Design Of Refrigerator Research Articles

Thermal design of a thermoelectric refrigerator operating near room temperature using artificial neural network

The current study aimed to design and test a prototype of a thermoelectric cooler (TEC) using thermoelectric modules (TEM) operating near room temperature. The thermoelectric cooler utilized in this investigation has a maximum cooling power of 46 W and dimensions of 40 mm × 40 mm × 3.6 mm. After a series of measurements, the device temperature decreased from an ambient temperature of 19.6 °C to 1.6 °C, with a notable coefficient of performance around 0.9, achieved through the utilization of both serial and parallel connections. The secondary objective of this research was based on an artificial neural network (ANN) approach. An ANN model was constructed using an experimental database acquired from our thermoelectric refrigeration device. The input parameters of humidity, time, performance coefficient, cooling power, and heat dissipation were introduced into the model to enhance the cold temperature as the output. Using a multilayer perceptron (MLP), the experimental dataset was used for training, testing, and validating the ANN. The precision of the model was evaluated using three established statistical metrics: mean squared error (MSE), mean absolute percentage error (MAPE), and R-squared (R2).

Imagining the future household refrigerator: A study investigating the dimension of user needs

Household refrigerator concepts have evolved with changing applicational scenarios and requirements, providing users with support for healthy eating, personal care, and other activities in the kitchen and other areas of the home. However, current research on exploring user expectations and requirements for household refrigerators lacks considering the perspective of applicational scenarios and activity support. For this study, we invited 45 participants to explore immersive experience methods and conducted semi-structured interviews to investigate user requirements for future household refrigerators in different home areas and obtain dimensional details related to user needs, ultimately generating new insights into the demand for connected, intelligent, emotional, easy to use. Our findings are instructive for the design of future refrigerators in household scenarios and provide guidance and references for the design of other smart home appliances.

Optimal Control of a Domestic Frost-Free Refrigerator Inlet Freezer from the Perspective of Reducing Energy Consumption

This study is dedicated to the development of a mathematical model based on shape optimal control of the inlet domestic frost-free refrigerator in the context of energy consumption reduction. A three-dimensional thermofluid model is established for the numerical studies. As the physical system (with shelves and fruits) can be seen as a porous medium, the coupled state equations of the transport mechanism (for velocity and temperature fields) are governed by Navier–Stokes–Forchheimer/Fourier equations. Then, based on the finite element method, the numerical scheme computation is made with FreeFem++ software (Version 4.6). Numerical results are shown for three different cases: empty without shelves, empty with shelves, and loaded with foods. For each case, the velocity and temperature fields’ results are discussed for the optimal configurations. The characterization of these physical parameters would help engineers in domestic frost-free refrigerator design.

Development of a two-stage thermoacoustic refrigerator prototype

A traveling-wave thermoacoustic refrigerator is a potential cooling option for electronics enclosures. The main advantage of this type of refrigerator is the lack of moving parts, which makes it a maintenance-free application. The design and laboratory implementation of a travelling-wave thermoacoustic refrigerator is studied and presented in this paper. The matching between the thermoacoustic refrigerator and a pair of linear motors is investigated. A model of the refrigerator was first developed via DeltaEC simulations and then validated experimentally. A final configuration comprising of a two-stage refrigerator driven by two linear motors is presented. The model of the refrigerator runs at a frequency of 60 Hz, and it is able to generate a cooling power of 446 W at a cooling temperature of 0 °C. The setup and instrumentation of the apparatus is explained in detail. Experimentally, the refrigerator's maximum cooling load was 298 W, and the lowest cooling temperature achieved was -0.2 °C. At the maximum cooling power, the COP is 2.35.

Experimental study of an absorption-based refrigeration driven by ocean thermal energy

Establishing an island-based cold chain is essential for ensuring food storage, vaccine preservation, and fish freezing on islands, which is indispensable for the sustainable development of island communities. The compression-absorption refrigeration system that uses ocean-thermal-energy is ideal for cold storage on islands as it efficiently utilizes local renewable energy sources and can meet refrigeration needs below 0 °C. Therefore, a refrigeration prototype has been constructed and thoroughly experimentally investigated to obtain refrigeration characterization under variations of refrigeration demand and environmental conditions. The system's energy-saving potential is evaluated by conducting comparisons with conventional refrigeration techniques. The results indicate that refrigeration temperature plays a crucial role in determining refrigeration capacity, with an increase of approximately 8.2 % observed for every 1 °C rise in refrigeration temperature. Lower cold-seawater temperatures or higher warm-seawater temperatures do not have a significant effect on the refrigeration capacity, but contribute to a reduction in compressor power due to increased thermally-driven compression force. Consequently, for every 1 °C change, the refrigeration capacity per unit compressor power increases by approximately 4 %. Additionally, the refrigeration capacity of the system is three times greater than that of a vapor-compression-refrigeration-system. The findings provide theoretical and experimental guidelines for the design and operation of refrigeration using ocean-thermal-energy.

Design of innovative phase-change cold storage refrigerator and simulation analysis of discharging progress

At present, the field of cold chain logistics experiences significant growth, with refrigerator playing a pivotal role in cold chain transportation. An innovative compartmentalized phase-change cold storage refrigerator has been proposed in this study, designed to address the increasing demand for efficient and energy-saving solutions in the cold chain transportation industry. A conceptual module prototype is designed and built in this study, with an analysis of the system's charging and discharging processes under varying conditions. The cold storage refrigerator exhibits favorable matching characteristics, the charging process requires approximately 270 min, and the cooling effect sustains for about 23 h. A three-dimensional simulation model of the cold storage refrigerator is developed, enabling a comprehensive evaluation of the cooling effect and further optimization of the cold storage plate layout. The results indicate that the layout of the three-sided type cold plate significantly reduces the pre-cooling time. It is determined through simulation calculations in this study that setting the loading capacity to 50 % can strike a balance between efficient cooling and transportation efficiency. Additionally, under high-temperature conditions, the cold storage refrigerator maintains a low temperature for up to 10 h at a filling rate of 50 %.

Design, analysis, and operation optimisation of a shipborne absorption refrigeration–ice thermal storage system based on waste-heat utilization

The integration of waste-driven absorption refrigeration technology into marine applications is recognized as a promising low-carbon solution. Nonetheless, its practical application does not inherently outperform electric compression technology, primarily due to the absorption system’s inherent thermal inertia and limited adjustability. This characteristic renders the system less responsive to the dynamic refrigeration requirements typically encountered on board vessels. In this study, a shipborne ammonia absorption refrigeration–ice storage system is proposed to balance the cooling load between supply and demand. To evaluate the efficiency of the integrated system for ice storage and cooling during ship sailing, key operational variables including refrigeration temperature, cooling water temperature, and generation temperature are analyzed to assess the thermal cycle performance of the system. A typical shipping route is considered for cooling operation optimisation of the absorption refrigeration–ice storage system. This paper explores four typical cooling-supply strategies and determines the operation modes for the ice storage period and the cooling period based on considerations of energy consumption, energy utilization, and economic factors. The final optimisation results indicate that the combined system has significant advantages based on energy consumption and operation cost. In comparison to compression and absorption refrigeration systems, the proposed system exhibits 52.4% and 8.31% reductions in energy consumption, respectively. Additionally, the operation costs are decreased by 12.27% and 27.41%, respectively, and the life cycle costs are lowered by 11.51% and 32.35%, respectively. The findings of this combined system can provide a technical reference for the design and operation of a ship waste-heat refrigeration system.

Design of nonflammable mixed refrigerants based on the partial molar enthalpy difference in mixed-refrigerant Joule-Thomson refrigerators with/no pre-cooling stage

Mixed-refrigerant Joule-Thomson refrigeration (MJTR) is an important cooling method at temperatures from 80 to 230 K. It can be used in cryosurgery, high-temperature superconductivity and sensor cooling etc. However, most of the studies are on nitrogen-hydrocarbon refrigerants, which are not allowed in applications where there is a special need to avoid flammability risks. Therefore, non-flammable mixed refrigerants were investigated in this study.The composition of the mixed refrigerant is a key factor in the system performance (refrigeration temperature, refrigeration capacity, etc). However, the purely mathematical optimization methods lack system knowledge in the optimization of the process, and may have the disadvantages of being a time-consuming process. In this study, the isothermal throttling effect of mixed refrigerants is optimized, and the optimization process is based on the partial molar enthalpy difference of each component. The method is based on thermodynamic properties and is time-saving relative to purely mathematical optimization techniques.Non-flammable mixed refrigerants (NFMR) with refrigeration temperatures from 100 K to 140 K were designed in this study. The results show that the designed mixed refrigerant has a higher COP compared to the reference. Argon has an advantage at refrigeration temperatures from 120 K to 140 K, while nitrogen has an advantage from 100 K to 120 K. In addition, mixed refrigerants for systems with pre-cooling stage were optimized and the results showed that the highest exergy efficiency is achieved at a pre-cooling temperature of 250 K. The exergy efficiencies with pre-cooling stage are nearly twice as high as those without that. Therefore, a pre-cooling stage for nonflammable mixed refrigerants is necessary where there is no requirement for system size.

The Design and Refurbishment of End Station Refrigerator 2 at JLab

The future operation of the 4 kW 15 Kelvin MOLLER experiment at Jefferson lab necessitates an increase of cryogenic capacity at the End Station Refrigerator. The current plant is the former 1.5 kW (4.5 K) ESCAR plant that has been operating at Jefferson Lab since 1995. The existing 1.5 kW plant is not able to support the load for MOLLER and will be replaced with a refurbished plant comprised of the cold box and compressors of the 4 kW ASST-A plant from the Superconducting Super Collider in Texas. This paper outlines the assembly, repair and modifications made to the cold box, along with the design of the plant as a whole and its integration into the existing distribution system.

Design of Excellent Mechanical Performances and Magnetic Refrigeration via In Situ Forming Dual-Phase Alloys.

Magnetic refrigeration technology can achieve higher energy efficiency based on the magnetocaloric effect (MCE). However, the practical application of MCE materials is hindered by their poor mechanical properties, making them challenging to process into devices. Conventional strengthening strategies usually lead to a trade-off with refrigeration capacity reduction. Here, a novel design is presented to overcome this dilemma by forming dual-phase alloys through in situ precipitation of a tough magnetic refrigeration phase within an intermetallic compound with excellent MCE. In the alloy 87.5Gd-12.5Co, incorporating the interconnected tough phase Gd contributes to enhanced strength (≈505MPa) with good ductility (≈9.2%). The strengthening phase Gd simultaneously exhibits excellent MCE, enabling the alloy to achieve a peak refrigeration capacity of 720 J kg-1. Moreover, the alloy shows low thermal expansion induced by the synergistic effect of the two phases. It is beneficial for maintaining structural stability during heat exchange in magnetic refrigeration. The coupling interaction between the two magnetic phases can broaden the refrigeration temperature range and reduce hysteresis. This study guides the development of new high-performance materials with an excellent combination of mechanical and magnetic refrigeration properties as needed for gas liquefaction and refrigerators.

Turbulent natural convection inside inclined enclosures: Effects of adiabatic and heat-conducting inserts

Natural convection phenomena are found in many engineering applications, ranging from building and refrigeration design to nuclear reactors. Such importance has prompted both experimental and numerical studies aiming at enhancing heat transfer characteristics. Turbulent natural convection in closed cavities, apparently simple, is a stepstone to such problems, which require mathematical and numerical tools capable of providing accurate results. This work is inserted within this framework, in which influences of insert size and type (adiabatic/heat-conducting), and cavity inclination angle are assessed for Rayleigh numbers 10 7 ≤ Ra ≤ 10 9 . The study shows that the insert is mostly detrimental to heat transfer owing to restriction to recirculation, irrespective of the cavity inclination angle. An operation envelope for the global Nusselt number for all cavity inclination angles, insert sizes and types, and Rayleigh numbers was also determined.

Research on User Demands for Future Household Refrigerators

Refrigerators can provide activity support for users in the kitchen and other areas of the home. However, there is currently a lack of research on the demand for preservation and storage space in other household areas. By conducting semi-structured interviews with participants, we investigated user needs for future preservation and storage space. This research has generated new insights in terms of the intelligence, connectivity, emotional appeal, and ease of use of preservation and storage spaces. Our findings provide valuable insights for the design of refrigerators in future home environments and can also serve as a guide and reference for the design of other smart home appliances.

An experimental study exploring heat transfer enhancement in tube in tube heat exchanger with pulsating flow

Rationalizing power consumption is crucial in air conditioning and refrigeration design. This study focuses on improving the coefficient of performance (COP) by applying pulsating flow. Experimental trials compared continuous counter and counter pulsating flow to continuous parallel flow, showing a 10% reduction in fluid temperature with continuous counter flow and a 20% reduction with counter pulsating flow. Sensible water heat rejection increased by 10.03% and 19.78% with continuous counter flow and counter pulsating flow, respectively. Overall heat transfer coefficient improved by 57.5% and 75% with continuous counter flow and counter pulsating flow. Effectiveness increased by 4.55% and 10.6%, while COP increased by 4.52% and 13.4% with continuous counter flow and counter pulsating flow, respectively. This research demonstrates the potential of pulsating flow techniques to enhance air conditioning and refrigeration efficiency.

Investigations on the throttling process of 3He in a dilution refrigerator used for cooling superconducting quantum chips

With the rapid progress of the superconducting quantum computing technology, the cryogenic technology capable of providing appropriate cooling in the millikelvin temperature region is desirable. The cryogen-free dilution refrigerator featuring high reliability, long lifetime, and continuous cooling has become one of the most promising cryocooler candidates for this purpose. As one of the key components of the dilution refrigerator, the impedance component is used to control the flow and to liquefy 3He, which is crucial to achieving the millikelvin temperature. In this paper, a throttling model is proposed to analyze the dilution cycle and to eventually improve the refrigeration performance, which focuses on the influences of the complex physical properties of 3He and the dilution cycle from the subcooled state to saturation state. The effects of the inlet pressure and inlet temperature on the flow rate are studied, and the energy conversion on the throttling process is discussed. It indicates that the throttling model can reasonably predict the flow rate under different inlet pressure and inlet temperature and is helpful to the design and optimization of the millikelvin cryogen-free dilution refrigerator.

Computer-aided molecular refrigerant design for adsorption chillers based on classical density functional theory and PC-SAFT

Adsorption chillers are a promising technology for sustainable cooling. The performance of adsorption chillers is highly influenced by the selection of the refrigerant. Still, systematic selection of refrigerants is challenging because evaluating adsorption properties requires significant experimental or simulation efforts. Thus, refrigerant design options are often limited.Here, we propose a systematic refrigerant design method for adsorption chillers assessing refrigerants based on their process performance. Our method quantifies adsorption isotherms by 1-dimensional classical density functional theory (DFT) based on the PC-SAFT equation of state. The method is used to screen over 1800 refrigerants based on their coefficient of performance (COP). We identify refrigerants with higher COPs than commonly used refrigerants and highlight the advantage of a process-based objective function over material-based heuristic selection criteria. Finally, we advance from screening to computer-aided molecular design of the refrigerant, leveraging the efficiency of the DFT model to explore the molecular design space systematically.

Effects of variable-temperature heat reservoirs on performance of irreversible Carnot refrigerator with heat recovery

The outlet temperature of the heat recovery reservoir is an important parameter in the design of refrigeration with heat recovery systems. In this paper the second law of thermodynamics has been applied to an irreversible Carnot refrigerator with heat recovery (CRHR) coupled to variable-temperature heat reservoirs. The refrigerating rate, input power, refrigeration coefficient, heat recovery coefficient, comprehensive coefficient of performance and exergy efficiency are chosen as the objective functions. The design rule chosen for this study is that the heat transfer area should be constrained. The mathematical expressions for assessing performance parameters with respect to area ratio, were derived for this study. These expressions are transcendental equations. The numerical solution method was employed to calculate the approximate solutions of the optimum performance parameters in a numerical example. The results indicate that the increase in the outlet temperature of heat recovery reservoir could lead to a rise in the maximum value of refrigerating rate and minimum value of input power; also it will lead to the decline in the maximum value of refrigeration coefficient, heat recovery coefficient, comprehensive coefficient and the exergy efficiency. When the ratio of heat recovery heat exchanger area to the summation of high temperature heat exchanger area and the heat recovery heat exchanger area is 1.0, the performance coefficients would attain their limit values and all of the condensing heat could be recycled. Our findings are helpful to the design and optimization to inform preparation of standard relating to the development of refrigerator with heat recovery.

Life cycle assessment of fluorinated gas recovery from waste refrigerants through vacuum swing adsorption

The refrigeration industry is facing a challenge due to stricter regulations on the use of fluorinated gases (F-gases) with high Global Warming Potential (GWP). In many cases, the design of alternative refrigerants requires the recycling of low and moderate GWP compounds from existing refrigerant blends, but currently there is no a standardized technology available to recover them, and finally most gases are incinerated at the end of the equipment's life cycle. Recently, Vacuum Swing Adsorption (VSA) has been proposed as a possible solution for the complex separation of F-gas mixtures. The environmental sustainability of the recovery of R-32 from R-410A blend using a VSA process (circular economy scenario), was analysed through a life cycle assessment (LCA) approach, and it was compared to the conventional R-32 production (benchmark scenario). The results show that the VSA technology can achieve a 30.9% recovery of 97 mol% R-32 suitable for further reuse, with a reduction in the environmental loads ranging from 58 to 99% compared to industrial R-32 production. The carbon footprint of the recovery process is 4.81 kg CO2 equiv., while for the industrial production of R-32 is 10.9 kg CO2 equiv. This study proves that the development of adsorption-based technologies for F-gas recovery can improve the environmental impact of these compounds from a circular economy perspective.

Experimental and simulation study of a U-shaped water-cooled sleeve heat pipe radiator for high heat flux density

Effective heat dissipation methods are desperately needed to ensure heat transfer of the large quantity of heat generated by radioactive isotopes in restricted places. This study employs the Bell-Delaware method to design a U-shaped water-cooled sleeve heat pipe radiator (UWC-HP) intended for heat dissipation on a 16 cm2 surface area with a heat flux density of 200 W/cm2. We have established a 3D model, which was experimentally validated, showing an error within 5 %. Subsequently, as the refrigerant and structural design of the condenser segment are crucial factors leading to the limitations of UWC-HP, this study aims to evaluate the impact of the condenser segment on the heat dissipation performance. Specifically, we investigated the effects of different cooling water temperatures, flow rates, and fin designs on the heat dissipation performance of the UWC-HP. Based on this, We found that the rib height, the number of ribs, and the rib material can strengthen the performance of the heat sink by a maximum of 12.3 %, 10.1 %, and 3.7 %, respectively. The heat sink optimized by orthogonal experiments has a maximum heat source surface temperature of 506.22 K and Nu of 101.85, which reduces the maximum surface temperature of the heat source by a maximum of 22 K and strengthens the heat sink capacity of heat pipes by 20 %. This article achieves efficient heat transfer for isotopic decay heat in a confined space by designing a heat pipe heat exchanger. It reduces the equipment's temperature and enhances the safety of the nuclear reactor.

Research on Refrigerator Design Based on Computer Vision: Designed for Visually Impaired People

With the continuous progress of technology, artificial intelligence (AI) technology, especially computer vision, has provided new possibilities for obstacle free design. This article focuses on how to use computer vision technology to create more user-friendly refrigerator designs for visually impaired individuals. Firstly, we introduced the basic concepts of computer vision and its applications in various fields. Through user research on visually impaired individuals, we understand their needs and challenges when using refrigerators. On this basis, we propose a series of design strategies for obstacle free refrigerators based on computer vision and propose some possible design solutions. However, there are also some challenges when implementing these design solutions, such as cost, device robustness, and privacy issues. Overall, this study provides a new perspective on how to use computer vision to improve the quality of life for visually impaired individuals.

A low-frequency ferrohydrodynamic pump for a magneto-caloric refrigerator

Ferrohydrodynamic or magnetic pumping enables the design of a magnetocaloric refrigerator with no moving parts. Existing magnetic pumps utilize travelling wave magnetic fields with frequencies in the range of 100 to 1000 Hz. Such high frequencies when utilized in the proposed refrigerator could cause heating which is detrimental to its performance. Hence, a magnetic pump that works with low magnetic field frequencies (¡ 1 Hz) is designed and its performance is experimentally characterized and compared against an one-dimensional model. The design of the magnetic pump consists of a rising and falling pipe, circumscribed by an electromagnetic coil. On application of a magnetic field, due to the inward acting force on either end of the pipes, the ferrofluid progresses in the rising pipe and reaches the falling pipe. On removal of the magnetic field, the portion of the fluid in the falling pipe falls down due to gravity, thereby achieving a net pumping action. Thus on continuously cycling the magnetic field, an intermittent motion of the ferrofluid is obtained. The maximum cross-sectional area and time-averaged mass flow rate of the proposed design is 1.8 g s-1 cm-2 at 0.74 Hz and 35.7 mT. This mass flow rate is comparable to pump designs that work on travelling wave magnetic fields, whose operational frequency is three orders of magnitude higher.