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The temperature rapid rise phenomenon often happens in the side-by-side frost-free refrigerators during the damper-off cycle, which leads to a decrease in damper-off duration and an increase in energy consumption. A three-dimensional transient model of natural convection during the damper-off cycle is established and experimentally validated to analyze the refrigerating compartment (RC) temperature rapid rise phenomenon. The results show that the violent natural convection airflow driven by the non-uniform temperature distribution will lead to the significant variation of RC temperature. The hot air rises from bottom into top layer along the three passages, which include the front gap (FG) between shelves and door boxes, the side gap (SG) between the right-side wall and door boxes and the rear gap (RG) between shelves and the rear wall. The air enthalpy along FG into the first layer is the dominant factor of the temperature rapid rise, accounting for almost 64.4% of the total inflow air enthalpy. The net air enthalpy flow along FG is larger than other passages in the first 15s and decreases rapidly as the temperature distribution becomes uniform.

Helical condenser coiled tube is widely used in refrigeration machines for water heating due to its higher heat transfer, compact structure, high energy efficiency, ease of manufacture and arrangement. In addition, developing and optimizing the helical condenser coil designs are considered a sustainable solution for improving the performance of the system. Based on this vision, a particular difference of this study with other studies performed on similar researches is the influence of different shapes of condenser coil designs on heat transfer and temperature distribution during heating process. Therefore, the main objective of this paper is to improve the thermal performance of a helical coil by modifying the coil shape. Based on the results, the average heat transfer coefficient and average COP of variable pitch coil were increased by 36.48% and 16.17%, respectively, compared with normal coil. Moreover, the obtained results indicated that the water temperature, the water velocity, the heat transfer and the performance of the helical condenser with variable pitch coil were improved in comparison with that of normal coil. However, this investigation could provide some guidance to obtain the optimum coil structure of refrigeration machines for domestic hot water production.

At the present scenario, the action of ensuing the philosophy of reducing energy consumption and saving it for longer period without drop off in performance is increased. On the other hand, global warming and ozone layer depletion become foremost challenges. These concerns are takes place in Thermal systems like refrigerator and air conditioning. To resolve the above challenges, the nano refrigerants are used in refrigeration, which has previously got the attention due to its distinctive properties such as thermal conductivity. They also have the potential to improve the heat transfer performance of refrigeration. This project interrogated on the performance of domestic refrigeration system using normal condenser and microchannel condenser with and without nanoparticles. The Cerium oxide and Zinc oxide nanoparticles in the size of about 20-30nm and 30-50nm respectively with R134a domestic refrigerant were used. The experimentation carried out using 2 gm ofCeO2and ZnO nanoparticles in three different ratios [0.5:1.5,1:1 and 1.5:0.5] with R134a refrigerant. Hereby, the result conquered that 33.3% increase in the Actual COP of domestic refrigeration system using normal condenser with 1:1 ratio of nanoparticles when compared with the refrigeration system using microchannel condenser with and without nanoparticles.

Refrigerant leak from refrigerator production and operation is one of major sources that causes greenhouse gases (GHG) emission due to the high global warming potential (GWP) from existing Tetrafluoroethane (R-134a) which is hydrofluorocarbon (HFC) refrigerants in Thailand. There are three factors to leakages, production, operation & maintenance and disposal of the refrigeration system. Therefore, replacing the refrigerant with a new lower GWP one will reduce GHG emissions from refrigerant leaks. For that reason, producers have started to use Isobutane (R-600a) refrigerants replacing R-134a by 97% from lower GWP. However, R-600a contains flammability competence which causes relatively small amount usage not more than 150 gram per refrigeration unit. This research provides a method to evaluate the greenhouse gas reduction from refrigerant modifications measured from 2016–2020,​ which reduced by 499,818 tons of carbon dioxide equivalent (tCO 2eq) furthermore, increased energy efficiency from refrigerant modifications reduced greenhouse gas 808,677 tCO 2eq. In the absence of statistics indicating the amount of refrigeration equipment disposed, an estimation of such is required. Provided that an appropriate base year of collected data is defined.

A high homogeneity superconducting magnet with conduction cooling is fabricated to calibrate Hall sensors for measuring mag-netic field in high energy particle accelerators. The magnet uses a single 1.5 W@4.2 K refrigerator. It combines indirect conduction of heat pipe and direct contact conduction to cool the magnet. The winding process of magnet are introduced and the magnetic field deviation is analyzed according to the manufacturing error. The excitation test and uniformity test are carried out and analyzed. The test results show that the uniformity does not exceed 20 ppm @ ϕ10 mm × 10 mm.

Refrigerators consume significantly high energy and the improvement on their efficiency is essential to minimize greenhouse gas emission. Understanding the power consumption patterns of refrigerators is a key element that is not thoroughly studied, especially in domestic PV system with an integrated battery-storage. Therefore, the main objective of the study is to develop strategies in decreasing the energy consumptions of systems including inverter-driven refrigerators in commercial and residential sectors. This paper compares measurements of the power consumption of two types of appliances, inverter-driven and traditional/non-inverter driven refrigerators when operating in DC and AC environment. The energy consumption was measured experimentally at four different temperatures from 10 °C to 40 °C to provide information on underlying energy changes due to changes during normal use. The work proposes an efficient configuration with DC environment appropriate for PV with battery storage applications. The overall system efficiency is adopted as a factor to evaluate the system performance for comparing two DC system topologies, DC-Load and DC-inverter-load. The comparison results of size equivalent refrigerators indicated that around 300 Wh of daily energy can be saved when just switching to the new inverter technology and smoother power pattern, especially at higher ambient temperatures. The results also found that the voltage level (310–325)VDC is the most appropriate value for the photovoltaic system integrated with battery storage of DC environment. This study provides researchers reasonable estimates on the daily energy consumption for other refrigerators at different operating conditions.

Nowadays, research has been focused on refrigerants from Hydrofluorocarbons (HFCs), which are not harmful to the ozone layer. Because of replacing refrigerants from chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). HFCs are used in many applications, including refrigerants, aerosols, solvents, and blowing agents for insulating foams. However, some HFCs have relatively high global warming potential (GWP) and are subject to further examination due to growing concerns about global climate change. The present work’s main objective is to select eco-friendly refrigerants from AC5, R430A and R440A, combining two or more refrigerants from HC, HFC and HFO groups as a direct substitute HFC-134a in a household refrigerator. The performance of the domestic refrigerator with liquid suction heat exchanger (LSHX) was compared in terms of compressor discharge temperature, coefficient of performance (COP), volumetric cooling capacity (VCC), and power consumption of a compressor. It was found that the average COP of R440A and R430A was higher by approximately 2.5% and 1.47% than HFC-134a. However, the COP of AC5 was 6.1% lower than that of HFC-134a. The VCC of R430A is almost equal to HFC-134a. The results also show that AC5, R440A and R430A consume less power than HFC-134a. The compressor outlet temperature with R440A, AC5 provide higher values than HFC-134a, which affects the compressor life. The best overall performance was achieved with the refrigerant R430A in the household refrigerator and suggested an alternative to HFC134a, which also has a very low GWP from the environmental safety perspective.

This paper presents the development of a sustainable and affordable domestic refrigerator for rural areas where grid setting is weak or non-existent. The refrigerator uses a miniature refrigeration unit based on a micro direct current (DC) compressor, which can adjust its speed according to photovoltaic output variation with solar radiation intensity, in order to maximize cooling production. The experimental investigation aims to define the cooling capacity management of the refrigerator through the use of phase change materials (PCMs). PCM packs in the fridge are charged during the period of high solar radiation and, afterward, melting of PCM releases cooling to maintain a cold temperature for extra hours when solar radiation is low or not available. The paper presents the design and construction of an experimental refrigerator with a miniature refrigeration unit of a finned tube heat exchanger for the fridge cabinet; PCM selection and, particularly, the effect of heat transfer enhancement at the condenser are discussed. Lab-scale tests were carried in the UK and field tests were carried out in Ghana in a collaboration project. In lab-scale tests, it is found that a condenser modification can decrease the transient power consumption by up to 26%. In contrast, the field-testing results show that the daily power consumption can be reduced only from 0.9 to 0.84 kWh. Additionally, field testing results show that the cabinet temperature of the PCM-enhanced refrigerator rose from 7°C to 11°C after a period of 5 hr power outage.

This work provides an analysis of the thermal flow and behavior of the (load-free) refrigerator compartment. The main goal was to compare the thermal behavior inside the refrigerator cavity to the freezer door (home refrigerator) effect and install a fan on the freezer door while neglecting the heat transmitted by thermal radiation. Moreover, the velocity distribution, temperature, and velocity path lines are theoretically studied. This was observed without affecting the shelves inside the cabinet and the egg and butter places on the refrigerator door as they were removed and the aluminum door replaced with a glass door. This study aims to expand our knowledge about the temperature and flow fields of this refrigerator model. Finally, the development of this work highlights the importance of numerical simulation in the search for improvements in the design of this refrigerator model, which may assist refrigerator manufacturers.

This study aims to find the effect of variations in the capillary tube winding on the suction line on achieving optimal temperature and room cooling rate. This study uses three variations: the capillary tube without being wrapped around the suction line, the capillary tube wrapped in half on the suction line, and the capillary tube fully wound on the suction line. Specifically, the purpose of this study was to determine the effect of variations in the capillary tube wrapped around the suction line, which led to efforts to maintain the performance of the refrigerator trainer prototype. The method used in this study uses an experimental method where the data collection process is carried out through observation and documentation. The data analysis technique used in this study uses quantitative descriptive research techniques where the research data will be tabulated and displayed in the form of tables and graphs, and data analysis is carried out to find out how much influence the achievement of the optimal room temperature and the cooling rate of the prototype trainer refrigerator room itself. From the research that has been carried out, it is obtained that the highest optimal room temperature achievement occurs in the variation of the capillary tube fully wound on the suction line, where there is an increase in the optimal room temperature achievement of 16.17% when compared to the room cooling rate using standard variations or without being wrapped. And the result in the form of the highest room cooling rate is the variation of the capillary pipe fully wound on the suction line.

The Kyoto protocol emphasized the need of replacement of HFC refrigerant due to their high GWP values that causes pollution in the environment. So in this paper the refrigerants R1234yf, R152a and HFOs/HFCs mixtures of R134a/R152a/R1234yf such as ARM42 (in the ratio of 8.5/14 /77.5 by mass), ARM42a (in the ratio of 7/11/82 by mass) with a view of replacement of the refrigerant HFC-134a in a domestic refrigerator were analyzed theoretically. Volumetric cooling capacity, compressor discharge temperature, coefficient of performance, compressor energy consumption and refrigeration capacity are the main parameters to estimate the performance of the refrigerator. The results are revealed that HFC-152a had gave a superior performance as compared to HFC-134a in terms of COP and equal cooling and volumetric cooling capacities. However, the refrigerant HFC-152a was flammable and runs with high compressor outlet temperature which may restrict its usage. The HFO refrigerant R1234yf showed an almost equal volumetric cooling capacity, compressor energy consumption, refrigerating effect and COP when compared with HFC-134a. Among the refrigerants ARM42 and ARM42a, the refrigerant ARM42a was selected as a good alternative for HFC-134a because the Volumetric cooling capacity and COP of ARM42a were almost equal to HFC-134a. Therefore ARM42a had better choice of direct substitute to HFC-134a in a domestic refrigerator when the corresponding safety requirements are adopted. So on overall comparison of every property of refrigerants we can conclude that R1234yf can be treated as best alternative to HFC-134a in a domestic refrigerator.

This paper proposes the performance improvement of the ejector refrigerator based water chiller (ejector-based chiller) by means of using different mixing chamber profiles. Two different ejector mixing chamber profiles are constructed which are based on the conventional method (CONV–ejector) and the constant rate of momentum change method (CRMC–ejector). With the different design methods, the ejectors have different flow areas along the ejector’s axis; however, they have identical ejector throat diameters of 9 mm. Both ejectors are equipped with two primary nozzles, and hence, they have the same ejector area ratio of 6.3 and 7.9, respectively. The refrigerator is powered by hot water at a temperature of 94–98 °C while the condenser is cooled by cooling water at 29–31 °C. The chilled water temperature (Tchill) under various cooling loads and COP is assessed. It is found that the CRMC–ejector produces a much lower chilled water temperature than the CONV–ejector at identical cooling load. The system COP can be increased by 27–63% via the CRMC–ejector. With the change in Thot, both ejectors produce identical Tchill; however, the CRMC–ejector still produces much lower Tchill at an identical cooling load. A larger primary nozzle throat yields a higher Tchill.

An experimental study on the performance of calcium chloride-ammonia adsorption system is described. A single bed water cooled condenser adsorption refrigerator prototype, which utilises calcium chloride-ammonia pair has been developed and tested in the laboratory. Experiments have been conducted for desorption temperatures of 100 °C with desorption time varying from 1 to 4 hours. An electric tape heater and a timer were used to perform the experiments. The adsorption temperature profile, adsorption rate and prototype performance have been analysed and discussed. The tested heating and desorption temperature of 100 °C and heating and desorption time of 1 to 4 hours was able to create a cooling effect of the cold chamber of the prototype of between -0.8 to 8.3 °C, which is adequate for vaccine storage requirement of 2 to 8 °C. The estimated Coefficient of Performance of the system ranges between 0.025 and 0. 076.

One of the most vital supports related to welfare and health is the Refrigeration Machine to ensure the quality and quantity of food ingredients. For meat and fish that is still good is the meat and fish are not mushy, not rotten and when stored can freeze completely and if necessary crystallize. In order for foodstuffs to remain good, they need a storage temperature of ± 2℃. For the storage of meat and fish we need a storage temperature of ± 15℃. The less than optimal working of the cooling machine is influenced by various factors, both internal factors such as the number of hours the machine works. For external factors, this is closely related to the lack of maintenance on the cooling machine. In the research that the author did, there were several factors that were very influential in the smooth operation of the food cooling machine. The presence of frost on the evaporator pipes is a problem that most often occurs in the work of the evaporator. This happens when the pipe surface temperature is lower than 00 (freezing temperature of water). Next is the lack of good condensation process. The suggestions given in this problem are: Immediately close the cooling room door when entering or leaving the cooling room and monitoring and periodical maintenance of the amount of freon through the guessing glass and lubricating oil contained in the compressor. So that the freon condensation process is perfect and can meet the cooling needs, then do the condenser maintenance properly. For normal conditions once a month and if in an emergency condition can be cleaned and checked as soon as possible.

The main purpose of our research is to increase the utilization of solar thermal energy to supply a refrigerator with vapor compression and reduce the refrigeration power needed for cooling. Combined Hybrid Solar - the vapor- compression refrigerating unit has been built and operates under Mutah University's environment in Jordan. The systems were made up of a capillary tube, condenser, evaporator, and collector. The vapor-pressure refrigerator was incorporated with the classic water-solar system to minimize the compressor's duty and to reduce power consumption in heating the amount of water held in the pipe to be sent along the tube outside the evaporator. After that, it will be returned to the compressor, But at a lesser temperature, to minimize compressor workload and enhance cooling performance. Before the compressor was developed, a solar collector system had been created to maximize its temperature before reaching the compressor to improve C.O.P, and the difference in temperature was remarkable. The vapor-compression refrigerator unit was powered by many generators: solar collector that has been discharged, photovoltaic system, flat plate solar collector. Two groups of tests have been performed experimentally on the partial solar compression refrigerator integrated into a hybrid system. First in the vapor compression refrigerator only, and the second in the Hybrid solar compression refrigerator incorporated. Total sunlight and different temperatures, current, and voltage were measured for many months each hour of the day. The performance coefficient was determined found 2.019, 2.432 respectively. Many auxiliary instruments are utilized to measure the temperature in irradiation networks, voltage, and night-time current every hour.

The study aimed to evaluate pork loin quality after short-term (ten-day) storage in a supercooling refrigerator. Pork loin samples were stored for 10 days in a traditional refrigerator (control) and a commercially available supercooling refrigerator (SC). Pork quality measurements included meat pH, meat color, water holding capacity (drip loss and cooking loss), tenderness (hardness), and a sensory evaluation. Temperature changes of 0.45 ± 0.2°C and 0.02 ± 0.25°C occurred in the control and the SC, respectively, during 10 days of storage. The temperature in the SC chamber did not remain below freezing point, failing to meet expectations. Regarding the pork quality measurements, only the drip losses in the control and the SC were significantly different (4.45% vs. 2.59%, p < 0.01) after 10 days of storage. There were no significant differences between the two types of refrigerator in terms of the other measurements. Additionally, the overall acceptability of the pork loin did not vary significantly between the control and the SC when the sensory evaluation was performed. Therefore, a commercial SC could prove beneficial in terms of water holding capacity during the short-term storage of meat. Further research should be performed to evaluate quality changes that occur during long-term storage of meat in SC s and evaluate a wide range of meat, such as beef and chicken.

Experiments were carried out initially by considering pure R134a and hydrocarbon refrigerant mixtures such as (R290/R600a) (HCM1 44/56, HCM2 50/50, HCM3 54/46, HCM4 64/36, and HCM5 74/26 wt %). Tests are conducted at the atmospheric temperature of 30°C in a domestic refrigerator system. The performance parameters such as pull-down time, desired effect, power consumption, and running cost of the system are to be analysed at different evaporator temperatures, the mass of refrigerant and varying length of capillary tubes. To evaluate the refrigeration effect, Power consumption and COP of the domestic refrigerator at various freezer temperatures (–9°C, –12°C & –15°C) were selected. Results report that out of all the alternative mixtures the amount of energy input was less consumed in the case of HCM1 at a minimal expansion length of 6.3 mm. In the case of HCM5, the least energy was consumed at a capillary length of 5.24 mm whereas in the case of R134a it was at 3.3 mm.

In the present study, numerical analysis of coiled tube heat exchanger used in J-T refrigerator is carried out. A computer code is developed to estimate the length of the heat exchanger by giving mass flow rate, diameter of tube and shell as input parameters. This code is verified against experimental data. Two different configurations are considered in this study viz., heat exchanger with wire fin wound around the inner tube of heat exchanger and without wirefin. Three different refrigerant mixtures are used to evaluate the performance of heat exchangers. The variations of temperature and heat transfer coefficient are brought out as result. Significant reduction in the length of heat exchanger is observed in all the cases. Mixture-1 causes 33% reduction in length of heat exchanger with wirefin. Similarly, for mixture-2 and mixture-3 the length is reduced by 15% and 30%. Additionally, heat transfer coefficient (HTC) values are also estimated for heat exchanger with wirefin and without wirefin. Considerable increase in HTC values is observed in the heat exchanger with wirefin.

The article describes the implemented system of pneumatic lifting of the bell of the state primary standard gas volume and volume flow rate units. The system is composed of unified elements of industrial air preparation. There are elements for air purification in front of the compressor, dehumidifier, refrigerator dryer. With the use of a pneumatic system, the bell can be filled with prepared air with different values of excess pressure. The system is installed as a backup to the current to increase security. Pneumatic lifting of the bell allows you to connect a set of cylinders with pure inert gases or mixtures thereof to determine the impact on the gas meters metrological characteristics.

This paper is focused on the performance of a solar-assisted DC refrigerator installed on the backside of the electric vehicle (EV). The experiments are performed by varying load conditions inside the refrigerator. The experimental setup consists of four solar PV panels, a charge controller, battery bank, voltage converter, DC refrigerator, and an electric vehicle. The temperature inside the refrigerator cabin was controlled with the thermostat position adjustment. The solar PV panels of the vehicle was generating 2.5-4 kWh energy on the average sunny day. The refrigerator's inside temperature was decreased with a faster rate at the third thermostat position and consuming higher energy at the seventh thermostat position among all load conditions. The fourth and fifth thermostat positions were better at maintaining the lower desired temperature inside the refrigerator cabin by consuming the minimum energy. The COP of the refrigerator was decreasing with the increasing compressor speed. The battery bank was able to run the refrigerator 240 hr, 96 hr, 72 hr for the no-load, 15 L load, and 25 L load conditions at the higher thermostat position. The vehicle was travelling 68.3 km, 65.3.6 km, 63.4 km distance in no-load, 100 kg, and 200 kg load conditions respectively by consuming 3010 Wh, 3230 Wh, and 3450 Wh energy. The travelling charge of this vehicle was 1-1.5 INR per kilometer

Dengan pesatnya perkembangan teknologi saat ini refrigerator freezer (lemari es) sebagai salah satu alat untuk membantu kita dalam menyimpan makanan agar tahan lama. Refrigerasi adalah suatu proses penyerapan panas dari suatu zat atau produk sehingga temperaturnya berada di bawah temperatur lingkungan. Refrigeran adalah zat yang digunakan sebagai fluida kerja dalam proses penyerapan panas. Zat inilah yang bersikulasi dalam mesin refrigrasi, yang menyerap panas dari benda atau udara yang didinginkan, kemudian membuangnya ke udara sekeliling di luar benda atau ruangan yang didinginkan. Dalam penggunaannya refrigenerator sering mengalami kerusakan, sehingga perlu dilakukan analisa kerusakan tersebut. Hasil analisa menunjukan terjadi kerusakan pada refrigerator freezer AR 763, yaitu pada system pendingin terjadi penyumbatan disebabkan refrigerator tidak beroperasi (rusak) dan menyebabkan refrigerant di dalam system membeku yang menyebabkan system tidak bekerja. Selanjutnya filter harus diganti karena filter banyak menyimpan kotoran dan komponen kelistrikannya ada yang rusak seperti thermo fuse dan timer disebabkan batas umur pakai dari komponen.

Based on a recently developed non-perturbative platform designed to simulate the full quantum dynamics of quantum thermal machines, the situation of a quantum refrigerator operating according to an Otto cycle is studied. The periodic steady-state dynamics is discussed in detail as well as the key thermodynamic quantities work, heat, and entropy. A particular benefit of the formulation is that it allows to access explicitly the work required for switching on and off the interaction with the respective thermal reservoirs in a consistent way. The domains in which the device operates in refrigerator mode are characterized.

This article examines experimentally the performance of domestic refrigerators with isobutene (R600a) and graphite nano-lubricants as working fluids. Graphene has an extremely thin layer structure that fills the friction surfaces and reduces friction losses quickly. However, there is a lower coefficient of friction (COF) and higher thermal conductivity of nano-fluids generated using graphite in the base fluid. The graphite nanoparticles modified in the surface are verified to continuously suspend for a long period of time in the form of clusters. The refrigeration test examined the application of the graphite nano-lubricants in the domestic refrigerator with a volume concentration of 0.1%, 0.3%, and 0.5%. The findings show that nano-refrigerants in the refrigeration system work safely and normally. And also compressor and refrigerator output have been analyzed. Moreover, refrigerator energy usage decreased by 15.26%, 17.10%, and 21.16% with graphite nano-lubricant as a concentration of 0.1%, 0.3% and 0.5%, respectively.

The BEPCII project is for upgrading the Beijing Electron Positron Collider to reach a higher luminosity. The cryogenic system has been firstly designed and deployed in BEPCII, which provides cooling capacity for SRF cavities, SCQ and SSM. The cryogenic control system consists of Siemens PLC for the refrigerator control and “PLC + IOC” for superconducting device control. The BEPCII machine commissioning with beam started in October 2006. This paper describes the design and the development of the cryogenic control system.

Thermal energy storage through phase change material has been used for wide applications in the field of air conditioning and refrigeration. The specific use of this thermal storage has been for energy storage during low demand and release of this energy during peak loads with potential to provide energy savings due to this. The principle of latent heat storage using phase change materials (PCMs) can be incorporated into a thermal storage system suitable for using deep freezers. The evaporator is covered with another box which has storage capacity or passage through phase change material. The results revealed that the performance is increased from 3.2 to 3.5 by using PCM.

Inconsistencies in fabricated thermoacoustic stacks are due to the methods available to obtain the desired geometry and dimensions even under optimized design parameters. This paper presents performance results from stacks fabricated using 3D printing technology which minimizes the error, disposes of irregularities and can reduce production time. In this study, the performance of a thermoacoustic refrigerator was determined from measurements of the temperature difference across various 3D printed stack lengths fabricated. Experiments were done at 400 Hz frequency with different stack plate spacing and thickness, in a 21-mm diameter resonator. Results show that a 0.7 mm stack plate spacing with a 0.5 mm plate thickness performed better compared to those with smaller spacing at the same thickness or with the same spacing but larger thickness. The outcomes of this study have shown the need for the fabrication technology to keep pace with optimized design to realize global efforts towards a sustainable environment.

In this work, Computational Fluid Dynamics (CFD) analysis was conducted considering three different turbulence (viscous) models for a fresh food compartment of a domestic refrigerator (DR), in order to not only gain idea on cooling down time rate of fresh food compartment but also present air and temperature distribution inside the compartment when it is loaded. The refrigerator composes of three compartments: Fresh food (FFC), chill (CC) and freezer (FC). The FFC compartment is cooled by a thermoelectric/Peltier cooler (TEC) while the other compartments are handled by a vapour compression (VC) system. To measure cooling times, tests were conducted according to new IEC62552:2015 standard in climatic chambers and the cooling time was measured as 146.5 min. The predictions of developed CFD model clearly visualize the airflow and temperature fields inside the FFC. Concerning numerical predictions for the packages in the upper regions were in better agreement (below 10%) with measurements than the predictions for the packages in the lower regions mainly due to convective heat transfer behaviour. (C) 2020 The Author(s). Published by Elsevier Ltd.

Refrigerators are the most energy demanding household devices since they are working 7/24. Improving insulation material is crucial for reducing this demand. One of the promising ways to improve insulation materials is to develop better-blowing agents. In this study, the effects of Liquid Blowing Agent (LBA) and Pentane Blowing Agent (PBA) on whole refrigerator insulation were investigated by experimental and numerical methods. The thermal conductivities of the insulation materials were measured by the hotwire method. The experimental results show that LBA has a 32.08% lower thermal conductivity regarding conventional polyurethanewith PBA. These experimental results utilized as boundary conditions for CFD model of the refrigerator. The numerical analysis suggests that LBA can decrease the refrigerators' heat loss between 5.52% and 19.34%

Objective Hypothermia secondary to environmental exposure is a serious condition. Active external warming measures to treat it may prove challenging in the prehospital setting. We conducted an experimental study to measure the ability of commercially available heating elements to warm intravenous (IV) fluids during infusion. Methods 250-milliliter bags of dextrose 10% solution were suspended inside a refrigerator. IV tubing was coiled, and the tubing output was placed inside a thermally insulated cup. The tubing was heated directly with a hand warmer, a meals ready-to-eat heater, or a heating blanket. Fluids were run through the IV line. The temperature of the fluid at the tubing output was measured. The initial and final infusion temperatures for the methods were compared. Results The use of hand warmers, meals ready-to-eat heaters, and heating blankets to warm IV tubing did increase the temperature of the fluids but was ineffective at achieving the desired mean infusion temperature of 35°C to 42°C. Conclusion Although the mean temperature increase did not meet the established experimental threshold, further research is needed to determine whether the fluid warming effect of these commercial heating elements used in the prehospital environment is significant enough to limit heat loss while repleting the dextrose of a hypothermic, hypoglycemic patient.

A single evaporator household refrigerator with a total volume of 70 L is used to evaluate multi-walled carbon nanotubes (CNTs) nanolubricant as a drop-in replacement for pure lubricant. Continuous running on the refrigerator is done with varying concentrations of multi-walled CNTs nanolubricant and different mass charges of R600a. The results show that using R600a with multi-walled CNTs nanolubricant concentration of 0.4 g/L to 0.6 g/L and a charge of 50 g to 60 g more result in a decreased pull downtime and evaporator temperature of -8 and -11 °C, respectively. Using 0.4 g/L multi-walled CNTs nanolubricant and 50 g of R600a, the lowest electric energy usage is attained. Higher refrigeration is attained with this combination. The pull-down time is lower and also the power consumption of the refrigerator is lower than those of pure lubricant in the refrigerator by about 25.9 %, 20.2 %, and 13.7 % for 50 g, 60 g, and 70 g, respectively, while using multi-walled CNTs nanolubricant of 04 g/L to 0.6 g/L. Finally, the proposed multi-walled CNTs nanolubricant appears to be a good choice for replacing pure lubricant in the refrigerator.

A medical refrigerator for safe storage of blood components and products has been designed. The refrigerator can be used at blood transfusion stations and departments. Its main parameters and operation are described.

The influence of latent heat storage elements on the cooling performance and the temperature rise time of household refrigerating appliances is studied experimentally in the context of the “new global refrigerator standard” IEC 62552:2015 (IEC 62552:2015, 2015). In addition to the daily energy consumption, this international standardization introduced performance tests for cooling capacity and temperature rise time. While the cooling capacity has long been anchored in various test procedures of consumer organizations, the temperature rise time, which has only been tested on freezers so far, will be a decisive factor in the future. Moreover, the need for so-called "smart appliances" that may balance power consumption compensate the volatility of renewable energies and thus stabilize the power grid is increasing. Against this background, eight commercial household refrigerators and refrigerator-freezers are equipped with polymer-bound phase change materials (PCM) and their performance is determined under the new standard test conditions. The results show that the introduction of PCM increases the cooling capacity by up to 33 % and also increases the temperature rise time by up to 145 %, without affecting power consumption, as compared to the unmodified refrigeration appliances.

This work presents an adaptive neuro-fuzzy inference system (ANFIS) artificial intelligence methodology of predicting the 2nd law efficiency and total irreversibility of a refrigeration system running on LPG/TiO 2 –nano-refrigerants. For this purpose, substractive clustering and grid partition approaches were utilized to train the ANFIS models required in estimating the 2nd law efficiency and total irreversibility using some experimental data. Furthermore, predictions of ANFIS models with subtractive clustering approach was found to be more accurate than ANFIS models predictions with grid partition approach. The predictions of ANFIS models with subtractive clustering approach were also compared with experimental results that were not included in the model training and predictions of already existing ANN models of authors previous publication. The comparison of variance, root mean square error (RMSE), mean absolute percentage error (MAPE) were 0.996–0.999, 0.0296–0.1726 W and 0.108–0.176 % marginal variability values. These results indicate that the ANFIS model with subtractive clustering approach having cluster radii 0.7 and 0.5 can predict the 2nd law efficiency and total irreversibility respectively, with higher accuracy than authors’ previous publication ANN models.

Solar power (photovoltaic) is one of the clean energies that is very well developed in a tropical country like Indonesia. This is due to the high intensity of the sun and shining throughout the year so that the annual energy obtained is relatively high. The solar energy system in this research was developed with a photovoltaic array system that can be optimized for angles and facing according to where the experiment was carried out. The solar system using Solar Control Charge (SCC) and an inverter in order to get both alternating and direct current output. This energy output from solar power is used to drive the medium temperature refrigerator system for storing fresh vegetables and fruit. The results obtained from this preliminary study are the best angle and direction is an angle of 15 degrees to the north. And this condition will be determined in the form of a fixed tilt on the solar power system located at the Bali State Polytechnic and its surroundings.

New options of the design of a vapor-compressor refrigerator with cold thermal energy storage are proposed. A comparative analysis of the performance of the considered systems is carried out. Results on the effectiveness of using various methods of cold thermal energy storage in the vapor-compression refrigerator circuit have been obtained. Recommendations regarding the field of application of these systems and the volume of cold thermal energy storages are given.

A model of quantum thermoacoustic refrigeration micro-cycle (QTARMC) is established in which heat leakage is considered. A single particle contained in a one-dimensional harmonic potential well is studied, and the system consists of countless replicas. Each particle is confined in its own potential well, whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions. Based on the Schrodinger equation, the expressions of coefficient of performance (COP) and cooling rate for the refrigerator are obtained. Effects of heat leakage on the optimal performance are discussed. The optimal performance region of the refrigeration cycle is obtained by the using of Q objective function. The results obtained can enrich the thermoacoustic theory and expand the application of quantum thermodynamics.

It is well established that storing hatching eggs over a longer period of time affects its quality. The current study evaluated the impact of egg storage duration in-relation to two different temperature conditions (room and refrigerator) to determine the bacterial load and shelf life of viable eggs. One hundred and twenty eggs were used for this study, 60 were boiled and 60 were raw. Thirty of the boiled eggs were stored at room temperature and the other 30 eggs were kept in the refrigerator. Similarly, 30 raw eggs were each stored at room and optimal refrigeration temperatures for eggs (< 7 oC) respectively, while the egg weight, viability and sensory tests were performed daily on the eggs. However, the eggs kept in the refrigerator were viable for longer and relatively maintained higher physical appearance and sensory quality compared to eggs kept at room temperature. In the investigation of bacterial load, the total viable count ranged from 6.0× 103 to 11.9 × 103 coliform forming unit per millilitre (cfu/ml) and 1.0 × 103 to 6.5 × 103 cfu/ml for the boiled eggs kept at room and refrigeration temperatures (BRT and BFT) respectively. More so, the bacterial counts in raw eggs obtained at room and refrigerator storage ranged from 4.8 × 103 to 6.5 × 103 cfu/ml. Subsequently, the characterization and identification of bacterial isolates indicated the presence of Salmonella pullorum, Proteus mirabilis and Pseudomonas sp. The Salmonella pullorum was isolated from all the egg samples (BRT, BFT, RRT and RFT). The Proteus mirabilis was isolated from boiled eggs kept in both room and refrigerator temperatures (BRT and BFT) while Pseudomonas sp. was obtained only from raw eggs stored in the refrigerator (RFT). In addition, the boiled eggs at room temperature started deterioration on Day 9, while its counterpart in the refrigerator began spoilage or decrease in quality from Day 16. The weight of the viable eggs in relation to the non-viable ones was statistically significant (P < 0.05). The refrigeration of eggs increases its longevity while proper hygiene and adequate boiling of eggs reduces the risk of acquiring infections through bacterial contamination.

Introduction. The use of electroplating in the production and restoration of machine parts is important for increasing reliability and reducing costs in the operation of cars. At the same time, strengthening and restoring parts with chrome, iron and alloys based on them leads to additional costs, due to the specifics of technologies and the need to maintain certain operating temperatures of electrolytes to obtain high-quality and high-performance precipitation. Since existing devices for maintaining the temperature of the electrolyte have a complex design and require additional energy costs, we are constantly searching for ways and designs that will simplify the design, increase its reliability and reduce energy costs.Materials and methods. The current method for maintaining the temperature of electrolytes of current bath is taken as a prototype for the research. An improved plant was designed and tested in real conditions for the production of chrome, iron precipitation and alloys based on them.Results. The developed installation makes it possible to reduce energy consumption and improve the quality of electrolytic coatings. The developed installation allowed maintaining the temperature in the required range, both at low temperatures of 20÷35oC and at high temperatures of 40÷60oC.Discussion and conclusion. As a result of the analysis of the existing methods for maintaining the temperature of the electrolyte, their shortcomings are identified and a new method is proposed that will allow controlling and maintaining the necessary operating temperature of the electrolyte in the required operating range without significant fluctuations. The developed installation can be put into production, which will allow industrial use of complex temperature-sensitive chrome plating technologies, while obtaining high-quality electroplating coatings.

Adsorption refrigeration systems become promising alternative cooling technology for refrigeration and air conditioning applications. Thermal energy is a primary source of such systems for producing cooling capacity with less electricity usage compared to vapour compression systems. Solar energy with free-access and abundant availability in the tropics have great potential as a renewable heat source to drive the adsorption refrigeration systems through direct conversion from solar irradiation to the thermal energy. This paper describes experimental work on the performance of a solar adsorption refrigerator working with activated carbon/methanol pair in Bali area. The solar refrigerator has an adsorber with an effective surface area of 0.259 m2 enclosed in a double-glazed collector box. The cooling load of the evaporator is 1 kg of water sited inside a cooler box of 0.37 x 0.25 x 0.345 m size. The experimental tests were performed outdoor to determine system cooling capacity and solar COP. Test results indicated that the refrigerator capable of bringing down water temperature at 18 ⁰C, while the system cooling capacity and COP reach 47.5 kJ and 0.046. Moreover, it is supposed that the solar adsorption refrigerator can be applied to pre-cooling post-harvest agricultural products, mainly tomatoes, before distribution to the grocery stores or end consumers.

A wind-and-react MgB 2 solenoid magnet for klystrons has been developed. While the current normal-conducting (Cu) magnet consumes 20 kW per magnet, this MgB$_2$ magnet consumes less than 3 kW in refrigerator power. The conduction-cooled half coil of the magnet is 337 mm in inner diameter; the winding pack, 19.4 mm wide × 136.6 mm high, uses 2.7 km of 10 filament circular conductor, which is insulated with glass 0.83 mm in diameter, and is reacted after being wound onto a stainless steel bobbin. The coil has Cu plates of 0.2 mm in thickness between each coil layer and on the inner and outer sides. The magnet has two coils and produces 0.8 T in the center and its stored energy is 11.8 kJ. Together with the above-mentioned coil structure, these coils can consume stored energy in itself at quench without a special quench protection system. A performance test of the magnet was successful.

A variable speed photovoltaic direct-current (DC) refrigerator (VSPVDR) system is proposed in this paper. In the VSPVDR system, the photovoltaic (PV) cells are directly connected to the compressor without batteries and inverter, and the DC compressor speed changes with the radiation intensity. In the paper, a dynamic model is presented to simulate the behavior of the VSPVDR, and several prototype experiments are conducted to validate the model. On this basis, the impacts of the compressor speed control strategy, ambient temperature and the radiation intensity have been studied. Compared with the fixed speed mode, the cooling capacity of the variable speed mode increases by 32.76% and the average PV utilization efficiency increases by 45.69%. When ambient temperature increases, the average cooling capacity decreases significantly, but the increase of average power consumption is not obvious, which reveals that the ambient temperature has greater influence on the cooling capacity and has less influence on the power consumption. The radiation intensity has a significant impact on system performance. When the radiation intensity increases, the cooling capacity increases significantly.