope. The equation of Knudsen number and contact stress relation is established to judgment the flow types. By comparing the critical and simulated contact stresses, it is inferred that moist air simultaneously occurs slip, transition and free-molecular flows. A multi-scale coupling model of permeation rate is constructed to obtain the apparent permeability coefficient characterizing the permeability intensity. The air pressure difference affects the permeability characteristics in the form of direct driving force and changing the contact stress of the interfaces. Free-molecular flow mainly occurs under the negative pressure condition with inhalation coefficient of 2.26 × 10−5∼2.84 × 10−5 m2, while the slip flow mainly occurs under the positive pressure conditions with exhalation coefficient of 2.87 × 10−5∼4.65 × 10−5 m2. The essence of enhancing the sealing performance of structural improvement is to increase the contact stress and length of permeation path. By increasing the height, increasing the inclination angle, adding the auxiliary edges and adding an auxiliary airbag, the inhalation coefficient of moist air, the exhalation coefficient of moist air and the inhalation coefficient of water vapor are decreased by 54.82 %, 51.46 % and 66.04 %. [ABSTRACT FROM AUTHOR]

The household refrigerator model used for freezing processes in this study was produced in the factory in different energy classes (C, D, and E). Equal amounts of beef (10 × 10 × 2 cm; 2 × 2 × 2 cm) and minced beef (10 × 10 × 2 cm) were placed in refrigerator bags before freezing. The freezing processes were carried out by placing beef samples on the top shelf where the radial fan was located in the freezer compartment of the refrigerators. After the frozen samples were thawed at +4°C, they were cooked in a water bath at 85°C. It was determined that the samples frozen in the refrigerator belonging to the D energy class at −24°C had shorter freezing times and therefore higher freezing rates. It was observed that pH (5.54–5.72) values of samples frozen in the D energy class were higher due to lower weight loss (0.32%–6.80%) values. When their color values were examined, the redness (a∗) values (15.09–17.61) were the highest, while the yellowness (b∗) values (10.31–13.29) were the lowest in these samples. In addition, the hardness (49.00–182.74) and chewiness (16.35–71.80) values of samples frozen in Energy Class D were found to be lower, while their protein denaturation temperatures were higher due to shorter freezing times. Consequently, in this study, the effects of the difference in energy classes of refrigerators on the quality characteristics of beef samples were examined, and the refrigerator belonging to the energy class (D) that gave the best quality properties was found to be the most suitable one for freezing the beef. [ABSTRACT FROM AUTHOR]

Soft and hard contact deformation is most common issue of the refrigerator gasket and it has almost been ignored in previous studies. In this paper, the novelty is to propose a thermal-solid coupling simulation to study the effect of assembly states on the heat transfer of gaskets, improving the accuracy of heat transfer simulation analysis. The numerical results indicate that the calculated temperature based on physical model of assembly state is closer to measured temperature. The assembly distance affects the assembly state of the gasket by changing the contact positions and lengths of contact interfaces. As a result, the heat transfer path and condition at the gasket region also changes. As the deformation increases form −1.0 mm to 5.0 mm, the heat leakage load of gasket rises firstly and then falls, in the range of 1.61 ~ 3.33 W•m−1. The heat leakage at the transfer paths of internal cold air, outer shell and cold bridge accounts for over 20%. Thus, it is recommended to reduce the contact interface length of internal cold air, increase the thermal resistance of auxiliary air-bag, reduce the thermal conductivity and thickness of magnetic strip and increase the contact thermal resistance of cold bridge. [ABSTRACT FROM AUTHOR]

Refrigerators are one of the common machines for Indonesian people. Refrigerators can be used to store foods and ingredients for longer shelf life. The temperature in the refrigerator and freezer is low because the heat is absorbed by the evaporator and then released into ambient air through the condenser. The heat transfer velocity from the condenser to ambient air depends on the convection heat transfer coefficient of air. This study was conducted experimentally by comparing the refrigerator's performance that use air-cooled condensers and water-cooled condensers. The equipment used is a refrigerator with a portable water bath. This study aims to know the temperature change speed in the storage room and freezer room, the temperature changes before and after the condenser was used, and the change of the temperature and pressure in refrigerant before and after the evaporator was used. The results showed refrigerator with a water-cooled condenser can give cooling process in the storage room faster, give freezing process in the freezer room faster, and enhance COP.

The aim of the study is to review the use of gas products of natural and synthetic origin and their future application prospects. To achieve this goal, a number of high-tech technologies were pre-sented and analysed. The phase equilibrium parameters of inert and fluorine-containing gases were shown, as well as the temperature ranges in which certain refrigerants can be applied. Ex-amples of cooler schemes for providing rectification processes at 28 and 210 K were given. The processes of refrigeration cycles in T-s diagrams of neon and R116 (hexafluoroethane) were shown. Schemes of helium systems for heat removal at the level of 5…28 K were considered. The areas of application of Xe, Kr, Ne, and He in modern technologies, particularly in laser technology, space exploration, lamp industry, and medicine, were highlighted. The most signifi-cant result of the work is the determination of the important role of isotopic components of inert gases for the future of energy, functional diagnostics, metrology, and other fields. In semicon-ductor manufacturing, many inert gases are used as protective environments and working media in ion-plasma and ion-beam etching in vacuum chambers. In plasma chemical surface treatment, substances containing one or more halogen atoms act as active gases. The significance of the results achieved is evident in that, in the context of a global shortage of technical gases, the de-velopment of resource-saving technologies is becoming relevant. Among these, gas product re-cycling, where gas concentrates were obtained from used mixtures, enriched, and subjected to deep purification for the secondary use of target products, is the most promising.

Improving the performance of drop-in hydrocarbon refrigerants for the increasing in-flow of conventional refrigerators to Nigeria is a necessary sustainable strategy. This experimental study investigates the enhancement limits of a liquid-line magnetic field, CNT nano-lubricant, and a combination of both on an R134a domestic refrigerator with 40–70 g each of R600a refrigerants. The study compares the performance of R600a refrigerant without enhancements (pure) and with two pairs of 3000 Gauss liquid-line mounted O-ring permanent magnets (Mag), 0.2 g L−1 concentration of CNT nano-lubricant (Nano), and both liquid-line magnet and CNT nano-lubricant (Mag-Nano). Test parameters include evaporator air temperature, discharge pressure, power consumption, coefficient of performance (COP), and total equivalent warming impact (TEWI). The results show that enhancement methods led to higher COP in the range of 16.64–42.38%. At the same time, evaporator air temperature, discharge pressure, power consumption, and TEWI were lower by 9.76% to 20.96%, 17.75% to 34.26%, 5.22% to 13.42%, and 5.88% to 10.86%, respectively. In conclusion, the proposed enhancement techniques in the refrigeration system provide normal, safe, and efficient operation. [ABSTRACT FROM AUTHOR]

The total fat content of the Farmed common carp studied was 13.2%, which is categorized as high fat fish. Considering the amount and type of fish fat, which is unsaturated and long-chain fats and are very vulnerable to the oxidation process, therefore, in order to maintain their quality, artificial or natural preservatives should be used and stored in cold conditions. In this article, common carp was filleted and immersed for 5 min in water extract extracted from mistletoe leaf (Viscum album L.) by percolation method as a natural antioxidant in proportions of 1, 2 and 4%. Then the extract was evaluated in terms of extraction efficiency, phenolic and flavonoid compounds and free radical inhibition (DPPH), and the quality of fillets stored in the refrigerator at time intervals of 0, 4, 8, 12, and 16 days was evaluated with the tests of peroxide values (PV), anisidine value (AV), thiobarbituric acid (TBA), free fatty acids (FFA) and TOTEX amount. The results of extraction efficiency, total phenolic compounds (TPC), flavonoid compounds (TFC), and DPPH were 5.23%, 62.4 mgGA/g E, 34.71 mg QE/g E, and 78.2%, respectively. In addition, the values of PV, TBA, FFA, AV, and TOTEX value in the 4% extract treatment were reported as the best treatment on the 16th day of the experiment, 3.42 (meq g O2/Kg Fat), 1.55 (MDA/Kg Fat), 0.85 (OA%), 4.67 and 11.51, respectively. According to these results, mistletoe aqueous extract with a concentration of 4% can be used to delay fat oxidation in farmed common carp. [ABSTRACT FROM AUTHOR]

Since 2010, vacuum insulation panels (VIPs) have steadily been used as a main insulator in refrigerators, but interest in the proper recycling of VIPs is lacking. Thus, the purpose of this study was to develop a VIP detection system to determine whether VIPs could be identified in end-of-life refrigerators at the recycling stage. We developed experiments to measure changes in the pressure and thickness of the perforating sidewalls of refrigerators. We conducted a pressure measurement experiment using 30 refrigerators and recorded pressure changes of 3.2 ± 1.1 kPa in the VIP refrigerator group and 0.5 ± 0.8 kPa in the non-VIP group. The mean thickness change for the 14 VIP refrigerators was 10.606 ± 4.128 mm. We conclude that the success rate of the VIP detection system developed in this study in determining VIPs present in refrigerators reached 96.7%. This study provides a basis for developing an infrastructure and environment to recycle end-of-life VIP refrigerators. [ABSTRACT FROM AUTHOR]

The efficient and rapid removal of volatile organic compounds (VOCs) holds significant importance for ensuring food quality and human health, particularly within the low-temperature confined spaces in refrigerators. However, achieving effective VOCs degradation under such conditions poses challenges in terms of activating inert bonds and facilitating mass transfer. In this study, we propose a novel solution by designing a cleaner module that incorporates 1.07% single Fe atom-anchored manganese dioxide catalysts (FeSAs-MnO2). The combination of single Fe atoms and defect-rich MnO2 substrate efficiently activates molecular oxygen, leading to enhanced generation of highly reactive oxygen species (ROS). Non-thermal plasma (NTP) and circulating fan are introduced to facilitate the regeneration of catalytic activity and improve mass transfer. The FeSAs-MnO2 cleaner module demonstrates exceptional performance in trimethylamine (TMA) removal, achieving a conversion efficiency of 98.9% for 9 ppm within just 9 min. Furthermore, accelerated aging tests predict an extended service life of up to 45 years for the FeSAs-MnO2 cleaner module, surpassing the expected lifespan of refrigerators significantly. [ABSTRACT FROM AUTHOR]

Refrigerated truck is indispensable transportation for food and medicine. However, the truck has been using the harmful substance such as CFC or HCFC. Therefore, an alternative cooler is essential such as thermoacoustic refrigerator. The refrigerator is driven by the thermoacoustic heat engine (prime mover), so the prime mover can convert the thermal or waste heat into the acoustic energy for driving the refrigerator. There are some parameters that can improve the efficiency of the refrigerator system. The aim is to investigate the impact of prime mover regenerator radius on the efficiency and characteristic of acoustic field. It was found that the best performance of the whole refrigeration system was achieved when the radius is 0.68. The engine and cooler efficiency are 84% and 38%, respectively. In addition, the acoustic field characteristic was also analyzed to elucidate the mechanism in the refrigerator system. [ABSTRACT FROM AUTHOR]

This study examines the performance enhancement offered by a phase change material (PCM) connected to the evaporator and condenser of a household refrigerator that utilizes R134a as the refrigerant. The features of the refrigerant and its properties determine how quickly a refrigerator releases and stores heat. The use of PCM accelerates heat transfer, leading to an improvement in the Coefficient of Performance (COP). This experimental study demonstrates how the COP of a typical refrigeration system can be significantly improved. In the present study, the PCM is utilized in a manually constructed enclosure that encloses the evaporator and condenser of a refrigerator. The purpose of the PCM is to decrease the condenser temperature, resulting in a substantial reduction of power consumption. The heat is transmitted from the refrigerator cabinet to the evaporator through PCM by conduction. Therefore, the rate of heat transfer from the evaporator to the refrigerant increases noticeably, which enhances the COP of the refrigeration system. From the experiment, it was found that COP increased by 12.7% and compressor off time increased about 1.5 times.

Amorphous manganese oxide catalysts, aimed at efficient ozone removal in refrigerators, were synthesized using a simple redox method. Factors like crystallinity of structure, textural properties, and Fe doping significantly affect the catalyst’s performance. The Fe-doped KMF-250 showcased outstanding ozone decomposition capabilities, efficiently eliminating 10,000 ppb of ozone at an average rate of ca. 13.3 ${\rm{mg}} \cdot {\rm{g}}_{{\rm{cat}}}^{{\rm{ - 1}}} \cdot {{\rm{h}}^{{\rm{ - 1}}}}$, under conditions of 6 °C and 36% relative humidity in a refrigerator chamber (144 L). Moreover, this catalyst exhibits extraordinary stability, outperforming existing commercial catalysts in terms of both durability and efficiency. The incorporation of even a minimal amount of Fe (0.84 wt%) considerably raised the amount of low-valence Mn, resulting in more crystal defects and oxygen vacancies. The existence of Fe in MnOx was also found playing an important role in promoting the desorption of the oxygen species and enhancing the oxygen mobility to generate oxygen vacancies, both of which contribute to the quick recovery of the catalyst. The catalyst’s large specific surface area, combined with optimal Fe doping, are crucial for its superior catalytic performance. This research delivers a potent MnOx catalyst suitable for ozone removal in refrigerators and viable for mass production. [ABSTRACT FROM AUTHOR]

Conventional household refrigerators consist of a motor-driven compressor, evaporator, condenser, and expansion valve. To determine the optimal operation strategies of refrigerators, it is essential to investigate the overall system performance, using an appropriate simulator. This study proposed a data-driven simulator based on engineering features and machine learning algorithms for conventional household refrigerators. The most correlated variables for identifying the indoor temperature of refrigerators were identified using variable importance, and these were revealed to be the circulation fan speed, compressor operation status, and refrigerant flow direction. A data-driven simulator was constructed using Bayesian calibration, which considers the important variables, combined with a straightforward heat balance equation. The Markov Chain Monte Carlo approach was used to simultaneously calibrate three coefficients on the critical variables based on the heat balancing equation on each time step, which is consistent with the actual temperature of the container. The results revealed that the proposed approach (equation-based Bayesian calibration outperforms) standard machine learning algorithms, such as linear regression and random forest models, by 38.5%. Additionally, compared to the typical numerical analysis method, it can reduce the delivery time and effort required to develop a reliable simulator for household refrigerators. [ABSTRACT FROM AUTHOR]

In this study, the influence of a super absorbent polymer (SAP) addition on the thermal properties of phase change material (PCM) was investigated. It was found that adding SAP reduced the melting temperature of PCM and improved phase separation properties. While the addition of 1.0 wt% of SAP to PCMs decreased latent heat by 3 J/g to 24.4 J/g, the addition was determined to be necessary to prevent leaks from a functional duct unit (FDU) and assure product stability. The results obtained from a series of brine refrigeration tests indicate that the supercooling temperature decreased by 0.3 °C to 1.7 °C when 1.0 wt% of SAP was added to PCM. The addition of SAP to PCM appears to promote supercooling by encouraging condensation during phase change. As a result of applying SAP-added PCM to the FDU, the isothermal operation performance was improved compared to existing refrigerators. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Different preservation temperatures for sample storage in space stations and corresponding refrigerator devices have been designed. In the below-freezing environment, frost will occur on the inner wall surface and the sealing place of the refrigerator device, which may have an impact on the operating performance and sealing performance of the refrigerator device. This paper analyzes the impact of frost on refrigerator storage devices, and designs and verifies a scheme of air cooling with a hollow seal method to reduce the impact of frost. The designed refrigerator was tested for air cooling, sealing, and long-term performance. The tests show that the air-cooling structure designed in this paper can effectively reduce the frost on the sample surface. A cumulative helium mass spectrometry leak detection method is applied to verify that the hollow seal structure designed has a better sealing property, which can prevent the diffusion of water vapor and frosting at the sealing position. The design with air cooling and hollow sealing has less frost and more stable performance for long-term operation. The results demonstrate this refrigerator would have the capability of operating on-orbit. The frost-preventing method for space station refrigerator designed in this paper has significance for the design of similar cryogenic equipment in microgravity environments. [ABSTRACT FROM AUTHOR]

South Africa has been challenged with loadshedding for the past decade. Most recently, loadshedding became a crisis as the year 2022 was reportedly the most in which electricity was load shed compared to the previous years. Guided by the South African Constitution of 1996, the right of South Africans to access electricity is embedded within the constitutional obligations of Eskom. The power utility is mandated to provide reliable electricity supply and ensure just administrative action when taking actions that deprive citizens of electricity access (Pieterse, 2023). In practice, however, it has become evident that rendering services such as electricity remains a major challenge. South Africans experience loadshedding daily, which affects their energy usage. In essence, loadshedding has impacted negatively, especially the disadvantaged. Despite planned loadshedding stages, households still experience direct impacts of loadshedding. Appliances such as refrigerators become mal-functional, resulting in food kept in cool temperatures being spoiled. Although loadshedding food spoils have been identified as a phenomenon at household level, the current response in terms of household planning and awareness has not been adequately documented. The paper aims to address this by arguing that there is a need for households to engage in targeted measures that help households cope and adapt to loadshedding food spoils. Furthermore, the study provides a TO-DO list on how households can improve their ability to adapt and cope with loadshedding. The paper used a qualitative methodology focused on analysing the lived experiences of News24 participants. Literature review was conducted where journal articles, newspapers and books were analysed. Thereafter, lessons are drawn from literature, to develop and provide a way forward towards dealing with loadshedding food spoilage at household level. The findings of the paper conclude that effective loadshedding and food spoil adaptation can limit food spoilage. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Refrigeration is the property of Journal of Refrigeration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of refrigerants with a global warming potential (GWP) greater than 150 is banned in small and medium-sized refrigerators in accordance with the European F-Gas policy. Therefore, the suitability of retrofitting an existing refrigerator using a low GWP working fluid (R152a), as a replacement for the usual refrigerant (R134a) that is harmful to the environment, was investigated experimentally in this paper. In this study, close trend and similarities have been observed between the retrofit refrigerant (R152a) and the traditional refrigerant (R134a) in terms of their thermophysical properties. This has shown the compatibility of R152a with the components of the existing refrigerator. The two refrigerants met the pull-down time standard for the refrigerator, but the values of R152a were consistently lower than those of R134a. In addition, R152a consumed less energy with higher coefficient of performance and cooling capacity (12.2 and 14.6 %, respectively) than R134a. Due to the superior performance and the eco-friendly properties of R152a, it is recommended as a retrofit refrigerant for the existing small and medium-sized refrigerators.

The present study examines experimentally the effect of pairing phase change material (PCM) with frozen items (ice/fish) contained in the freezer cabin of an energy-efficient refrigerator. The significance of (PCM) presence was underscored throughout extended periods of electrical grid failure in diverse environmental circumstances. Tests are started by power absence (after cyclic operation) until reaching a temperature of (−2 °C) to avoid ice melting or fish spoilage.The optimal PMR (product to PCM mass ratio) for frozen ice and fish is recommended via the extended under-thawing duration. RSER (Recovered and Saved Energy Ratio) was coined to describe the relationship between the amount of energy saved by utilizing the device during a power outage and the amount of energy the device is designed to consume on a normal day. The highest acquired RSER for ice products is 8.14% at PMR equal to 4.0 under summer conditions, while during winter conditions the highest value of 20.44% is demonstrated at PMR equal to 1.0. On the contrary, fish products reveal the highest RSER values at the same PMR of 5.0 under different ambient conditions. The ratio reached 12.5% during summer conditions, while the RSER acquired 36.5% under winter conditions.

Dynamic load of compressors is of great concern to designers of refrigeration products since pipes and sheet metals are easy to be excited, leading to noise or fatigue failure. The excitation is impossible to measure directly and difficult to calculate according to generation mechanism; thus, dynamic load identification which skips the mechanism is a more practicable way. However, the reported approaches have the problems of inaccuracy and clumsy. Therefore, an easy-to-implement approach is proposed, in which the accelerations and the frequency response functions from test are transformed to an arbitrarily given point based on rigid body dynamics, and then the equivalent six-degrees of freedom dynamic load of this point is calculated. This approach is validated using a motor with eccentric mass, whose centrifugal force is identified with the proposed approach and also calculated in analytical way. Comparison indicates that the error is within 5% except for the rotational speeds close to natural frequencies. Curve fitting or interpolation is recommended to correct the data in order to reduce the influence of natural frequencies. Cases studies with a rotary compressor and a scroll compressor respectively are presented. For the rotary compressor, the force magnitudes in X and Y directions are almost the same and pretty close to their quadratic polynomial fitting curves with zero intercept respectively, conforming to the characteristics of centrifugal force; the RZ component is larger than the RX and RY components as expected, but the latter two are not negligible; and there is a step change at 45 rps due to the removal of torque compensation. For the scroll compressor, the force magnitudes in X and Y directions are different, but very close to their quadratic polynomial fitting curves, respectively; the Z component has a jump in high-speed range; and there is no significant difference of dynamic force in the cooling and the heating modes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Goal: Analyze the benefits of the application of recycled polypropylene in the evaporation tray of refrigerators in a multinational company of electro-electronic equipment. Design / Methodology / Approach: This research conducts a systematic literature review; performs a Life Cycle Analysis (LCA) of the polypropylene production, interpreting its results through a Pareto Diagram; and presents a case study in a multinational company of white line electro-electronic equipment. Results: The LCA results point out that propylene and the components released by the chemical plant cause the main negative externalities under the environment and human health, so that during PP production, propylene is responsible for 72% of the impacts under global warming and 86% in the face of scarcity of fossil resources. Thus, the case study proposes recycling polypropylene, following the Circular Economy guidelines by aligning the proposal with the Zero Waste policy, with modular design, with Reverse Logistics, and with Sustainable Development Goals. Research limitations: The work presents limitations inherent to literature review works, where filters are used to limit the search (limited to articles, published between 2012 and 2021 and written in English). Practical implications: The research encourages recycling, pointing out its contribution under the environmental, social and economic spheres. Originality / Value: The research presents originality and methodological value by combining qualitative and quantitative methods, and a theoretical and practical approach. Thus, it was possible to implement the research in the multinational company analyzed, and to measure the benefits obtained. [ABSTRACT FROM AUTHOR]

The correct storage of vaccines is vital to ensuring that they work effectively and keep patients safe. In this article the author explains how to ensure compliance with regulations without placing an undue burden on community nursing staff. [ABSTRACT FROM AUTHOR]

Goal: Analyze the benefits of the application of recycled polypropylene in the evaporation tray of refrigerators in a multinational company of electro-electronic equipment. Design / Methodology / Approach: This research conducts a systematic literature review; performs a Life Cycle Analysis (LCA) of the polypropylene production, interpreting its results through a Pareto Diagram; and presents a case study in a multinational company of white line electro-electronic equipment. Results: The LCA results point out that propylene and the components released by the chemical plant cause the main negative externalities under the environment and human health, so that during PP production, propylene is responsible for 72% of the impacts under global warming and 86% in the face of scarcity of fossil resources. Thus, the case study proposes recycling polypropylene, following the Circular Economy guidelines by aligning the proposal with the Zero Waste policy, with modular design, with Reverse Logistics, and with Sustainable Development Goals. Research limitations: The work presents limitations inherent to literature review works, where filters are used to limit the search (limited to articles, published between 2012 and 2021 and written in English). Practical implications: The research encourages recycling, pointing out its contribution under the environmental, social and economic spheres. Originality / Value: The research presents originality and methodological value by combining qualitative and quantitative methods, and a theoretical and practical approach. Thus, it was possible to implement the research in the multinational company analyzed, and to measure the benefits obtained.

The issues of flammability associated with A3-class hydrocarbon-based refrigerants are controllable by limiting their mass charges. However, these reductions in their mass charge below certain limits deteriorate their performance efficiency. In this experimental study, we analyzed the effects of a liquid line magnetic field (Mag), multi-wall carbon nanotube (CNT) nano-lubricant, and the combination of both (Mag-Nano) on the performance of a very low mass charge (i.e., 30 g) of R600a and LPG refrigerants, as a replacement to the 100 g R134a refrigerant in a domestic refrigeration system. The refrigerants were tested with and without CNT nano-lubricant (pure), two pairs of 3000 Gs liquid line mounted O ring N50 permanent magnets (Mag), 0.2 g/L concentration of CNT nano-lubricant (Nano), and in combination with a liquid line magnetic field and CNT nano-lubricant (Mag-Nano). The performance evaluation of the refrigerants includes the determination of coefficient of performance (COP), evaporator air temperature, volumetric refrigeration capacity, instantaneous power consumption, cumulative energy consumption, and energy cost. A reduction in the COP of R600a and LPG was observed to be about 11–42% and 14–26%, respectively, when compared to R134a. The R134a refrigerant had the lowest evaporator air temperature of −24.5 °C and the highest instantaneous power consumption of 74.6 W. The R600a-Mag-Nano refrigerant is the most efficient option, having the lowest instantaneous power consumption, energy cost, and cumulative energy consumption. The adoption of hydrocarbon refrigerants is more cost-effective than using the R134a refrigerant, resulting in a cost saving of about 8–26%. In conclusion, the proposed methods adopted to enhance the performance of refrigeration system, are very safe and effective.

Copyright of Storage & Process is the property of Tianjin Academy of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Air cycle refrigeration technologies are reviewed. • Components, working principle and performance improvement methods are detailed. • Typical application fields are analyzed. • Challenges and future research directions are discussed. Currently, the alternative refrigerant in air conditioning systems has become a global problem, and air as a natural working fluid has several advantages of zero ODP, low GWP and satisfactory thermodynamic properties, thus it is a long-term development. However, the poor performance of reverse Brayton air cycle limits their application, and how to improve the performance is the main problem we must face at present. Thus, enhancing the components' efficiency and improving the system comprehensive performance have become the most effective way. The output power produced by the expander can be used for coaxial compressors, such as turboexpander compressor (TEC), turbocharger, and rotary vane compressor-expander (ROVCE). What's more, amounts of new technological approaches have been used to improve the performance of the systems such as regeneration, multi-stage compression, mixed working fluid, water removal and integrated system. In addition, thermodynamic optimization methods have become one of the most important approaches to reduce the irreversible losses and enhance the system performance. At present, reverse Brayton air cycle machines have been applied in various fields such as food freezing, transportation, heat pump, refrigerator, and dryer, etc. With the increasingly stringent environmental laws and regulations, the air cycle system will have a wide perspective application in the future. [ABSTRACT FROM AUTHOR]

The Saudi Ministry of Municipal and Rural Affairs is planning to initiate a hazard analysis critical control point (HACCP) system in restaurants and cafeterias to manage issues of food safety in Saudi Arabia. One of the most important elements in the HACCP system is the monitoring temperature of cooked and stored food. The present study aimed to investigate the prevalence and use of refrigerators/freezers and food thermometers among food handlers in local and international restaurants in Dammam, Saudi Arabia. A cross‐sectional study was conducted in municipality‐licensed restaurants. The temperatures of refrigerator and freezer were checked, and the survey form was completed by the researcher according to logbook entries. We then checked for the presence of a food thermometer, and if a functional thermometer was present, the chef was asked to complete an online questionnaire using Survey Monkey website on a tablet. The response rate of the survey was 68% (238/350 restaurants). We found that 88.1% of restaurants used a thermometer to check the temperature of their refrigerators and freezers. Thirty‐one restaurants (13.0%) had a regular temperature‐monitoring record available for both the refrigerator and freezer. International restaurants had significantly greater temperature‐monitoring data than local restaurants (88.1% vs 63.3%; p =.0001). The prevalence of food thermometers in restaurants was 53.4% (127/238 restaurants), with significantly higher prevalence in international restaurants than in local restaurants (96.6% vs 10.8%; p =.0001). The practice of using food thermometer "always" when meat turned brown was significantly associated with the chef's age and education level. The study results showed poor monitoring and documentation of refrigerator and freezer temperatures along with a low prevalence of food thermometer use. The study result provides an insight into one of the barriers to the implementation of the HACCP system in Dammam. The research is of Public Health Importance as it deals with the temperature‐monitoring practice followed by restaurants. Temperature monitoring is one of the principles of HACCP, which can help to reduce the risk of foodborne illness. [ABSTRACT FROM AUTHOR]

A compressor is the most power-consuming component in a refrigeration system, and energy scarcity in the form of electricity has become a grave challenge in today's world. Replacing the compressor with solar-powered clean energy could be an efficient alternative to reduce energy consumption significantly. The system presented comprises a Solar-powered Thermal Refrigeration System based on the Peltier Effect, functioning on a cooling module. Since the system is solar-powered, an automatic solar tracker that incorporates Light Dependent Resistors and a servo motor is integrated to supply maximum power by continuously orienting the panel in the direction of sunlight and thus always keeping it charged. This research aims to analyse the performance of a solar-powered thermoelectric refrigeration system. The model developed is a promising alternative for domestic refrigerators, accounting for a 44–63% drop in power consumption to cool a commensurate capacity refrigerator of 2.6L. From definitive experimentation, the lowest temperature of 15.15°C was achieved within the refrigeration chamber after powering the circuit for 136 seconds. Initially, the air inside the refrigeration chamber at 22.48°C (ambient temperature) was dropped by 7.33°C. A high COP of 0.54 is achieved on experimentation. [ABSTRACT FROM AUTHOR]

Artificial intelligence (AI) models for refrigeration, heat pumps, and air conditioners have emerged in recent decades. The universal approximation accuracy and prediction performances of various AI structures like feedforward neural networks, radial basis function neural networks, adaptive neuro-fuzzy inference and recurrent neural networks are encouraging interest. This review discusses existing topographies of neural network models for RHVAC system modelling, energy prediction and fault(s), and detection and diagnosis. Studies show that AI structures require standardization and improvement for tuning hyperparameters (like weight, bias, activation functions, number of hidden layers and neurons). The selection of activation functions, validation, and learning algorithms depends on author’s suitability for a particular application. Backpropagation, error trial selection of the number of hidden layer, and hidden layers’ neurons, and Levenberg–Marquardt learning algorithms, remain prevalent methodologies for developing AI structures. The major limitations to the application of AI models in RHVAC systems include exploding or/and vanishing gradients, interpretability, and accuracy trade off, and training saturation and limited sensitivity. This review aims to give up-to-date applications of different AI architectures in RHVAC systems and to identify the associated limitations and prospects.

Phase change material (PCM) has become a topic of study in thermal management, as it has a high-energy storage density. Most refrigerators have a fixed-speed compressor, which operates randomly (on/off) during their cycle. This leads to a high-power peak of electricity when the refrigerators start at the same time. Therefore, this study aims to investigate the reduction potential of the power peak and energy consumption of a refrigerator using PCM as a heat absorber. Nine testing conditions were performed by using water as the internal thermal load, at 1, 2, and 3 kg. Besides, each internal thermal load condition was varied with a PCM mass of 500, 1,500, and 2,500 g. The necessary data, such as the internal temperature and power of a refrigerator and the outside ambient temperature, were collected. The results show that the mass of PCM significantly affected the peak power of the refrigerator and energy consumption. Moreover, the results clearly show that the PCM can be used to reduce the peak power and energy consumption of the refrigerator. The correlation of the power, related to the mass of the internal heat load, and the mass of PCM was also reported. The conclusion of this study is that the PCM is suitable for reducing the peak power and energy consumption of a household refrigerator.

This work aims to predict the moisture evaporation in vegetable storage drawers of a household refrigerator with considering the operating conditions of a refrigerator and to propose a prediction model of moisture preservation for a long-term storage of vegetables. An experimental equipment was setup to evaluate the operating conditions, such as temperature and humidity control, cold airflow path, and structural design of a drawer. Moisture evaporation in fresh vegetables was evaluated quantitatively, and a new predictive model of moisture evaporation was developed on the basis of the data. The coefficient of determination was 93.2 % in the prediction model developed when spinach and bok choy were used in the basic experiment, which matched well with the experimental data obtained from a real refrigerator test with difference of approximately 0.4 %. We believe that the proposed approach can be utilized in the initial design stage of a vegetable drawer of a household refrigerator and is expected to be implemented in diverse applications related to fresh storage of vegetables. [ABSTRACT FROM AUTHOR]

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Adjuevan is an Ivorian traditional fermented fish used as a condiment. However, the fermentation process and storage conditions may lead to the production of biogenic amines (BA) which can induce severe human toxicological effects. Thus, this study aimed to reveal the bacterial community diversity and the BA contents during the storage. Samples of adjuevan from the fish species Chloroscombrus chrysurus, Galeoides decadactylus, and Thunnus thynnus were collected from local producers, stored at ambient temperature (28–30 °C) and in a refrigerator (4 °C) over a period of 8 weeks. At 2-week intervals, BA were determined by HPLC and the bacterial communities analyzed using high-throughput sequencing (NGS) of the V3-V4 region of the 16S rRNA gene. Results showed that histamine, cadaverine, putrescine, and tyramine were the major compounds. In adjuevan from T. thynnus, the level of histamine was over the maximum level of 200 mg/kg determined by Codex Alimentarius. For the other amines, no safety concerns are related. In total, 21 bacterial genera with a relative abundance ≥ 1% and belonging to 14 families and 5 phyla were detected. The Bacillaceae family was the most found at ambient temperature while Staphylococcaceae and Enterococcaceae were the most abundant in a refrigerator. The analysis of correlation showed that the increase of Lentibacillus leads to a decrease of the major BA at ambient temperature. On the contrary, the increase of Staphylococcus, Lactobacillus, Psychrobacter, Peptostreptococcus, and Fusobacterium leads to an increase of these biogenic compounds. Thus, Lentibacillus acted as BA-oxidizing bacteria while the others were found as BA–producing bacteria during adjuevan storage. [ABSTRACT FROM AUTHOR]

Thermoacoustic refrigeration systems are one of the best alternative solutions for conventional refrigeration systems that are harmful to the environment and humans due to global warming and ozone layer depletion issues. Thermoacoustic technology can be considered a renewable and clean technology with a promising future for its many advantages. A thermoacoustic refrigerator converts acoustic energy to thermal energy (creating a cooling effect). In the present research, the focus is on the design of a standing-wave thermoacoustic refrigerator driven by an ordinary loudspeaker using the numerical simulation program DELTAEC with the concern of building the apparatus at a low cost. In addition, investigating the influence of some crucial parameters on cooling power and thermal/overall performance. Hence, the designed thermoacoustic refrigerator performed well in respect of cooling power and coefficient of performance. It has achieved a cooling power of 134.34 W with a temperature difference between the ambient and cold heat exchangers of 25 K at a COP of 1.956 and the overall efficiency (electrical power converted into cooling power) amounted to 113.43%. The achieved cooling power and COP could be significant when compared to others’ results. [ABSTRACT FROM AUTHOR]

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Conventional household refrigerators consist of a motor-driven compressor, evaporator, condenser, and expansion valve. To determine the optimal operation strategies of refrigerators, it is essential to investigate the overall system performance, using an appropriate simulator. This study proposed a data-driven simulator based on engineering features and machine learning algorithms for conventional household refrigerators. The most correlated variables for identifying the indoor temperature of refrigerators were identified using variable importance, and these were revealed to be the circulation fan speed, compressor operation status, and refrigerant flow direction. A data-driven simulator was constructed using Bayesian calibration, which considers the important variables, combined with a straightforward heat balance equation. The Markov Chain Monte Carlo approach was used to simultaneously calibrate three coefficients on the critical variables based on the heat balancing equation on each time step, which is consistent with the actual temperature of the container. The results revealed that the proposed approach (equation-based Bayesian calibration outperforms) standard machine learning algorithms, such as linear regression and random forest models, by 38.5%. Additionally, compared to the typical numerical analysis method, it can reduce the delivery time and effort required to develop a reliable simulator for household refrigerators.

The need for isothermal vans for the transportation of perishable goods and cargo is currently relevant in our country. An acute problem is also the evaluation of refrigerators in order to determine the most important indicator of the quality of the insulation of the van — the heat transfer coefficient and the efficiency (cooling capacity) of the automobile refrigeration unit. According to Decree of the Government of the Russian Federation of December 21, 2020 No. 2200 “On approval of the Rules for the carriage of goods by road and on amendments to clause 2.1.1 of the Rules of the Road of the Russian Federation”, the draft Law of the Russian Federation “On the requirements for vehicles intended for the transport of perishable food products”, all specialized vehicles in operation on the territory of the Russian Federation and duly registered are subject to assessment of compliance with international standards. In this regard, the relevance of this problem is obvious. It requires an immediate solution to the current situation. In order to check the efficiency of refrigeration equipment, as well as to classify an isothermal vehicle equipped with a refrigeration unit to one or another class of refrigerated vehicle during certification, tests are carried out to measure the refrigeration unit’s cooling capacity. Recently, a number of works devoted to obtaining similar results have been published. But the question of the mechanism for determining the exact characteristics of automotive refrigeration equipment has not been fully disclosed. The emphasis on the study of the properties and characteristics of specialized vehicles, as well as the choice of refrigerated trucks for the transportation of perishable goods and cargo was made in the works of A. Gryzunov, V. Kornienko, S. Vavilova [2–5]. The result of the study is to study in detail the existing regulatory framework and, on the basis of it, develop a methodology, a model that differs from those currently available, to facilitate, simplify the test to determine the main characteristics of automotive refrigeration equipment. The article presents the features and capabilities of an isothermal chamber for testing vehicles and refrigeration equipment. The device of the camera and the equipment used are described. A test procedure for measuring the cooling capacity of an automobile refrigeration unit is described. The results of an experimental evaluation of the refrigeration capacity of the refrigeration unit of an isothermal car van are presented. The testing methodology has its origin in the master’s final qualifying work “Theoretical foundations of thermophysical tests of special vehicles.” The practical significance of the presented results lies in the fact that this technique simplifies the process and reduces the time for testing, without changing the quality of the results obtained.

Guest editors' introduction to Theme: Cold and freezing.

The performance of the refrigeration system is largely influenced by the heat exchanger, and there are various methods for increasing heat exchange efficiency. In this paper, the effect of changes in the internal shape of an evaporator with different heat transfer areas on the performance under actual refrigerator operating conditions was analyzed. The type of evaporator includes a grooved evaporator and a composite grooved evaporator with a relatively large heat transfer area. The performance evaluation was evaluated by refrigerant optimization, on-off operational test, and steady state energy test. The optimum refrigerant amount for both systems is 76 g. When a composite grooved evaporator was used, monthly energy consumption was relatively saved by 2.7 kWh/month. In addition, the composite grooved evaporator has consumption and 2.2 % higher cooling capacity than the grooved evaporator. In conclusion, COP improved by 1.33 %. [ABSTRACT FROM AUTHOR]