Performance Of Refrigerator Research Articles

HoDyGdCoAl high-entropy amorphous alloys working at full temperature range for hydrogen liquefaction with large magnetocaloric effects

Cryogenic magnetic refrigeration materials based on magnetocaloric effect can be used for hydrogen liquefaction. In this work, glass formation ability (GFA), magnetocaloric effect (MCE), refrigeration performance of melt-extracted HoDyGdCoAl amorphous ribbons have been investigated. Amorphous ribbons undergo a second order magnetic phase transition which achieve a table-like behavior broaden the range of magnetic transition temperature in hydrogen liquefaction.The maximum magnetic entropy change (-ΔSmaxM), the δTFWHM and the refrigeration capacity (RC) achieved 10.9 J/ (kg K), 84.2 K and 742.4 J/ kg (x = 5) and 11.2 J/ (kg K), 69.8 K and 643.0 J/ kg (x = 20) under a magnetic field change of 7 T, respectively. Combining wide magnetic transition temperature and large refrigerant capacity, the present amorphous ribbons can be used as potential magnetic refrigerant materials in hydrogen liquefaction temperature region.

Local Symmetry Deviation from the Average Structure of MnAs Revealed by Pair Distribution Function.

MnAs is an interesting material due to its magnetocaloric properties, which can be utilized in magnetic refrigeration. However, despite major efforts, its magnetic refrigeration performances in the substituted forms could not be improved compared to the parent MnAs phase. Both small and big box modeling of the pair distribution function of MnAs for the local structure description and powder X-ray diffraction for the average structure reveal an inherent local orthorhombic distortion in the hexagonal structure of MnAs. As a result of this distortion, any modification to the hexagonal structure results in an orthorhombic structure and a weaker magnetocaloric performance. This study highlights the importance of studying local distortion in magnetic materials. This is achieved by combining X-ray absorption spectroscopy with total scattering X-ray diffraction.

Assessing refrigerated preservation performance using Listeria predictive microbiology models and temperature data: Refrigerator performance indicator and time-temperature equivalent.

Time-temperature data for queso fresco (QF) cheese varieties stored in a residential refrigerator operating at 5°C and a predictive microbiology secondary model for Listeria monocytogenes in QF were used to estimate a refrigerator performance indicator (RPI) of microbial preservation. RPI values were used to assess how compressor technology (single [SS] and variable speed [VS]), ambient temperature (21.1°C [LT] and 32.2°C [HT]), and refrigerator load (22.5kg regular load and 39kg higher load) affected preservation performance. All deterministic and probabilistic RPI estimations slightly exceeded the desirable 1.0 value, i.e., the variable temperatures for the QF kept in the refrigerator were worse than keeping it constantly at the temperature recommended by food safety agencies for QF. Furthermore, the mean comparison of estimates of the time-temperature equivalent indicator previously developed by French researchers showed similar behavior to those observed for RPI. Finally, statistical analysis showed that Tambient was the factor with the highest impact on refrigerator performance because of its impact on the sample temperature increase during door openings and when exposed to ambient temperature during product use. This highlights the need to reduce the time for product temperature recovery by improving the compressor operation logic. Also important are consumer behavior changes such as a reduction in product exposure to ambient temperature and in the door opening duration and frequency. PRACTICAL APPLICATION: This study demonstrated how a quantitative tool (RPI) can assess refrigerator preservation performance. Although the findings presented can be applied to any cold chain segment, the data used was collected for its weakest link, the domestic refrigerator. Surveys show that 77% of them operate above the recommended 4°C. The RPI methodology is ready for use by refrigerator designers to assess performance improvements possible by modifications of the compressor operation logic. Moreover, it can be integrated into smart-hubs monitoring the frequency and duration of refrigerator door openings to inform consumers when their habits are compromising the preservation performance of the refrigerator.

Implementation of Rapid Nucleic Acid Amplification Based on the Super Large Thermoelectric Cooler Rapid Temperature Rise and Fall Heating Module.

In the rapid development of molecular biology, nucleic acid amplification detection technology has received more and more attention. The traditional polymerase chain reaction (PCR) instrument has poor refrigeration performance during its transition from a high temperature to a low temperature in the temperature cycle, resulting in a longer PCR amplification cycle. Peltier element equipped with both heating and cooling functions was used, while the robust adaptive fuzzy proportional integral derivative (PID) algorithm was also utilized as the fundamental temperature control mechanism. The heating and cooling functions were switched through the state machine mode, and the PCR temperature control module was designed to achieve rapid temperature change. Cycle temperature test results showed that the fuzzy PID control algorithm was used to accurately control the temperature and achieve rapid temperature rise and fall (average rising speed = 11 °C/s, average falling speed = 8 °C/s) while preventing temperature overcharging, maintaining temperature stability, and achieving ultra-fast PCR amplification processes (45 temperature cycle time < 19 min). The quantitative results show that different amounts of fluorescence signals can be observed according to the different concentrations of added viral particles, and an analytical detection limit (LoD) as low as 10 copies per μL can be achieved with no false positive in the negative control. The results show that the TEC amplification of nucleic acid has a high detection rate, sensitivity, and stability. This study intended to solve the problem where the existing thermal cycle temperature control technology finds it difficult to meet various new development requirements, such as the rapid, efficient, and miniaturization of PCR.

Advanced vapour compression refrigeration system dispersed with hybrid Nanolubricants: ANN-Based approach

In this study, the R600a refrigerator’s performance evaluation has been investigated utilizing the implementation of hybrid nanolubricants (SiO2/CuO) at various quantities and mass charges. The outcomes of the experiments compared to those achieved using SiO2/CuO hybrid nanolubricants and R600a charges are examined. Hybrid nanolubricants are used as substitutes for pure lubricants, and the performance parameters are assessed against the results of the experiments. SiO2 at 0.2 g/L and CuO at 0.4 g/L hybrid nanolubricants provided an optimal cooling effect of 259 W and consumed a minimum quantity of energy of 73 W resulting in a maximum enhanced predicted COP value of 3.547 compared to experimental results. The clean lubricant system resulted in a minimum COP and refrigeration effect of 2.6 and 246 W and consumed more energy of 95 W. It has been observed that adding hybrid nanoparticles to compressor mineral oil substantially loweredcompressor energy consumption and enhancedrefrigeration effect, refrigerator performance. By using the ANN prediction approach, the use of SiO2/CuO hybrid nanolubricants led to maximum increased COP, refrigeration effect, and lower energy consumption when compared with experimental findings.

Large magnetocaloric refrigeration performance near room temperature in monolayer transition metal dihalides

Magnetocaloric effect (MCE) exhibits highly efficient and ecological cooling abilities for solid-state refrigeration in contrast to traditional vapor-compression refrigeration. Successive emerging two-dimensional (2D) magnetic materials provide a fertile platform for exploring low-dimensional MCE systems. Here, we focus on a series of 2D transition metal dihalides MX2 (M = Fe, Ru, Os; X = Cl, Br) to explore the maximum isothermal magnetic entropy change (−ΔSmagmax) and adiabatic temperature change (ΔTadmax) under external magnetic field. It is found that FeCl2, FeBr2, and RuCl2 have intrinsically sizable −ΔSmagmax, ΔTadmax, and high thermal conductivity near room temperature, demonstrating superior comprehensive refrigeration performance in comparison with other 2D magnets. It is revealed that strong nearest-neighbor ferromagnetic exchange interaction plays a decisive role in −ΔSmagmax, and the high lattice thermal conductivities of FeCl2 and RuCl2 are attributed to the longer phonon lifetime and larger group velocity of low-frequency acoustic branch. Moreover, moderate strain and carriers doping are able to effectively regulate Curie temperature and magnetocrystalline anisotropy energy and correspondingly enhance −ΔSmagmax. The present work provides important insights for the exploration of 2D magnets for magnetocaloric refrigeration near room temperature.

Optimizing quantum refrigerators with a qubit on the hot side

We study the performance of one-qubit quantum and semiclassic refrigerators with the qubit on the hot side. We obtain the cooling power and the Ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Omega$$\\end{document} function. We discover that the quantum refrigerators perform differently to classic ones. We also prove that even in the high-temperature limit, where the semiclassic version of the refrigerator is valid, the results of the optimization are different to those obtained by optimizing classic refrigerators.

General approach for efficient prediction of refrigeration performance in caloric materials

General approach for efficient prediction of refrigeration performance in caloric materials

Numerical simulation and experiment to study the effect of one-way fluid interception channel on the cooling efficiency of gas wave tubes

This study investigates the enhancement of gas wave refrigerator performance through the introduction of a one-way fluid interception channel. Gas wave refrigerators, which use pressure energy for cooling, are widely used in the natural gas and chemical industries. Traditional gas outlet structures suffer from fluid entering the nozzle during the exhaust stage, causing temperature mixing of cold air and intake gas. This interference with the jet flow of pulsating intake gas reduces cooling efficiency. To address this issue, we analyzed and compared seven outlet structures: straight-type, straight-wide, vortex, interception, interception-wide, interception-optimized, and interception-bigger channels. Computational Fluid Dynamics (CFD) simulations evaluated leakage rate, pressure retention, cooling efficiency, and reflux inlet pressure under various pressure ratios and pulsating intake frequencies. Experimental results validated the simulations, revealing that the commonly used straight-type channel had high leakage and low cooling efficiency. Conversely, the interception-optimized channel demonstrated superior performance, with significantly reduced leakage and enhanced cooling efficiency. The findings indicate that the one-way fluid interception channel effectively prevents reflux, stabilizes jet flow, and improves overall cooling efficiency. This innovation offers substantial benefits for industrial applications in natural gas and chemical processing, highlighting the potential for more efficient and reliable gas wave refrigeration systems.

Hybrid air conditioning and seawater desalination system assisted by solar energy: thermoeconomic investigation and optimization

The demand for freshwater has become progressively critical due to population growth and water scarcity. The current work investigates the energetic performance of a hybrid absorption refrigeration and desalination system. A parametric study for the system operating conditions has been performed to get the optimal conditions. Also, economic analysis and a multi-objective optimization method are used with the aim of maximizing the energy utilization factor of the system and minimizing total costs. The specific cost of desalinated water from the multi-objective optimization is calculated as (1.728 Cent/L) with the greatest energy utilization factor of (2.214). It turns out that, the system performs optimum at condensation and generation temperatures of 30 and 65 °C respectively, with resultant COP and GOR of 0.84 and 1.37. Using the optimum conditions, TRNSYS has been used to investigate the transient performance of the system for Marsa–Matrouh City in Egypt. The cooling and freshwater demands are 10 kW and 24 L/h. It was concluded that the input energy required to run the hybrid system decreased by about 65% less than that required for separate systems. With the assistance of solar energy, it became clear that the energy required was 60% less than the hybrid system as well.

COMPARATIVE THERMODYNAMIC AND ENVIRONMENTAL ANALYSIS OF VAPOR COMPRESSION REFRIGERATION SYSTEM USING C-PENTANE AS REFRIGERANT

The selection of refrigerant is one of the most important parameters when designing a cooling system. Hydrocarbon refrigerants have low primary energy requirements for effective cooling capacity and favourable thermodynamic properties that reduce both direct and indirect greenhouse gas emissions. In this study, a comparative performance and environmental analysis of the vapor compression refrigeration cycle using C-Pentane as the refrigerant was performed. The cooling performance and environmental effect of C-Pentane has been compared with the cooling performance and environmental effect of R134A, R407C and R404A refrigerants in the cooling system. During the analysis, the cooling system was examined under different operating conditions. The highest coefficient of performance (COP) value in the analysis was 6.485 for the refrigeration cycle using C-Pentane, and this value was obtained at 0 oC evaporator temperature and 25 oC condenser temperature operating condition. According to the Life Cycle Climate Performance (LCCP) analysis for refrigerants, the lowest total emission value belongs to C-Pentane. Direct Emission (DE) value and indirect emission (IE) value of C-Pentane are 57.5 kgCO2 and 24928.04 kgCO2, respectively.

Exploring the potential for household refrigerator replacement in Mexico City

Many studies have focused on improving the energy performance of household refrigerators and finding out their performance under different operating conditions. However, there seems to be a gap regarding the potential for electrical energy savings due to retrofitting household refrigerators. This study focuses on the replacement potential of household refrigerators eight or more years old in poor households in Mexico City. The study uses a stratified sampling methodology. The results show that it is advisable to replace 77.75% of the household refrigerators that are in operation in poor households in Mexico City. The replacement of household refrigerators with energy-efficient equipment represents 36% of the electrical energy consumption for food refrigeration in the domestic sector in Mexico City.

Simulation study of heat transfer enhancement for all-solid-state room temperature magnetic refrigeration system

To address issues relating to large thermal resistance and low heat transfer efficiency between and inside magnetocaloric materials (MCM) in all-solid-state room-temperature magnetic refrigeration technology, this study adopted the method of inserting high thermal conductivity materials (HTCM) into MCM and coupling Peltier elements between MCMs to enhance the heat transfer inside MCM and between microcells, thereby improving the refrigeration performance of the system. In doing so, a two-dimensional simulation model was developed using COMSOL Multiphysics software. The cooling performance enhancement effect of the system resulting from heat transfer improvement within MCM and between MCMs was investigated separately. Furthermore, the impacts of various system operating parameters (such as the number of micro-cell divisions, initial operating temperature, heat transfer time, magnetic field strength, Peltier input voltage), different HTCMs and insertion volume ratios on the system’s cooling performance were explored. The simulation results reveal that, in comparison with the original magnetic refrigeration system, the optimized heat transfer time of the system following enhanced heat transfer within the MCM is reduced from 180s to 8s, accompanied by a 115% increase in the maximum temperature span. Furthermore, coupling the Peltier elements elevates the maximum temperature span by 274%.

The effects of common reservoirs on the performance of a quantum refrigerator

In this work, we study and find that the performance of an autonomous refrigerator can be improved by means of collective dissipations of common reservoirs. The refrigerator is based on a four-level system with two degenerate levels, coupled to three thermal reservoirs with different temperatures. Our study reveals that utilizing only one common reservoir can not significantly enhance the refrigerator’s performance. However, when two reservoirs are shared simultaneously, the performance improvement becomes more evident. Furthermore, we find that the refrigerator’s performance can be further enhanced by operating in a regime where the decoherence-free subspace is present. Our results indicate that careful engineering is essential to maximize the benefits of common reservoirs in enhancing the performance of quantum thermal machines.

Thermodynamic analysis of a hybrid ammonia-water refrigeration cycle with low-temperature solar heat

The performance of a solar-driven single-effect ammonia absorption refrigeration unit was studied numerically and experimentally. The thermal performance and unit operation status of small refrigerators were studied under various designing and operating conditions. A thermodynamic cycle scheme of hybrid ammonia-water refrigeration (HAWR) is proposed to operate in parallel with the compressor and ammonia absorption refrigeration, and the performance of the thermodynamic circulation system is evaluated by considering the thermodynamic coefficient and thermodynamic refrigeration ratio as evaluation indexes. Aspen Plus simulation software was introduced to simulate the HAWR and optimise the operation strategy. The results indicate that adjusting the compressor outlet pressure can stabilise the refrigeration capacity of the ammonia refrigeration system. The optimised working point pressure is 600 kPa, while the corresponding evaporation, condensation, absorption, and generation temperatures are 15 °C, 40 °C, 42 °C, and 85 °C respectively, the thermodynamic coefficient is 0.307, and the thermodynamic refrigeration ratio is 0.443. Under the rated cooling conditions, 44.3 % of the cooling capacity is driven by solar energy, and 55.7 % is driven by electric energy in the optimal working state. Under non-optimal working conditions, the proportion of the cooling capacity driven by electric energy is as high as 79.5 %. Under the conditions of sunny weather and with the absence of the compressor, the cooling capacity increases from 2.5 to 7.5 kW as the radiation intensity increases from 600 to 950 W/m2, while the system performance tends to be stable and the coefficient of performance maintains around 0.738 as the irradiation intensity exceeds 800 W/m2.

An efficient high cooling capacity Stirling cryocooler and its application for capturing boil-off methane from liquefied natural gas

Natural gas is a cost-effective energy supply for the development of low-carbon economy and environmental protection worldwide. Despite the environmentally friendly properties of natural gas, methane is a potent greenhouse gas. Therefore, efficiently recovering the boil-off methane gas (BOG) generated from liquefied natural gas (LNG) devices is becoming a pressing problem involving both the economy and the environment. The Stirling cryocooler is a promising technology in dealing with BOG. This technology has superior characteristics, including large cooling capacity, high efficiency, compact configuration, and flexible operating characteristics. In the study, a high cooling capacity Stirling cryocooler was developed. The influences of the regenerator on the cryocooler were studied. The refrigeration performance and the operating characteristics were systematically analyzed. A cooling power of 1050 W at 77 K with a relative Carnot efficiency of 33.28 % was achieved. Accordingly, the cryocooler outperforms the reported Stirling-type cryocoolers in terms of overall performance. A BOG liquefaction system based on the cryocooler was installed in an LNG refueling station. On-site test results demonstrated that the system can produce 27.3 L/h LNG with a power consumption of 14.5 kW. The present research lays a good foundation for future optimizations and applications of the cryocooler in liquefying BOG.

Effect of Heat Exchanger and Capillary Geometry on the performance of Joule- Thomson Refrigerators operating with different mixtures

Abstract Joule-Thomson (J-T) refrigerators or J-T cryocoolers are extensively used in many low-temperature applications. J-T refrigerators operating with nitrogen-hydrocarbon (N2-HC) refrigerant mixtures offer several advantages, such as low operating pressures (&amp;lt;20 bar), high exergy efficiency, no moving parts in the cold section, and low cost. The cooling power or cooling capacity of the J-T refrigerator depends on the hardware used as well as the refrigerant composition. The proposed work focuses on estimating the cooling capacity of a mixed refrigerant J-T (MRJ-T) refrigerator of the given hardware and specified refrigerant. An iterative steady-state full-cycle simulation procedure has been presented in this work to simulate the complete system and estimate the cooling capacity, taking into account the possibility of choking of the expansion capillary. Some of the results have been validated against experimental results of an MRJT refrigerator available in the open literature. The details of the simulation model and the results of our studies on the prediction of stable operating range, maximum cooling capacity, the effect of heat exchanger geometry, expansion capillary geometry, mixture composition, and choking of the refrigerant mixture on the performance of an MRJ-T refrigerator are presented in this paper

LOW-COST OPERATING LPG REFRIGERATOR SYSTEM

The study explores the use of liquefied petroleum gas (LPG) as a refrigerant in domestic refrigerators to provide continuous refrigeration in areas without steady electricity supply. LPG, consisting of propane, butane, and isobutene, is cost-effective and environmentally friendly with no Ozone Depletion Potential or Global Warming Potential. The experiment compared the performance of an LPG-based refrigerator to one using R134a, finding LPG to be more efficient. By analyzing the refrigeration effect over time, the study determined the optimum cooling effect based on valve and capillary tube settings. LPG undergoes a phase change in the capillary tube, resulting in a drop in pressure and temperature, allowing it to produce a refrigerating effect. The Coefficient of Performance (COP) of an LPG refrigerator was found to be higher than a traditional refrigerator. Overall, using LPG as a refrigerant in refrigerators can be a sustainable and environmentally friendly solution for regions with unreliable electricity access. Key Words: LPG, REFRIGERATOR, REFRIGERANT, OZONE DEPLETION POTENTIAL.

3-D numerical simulation of forced convection heat transfer in microscale rectangular channels for low GWP refrigerants

This study presents a numerical evaluation of the performance of low Global Warning Potential (GWP) refrigerants R600a, R290, R1270, and R134a in heat dissipation by forced convection in a microchannel heat sink. The heat sink comprises 50 parallel microchannels with a cross-sectional area equal to 123 × 494 [µm2]. The differential equations describing the physical behavior interaction between the refrigerant and the copper matrix are solved using the finite volume method and the SIMPLEC coupling algorithm. The numerical model is used to predict fluid mechanics and heat transfer for single-phase laminar conditions including the friction factor, the Nusselt number and the average wall temperatures, as well as the whole performance of the microchannel heat sink. The accuracy of the numerical model is validated by comparing the performance of R600a with experimental data, resulting in deviations within the range of the uncertainty of each parameter. The evaluation of the performance of different refrigerants reveals that the friction factor and Nusselt number are significantly influenced by the microchannel geometry and thermal conditions, exhibiting unique yet similar trends for different refrigerants. Furthermore, the analysis of the average wall temperature in the microchannels demonstrates that the hydrocarbon-based refrigerants effectively reduce the temperature of the copper matrix compared to R134a, suggesting a superior performance in the dissipation of heat flux under single-phase laminar conditions.

Effect of stack geometry and operating frequency on performance of thermoacoustic refrigeration

Effect of stack geometry and operating frequency on performance of thermoacoustic refrigeration