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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.

The principal factor controlling the safety of a refrigerated (chilled or frozen) food is its temperature. In many cases the time taken to reach the desired temperature is also important. To provide safe refrigerated food products of high organoleptic quality, attention must be paid to every aspect of the cold chain from initial chilling or freezing of the raw ingredients, through storage and transport, to retail display. The cold chain consists of two distinct types of operation. In processes such as primary and secondary chilling or freezing the aim is to change the average temperature of the food. In others, such as chilled or frozen storage, transport and retail display, the prime aim is to maintain the temperature of the food. Removing the required amount of heat from a food is a difficult, time- and energy-consuming operation, but critical to the operation of the cold chain. As a food moves along the cold chain it becomes increasingly difficult to control and maintain its temperature. This is because the temperatures of bulk packs of refrigerated product in large storerooms are far less sensitive to small heat inputs than single consumer packs in open display cases or in a domestic refrigerator/freezer. This chapter describes and explains the technologies used to produce and ensure the safety of chilled and frozen foods and maintain the cold chain.

Solid-state refrigeration technology has become a promising candidate to replace the traditional low-efficiency and environment-harmful vapor compression refrigeration. However, the narrow temperature region becomes a critical problem which hinders the practical applications of caloric materials to a refrigerator. Here, we report a potential way to solve this problem by combining different caloric effects in one refrigerant. A multiferroic ferromagnetic shape memory alloy Ni45Co5Mn37In13 can exhibit large inverse magnetocaloric effect and elastocaloric effect in adjacent working temperature regions. Thus a broad refrigeration temperature span can be realized in Ni45Co5Mn37In13 alloy by applying magnetic field or external stress at different temperature. Moreover, we propose a potential equipment schematic drawing to achieve it. The system can facilitate the multiferroic materials to produce useful cooling at a much larger temperature range. This combined caloric effect and the concept system proposed in this study would inspire researchers working in this field.

In this study improvement in performance of vapour compression refrigeration using R600a as refrigerant is enhanced by using CuO/Sio2 hybrid nanolubricants. The experiment was performed with four various nanolubricants concentration of 0.2, 0.4, 0.6 and 0.8 g/L and refrigerant mass charges of 60, 70 and 80 g. Three significant variables like coefficient of performance, cooling effect and compressor work was determined. Artificial neural network (ANN) techniques are applied to predict the R600a refrigerator performance dispersed with hybrid nanolubricants by training the input parameters like nanolubricants concentrations, refrigerant mass flow rate, evaporator and condenser temperatures. MATLAB tool box is used to predict the experimental data’s. In the network, the back propagation algorithm was utilized. The ANN predicted outputs in comparison to experimental output of refrigeration effect, compressor and COP were significantly enhanced. The ANN predicted coefficient of performance is enhanced from 2.4 to 3.8 with 36% increase in COP, refrigeration effect from 112 to 253 W with 55% increase in refrigeration effect and reduction in compressor work from 147 to 108 W with 27% reduction in power utilized by the compressor in comparison with the system without dispersion of nanolubricant. The ANN model predicted output is accepted with the experimental and the values of mean square error and percentage error are also provided. The predicted data are useful and significant for substituting CuO/Sio2 hybrid nanolubricants with vapour compression refrigeration without addition of nanoparticles and this trained output provide the optimization of CuO/Sio2 hybrid nanolubricants in household refrigerator.

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.

The typical domestic refrigerator employs a blind and periodic defrost strategy that leads to the clogging of the evaporator between the consecutive defrost cycles. The clogging of the evaporator causes a loss in performance which can be minimized using the demand defrost technique. The demand defrost systems proposed in the literature rely on the detection of frost as the defrost triggering criterion, rather than the real-time quantification of the thickness of frost. The initial frost layer improves the performance and therefore, the thickness of frost must be taken into consideration. Frost becomes detrimental only after it crosses a critical threshold. Defrosting the system at lower thicknesses may lead to frequent defrosting cycles which in turn increases the defrost energy. Therefore, the defrost triggering criterion must be selected tactfully to utilize the benefit of the initial frost layer along with the minimization of the defrost energy. In this article, a novel real-time thickness of the frost-based demand defrost technique is presented for a domestic refrigerator. A hybrid system comprised of a frost detection and defrosting modules is employed to quantify the thickness of frost in real-time and to defrost the evaporator using a 12 W heater. The effect of the thickness of the frost-based defrost threshold on the energy consumption of the refrigerator is evaluated. The defrost threshold of 6 mm yields the maximum energy conservation of 10% as compared to the default blind and periodic defrost strategy of the test refrigerator.

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.

A few researchers recently reported the presence of vapor bubbles of R600a at the inlet of the capillary tube of refrigerators under subcooled conditions. However, the effect of a non-equilibrium two-phase state on the refrigerant mass flow rate has not yet been addressed. The aim of this study was firstly to investigate the effects of ambient temperature and R600a charge amount on the refrigerant state at the inlet of the capillary tubes and, secondly, to examine the ability of empirical correlations for prediction of the refrigerant mass flow rate under a non-equilibrium two-phase state. A transparent tube was installed at the inlet of the capillary tubes of a parallel two-circuit cycle refrigerator-freezer for visualization of the refrigerant flow. The visualization results demonstrated the presence of a non-equilibrium state under subcooled conditions. The experimental mass flow rates were compared with predictions by empirical correlations of Rasti et al. and Wolf and Pate. Both correlations predicted the mass flow rate with a large deviation under a non-equilibrium state and acceptable deviation under a fully liquid state. Results showed that the mass flow rate under a non-equilibrium two-phase state significantly decreased compared to the fully liquid condition. Finally, a new empirical parameter was introduced to consider the non-equilibrium two-phase flow. The new parameter was applied to previous empirical correlations and the modified version of Rasti et al.’s correlation showed good agreement with the experimental data under a non-equilibrium two-phase state.

Aim: Develop machine learning models for the performance of refrigerator and airconditioning system. Background: The Coefficient Of Performance (COP) of Refrigerator and Air-Conditioning (RAC) is a complex function of evaporative temperature and concentration of nano-particle in lubricants. In recent years, researchers focus on experimental study for improvement of COP. Further, few researchers applied simulation techniques such as fuzzy system, Artificial Neural Network (ANN), simulated annealing, etc. to the Vapour Compression Refrigeration (VCR) cycle. There is a scarcity of modeling research work for the performance of RAC system. Objective: The study aims to develop the machine learning predictive models for the performance of refrigerator and air-conditioning system using experimental data. Methods: The experiment was performed on VCR system to determine COP. Three different concentration of lubricants (added 0.5, 1.0 and 1.5g nano-TiO2 particle on 1 liter of Polyolester (POE) oil) were used. The experimentally calculated COP was used to train and test the machine learning models. Gaussian Process Regression (GPR) and Support Vector Regression (SVR) methods were applied to develop the models. Results: The experimental result reveals that the COP increases with increasing the concentration (of nano particles) at a given temperature. The addition of 0.5 and 1.0g TiO2 in the POE oil shows better rate of increment in the COP in comparison to addition of 1.5g TiO2 in the POE oil. Machine learning models using GPR and SVR with RBF kernel function is the most appropriate machine learning model for the nonlinear relationship between the output parameter (COP) and the input parameter (evaporative temperature and concentration of TiO2). Conclusion: The present study was conducted to investigate the machine learning approaches for performance of RAC system using experimental data sets. The experimental result shows that R134a and TiO2-POE nanolubricant work efficiently and the coefficient of performance of VCR system increases with concentration of nano-particle. The developed model performance is compared using coefficient of correlation and RSME values. After comparison, it is concluded that RBF based GPR model is the best fit machine learning model to predict the COP in the context of any other model for this data set.

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.

Thermoelectric refrigerating systems (TER) are environment-friendly technologies. They have several advantages such as low maintenance costs, are less cumbersome and long lifetime. However, these systems have low coefficient of performance and are limited in achieving low temperature levels. This study investigates a new configuration of TE refrigerator employing a novel arrangement of heat sinks with integrated flat and finned heat pipes. A mathematical model is firstly developed to predict transient temperatures and cooling limit time. An experimental characterization is then performed and it includes optimization of energy consumption, cooling time, temperature levels and TE refrigerator related COP. TE module coefficient of performance (COPTEC) is evaluated at 0.74 while the hot and cold sides temperature difference ΔT is equal to 32.7 °C. The coefficient of performance of the TE refrigerator (COPTER) is evaluated at 0.297 with an inside/outside temperature difference ΔTi/o = 13 °C and an energy consumption rate of 42.7 Wh. Multiple experiment's results lead to a specific characterized chart adapted for this TE refrigerator. An empirical equation for transient temperature prediction is established and presents a novel contribution in this work.

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 is aimed at investigating the effects of the refrigerant charge, expansion device restriction, compressor speed, and their interactions on the performance of a household refrigerator. To this end, a micrometric valve was installed in series with the capillary tube of a frost-free refrigerator to vary the expansion restriction within a range equivalent to capillary tubes with inner diameters spanning from 0.55 to 0.85 mm. The refrigerant charge was manually changed from 35 to 65 g whereas the compressor speed was adjusted between 2500 and 4500 rpm. In total, 294 steady-state energy consumption tests were conducted, being 147 at a surrounding temperature of 32 °C, and the rest at 16 °C. It was noticed that low energy consumptions can be achieved for several combination of refrigerant charge and expansion restriction, albeit the minimal energy consumption figures were always achieved for the highest charges and restrictions. It was also verified that the refrigerator operates in a sub-optimum region so that increasing the charge from 42 g to 52 g while decreasing the capillary tube diameter from 0.64 mm to 0.60 mm led to a 3% decrease on the energy consumption. It was also found that a single combination of refrigerant charge and equivalent diameter provided satisfactory performance levels regardless of the compressor speed. Finally, a method to reduce the number of tests was proposed, in such a way that only 9 datapoints are required to generate a full energy consumption map for a given compressor speed and surrounding temperature.

A key issue in the optimal designing of a Stirling machine is to develop a precise thermodynamic numerical model that could predict the performances and provide means for further optimization. In this paper, a non-ideal second-order numerical model called modified simple analysis model has been presented for the Stirling cycle refrigerating machine. The model incorporates effects of shuttle heat loss to the expansion space and mass leakage to the crankcase in the differential equations of pressure change, rate of change of mass of gas in compression and expansion spaces, and mass flow rates across these working spaces. The model was simulated using MATLAB code for Beta configuration FEMTO 60 Stirling engine operating as a refrigerator and validated with an experiment. The validation of the numerical model with experimental work showed that the results of the simulation are consistent with the results of the experiment. Hence, the numerical model could be used to design a Stirling cycle refrigerating machine for moderate temperature applications with reasonable accuracy especially if optimization is performed further. The effects of incorporating shuttle heat loss in the differential equations on the temperature of working gas and the overall performance of the Stirling refrigerator have been analyzed. Lastly, parametric investigations have also been performed to evaluate the effect of operating parameters (temperature, pressure, and frequency) on the performances of the refrigerating machine. Better performance could be achieved at relatively lower frequency or higher pressure.

The infiltration of warm and humid air from the outside into a freezer results in frost accumulation around the evaporator in household refrigerators. This can significantly reduce the cooling capacity of refrigerators. In this study, the pressure, temperature, and frost around a proposed drain tube were monitored through in-situ measurements until the first defrost process (about 54 h). The proposed drain tube has 220 times higher hydraulic resistance and shows 55 times lower inflow in computational fluid dynamics (CFD) analysis. Once the door of the freezer compartment is opened and closed, external warm air replaces the cold air in the freezer. Negative pressure is produced by the shrinkage of this external air under low-temperature conditions. The other role of the drain tube is to vent air between the outside and inside of the refrigerator under negative pressure. To release the negative pressure, the proposed drain tube has a movable shutter. In the CFD results, the secondary inlet increases the inflow by 3.2 times compared to the inflow in an I-type tube. To determine the design, the weight and inner diameter of the drain tube were changed. The performance of the proposed tube was validated by the lack of blockage of discharge until the first defrost process. The movable shutter did not allow the negative pressure to exceed -100 Pa by facilitating air venting after opening the door for 10 seconds and then closing it.

Single and multi-stage Joule-Thompson refrigerators operating with natural nitrogen-hydrocarbon mixtures are marketable for creating refrigeration equipment for freezing and cryopreservation of biomedical materials, liquefaction of certain gases, high-temperature superconductors cooling, conducting climate tests without using cryogenic liquids. One of the main objectives of the development of such refrigerators is to determine the optimal weight of mixed-refrigerant charge with the known geometry of the refrigeration circuit and to ensure the optimal “circulating” composition in the steady-state mode. This article proposes an analytical method for solving this problem and presents the experimental results. The accuracy of the method is determined by the validity of calculating thermodynamic properties of the mixed refrigerants forming solutions with limited solubility in the liquid phase and by taking into account the shift of the “circulating” working body composition relative to the “charge” composition in the steady-state mode due to structural specifics of real refrigerators. The application of the method will allow reducing the time and cost of experimental development of new refrigeration equipment.

In this study, an experimental determination of the refrigerant charge and the operating conditions in a vertical display refrigerator using R134a, R513A, and R1234yf is presented. The three refrigerants' energy inputs under ambient temperatures of 24, 32, and 40°C are compared. The refrigerator is instrumented with a mass flow meter, thermocouples, and pressure transducers. The evaluations are carried out inside a room with controlled temperature and air recirculation. For each analysis, the refrigerator is operated for a period long enough until differences among operation on/off cycles are negligible. Batch loads of 15 g are used for determining an adequate refrigerant charge. The results show a recommended charge of 175g for the three refrigerants and the range of temperatures. The electric energy consumption increase on average 20 kJ per hour of operation for every degree the ambient temperature increases. Compared with R134a, the R513A results in lower energy input in 3.8, 3.9, and 0.3% for 24 and 32 and 40°C, respectively. The experimental determination of EER values does not give accurate guidance for the adequate refrigerant charge. The assumption of isobaric heat exchange results in a maximum deviation of the actual cooling duty of 13, 18.7, and 16.6% for R134a, R1234yf, and R513A, respectively.

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.

Vegetables lose quality after harvest mainly due to water-related weight loss. In households, vegetables are usually stored in refrigerators, typically providing temperatures from 0 – 14°C and relative humidity ranges from 20 – 100 %. Weight loss is related to the storage humidity conditions. As a consequence, storage systems providing humidity-controlled conditions are decisive for the evaluation of the freshness performance of refrigerators. To evaluate the impact of storage zones on the fresh weight loss of stored goods, the international standard IEC 63169:2020 “Electrical household and similar cooling and freezing appliances – Food preservation” has been released. It uses a cellulose based food simulant, overcoming influences of cultivar and post-harvest handling conditions of real vegetables. This publication compares the weight loss of spinach and the food simulant in chilled storage conditions at three ranges of relative humidity. Different cultivars and pre-handling modifications of the spinach were used to determine the impact of product parameters on weight loss. A round robin test was performed to analyse the applicability of the IEC 63169:2020. The results prove the applicability of the standard to analyse the impact of humidity controlled storage on weight loss: It is shown that pre-handling has an impact on spinach's weight loss, which is overcome by the food simulant. For all tested conditions, the weight loss behaviour from spinach and the food simulant is correlating in test durations up to 72 h. The round robin test shows that the test method of IEC 63169:2020 provides repeatable and reproducible results.

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.

Cool storage has been considering an efficient and cost-effective means to enhance the behavior of a refrigerator. However, its drawback in temperature control of the refrigerator compartment has not received enough attention. The controllable two-phase loop thermosyphon has the prospect of solving this problem. In this study, a novel cool-storage refrigerator integrated with a controllable two-phase loop thermosyphon is built to investigate its precise temperature control capacity. The phase change material is optimized by the orthogonal experiment method. The controllable two-phase loop thermosyphon presents the optimal cooling performance for the fresh food compartment when the filling ratio is 27.0%. As the average temperature of the fresh food compartment increases, the one on–off cycle of the controllable two-phase loop thermosyphon maintains at 32.0 min, and the operation ratio varies from 86.3% to 13.6%. The temperature control accuracy can be improved from 2.1 °C to 0.6 °C and the overall time of one on-off cycle decreases from 49.8 min to 22.4 min. The operation ratio gradually increases from 7.2% to 38.6% as the ambient temperatures increase. The results demonstrate that the controllable two-phase loop thermosyphon is a feasible and effective way to improve the temperature control performance of the cool-storage refrigerator.

The present paper is focused on development of the thermodynamic model and a heat-driven Vuilleumier refrigerator. Thermodynamic properties and performance are predicted by thermodynamic model. On the other hand, a prototype Vuilleumier refrigerator with crank drive mechanism is built and the performance is measured. In the thermodynamic model, the refrigerator is divided into five working spaces for analysis, including hot chamber, hot regeneration chamber, middle chamber, cold regeneration chamber and cold chamber. Also, the influence of clearance leakage between middle chamber and buffer chamber is investigated. The effects of geometrical parameters, charged pressure, rotating speed, heating temperature, cooling temperature and heat loading on the cold head temperature are evaluated. In addition, the numerical results and the experimental data under different operating parameters are compared for model validation. As the Vuilleumier refrigerator operated at 22 bar pressure, 600 rpm rotating speed, 900 K heating temperature and 276 K cooling temperature, the cold head can reach a zero-load temperature of 221 K. When a 0.7 W heating load is applied on the cold head, cold head temperature of 252.6 K and coefficient of performance of 0.0068 can be obtained.

The Stirling cycle is regarded as one alternative to the compressive cooling cycle. The current study examines the performance of a beta Stirling refrigerator with a cylinder with different bores. Bores differ in terms of the diameters of the compression and expansion cylinder. The refrigerator comprises a twin shell and tube condenser, and evaporator. The evaporator and condenser tubes show an elliptical cross-section. The elliptical ratios in the evaporator and condenser (1, 0.75, 0.50, 0.25, 0.20) with a fixed cross-section area are compared. A wire mesh regenerator uses as the regenerator. The selection of the working fluid is helium. The current work prepares a spreadsheet program to overcome the reversed Stirling refrigeration cycle. The suitable dimensions of the refrigerator to obtain a high cooling load are determined. The results recommended that using tubes with elliptical cross-sections in both evaporator and condenser enhances the COP of the refrigerator by about 33% (COP = 1.3). Also, using tubes having elliptical cross-sections in both evaporator and condenser enhances the cooling load of the refrigerator by about 24% at a 0.2 elliptical ratio. Furthermore, the use of different bores of refrigerator cylinder increases the cooling load of the refrigerator by about 25% when the expansion to compression bore ratio is 1.5. Additionally, the use of different bores of refrigerator cylinder increases the COP of the refrigerator by about 40%, especially at low pressures at expansion to compression bore ratio of 2.0. The proposed refrigerator can achieve a cooling capacity of 450 W at COP = 0.9 under a charged pressure of 5 bar. Comparing the current work and earlier studies shows that the proposed refrigerator achieves a 60% improvement in cooling load at the same pressure.

There are considered analysis results of stress-strain state in the load-bearing structure of three versions of refrigerator cars with different arrangement solutions of refrigerating-heating plants (RHP) and a thermos car at its cooling with liquid nitrogen. By means of the “APM WinMachine” application there are presented model parameters of a basic universal body. The analysis of calculation results has shown sufficient strength and potentialities for updating an available car metal structure for the application as a universal body of a refrigerator car. Work purpose: the estimation of a stress-strain state in the load-bearing structure of a basic body for insulated cars of different types of refrigerator- and thermos cars. Investigation methods: for the analysis of the stress-strain state in a load-bearing structure in three versions of the bodies of refrigerator- and thermos cars under loads with “Normal” modes there was used the “APM WinMachine” software complex realizing a finite element method. Results and novelty: for the first time there are offered arrangement solutions for the location of refrigeration-heating plants earlier not used for refrigeration rolling-stock (RRS). A stress-strain state of the body of the thermos car at the impact of overpressure upon it of gaseous nitrogen evaporated in cargo compartment is estimated. Conclusions: the analysis of calculation results for all three versions of the RHP arrangement and a solid body of a thermos car has shown sufficient strength and possibility regarding simple updating an available body metal structure which may be used as a universal car set.

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.

In this study, we carried out subjective evaluation tests employing 19 refrigerator door closing sounds to quantify the luxury feeling. By applying factor analysis to the subjective evaluation results, the sound quality of the refrigerator door closing sound was found to be expressed by the following two factors: overall loudness and the pitch of the sound. Subsequently, luxury feeling evaluation model was obtained through multiple regression analysis. As the result, the luxury feeling of the door closing sound was evaluated to be high when the sound was softer and had lower pitch. Then, we prepared several luxury door closing sounds according to the obtained evaluation model through a filter processing and conducted subjective evaluation tests again to verify the evaluation model. The result shows that the amplitude increased sound at low frequency band under 100 Hz, which was calculated to be high luxury by the evaluation model, was actually evaluated as the best among the presented sounds through the subjective test. And the luxury sound quality evaluation method was confirmed to be useful to quantify and estimate the sound quality of the refrigerator door closing sound.

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.

Finding an alternative solution to conventional refrigerators, which often use a vapor-compression refrigeration cycle, has always been an environmental concern. Thermoelectric refrigerator, despite its lower efficiency yet very low pollution, is one of these alternative methods. This study aimed to evaluate the performance of this type of refrigerator and compare it in terms of pollution and performance with refrigerators with vapor-compression refrigeration cycle. For this purpose, by simulating the problem, the general design of the problem is obtained. Then, by determining the type of thermoelectric used and the geometry of the refrigerator, a laboratory setup is made. Finally, a laboratory test is performed on the setup. By adjusting the required voltage and input current of the thermoelectric, this refrigerator can have a coefficient of performance of 0.38 but instead reduces pollution by about 95%.

The maximisation of cooling capacity and thermodynamic efficiency of a Gifford-McMahon refrigerator is a tedious task due to the occurrence of complex thermo-physical mechanisms inside its expander...

In this research, the performance of serial two-stage compression (STC) cycle and bypass two-stage compression (BTC) cycle on the household refrigerator-freezers is tested in the laboratory. Then, based on the results of the experiments, exergy, exergoeconomic analyses, and cycle optimization are carried out. Considering that replacing refrigerants in household refrigerator-freezers is one of the approaches to increase the performance and environmental impact of these systems, R436A refrigerant (46% Isobutene and 54% Propane mixture) is used and analyzed to replace previous refrigerants. Finally, the multi-objective optimization of the mentioned cycles is performed with both refrigerants. For analyses, two models of refrigerator-freezers with different cycles are used (STC cycle with R134a refrigerant and BTC cycle with R-600a refrigerant). In both models, two evaporators for refrigerator-freezer compartments are used. International standards (IEC 62552) are used to test refrigerator-freezers. MATLAB and REFPROP 9.1 software are used to model the systems. According to the results of the analyses, the STC cycle with R436A refrigerant has more total exergy destruction rate (0.727 kW) compared to R134a refrigerant. In the BTC cycle, in which the fresh food compartment (FFC) and freezer compartment (FZC) operate, the total exergy destruction rate with R-600a refrigerant (0.422 kW) is less than with R436A refrigerant. In the case of the BTC cycle in which only the FZC operates, the total exergy destruction rate with R-600a refrigerant (0.455 kW) is less than with R436A refrigerant. The most exergoeconomic factor among cycle equipment is related to the compressor (about 98%). The highest COP value between cycles is related to the STC cycle with R134a refrigerant.

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.