Energy Consumption Of Refrigerator Research Articles

Simulation Study of Thermal Performance on the Inner and Outer Surfaces of Semi-Transparent Photovoltaic (STPV) Glass with Different Transparency

This paper used the experimentally verified one-dimensional steady-state heat transfer numerical model of the semi-transparent photovoltaic (STPV) glass to simulate the influence of wind speed, ambient temperature and air gap thickness on the surface temperature of PV modules, and analyzed the thermal performance of the inner and outer surfaces of STPV glazing with different transparency. Results shows that for every 1m/s increase in wind speed, the outer surface temperatures of SL-STPV glass with transparency of 10%, DL-STPV glass with transparency of 20% and 40% decreased by 3 °C, 3.02 °C and 2.22 °C, respectively. For every 10 °C increase in ambient temperature, the outer surface temperatures of SL-STPV glass with transparency of 10%, DL-STPV glass with transparency of 20% and 40% increase by 8.45 °C, 7.6 °C, and 7.79 °C, respectively. For the DL-STPV glass with transparency of 20% and 40%, for every 2 mm increase in the thickness of the air gap, the outer surface temperature increases by 0.13 °C and 0.12 °C, respectively. The heat transfer between the inner surface of the glass and the indoor environment increases the heat gain through the glass into the room in summer, which will lead to an increase in refrigeration energy consumption. However, in winter, the heat exchange between the inner surface and the in-door air to heat the indoor air reduces the heating energy consumption to a certain extent, and achieves the effect of building energy conservation to a certain extent.

Simulation of faults in domestic refrigerators of different volumetric capacity: Effect on thermal and energy behavior

The present study compares the thermal and energy performance of refrigerators with varying volumetric capacities when faults occur. Simulated faults include the malfunction of the fan attached to the evaporator and the airflow return area obstruction in the freezer. The proposal above included three intensity levels for each fault. Both refrigerators were instrumented to measure temperature conditions within the fresh food compartment and the freezer. In addition, during the test period, energy consumption was measured until thermal stability was reached in both compartments. The effect of each fault’s levels was compared with the reference condition for each refrigerator, which was without faults, as they left the factory. The results show that the fan fault caused the most significant variation in the thermal condition of both refrigerators. The temperature increased from 2°C to 4°C in the fresh food compartment, and from 1°C to 14°C in the freezer. The above causes warmer spaces compared to the reference refrigerator. Consequently, each refrigerator's energy consumption increased from 36% to 65%.

Effect of structural improvement of gaskets on the heat leakage load and energy consumption of the refrigerator

Gaskets play a significant role in the thermal insulation of refrigerators. Previous studies mainly focused on how to obtain the heat and moisture transfer load of a given gasket, but lacked appropriate structural improvement measures and their effect on the heat leakage load and energy consumption of refrigerators. In this paper, the heat transfer analysis of an original gasket was conducted via numerical simulation. It was found that the main thermal insulation weaknesses of the original gasket are gasket-cold air, gasket-outer shell of the cabinet, gasket-inner lining of door and gasket-hot air. Thus, adding an auxiliary-airbag to the original gasket and a comprehensive new-design gasket were proposed to improve the thermal insulation. Compared with the original gasket, the numerical simulation results showed the heat leakage loads of the auxiliary-airbag and new-design gasket were reduced by 18.44 % and 27.49 %. The total heat leakage loads of refrigerators equipped with improved gaskets were reduced by 4.46 % and 6.64 %. The effect of two structurally improved gaskets on the refrigerator energy consumption was experimentally studied. The repetitively measured results showed the energy consumption of refrigerators with the auxiliary-airbag and the new-designed gasket were reduced by 0.93 % and 3.19 %. The reason why the reduction in refrigerator energy consumption is lower than the reduction in heat leakage load is due to the difficulty in achieving the designed assembly state of the gasket during actual installation. Based on the holdings of refrigerators around the world, it is estimated that the refrigerators energy consumption can be reduced by 106.776 billion kWh per year and carbon emissions can be reduced by 12.74 million tons per year when using the new-design gasket proposed in this study.

Optimization and Renovation Design of Indoor Thermal Environment in Traditional Houses in Northeast Sichuan (China)—A Case Study of a Three-Section Courtyard House

The three-section courtyard is the most representative traditional residence in the traditional villages in northeast Sichuan. As a unique cultural landscape, it carries the local historical style and cultural connotation. However, the high temperature weather in summer leads to a poor thermal environment in traditional residential buildings, which cannot meet the needs of building users for human thermal comfort, and the wall is the most critical factor affecting the indoor thermal environment. Therefore, to optimise the indoor thermal environment of traditional residential buildings, this study designed four groups of wall renovation schemes according to the original traditional residential buildings and modern technology, and simulated and verified the feasibility of the building renovation schemes by using Design Builder. Then, the four groups of wall renovation schemes were compared and tested based on the Design Builder. Comparative results of the thermal-performance evaluation index revealed that compared with Case 1 and Case 2, the building refrigeration energy consumption of Case 3 in the hottest week was the least, only 427.7 kW·h, which indicates that the external wall renovation scheme using aerated concrete blocks had the best thermal insulation and energy-saving effects. The cooling energy consumption of Case 4 in the hottest week was 422 kW·h, which was 4.3 kW·h less than that of Case 3, indicating that the wall renovation scheme with an air inter-layer had better thermal insulation and energy-saving effects. The refrigeration energy consumption of Case 7 in the hottest week was only 409.8 kW·h, which was 4.19% lower than Case 3 (without insulation material), indicating that the scheme of selecting central insulation and extruded polystyrene board (XPS) had better thermal insulation and energy-saving effects in practical projects. In summary, the above transformation scheme not only improves the indoor thermal environment of traditional residential buildings, but also provides guidance for architectural designers on green, energy-saving and sustainable design.

Design, preparation, and property analysis of metal/dielectric multilayer film with wavelength selectivity

Metal/dielectric multilayer films have important applications in energy-saving glass, stealth materials, solar energy utilization and other fields. In the current study, the thickness of each layer of TiO2/Ag/TiO2/Ag/TiO2 film is optimized. The effects of the number of metal/dielectric multilayer films and the incident light angle on their optical properties were investigated. The TiO2/Ag/TiO2/Ag/TiO2 film was prepared by electron beam evaporation coating technology, and their reflectance and transmittance were measured. The measurement results show that the visible light transmittance (380–780 nm) of the film can achieve 68.7%, and the infrared reflectance (780–2500 nm) can reach 95.9%. Compared with the traditional dielectric/metal/dielectric three-layer film, the visible light transmittance of the film is higher, and the solar infrared reflectance is greatly improved. In the solar radiation band (280–2500 nm), the average error between the experimental reflectance and transmittance and the theoretical prediction results is less than 0.03. The distribution of electric and magnetic fields inside the film was simulated by finite-difference time-domain method. The simulation results show that the high visible light transmittance is due to the interference resonance of electromagnetic waves inside the film. Taking Shanghai as an example, under our calculation conditions, compared with ordinary SiO2 glass, TiO2/Ag/TiO2/Ag/TiO2 film can reduce the total energy consumption of buildings by 14.3% and refrigeration energy consumption by 17.2%.

Experimental study on performance improvement of a household refrigerator with a flying-wing evaporator

In order to improve the performance of a household refrigerator, a flying-wing evaporator (FWE) is to replace the original finned tube evaporator (FTE). Different from the FTE, the fins of the FWE are formed directly on the tube by shoveling movement. Therefore, the FWE has high efficient heat transfer performance due to no thermal contact resistance between the tubes and the fins. According to different combinations of fin pitch and number of tube rows, three different structures of FWE are designed and tested in comparison with the original FTE on a double-door household refrigerator. The results show that the FWE shortens the cooling duration by 0.32 h (9.3%) and reduces the annual energy consumption by 4.28% with a 25% reduction in volume and a 13.5% reduction in refrigerant charge. This study proves that applying a FWE into a household refrigerator instead of the traditional FTE is one of the effective ways to decrease the volume of evaporator, reduce the energy consumption of refrigerator and enhance the effect of food preservation.

Experimental investigation and dynamic modelling of an upright freezer under periodic door opening conditions

This paper performs a comprehensive experimental and modelling study to examine the dynamic behaviour of an upright freezer with adjustable shelving under periodic door opening conditions with different temperature, pressure and relative humidity values. An uncertainty analysis is carried out for the experimentally measured data. Additionally, the dynamic model is developed with crucial sub-components, such as discretized upright cabinet, frosted evaporator and semi-empirical door opening mechanism using an object-orientated programming language called Modelica. The present model is the validated with experimental data employing the values of the airflow from ambient into the cabinet along with the average cabinet air flowrate and back wall temperatures, transient evaporation and condensation pressures, cabinet average relative humidity change, compressor operation time and power consumption, and finally total energy consumption of refrigerator for both 85%RH and 65% RH conditions at 32 °C ambient. The results show that the model predictions have a similar trendline with the experimental findings within ±3 K error bands regarding average cabinet air and back wall temperature. In contrast, the dynamic cyclic trend before and after door opening is closer to the experiments within ±1 K. The current model predictions for the low and high pressures are found to be within ±3% and ±5% error bands, respectively, whereas the average relative humidity level of the cabinet is captured within ±10% deviation. Furthermore, transient compressor power is well predicted with deviations, but not exceeding 4.5%, and the total energy consumption level is compatible with 6% error bands during the entire experimental period.

Influences of the ambient temperature, degradation effect and usage habits over the energy consumption of domestic refrigerators in Brazil

Considering the relevance of the consumption of domestic refrigerators in the Brazilian residential sector, representing about 30% of the sectorial consumption, studies of factors that influence this consumption, such as ambient temperature, age of equipment and usage habits, are of great importance to a greater understanding of these effects and, thus, to promote better energy strategies for the country. In this sense, the present study evaluates the impacts of ambient temperature, age of the equipment and habits of use in the consumption of domestic refrigerators, based on theoretical models and laboratory tests. The laboratories assays, adhering to theoretical models, showed that the environment temperature can influence the consumption of refrigerators up to 50% less (taking into account the south region temperature), when comparing to the value that are labeled by PBE/INMETRO. When the usage habits are assayed, it was verified that the consumption of the refrigerator could be increased in up to 53%, depending the frequency of door opening.

Evaluating the environmental sustainability of durable products through life cycle assessment. The case of domestic refrigerators

Sustainability and durability are not always interchangeable concepts, especially for products that require many resources during their long use phases, like energy related products. In addition, the literature either focuses on how the product performances change over time or evaluates the convenience of durable goods. In this context, the present work presents a durability assessment from an environmental perspective. Unlikely the existing literature, it simultaneously compares the different methods that describe how the product performances may vary with time, specifically how the foam aging influences the yearly energy consumption of refrigerators and assess the durability from the environmental point of view under different circumstances. The primary outcomes highlight the need to introduce a more accurate description of product performances during their lifetime (i.e. aging of components) to obtain realistic results. Furthermore, this work enlightens the need to align the analytical report on the deterioration of refrigerators' components and provides alternative exemplifications to assess the environmental sustainability of durability. As far as the latter case is concerned, multiple products can take advantage of it and have durability considered from the environmental point of view.

Electricity peak load reduction of a refrigerator using phase change material

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

A lumped-element magnetic refrigerator model

This work presents a dynamic lumped parameter model to predict the transient and steady-state cabinet temperature, energy consumption and efficiency parameters of a small capacity magnetic refrigerator equipped with a retrofitted thermally insulated wine cooler cabinet. The model is divided into independent, experimentally validated sub-models for the active magnetic regenerator (AMR), magnetic and hydraulic circuits, heat exchanger/fan assemblies and refrigerated cabinet. Primary inputs to the model are the geometric features and component dimensions, frequency and speed of power sources (hydraulic pump, axial fans and induction motor), and composition and properties of magnetic materials. Special emphasis is put on the lumped AMR model, which accurately predicts the performance of first- and second-order materials in single- and multi-layer configurations in terms of the cooling capacity, heat rejection rate and magnetic work. The model predicts the experimental steady-state cabinet temperature of a compact magnetic wine cooler prototype to within 1.5 oC, while estimating the coefficient of performance with a mean error of 6.5%. The time response of the magnetic wine cooler during a temperature pull-down test is also correctly reproduced by the model, enabling its use in the design of future magnetic heat pumping systems.

Energy-Saving Design and Energy Consumption Analysis of a New Vacuum Refrigerator

With the goal of carbon peak and carbon neutrality, fossil energy is becoming increasingly exhausted. Optimizing energy structure and saving energy and reducing consumption are the top priority. With the rapid development of modern science and technology, vacuum refrigerator has been greatly applied and popularized in various fields, such as food production, medicine and biology. However, in the actual operation process, the energy consumption of vacuum refrigerator is high, which does not meet the concept of energy conservation and environmental protection. The inner and outer push–pull structure of the sealing door makes it occupy too much space when opening the door, which is very inconvenient. In this paper, a vacuum refrigeration energy-saving device and the TRNSYS 16 software are used to simulate the energy-saving device. The results show that the device can reduce the number of vacuum refrigeration pumps and greatly reduce the loss of energy consumption. In addition, the new sealing door structure can also reduce the space occupied during its expansion and improve the utilization of space.

A novel intelligent control method for domestic refrigerators based on user behavior

Energy consumption and food safety issues of household refrigerators have attracted considerable attention in recent years. Today, most household refrigerators use conventional controllers for adjusting the compressor speed to regulate the air temperatures inside cabinets. This research aims to design an intelligent control concept that integrates machine learning-based forecast of door opening events with fuzzy logic controllers. Firstly, bayesian neural network, logistic regression, and decision tree techniques are investigated to predict user behavior with data obtained from 18 real users of domestic refrigerators. Results show that logistic regression has the best performance in hourly predicting the door opening events after one week of training with more than 80% accuracy. Secondly, fuzzy logic controllers are designed to use the door opening predictions to regulate configuration parameters of the main refrigerator controller: maximum compressor speed, air temperature setpoint of fresh food compartment, and time offset to control the time of defrosting events. Finally, simulation studies are performed on a domestic refrigerator model developed at MATLAB Simscape. The developed model is based on an existing product in the market, and the accuracy of the model is verified by actual lab tests. Daily simulations of the household refrigerator for sample day profiles of an inactive and active user are performed for ambient temperatures of 16 °C, 25 °C, and 32 °C. Results show that the designed smart controller can achieve up to 2.5% and 4.5% of energy gain for active and passive user-profiles respectively, while maintaining the desired cabinet temperatures.

A case study on experimental and statistical analysis of energy consumption of domestic refrigerator

This paper presents the energy consumption analysis of the refrigerator and the effect of the condenser on it. According to the Bureau of Energy Efficiency (BEE), India, the energy efficiency of electric appliances is the key parameter for testing their performance before domestic use. For energy consumption analyses, the experimentation was conducted on the domestic refrigerator (165 L) top-mounted evaporator by retrofitting the refrigerator with an Elliptical Helical Coil Condenser (EHCC) and existing refrigerator with a Straight Tube Condenser (STC). Box-Behnken Design (BBD) is very significant in determining the significant factor and reducing the number of experiments. BBD has been performed to analyze the significance of factors ambient temperature, fresh food compartment temperature and the heat load in energy consumption, and the Coefficient of Performance (COP) of a refrigerator. The heat load and the ambient temperature are both very significant in determining the refrigerator's energy consumption. The most important thing is to increase the liquid content in the charge before it is supplied to the evaporator to extract more amount of heat to increase the cooling effect. The ANOVA (Analysis of Variance) results show that the ambient temperature and the heat load were more significant in increasing energy consumption and decreasing the COP and vice versa. The results of ANOVA and the experiment are very close; the R2 value 0.995 precisely matches the R2 adj. value 0.994. The statistical analysis using the Box-Behnken design produces a good fitting of the modeled and experimental data set. The present study aims to examine the effects of said factors and the condenser on the domestic refrigerator's energy consumption and COP. The study exhibits some enhancement in the COP to 2.59 contrary to 2.45 and energy consumption reduced to 1191 Wh from 1755 Wh during the trial of 24 h.

Optimization of Daylighting, Ventilation, and Cooling Load Performance of Apartment in Tropical Ocean Area Based on Parametric Design

In tropical areas of China, energy saving is an important part of architectural design, and the energy-saving potential of residential buildings has attracted extensive attention. This paper studies the daylighting, ventilation, and building energy consumption in tropical areas to find out the best energy-saving performance parameters. The building model is established by grasshopper, and the parameters of daylighting, ventilation performance and cooling load are simulated. The octopus plug-in in grasshopper is used to calculate the target value iteratively, so as to find the relative optimal value of multiobjective. Finally, the optimized design value is compared with the initial value. The results show that the refrigeration energy consumption is greatly reduced from 188.20 kwh/m2 to 163.02 kwh/m2, the Daylight Autonomy (DLA) is reduced from 60.71% to 58.56%, and the ventilation wind speed is increased from 0.62 to 0.63 m/s. It can be seen from the results that although the daylighting objectives was reduced, the cooling energy consumption is greatly reduced, and the optimized daylighting layout is more balanced and reasonable. Therefore, on the basis of reasonable layout, this optimization study effectively reduces the refrigeration energy consumption and achieves the goal of green energy saving.

Solution-Based One-Step Preparation of Three-Dimensional Self-Assembled Octadecyl Silica Nanosquare Plate and Microlamella Structures for Superhydrophobic and Icephobic Surfaces.

Icephobic surfaces have gained immense attention owing to their significant roles in decreasing the energy consumption of refrigerators and in improving safety issues by preventing the formation of ice on them. Superhydrophobic surfaces incorporating micro- or nanoscale roughness and hydrophobic functional groups have been shown to prevent ice accumulation. Herein, we report a simple, low-cost, and solution-based one-step process for the production of superhydrophobic surfaces with three-dimensional (3D) self-assembled structures. The controlled hydrolysis and polycondensation of n-octadecyltrichlorosilane (OTS-Cl) in an acetone solution produced a highly uniform superhydrophobic surface on various substrates such as glass, metals, and polymers without the limitation of the surface curvature structure. The as-prepared 3D self-assembled surface exhibited a very high contact angle of 161.7° and a low contact hysteresis of 1.47°. The solvent type, H2O content in acetone, and carbon chain length of the silane compound were critical in the formation of self-assembled nanostructures. The thickness of the superhydrophobic 3D self-assembled structure could be varied by controlling the surface properties of the glass substrate. In addition, a novel octadecyl silica nanosquare plate structure was formed as an intermediate for the microlamella structure. The water drop impact experiments on the 3D self-assembled superhydrophobic glass substrates at low temperatures (T < -25 °C) showed that the as-prepared superhydrophobic glass possessed a high impalement threshold for water contact, resulting in excellent and stable icephobic properties. The preparation method proposed in this study is scalable and can be used on a flat glass surface or in a glass vial inside a glass tube. Moreover, it can be applied to various substrates such as metals and polyurethane surfaces with curvature. Therefore, the solution-based self-assembly method proposed in this study is a promising approach to produce superhydrophobic and icephobic surfaces on a wide range of substrates regardless of their structure and properties.

Interactions between refrigeration temperatures, energy consumption in a food plant and microbiological quality of the food product: Application to refrigerated stuffed pasta

Food refrigeration is essential to maintain microbiological quality but it accounts for high energy impact. An integrative modelling approach was developed to estimate the impact of increasing refrigeration temperature in the processing plant, on energy consumption, products temperatures, and the food product microbiology. The food product was a pasteurized refrigerated fresh pasta. The microbial indicators considered were Bacillus cereus for safety and total aerobic microflora for spoilage, with limits at consumption of respectively 105 CFU g−1 and 106 CFU g−1. Through six scenarios, the impacts of temperatures ranging from −2 °C to 8 °C in the cooling tunnel, and from 4 °C to 6 °C in the end products cold room storage in the processing plant, were simulated. The same refrigeration conditions throughout the entire cold chain up to the consumer, based on temperature and residence time data of a field study, were applied to all these processing plant refrigeration scenarios. Fixing 8 °C to the cooling tunnel and 6 °C to the cold room reduced the absorbed electrical power by ~20% with ~10% increase of microbiologically defective products at time of consumption. Increasing cooling tunnel temperature saved more energy than increasing cold room temperature for the same impact on microbiology. The modelling approach presented could help food companies to design the best strategy to reduce refrigeration energy consumption in their processing plant.

Marine Cold Chain Transportation Monitoring and Route Scheduling Optimization Based on IoV-BDS

Recently, the research of the internet of vessels system is a hotspot in the marine engineering area. In this article, the Internet of Vessels based on Beidou satellite navigation system (IoV-BDS) architecture is proposed for marine cold chain transportation monitoring and scheduling. An improved communication method using Beidou short-message communication (SMC) is designed to ensure the reliability of ship-shore data transmission. Additionally, based on the IoV-BDS, we proposed a novel route scheduling optimization model which considers the key costs for marine cold chain transportation, such as fuel, catches damage, and refrigeration energy consumption, and designed a speed selection mechanism. Furthermore, an improved ant colony optimization (IACO) algorithm was utilized to optimize the whole fleet transportation routes, which takes advantage of the A-star algorithm to speed up the convergence of ant colony algorithm (ACO), a novel state transition rule was used to prevent falling into a locally optimal solution. The applicability of IoV-BDS was verified by the shipboard data acquisition and Beidou SMC experiments. The performance evaluation and analysis of route optimization schemes were presented by simulations and comparison with other schemes. The results demonstrated the benefit of our proposed schemes, in terms of solution quality and convergence of the algorithm.

How to achieve a win–win scenario between cost and customer satisfaction for cold chain logistics?

This paper aims to study how to achieve a win–win scenario between distribution cost and customer satisfaction; and propose a reasonable scheme for the terminal distribution of cold chain logistics. The paper focuses on the customers’ time requirements and establishes the penalty costs incurred when service time requirements are not met. In addition, this paper combines different aspects, such as considering the refrigeration energy consumption and the damage costs. Meanwhile, because of the different potential impacts of the various costs, different weights are assigned to each cost. Then, a cold chain logistics vehicle routing optimization model considering time windows is constructed. Finally, the Clarke–Wright (CW) algorithm, which is suitable for the model, is selected to solve the problem, and the validity of the model is verified by an example. The results of the calculation example show that although the transportation cost and energy cost of the optimized distribution route increase slightly, the optimized distribution route greatly reduces the total cost. Customer satisfaction and vehicle load rate have also increased significantly. Cost reduction and satisfaction improvement can sometimes be achieved at the same time. Using mathematical methods to plan routes can help companies save costs. And help planners and delivery staff to improve the timeliness of the last-mile delivery. Simplify complex algorithms without having to use professional software. More ordinary employees can also use this method.

Refrigerator cost trap for low-income households: Developments in measurement and verification of appliance replacements

Energy efficiency of domestic refrigerators has markedly improved over recent years. Despite these improvements, low-income households in Australia still tend to own older and less energy-efficient refrigerators. Replacement of old refrigerators with energy-efficient appliances presents an important opportunity to reduce both greenhouse gas emissions and the electricity bills of households for sustainable development. This paper presents the measurement and verification of energy savings from a sample of 16 household refrigerator replacements under the Appliance Replacement Offer of the New South Wales Government, Australia. In-home monitoring and laboratory testing were conducted for both old and new refrigerators. A key challenge for this study was to estimate the energy savings of the replacement in each household based on limited in-home monitoring data. The annual energy savings from the refrigerator replacement in the households were estimated using the artificial neural networks (ANN) models for indoor air temperature prediction and the empirical models for the refrigerator energy consumption estimation. The experimental and estimation results both showed that most of the households achieved substantial energy savings from the replacement. The average annual energy cost savings and the average payback period of the refrigerator replacements were 53% and 4.3 years, respectively. It was also found that the energy savings could be compromised if the size of the new refrigerator was much larger than the old unit or if the efficiency of the old refrigerator was reasonably good.