Refrigerator Compartment Research Articles

Inactivation of microorganisms on surfaces of a refrigerator compartment with low-pressure mercury lamps

Household refrigerator compartments and cold chain systems are highly susceptible to microbial contamination. To minimize the surface-contact disease transmission, low-temperature surfaces must be inactivated. Currently, there is no environmentally friendly and convenient means for surface sterilization at low temperatures. This investigation proposed the use of low-pressure mercury lamps to sterilize the bottom surface of a refrigerator. The mercury lamps emitted UVC irradiation and were mounted horizontally on the sidewalls of the refrigerator compartment to inactivate Escherichia coli (E. coli) on the bottom surface. The measured irradiances and E. coli inactivation efficiencies were used to validate the surface-to-surface (S2S) model. The impacts of the refrigeration temperature (20 °C, 4 °C, and −18 °C, respectively) on the UVC output and E. coli sterilization efficiency were evaluated. And so did for the impacts of the relative humidity (ranging from 45 % to 85 % at 4 °C). The required time for operation of the UVC lamps to reach a 3-log reduction in E. coli was calculated for different lamp placements. The results revealed that the UVC emission of low-pressure mercury lamps decreases remarkably with the temperature. The necessary UVC irradiation dose to achieve the same inactivation efficiency increases as the temperature decreases. To extend the operating life of UVC lamps, the installed lamps should make the irradiance distribution on the target surface as uniform as possible.

Low-Cost Potassium Chloride Saltwater Phase Change Material System for a Household Refrigerator

Thermal energy storage systems (TESS) are receiving attention because there are constant power cuts, major changes in electrical rate structures, increased maximum power demands, and incentive programmes sponsored by utilities. Household refrigerators were one of the main consumers of residential electricity, as they consume up to 26% and have an additional 17% greenhouse gas emissions. By incorporating TESS, this figure can be reduced. This study presents a low-cost potassium chloride saltwater phase change material (PCM) system to maintain a household refrigerator compartment below 5 ° C to preserve food and pharmaceutical products. After determining the 5-liter volume of PCM required, the experiments were carried out on a KIC KBF 525/1 ME refrigerator with an average daily power consumption of 0.567 kWh. With a heat transfer rate of 5 W and a total of 80 kJ of energy, the PCM took 2.5 days to fully solidify. It was then able to maintain the frigerated compartment at a temperature below 5 ° C for close to 25 hours, resulting in a 8W output power and a total of 90 kJ of energy being released. For power consumption analysis, 1.4175 kWh was used during the charging phase and 0.567 kWh was saved during the discharging phase. Heat transfer during the charging phase needs to be improved to better optimise the TESS.

Experimental investigation and analysis of cooling performance of solar thermoelectric refrigerator

Nowadays, a potential alternate source of renewable energy for heating and cooling purposes is solar thermal energy. In remote areas electricity problems, the solar cooling and heating are very useful for living. The present research is focus to develop a solar thermoelectric refrigerator (STER) by using thermoelectric module based on principles of Peltier effect (creating cold and hot zone). Inside the refrigerator compartment, the cold side zone of the thermoelectric module is used for refrigeration. However, the rejected heat from other hot side of module to ambient surrounding through heat sinks and fans. The experimental model considers a steel aluminium box of dimension 200 × 195 × 300 mm3 having two thermoelectric (TE) modules and two heat sink with cooling fan to investigate the performance evaluation of solar thermoelectric refrigerator. The STER unit utilises a 100 W solar panel. The experimental result of double module with internal fan shows that the STER unit reduces room temperature of 33 °C to 4.1 °C in 44 min with coefficient of performance (COP) of 0.61. Therefore, the present novel refrigeration system is augmented for domestic and medicine storage purpose in remote area with economically viable and environmental friendly.

Performance analysis of a hybrid solar-driven cooler for refrigerator vehicle

This study focused on investigating the annual performance of a novel hybrid solar-driven cooling system that can be used on refrigerator vehicles. The cooling system is mainly driven by a DC compressor which is powered by a PV array, while an AC compressor which is powered by the car alternator assists the cooling system when the cooling load is higher than the capacity of the DC compressor. Detailed electrical modeling of the PV panels in the array is performed based on an algorithm that comprises a set of mathematical equations and is validated against the manufacturer's test data. The detailed transient electrical power generation of the PV array is analyzed. The effect of solar irradiation and ambient temperature on the performance of the PV modules is presented. Considering the refrigeration cycle, detailed thermodynamics and heat transfer analysis on the cycle are carried out. The effect of ambient temperature and refrigerator compartment temperature on the performance of the refrigeration cycle is investigated. It is concluded that an increase in ambient temperature decreases the performance of both the PV panel and the refrigeration cycle. While an increase in refrigerator compartment temperature increases the performance of the refrigeration cycle.

Performance Improvement of The Domestic Refrigerator Using Phase Change Materials

A growing environmental Impact of global warming and rapidly increasing cost of the electrical energy cause researchers in the field of refrigeration and air conditioning to develop the sustainable cooling technologies. This study investigated the influence of latent heat storage materials on the power consumption and the temperature distribution of a commercial domestic refrigerator. The 2 kg PCMs (Phase change materials) slab of thickness 5 mm, which consisted of a 2:1 by weight mixture of refined paraffin wax and kerosene oil, were located on the back side of the roll-bond evaporator and the copper coated steel tubing coils of the hot-wall condenser, in order to improve the higher performance of refrigerator and to decrease the operating cycle time of the compressor. The experimental and CFD (Computation fluid dynamics) simulation results indicated that the refrigerator equipped with the PCMs storage unit showed a significant enhancement of the system performance and a reduction of the temperature fluctuations in the refrigerator compartment compared to a conventional system. In this investigation, the electric power consumption and the compressor on-time ratio were reduced by 15.69% and 12.13%, respectively. Moreover, the COP (Coefficient of performance) of the refrigeration system was increased by 9.53%.

Air contamination of therapeutic drug monitoring assay reagents results in falsely high plasma ammonia levels.

Accumulating evidence shows that contamination of blood samples by atmospheric ammonia affects blood ammonia test levels; however, reports on the effect of ammonia contamination of assay reagents are limited. Here, we aimed to clarify the effect of ammonia contamination of assay reagents, particularly the therapeutic drug monitoring (TDM) reagents, on the detection levels of blood ammonia using enzymatic assays. Ammonia gas was measured in the refrigerator compartment of the automatic analyser and the reaction tank water, probe wash water and drain outlets connected to the automatic analyser. At different time points following the closure of the cold storage, ammonia levels in quality control plasma samples were measured using three commercial assay reagents to evaluate the effect of air contamination. The distribution of evaporated ammonia in the reagent was measured using the CicaLiquid NH3 assay kit containing the assay reagent most affected by air contamination. It was confirmed that ammonia gas was generated in the cold storage of the automatic analyser. More than half of the reagents detected >0.25 ppm ammonia, and the highest concentration was detected in the TDM reagent. The ammonia levels obtained using all three reagents increased significantly after 3h of air contamination. The effect was resolved by measuring a 'dummy' sample or mixing the reagents by inversion. We demonstrated that air contamination by TDM reagents placed in cold storage could result in significantly falsely high ammonia measurements. Preventing this effect would improve the accuracy of ammonia measurements.

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.

Experimental study of a novel cool-storage refrigerator with controllable two-phase loop thermosyphon

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.

ОЦІНКА ЕНЕРГОЕФЕКТИВНОСТІ ВИКОРИСТАННЯ СИСТЕМ КЕРУВАННЯ МОТОР-КОМПРЕСОРОМ ПОБУТОВОГО ХОЛОДИЛЬНИКА

Determining the rational structure of the automatic control system of the motor-compressor, which provides minimal energy losses when switching on and going to a steady state mode of operation of a household refrigerator. The methods of simulation modeling, comparative analysis, research of control systems and the main provisions of technical thermodynamics and the theory of automatic control are used in the work. The paper considers the principle of operation of the refrigeration unit of a household refrigerator, schematically shows its main elements and the relationship with the steam compression cycle. Simulation models of automatic control systems based on proportional-integral-differential controller, fuzzy and hybrid controllers have been developed. The proposed models allow to evaluate the quality of temperature control in the refrigeration compartment and to determine energy losses during transients. The results of computer simulation of transients in temperature control systems due to changes in the performance of the motor-compressor and the obtained values of power losses are presented. It is established that the smallest losses of the electric power at instant increase of heat inflows in refrigerating department occur at application of a fuzzy regulator. It is determined that the use of fuzzy controllers in automatic control systems reduces the duration of transients, the time of the first negotiation, the number of oscillations, but leads to static error and increases the maximum deviation from the set temperature in the refrigerator compartment. Simulation models of control systems of the motor-compressor of a household refrigerator for assessment of quality of regulation and definition of losses of the electric power during transient processes are developed. The ways to increase the energy efficiency of household refrigerators through the introduction of control systems with fuzzy regulators are proposed.

Intelligent Prediction of Refrigerant Amounts Based on Internet of Things

In a refrigeration unit, the amount of refrigerant has a substantial influence on the entire refrigeration system. To predict the amount of refrigerant in refrigerators with the best performance, this study used refrigerator data collected in real time via the Internet of Things, which were screened to include only the effective parameters related to the compressor and refrigeration properties (based on their practical significance and the research background) and cleaned by applying longitudinal dimensionality reduction and transverse dimensionality reduction. Then, on the basis of an idealized model for refrigerator data, a model of the relationships between refrigerant amount (the dependent variable) and temperature variation, refrigerator compartment temperature, freezer temperature, and other relevant parameters (independent variables) was established. A refrigeration model based on a neural network was then established for predicting the amount of refrigerant and was used to predict five unknown amounts of refrigerant from data sets. BP neural network and RBF neural network models were used to compare the prediction results and analyze the loss functions. From the results, it was concluded that the unknown amount of refrigerant was most likely to be 32.5 g. It is of great practical significance for refrigerator production and maintenance to study the prediction of the amount of refrigerant remaining in a refrigerator.

Experimental study of a diffusion absorption refrigeration cycle supplied by the exhaust waste heat of a sedan car at low engine speeds

The wasted energy from a car exhaust can be considered as the heat supply for an absorption refrigeration cycle. In practice however, application of such cooling systems in automobiles has been facing a number of technical restrictions one of which is once the car engine runs idle or at low speed. To tackle this matter, the present experimental study has been carried out. A commercial diffusion absorption refrigerator with internal volume of 0.04 cubic meters (Electrolux 27A1) and the exhaust flow from a compact car engine (X100 KIA) are applied. Various engine speeds (1000–2500 rpm) have been tested. First, it was confirmed that the amount of heat transferred to the generator at low engine speeds was not adequate to obtain the low temperature required for the refrigerator compartment. A new generator was therefore designed and built. The experimental results show that by using the modified generator, the heat transfer to the generator improves by more than 19%. The evaporator and refrigerator compartment reached the desirable temperatures of −5.7 °C and 4.2 °C respectively at the engine speed of 2000 rpm. Further improvement of the results was observed at the engine speed of 1000 rpm where the temperatures at the evaporator and the refrigerator compartment were reduced by about 4 °C once the modified generator was applied.

Non-season production of raspberry of red berry products in conditions of heated winter greenhouses

Relevance. Currently, in many countries of the world, the production of non-season raspberry berry products has become widespread. Recently, interest in this technology has arisen in Russia, which has great prospects for the development of industrial gardening. In our opinion, it is promising to develop elements of technology for the non-seasonal production of red raspberries, propagated by the method of clonal micropropagation with a traditional and remontant type of fruiting in the conditions of winter heated greenhouses.Material and methods. The experiments were carried out in the laboratory of clonal micropropagation of garden plants in the fruit growing laboratory of RGAU-MSHA named after K.A. Timiryazev. The objects of research were varieties of red raspberries with a traditional (variety Volnitsa) and remontant (varieties Orangevoe Chudo and Bryanskoe Divo) type of fruiting. The experimental plants were propagated by the method of clonal micropropagation and grown before distillation in open and protected ground; plants propagated by root offspring served as control. Experimental plants were planted in open ground for growing in mid-May, in mid-October they were transplanted into 10 liter containers and transferred to protected ground conditions. Then put in the refrigerator compartment with a temperature of + 1 ... + 5°C. For distillation, the raspberry repairing plants were exposed in the winter heated greenhouse on January 20, while the shoots of replacing the aboveground system were normalized: without normalization, 3 shoots per plant, complete pruning of the aboveground system. Raspberries with a traditional type of fruiting were exposed in a winter heated greenhouse in three periods on January 20, February 10, March 2. Accounting for the passage of the phenological phases of development and yield was made for 3 months every 5 days.Results. In the conditions of winter heated greenhouses, efficiency has been shown and elements of technology for non-season production of raspberry berries remontant and berries with a traditional type of fruiting, propagated in vitro and grown before open field distillation are developed. It was revealed that it is necessary to normalize the shoots before distillation of raspberry remontant, and the optimal timing for the start of distillation for raspberries with a traditional type of fruiting has been established.

CFD Simulation of Velocity and Temperature Distribution inside Refrigerator Compartment

The utility of a household fridge is to preserve the food eminence. Eminence of food unswervingly be reliant on temperature and air velocity distribution esoteric the stowing compartments. Disapproving temperature for food preservation will cause food to worsen or dwindling. Proper temperature distribution as well air flow keep the food fresh in the food chambers. This work presents the air flow and temperature distribution through natural convection warmness switch in severally modeled freezer is studied. The freezer and refrigerant compartments is studied for three configurations. The freezer and refrigerant compartments is studied for three configurations. In initial configuration using Plate-evaporator with rectangular finned surface and In second configuration Plate-evaporator while not finned surface and In third configuration Plate-evaporator with perforated finned surface. The simulations are carried out using ANSYS 16 work bench computational fluid dynamics software program package. The heat transfer between the freezer and refrigerating compartment is neglected and laminar air flow conditions were assumed. Simulation consequences demonstrate temperature stratification inside the refrigerating section cold and warm region were top and bottom respectively, in freezer compartment warm and cold region were top and bottom for each configurations. Comparison of temperature variation for numerous configurations of refrigerating compartment. The freezer and cold compartments is studied for three configurations. The perforated finned surface provides best result.

Experimentation & Analysis of Door Sag for Refrigerator

This project is sponsored by the company Whirlpool of India Limited, situated at Ranjangaon MIDC, Pune. The company is going to launch a new model of refrigerator. In that model they have introduced VACCUM INSULATED PANEL (VIP) inside the product to reduce the heat load on compressor. The VIP of type A has been used which is having thickness of 32 mm. The product weight has been increased by 25% along with increased in door weight.ThefunctionofVIPistoprovidebetterinsulationthanany otherconventionalinsulationmaterials.DuetoadditionofVIPand increase in weight of product there will be effect on structure of refrigeration.Thepresentworkfocusesonstructural/Experimental testing of product, simulation of Freezer Compartment (FC) & Refrigerator Compartment (RC) door for door sag, analytical calculation of door sag & validating theresult.

Auto-optimization control of hybrid ecological refrigeration system

The optimization problem of the two-stage hybrid compression-sorption refrigeration control system is presented. The idea is an eco-friendly energy conversion, powered by the waste heat or renewable energy. Eco-friendly means that using only natural energy carriers H2O and CO2 are used. The goal of the optimization is maximization of the renewable energy usage and increasing of the system COP, by minimization of the power consumption. The optimization problem is complex due to the large amount of control parameters. In the programmable logic controller (PLC) a set of functions is implemented. As a result the consumption of all kinds of energy supplied to the system in the different modes of operation may be calculated online. This can be applied as the control function for optimal usage of the available heat sources, while maintaining the temperature in the refrigerator compartment at desired level. Similar method of process optimization in the last years was introduced for the energy consumption and cost reduction in the operation of industrial and home appliances. In larger industrial scale more energy savings are possible using this approach. The work of entire refrigeration system can be based on this idea, reducing the consumption of electricity used to drive compressors, fans and pumps. Each step of the optimization has to consider process disturbances and external condition changes, therefore the system control becomes a complex issue. Number of optimization methods may be found in the literature. However in this case the application of the simple adjustment method based on the selected variables, control parameters, with dependence between them was proposed. This approach has been called auto or self-optimization. In this method the nominal value is set, but some possibility of losses are accepted. This type of optimization is used with single or several linear variables depending on the measured value in the system, which are usually controlled by PI or PID controllers.

Performance of the Bond Graph Approach for the Detection and Localization of Faults of a Refrigerator Compartment Containing an Ice Quantity

In this paper, a robust fault diagnosis for a refrigerator compartment containing a quantity of ice using the bond graph (BG) approach is performed by linear fractional transformations (LFTs). The BG model describes heat transfers supported by the amount of ice placed in the refrigerator compartment, as well as a water container. The LFT modeling of BG elements offers advantages from the point of view of structural analysis and data processing implementation. We have introduced four faults, which consist of ice temperature rise, water leakage, insulation failure at the hot walls of the refrigerator and an increase of the internal temperature due to poor door sealing. The faults are in the form of additional heat fluxes. The simulation results show the effectiveness of the proposed method for detecting and localizing faults. In addition, the lack of door sealing has the most influence on the temperatures in the internal cooling space, water, and ice compared to the other faults.

Performance analysis of a household refrigerator integrating a PCM heat exchanger

An experimental investigation was carried out to improve the energy efficiency of a household refrigerator by integrating a Phase Change Material (PCM) to accumulate thermal energy and stabilize the temperature in the refrigerator compartment. A novel design of PCM heat exchanger is proposed in this investigation. The experimental results indicate that by integrating this novel PCM heat exchanger, power consumption is reduced by 12% and the COP is increased by 8% compared to the refrigerator without PCM. In order to identify the best performing designs among various cases of refrigerator compartments placed with PCM, 2D unsteady state CFD simulations were made. For all the cases, the household refrigerator was simulated to study the influence of the PCM emplacement on the temperature and velocity fields. The computational results indicate that using PCM emplacements on the evaporator, walls, and in the racks of the refrigerator compartments has a significant influence to stabilize and homogenize rapidly the temperature (86.66% improvement over the basic configuration). However, there is a limit beyond which increasing PCM coverage in the racks more than 75% does not lead to any significant improvements.

Observability and Controllability Study of a Household Refrigerator Exposed to an Outdoor Cold Airflow Using Bond Graph Approach

The present paper studies the properties of observability and controllability using Bond Graph (BG) approach. It is especially applied to a pseudo BG model that describes the thermal transfers in a household refrigerator compartment exposed to an outdoor natural cold airflow. This latter is spread out in an installation, which consists of a cavity covering the side wall of the appliance and connected to inlet and outlet ducts through two openings. The study results show that the pseudo BG model is observable and controllable in time-varying (TV) systems using the concept of duality.

Optimisation of the design parameters of a domestic refrigerator using CFD and artificial neural networks

This paper reports the use of computational fluid dynamics (CFD) and artificial neural networks (ANN) for optimising and improving the performance of a static type domestic refrigerator. The effects of the hydrodynamic and thermal fields on the air flow inside of the refrigerator compartment were considered by exact modelling of the fan. The interior volume of air of the refrigerator was modelled using a CFD method, and analyses were performed. The numerical results were validated by comparing experimental results with the calculated interior design parameters. An optimisation study of the obtained design parameters was performed using a parametric method. The optimum design case was predicted by the ANN. The performance of the refrigerator improved by approximately 7.7% based on the amount of heat taken from the evaporator surface assuming thermal uniformity of the interior volume of air and the ISO 15502 standards. As a result, the annual energy consumption will decrease by 17.52 kWh.

МОДЕЛЮВАННЯ ШВИДКОСТІ РОЗПОДІЛУ ПОВІТРЯ У ВІДСІКУ ВИПАРНИКА ХОЛОДИЛЬНОЇ УСТАНОВКИ РЕФРИЖЕРАТОРНОГО КОНТЕЙНЕРА

The study is aimed at solving the problem of convective heat transfer calculating in the tubular evaporator unit of refrigerating container, which is equipped with fan forced convection. The mathematical model of the problem as a differential equation that establishes the energy conservation law in the air cells through the surface of which its movement is carried out is given. Inthe process of the convective heat transfer around the evaporator problem calculating the link between the basic physical quantities in the air − temperature fields and velocity of its movement was considered. Close relationship of obtained temperature values and air velocity at the outlet from evaporator unit as boundary conditions for further calculation of temperature field in the refrigerator compartment of refrigerating container was proved. Statement of the problem and its simulation wereperformed in a two-dimensional coordinate system, and software environment COMSOL Multiphysics, Femlab 3.0, Fluid Dynamics - Incompressible Navier-Stokes - Convection and Conduction was applied for its solution. he accomplished calculations have shown that the integral temperature value at the outlet of the evaporator unit, was calculated taking into account air velocity, which is lower than its values obtained without air movement consideration. The results of the study should be useful during the research of the convective heat transfer phenomenon in the different refrigerating devices, allow to choose evaporator and fan capacity morereasonably under conditions of obtaining the desired cooling mode for perishable products as well asin the learning process