Refrigerator Manufacturing Research Articles

Automatic detection surface defects based on convolutional neural networks and deflectometry

AbstractSurface defects in industrial refrigerator manufacturing processes can cause significant production losses and compromise product quality. This area is underexplored and currently, visual quality inspection is a subjective process that requires expert intervention, which limits process efficiency and can lead to errors in defect detection. This paper presents a novel approach for automatic surface defect detection using a combination of convolutional neural networks (CNN) and deflectometry. The proposed method takes advantage of the high accuracy and robustness of CNNs in image classification tasks and the sensitivity of deflectometry to detect subtle surface variations. First, a prototype was built to get the images from the refrigerator. Second, using video recordings, we captured surface topographic data using deflectometry, which we then use to generate surface images. Next, we train a CNN to classify the surface images as defective or normal. The proposed method offers a promising solution for automatic detection and quality control of surface defects in refrigerator manufacturing processes. However, this method could also improve the production of vehicles, household appliances in general, and any product that can suffer scratches and dents.

Experimental investigation of R600a as a low GWP substitute to R134a in the closed-loop two-phase thermosyphon of the mini thermoelectric refrigerator

Various energy efficiency and environmental regulations around the world, such as the European Union's (EU) F-Gas regulation, are pushing refrigerator manufacturers to replace halogenated refrigerants with environmentally-friendly alternatives with low Global Warming Potential (GWP) without energy efficiency decrease. In this respect, increasing energy conversion performance by using a low GWP refrigerant in the mini thermoelectric refrigerators (MTERs) gains important for revealing sustainable and environmentally friendly refrigerators. To make this possible, the paper provides a comprehensive examination of the effect of climate-friendly refrigerant replacement in the closed-loop two-phase thermosyphon (CLTPT) on the performance of the MTER. This study treats the experimental investigation of the R600a as a low GWP substitute to R134a in the CLTPT of the MTER. Different from the other study in the literature, an extensive performance evaluation of the commercial MTER in terms of exergy as well as energy was performed and the various filling ratios (FR) of the R600a from 19% to 78% were analyzed for the best performance. The results showed that the MTER with a 46% and 32% FR of R600a had the highest exergy efficiency with 8.55% and 8.11%, respectively while reference MTER with R134a had 5.27%. It is concluded that 32% and 46% FR of the R600a enhanced the MTER energy conversion performance according to the 19% FR of the R134a, in line with the F-Gas regulation. The 32% and 46% FR of the R600a for MTER are the best refrigerant replacement, both from thermal performance and environmental points of view.

The Construction of Haier Financial Shared Service Center under the " Integrating Order with Personnel " Model

Founded in Qingdao, Shandong in 1984, Haier Group has grown from a small refrigerator manufacturer to the world's No. 1 white goods brand. In 2005, the concept of " Integrating Order with Personnel " was put forward, and in 2006, under the guidance of this concept, it became one of the first enterprises to establish a financial shared service center in China. This paper mainly analyzes the structure of Haier Financial shared service center from three aspects: the background, development and effect of its construction, so as to deepen the understanding of the financial shared service center.

Experimental Study of Natural Convection in a Closed Cavity (Static Type Domestic Fridge)

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.

Qualitative and quantitative assessment of waste generation in a refrigerator-manufacturing plant based on a waste tree and mass balance.

In this study, wastes originating at each production station during refrigerator manufacturing were identified and classified based on a waste tree. A mass balance study revealed a total waste production factor of 0.046 kg/kg of a product of which 75.3%, 23.9%, and 0.8% were non-hazardous wastes (NHWs), packaging wastes (PWs), and hazardous wastes (HWs), respectively. Wastes produced during refrigerator manufacturing were grouped under 35 different waste codes. Waste codes that contributed more than 5% by weight were 15 02 02 (contaminated absorbent material), 15 01 10 (contaminated packaging), 16 02 13 (electronic cards), 07 02 14 (polyol) and 08 05 01 (isocyanates), 19 08 13 (treatment sludge), 16 02 15 (capacitors), and 13 01 13 (hydraulic oil) for HWs, 12 01 01 (ferrous metal), and 16 02 16 (components) for NHWs, and, finally, 15 01 03 (wooden), 15 01 01 (paper&cardboard), and 15 01 02 (plastic) for PWs over 5 years. Scrap costs were used as a surrogate to determine production stages that generated high amounts of metal and plastic wastes. Logarithmically, increasing and decreasing trends were observed for PWs and NHWs over the study period, respectively. HW amounts did not exhibit a statistically significant trend. Twenty-eight BATs (best available techniques) were identified that could be applied in refrigerator manufacturing for waste minimization and management. Among those, 8 of them were proposed for further improvement for waste management in the facility.

Analysis on Chemical and Physical Behaviors of Polyurethane Foam for Prediction of Deformation of Refrigerator Panels

Polyurethanes foaming is considered as one of key technologies in refrigerator manufacturing to ensure insulation performance. We propose a method for the prediction of refrigerator panel deformation with considering full processes such as filling of polyurethane, chemical reactions, and thermal deformation of solidified polyurethane during foaming. The important influencing factors of the after-foaming deformation are studied and defined using three physical properties: temperature, density, and pressure in order to predict the panel deformation precisely. Analysis of the factors affecting the final deformation resulted in greater than 80% accuracy for each factor compared with those of experiment. Based on the fundamental research results, we tried to predict the deformation of a rear panel after foaming process. We evaluated the usefulness of the proposed analytical approach by experiments, and good agreements between two results obtained. So, we believe that this approach can be used to predict the deformation of a refrigerator panel and some side effects on it.

Estimation of Safety and Quality Losses of Foods Stored in Residential Refrigerators

This article overviews the technological evolution of residential refrigerators, key national and international regulations covering them, and summarizes the information available to estimate the quality and safety deterioration in foods and beverages stored in them. At present, the national and international government standardized performance tests used to assess residential refrigerators focus on energy consumption. Efforts by refrigerator manufacturers to consider the impact of temperature fluctuation, temperature recovery, extreme ambient temperature, door openings, and other factors affecting temperature control and, thus, food safety and quality need to be harmonized, validated, and implemented as official standardized tests. Published predictive models here summarized, and describing microbial growth and other product degradation mechanisms, could be combined with energy efficiency evaluations in future science-based regulations seeking a balance between energy consumption and food preservation. While numerous mathematical models are available, this review identified a serious lack of model parameter values to allow a combined assessment of energy consumption and food preservation in residential refrigerators. Much of past research has focused on temperature abuse effects and, thus, not applicable to estimating food preservation under the prevailing temperatures in residential refrigerators. Particularly urgent is the data on the microorganisms’ response at multiple temperature levels, allowing the development of secondary models to assess the temperature effect on the safety and quality of a diverse but representative pool of products. New standardized testing procedures could then be developed to guide the design of new residential refrigerators minimizing food waste and the frequency of foodborne diseases while meeting energy consumption requirements.

U.S. political backing sought for HFC pact

A group of unlikely allies wants the Trump administration to require reduced U.S. use of a class of synthetic chemicals that are potent greenhouse gases, in line with an international agreement. The organizations lobbying for the restrictions include rival international chemical producers Arkema, Chemours, Honeywell, and Mexichem Fluor as well as a U.S. business that builds refrigerated trailers for shipping. Then there are environmental advocates, domestic manufacturers of home refrigerators, and a company that makes aerosol tire-inflating products. The organizations hold different views on how the U.S. should implement a 2016 treaty on hydrofluorocarbons (HFCs)—chemicals used as refrigerants, aerosol propellants, and blowing agents that puff up plastic into foams. But they are delivering a unified appeal to the Trump administration, which has generally disparaged international deals, from trade pacts to the Paris Agreement to combat climate change. Their message is simple: Back the global accord on HFCs...

Risk factors associated with musculoskeletal disorders in a refrigerator manufacturing company

To establish the risk factors associated with musculoskeletal disorders in operative workers of a refrigerator manufacturing company in Barranquilla, Colombia. Cross-sectional, descriptive research. A convenience sampling was carried out, consisting of 79 workers. The instruments used were: PAR-Q (Physical Activity Readiness Questionnaire), BMI (Body Mass Index), Nordic questionnaire and REBA method. Of the total population surveyed, 60.8% reported some musculoskeletal symptoms; 48.1% said they had a single body segment affected, 10.1% had 2 segments affected, and 1.3% had 3 or 4 segments involved. The most involved body segment was the thoracolumbar segment, which was related to positions such as assembly operator, veneer operator, injection operator and welder. The group of workers in the areas of assembly, veneer, injection and welding is especially exposed to risk factors that increase the likelihood of suffering discomfort and musculoskeletal damage. Moving the upper limbs repeatedly and handling loads manually are some of the ergonomic risks and demands for attention, while psychosocial risks to which this group is exposed include high work rates and short deadlines. In addition, the body mass index is an important factor for the onset of musculoskeletal disorders.

Assembly system configuration through Industry 4.0 principles: the expected change in the actual paradigms

Industry 4.0 creates what has been called a "smart factory". The possibility to a wide data collection from industrial processes makes possible to act smart action related to the system changes. Cyber-Physical Systems monitor physical processes and make possible decentralized decisions or even, in the last stage, a self-smart system adaptation. Thanks to the connectivity of the different production resources (machines, work stations, etc.) it is possible to generate information, to share and provide it and finally to create a smart system in which a predictive and automated decision making process with potential self-reconfiguration of the production system is possible to occur. As consequence Industry 4.0 could strongly impact on the actual assembly paradigms, even in the cases in which the human factor is prevailing, as manual assembly. This paper aims to investigate how these transformations are expected to occur. A future state map of the assembly paradigms as effect of the integration with the Industry 4.0 principles is presented. Moreover, a general architecture to implement Industry 4.0 principles into existing assembly systems is provided, highlighting how the final steps of implementation represented by the Operator Support Systems (OSS) and Self-Adapting Smart Assembly System (SASS) are crucial. A detailed report of a real case study derived by an Italian worldwide industrial refrigerator manufacturer represents a further element of interest of the research and demonstrates the practical implication of the study.

The design of a novel and portable energy performance-measuring device for household refrigerators

Refrigerators are one of the main devices used in our daily lives, and they play important roles in storing food and maintaining its freshness. Refrigerator manufacturing is improving day by day and it is important for the appliance to present a diverse array of functions to its users, since usage requirements vary from region to region. For this purpose, refrigerators must pass through various performance tests like an energy efficiency test while they are produced in factories. Factories have designated testing rooms for these performance tests. After the products' release, technical services and customers do not have such a luxury of pretesting the machines.In this study, a portable performance-testing device was designed specifically for household refrigerators. Experimental analyses were based on the TS EN 15 502 standards, which are compatible with the IEC 62552 standards. The test series consisted of temperature, current, voltage, and humidity measurements. The control results were indicated by an Arduino-based microprocessor. The tests could be controlled by the users in real time via an LCD panel on top of the indicated testing device. The monitor showed the relevant interface programs written in C# and a web interface. Moreover, the developed setup could determine the energy efficiency class of refrigerators, among their other qualities.

Analysis of the flow and temperature distribution inside the compartment of a small refrigerator

This work presents the analysis of the flow and thermal behavior of the compartment in a refrigerator, in which its cooling effect is based on diffusion-absorption technology. CFD was used to model and simulate the refrigerator. The main objective was to compare the thermal behavior of a plate-evaporator design with a finned surface (reference refrigerator) and a plate-evaporator with a smooth surface (proposed design). Moreover, the study was completed with the discussion about the velocity distribution and the pathlines of the temperature and velocity. This was also observed under the influence of the wired shelf location inside the compartment. Additionally, the performance of the refrigerator was evaluated. 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 the numerical simulation in the search for improvements in the design of this refrigerator model, which might help manufacturers of diffusion-absorption refrigerators.

Forensic Engineering Analysis of Unvented Gas Appliances in High Altitudes

A family moves into a house about 4,000 feet above sea level. They use a refrigerator powered by LP gas. A short time after the refrigerator was installed, they notice and complain about smells and soot. They take their 9-month-old to a hospital in response to persistent crying. A short time later, they notify the refrigerator manufacturer, which examines and tests the refrigerator. They find the refrigerator’s burner venturi blocked, generating high levels of carbon monoxide. Twelve years later, the parents bring a lawsuit against the installers of the refrigerator. At that time, the appliance is not available, and the house has been remodeled. A forensic engineering study is assigned to determine the effect high altitude has on this particular appliance design.

Geely Automotive's Acquisition of Volvo

The case describes Geely Automotive's strategy to grow from an unknown Chinese refrigerator manufacturer into a global international player. A big step toward Geely's internationalization was its acquisition of Volvo Car Corporation in 2010. The acquisition prompted the largest profits and most intense technology transfer in Geely's history. But it also created conflicts between the two merging organizations including differences over leadership style, resource sharing, and branding strategy. The case discusses the synergies and challenges encountered by Geely and Volvo and illustrates the details of the acquisition. The case also provides lessons for other enterprises from emerging economies that are increasingly wishing to expand to well-developed markets such as America and Europe.

An integrated TRIZ approach for technological process and product innovation

Process trimming (also can be called as trimming for process) helps to trim and eliminate process operations by redistributing their functions among other operations. It offers one way to eliminate key disadvantages in product and manufacturing process that other methods do not see. However, few methods have been disclosed in a structured way for process trimming effectively. Therefore, this article proposes an integrated process focused on technological process and product innovation to solve the key problems with process trimming-based TRIZ (theory of inventive problem-solving) approach. This method helps to identify and inventively solve the key problems and maximize use resource of system and supersystem. First, process trimming candidates are identified based on component function model, component trimming rules, process function model analysis, component–process interaction matrix, and root cause analysis. Then, three types of process trimming strategies are presented. Algorithm of process trimming is developed to identify key problems in technological process. TRIZ problem-solving tools are used to solve these key problems. Finally, a case study of refrigerator door foam innovative design and manufacturing process is investigated to test the efficiency of the approach. The innovative solution significantly decreases manufacturing defects and service cost.

An operational policy for a three-stage distributive supply chain system with retailers’ backorders

This research deals with a production-inventory problem consisting of three-stage tree-type single-producer multi-distributor and multi-retailer supply chain network where a model has been developed for achieving the lowest total cost for operating a supply chain system with allowable shortage. In this research, the shortage is assumed to occur in a form of backorder. The refrigerator manufacturing can suitably be used to illustrate the scenario which makes the situation more rational and realistic. By assumptions, the customers will not go somewhere else, the cost of lost sale is not included in this case. The total cost of this tree-type distributive supply chain system is comprised of setup costs and holding costs at all echelons, and the backorder cost at retailer level only. A replenishment policy is sought to operate the system at a minimum cost. The problem is formulated as an unconstrained mixed-integer programming problem and a newly developed doubly hybrid meta-heuristic algorithm is adopted as the solution procedure. The solutions which determine the desired replenishment policy for the producer, distributors, and retailers are obtained to minimize the total system cost. A sensitivity analysis is performed to evaluate the outcome of the proposed solution procedure presented in this research. Numerical results are generated to demonstrate the solution procedure, and future research is indicated for further study.

A novel algorithm for layout optimization of injection process with random demands and sequence dependent setup times

Injection molding is an ideal manufacturing process for producing high volumes of products from both thermoplastic and thermo setting materials. Nevertheless, in some cases, this type of manufacturing process decelerates the production rate as a bottleneck. Thus, layout optimization plays a crucial role in this type of problem in terms of increasing the efficiency of the production line. In this regard, a novel computer simulation–stochastic data envelopment analysis (CS-SDEA) algorithm is proposed in this paper to deal with a single row job-shop layout problem in an injection molding process. First, the system is modeled with discrete-event-simulation as a powerful tool for analyzing complex stochastic systems. Then, due to lack of information about some operational parameters, theory of uncertainty is imported to the simulation model. Finally, an output-oriented stochastic DEA model is used for ranking the outputs of simulation model. The proposed CS-SDEA algorithm is capable of modeling and optimizing non-linear, stochastic, and uncertain injection process problems. The solution quality is illustrated by an actual case study in a refrigerator manufacturing company.

Optimisation of complex and large-sized single-row facility layout problems with a unique hybrid meta-heuristic framework

This paper proposes a hybrid framework based on genetic algorithms (GAs) and discrete-event simulation (DES) for optimisation of large-sized single-row facility layout problems (SRFLPs). For a SRFLP with n number of facilities, there are n! layout formations that have to be modelled and evaluated so as to find the optimal single-row formation of facilities. For that reason, as the number of facilities gets larger, the solution space grows exponentially and so evaluation of all potential layout formations could be extremely hard or even impossible. For dealing with non-deterministic polynomial-time hardness of large-sized SRFLPs, this study puts forward a novel GA wherein DES is applied as a performance evaluation tool for calculating the fitness function. The proposed framework employs DES for modelling and evaluating diverse layout formations. Manufacturing lead-time is taken into consideration as the performance evaluation measure. The solution quality is investigated through a real case study in an injection moulding process with sequence-dependent set-up times in a refrigerator manufacturing company. Notably, significance of the proposed framework in comparison with previous studies in this area lies in integrating GAs and DES for optimising large-sized SRFLPs in presence of complexity, non-linearity and stochasticity.

Popping noise in household refrigerators: Fundamentals and practical solutions

An intermittent noise that occurs around 30 s after compressor start-up has been disturbing customers of different domestic refrigerator manufacturers over the past 10 years. This noise is very similar to that produced by popcorn popping, being referred to as popping noise. The most probable cause of this strange and unpleasant noise is thought to be the CIS (Condensation Induced Shock) phenomenon. The aim of this study was firstly to check the possible occurrence of CIS in a specific household refrigerator and, secondly, to identify ways to avert it without affecting the product performance. To this end some changes were made to the refrigerator: i) the diameter of the filter dryer was altered; ii) the slope of the filter dryer was altered; iii) the compressor was replaced; and iv) an additional internal heat exchanger was installed. The noise was effectively eliminated only by placing the filter dryer horizontally or by installing an additional internal heat exchanger. Visualization studies were also carried out, making it clear that the occurrence of the popping noise is closely related to the flow pattern at the capillary tube inlet.

Experimental Investigation of the Defrosting Process on Domestic Refrigerator Finned Tube Evaporators

Frost formation is an important problem for household refrigerator and air conditioning equipment manufacturers. When frost accumulates on the evaporator surface, it acts as a thermal insulator and reduces heat flow. Therefore, frost negatively affects evaporator performance. The purpose of this study is to decrease energy consumption and increase the efficiency of the defrosting process. In the first part of the experiment, frost formation on a no-frost refrigerator evaporator at real operating conditions was investigated. The ambient temperature was maintained at a constant 23°C. It was observed that when the evaporation temperature reaches –35°C, the frost formation on the evaporator exhibits a rather dense structure that is unlike the needle-type structure observed at higher temperatures. In the second part of the experiment, the defrosting process was observed with an endoscopic camera, and the initial melting points were investigated. The experiment revealed that although the heater density is higher on the lower rows, the frost on the higher rows of the evaporator melts faster. On the theoretical side, we prepared an analytical model that calculates the melting time of the frost on the fin. The experimental and theoretical results are within 5%.