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This study examines the performance enhancement offered by a phase change material (PCM) connected to the evaporator and condenser of a household refrigerator that utilizes R134a as the refrigerant. The features of the refrigerant and its properties determine how quickly a refrigerator releases and stores heat. The use of PCM accelerates heat transfer, leading to an improvement in the Coefficient of Performance (COP). This experimental study demonstrates how the COP of a typical refrigeration system can be significantly improved. In the present study, the PCM is utilized in a manually constructed enclosure that encloses the evaporator and condenser of a refrigerator. The purpose of the PCM is to decrease the condenser temperature, resulting in a substantial reduction of power consumption. The heat is transmitted from the refrigerator cabinet to the evaporator through PCM by conduction. Therefore, the rate of heat transfer from the evaporator to the refrigerant increases noticeably, which enhances the COP of the refrigeration system. From the experiment, it was found that COP increased by 12.7% and compressor off time increased about 1.5 times.

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.

The performance of the refrigeration system is largely influenced by the heat exchanger, and there are various methods for increasing heat exchange efficiency. In this paper, the effect of changes in the internal shape of an evaporator with different heat transfer areas on the performance under actual refrigerator operating conditions was analyzed. The type of evaporator includes a grooved evaporator and a composite grooved evaporator with a relatively large heat transfer area. The performance evaluation was evaluated by refrigerant optimization, on-off operational test, and steady state energy test. The optimum refrigerant amount for both systems is 76 g. When a composite grooved evaporator was used, monthly energy consumption was relatively saved by 2.7 kWh/month. In addition, the composite grooved evaporator has consumption and 2.2 % higher cooling capacity than the grooved evaporator. In conclusion, COP improved by 1.33 %. [ABSTRACT FROM AUTHOR]

Copyright of Ciencia e Ingenieria Neogranadina is the property of Ciencia e Ingenieria Neogranadina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. • A method to determine the thermal insulation weaknesses of the gasket is proposed. • Comprehensive structural improvements to reduce gasket heat load are proposed. • Thermal insulation improvement of gaskets will decrease refrigerator temperature. • Energy consumption of refrigerators with new-design gaskets is reduced by 3.19 %. [ABSTRACT FROM AUTHOR]

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

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, an analytical study of a household refrigerator was achieved. In this context, the cooling load of the refrigerator was calculated, the main and auxiliary components were choosen and the energy consumption value of the designed refrigerator was also determined. Creating the cooling loads; the effects of transmission heat load, product heat load, infiltration (air exchange) heat load and other heat loads on the cooler and freezer sections of the refrigerator were calculated. Besides, the effect of each heat load, forming the cooling load, on the total cooling load has been demonstrated. It has been observed that the conduction (transmission) heat load constitutes 39.85% of the total heat load, the product heat load 25.90%, and the infiltration heat load 20.74%. The remaining heat loads constitute 13.51%. In this study, the values in the literature and the methods used by a company that manufactures refrigerators in our country together with the TSE EN 62552 standard were taken into consideration. At the end of the study, taking into account the energy consumption of the refrigerator, it was determined that the energy class was A ++. [ABSTRACT FROM AUTHOR]

• The cycle model of a finite-time measurement-driven machine has been proposed. • The average work and entropy change of the atom have been unveiled. • The performances of the machine in two different modes are discussed and analyzed. • Energy conversion efficiency is enhanced by using an appropriate unitary evolution. The cycle model of a finite-time measurement-driven machine is proposed by repeatedly performing the quantum measurement, interaction of an atom with the single-mode field, and thermalization with heat reservoirs. The trajectories of the evolution of the atom reach a stationary probability distribution after sufficiently many iterations of the cycle, from which the average changes of the internal energy and the entropy of the atom are calculated. By taking the total work input as the sum of the average works during the measurement, unitary evolution, and information erasure processes, the energy conversion efficiencies of the machine as a refrigerator and a heat engine are determined. Results show that the cooperation of the quantum measurement and the unitary operation always turns the state of the atom into a desired state in every trajectory, yielding a high energy conversion efficiency. The investigation on the proposed model has potentially significant applications where the thermal manipulation at the quantum level is required. [ABSTRACT FROM AUTHOR]

In the perspective of reducing the household energy consumption, current research in conventional refrigeration is concentrating on introducing innovative designs and enhances the energy efficiency of the refrigeration system. This research work compares the performance of the domestic refrigerator by employing hotwall air cooled and box type shell and tube water-cooled condenser. The energy and exergy analysis methods help to localize exergy losses in the refrigerator. The investigation is carried out according to ISO 15502:2005. Experimental studies were conducted in the same refrigerator unit operating with a different condenser to determine the coefficient of performance, exergy efficiency, and exergy loss in all components of the domestic refrigerator. The experimental result shows that COP is increased by 18-20% and the exergy efficiency of the refrigerator with water cooled condenser unit is found to be higher by 6.89-9.13% than the one with a hot-wall air cooled condenser. The per day energy consumption of a refrigerator with a water-cooled condenser reduces by 17% in comparison with conventional refrigerator. The irreversibility of the refrigerator with the water-cooled condenser is reduced by 34% than that of the conventional system under similar operating conditions. The total equivalent warming impact of refrigerator working with the water-cooled condenser is 16% lower than that the refrigerator with air cooled condenser. The utilization of water-cooled condenser in household refrigerators enhances energy efficiency. [ABSTRACT FROM AUTHOR]

In this study, a series of experimental runs performed under different conditions in order to evaluate the effectiveness of a household refrigerator. Two eutectic phase change materials (PCMs) arranged in a cascade configuration have been tested on the performance of the system. The PCMs were placed on the back-side of the wire-and-tube condenser in a decreasing order of their melting temperatures along the refrigerant flow direction to achieve a high heat transfer rate and to reduce energy consumption. The operating characteristics of the novel refrigerator were studied and compared with the results of a refrigerator equipped with a single PCM and two ordinary refrigerators with and without measurement packages (M-packs). All the tests have been performed in standard condition in Philver Company in Tehran, Iran. For the novel refrigerator, the temperature of the condenser surface significantly decreased, which led to a lower condensing temperature during the refrigeration cycle and improved the coefficient of performance (COP). Also, the ratio of the on-time to the total experiment time was considerably shorter compared to the refrigerator equipped with a single PCM and two ordinary refrigerators. According to the results, integration of two different PCMs on the condenser surface in a cascade arrangement decreases the compressor work time percentage from 32.7 to 27.6, while this parameter was decreased to 29.6 with a single PCM. Finally, the energy consumption was reduced by 13% in the novel refrigerator whereas it was only reduced by 8% in the refrigerator equipped with a single PCM. • Efficiency enhancement of a household refrigerator has been studied. • Eutectic phase change materials with cascade configuration have been used in the system. • The compressor off-time of the novel system lowered significantly. • Energy consumption of the refrigerator with single PCM was reduced by 8%. • Further energy consumption reduction up to 13% has been achieved in cascade configuration. [ABSTRACT FROM AUTHOR]

Highlights • Improvement of a hybrid household refrigerator (HHR) of which fresh food compartment cooled by thermoelectric cooler (TEC). • Numerical analysis for reference HHR through CFD tool to find optimum location for the TEC. • Two samples were manufactured after CFD analysis. • Verification of the numerical analysis's results by tests. • Comparison between reference HHR and samples. Abstract Numerical and experimental analysis of a previously investigated hybrid household refrigerator (HHR), HHR I, were conducted in this study. To determine the optimum location for the thermoelectric cooler installed in HHR I, CFD analysis was performed. As a result of the CFD predictions, two new HHRs, namely HHR II and III, were created and experimentally investigated. CFD predictions showed a more uniform air velocity and temperature distributions inside the fresh food compartments of HHR II and III compared to HHR I. Additionally, experimental measurements indicated a considerable increase in the energy efficiency of HHR II and III. Their energy consumption was nearly identical and improvements of up to 10% and 27% at the ambient temperatures of 16°C and 32°C, respectively, were observed when compared to HHR I. Regarding the cooling time, no effect of the relocation of the TEC was observed at the TEC's nominal voltage of 24 V. [ABSTRACT FROM AUTHOR]

In this study, an existing laboratory heat pump is converted to a refrigeration unit in order to evaluate efficiency, power consumption, pressure and temperature variations and optimal charge amount of the system in new mode using refrigerant R-407C. Refrigerant charge amount has a key role in the terms of performance, operating cost (regarding to the charge reduction and energy consumption) and environmental concerns in all heat pump and refrigeration systems, which work on the same principles. Heat pump charge amount is the subject of many research, but less studies have been done in the case of refrigerators and freezers where the system works in the transient condition, on the contrary to the heat pump units. Although this study has been devoted to a detailed attempt to examine the possibility of converting the heat pump into the refrigerator, energy aspects of the whole system and the compressor have been analyzed under different working conditions. In the installed setup, the COP value of the system is tested with charge amount between 1 kg and 7 kg, but obtained results show that, this value is so lower than that of heat pump unit due to restricted energy source in cooling chamber. [ABSTRACT FROM AUTHOR]

Highlights: • Cabinet-door liner using Ingeo PLA improves energy efficiency of refrigerators. • Ingeo is made using carbon derived from sustainable, renewable plant sugars. • Ingeo saves energy by reducing degradation in thermal resistance of foam insulation. • Ingeo resists degradation from cyclopentane blowing agents better than HIPS. • Total energy use for a refrigerator was reduced 7.3–12.5% over a 15-year period. Abstract This paper presents the energy savings potential of a newly developed liner applied on the foam insulation used in refrigerator and freezer cabinets, compared with using a more commonly used liner made from high-impact polystyrene. The new polylactic acid polymer liner is made from renewable feedstock such as carbon found in plant sugars. The energy use over the life of refrigerator and freezer is calculated using the Energy-Efficient Refrigerator Analysis program developed by the United States Department of Energy to estimate the energy savings potential of various technology option upgrades (cabinet and refrigeration system) for rulemaking purposes. The simulation results show that energy savings from implementing the Ingeo liner range from 818 to 1395 kWh (7.3–12.5% of total energy use) over a 15-year period. In addition to the energy savings, the slower increase in the thermal conductivity of the insulation could allow the compressor to run fewer hours per year compared with a case in which the foam thermal conductivity increases rapidly. This change could increase the life of the compressor and the refrigerators and freezers. This study does not attempt to quantify the impact of slower foam aging on the compressor life. [ABSTRACT FROM AUTHOR]

Highlights • Building two hybrid refrigerators including vapour compression and thermoelectric cooling technologies. • Focusing on thermal analysis of the thermoelectric coolers' influence on the refrigerator performance. • Testing serial and hybrid refrigerators according to different standards. • Hybrid refrigerators have three to four times higher energy consumptions at different ambient temperatures compared to serial ones. • 40% less cooling time and more accurate temperature control can be achieved with thermoelectric coolers. Abstract Two different hybrid refrigerators which include vapour compression and thermoelectric (TE) cooling technologies were built and tested. Serial refrigerators, which use vapour compression only were first tested to collect reference data for comparisons. Then, the hybrid prototypes were constructed by attaching thermoelectric coolers (TECs) to different compartments of these serial units. Among the chill, fresh food and freezer compartments of the refrigerators, the TECs were only used at chill and fresh food compartments, which have different cooling power requirements. Energy consumption, cooling and freezing capacity, and noise tests were conducted in compliance with three different standards. All hybrid refrigerators operated successfully in various ambient temperatures and loading conditions. The test results showed that the hybrid refrigerators had at least three times higher energy consumption levels over those of serial ones, because of the lower operating efficiencies of the TECs and higher transmission losses. Moreover, their noise levels are extremely high, at least 25 dB(A) higher than those of serial ones. However, the TECs provided a more sensitive temperature control in the compartment in which they were used. Additionally, the hybrid refrigerators' performance in terms of cooling capacity was very promising. They were able to cool 17.5 kg of loads from an ambient temperature of 25 °C to the desired temperatures faster than the original serial refrigerators. Since the freezer compartments of both the serial and hybrid units are cooled by compressor-based cooling systems, the freezing capacity results were identical. [ABSTRACT FROM AUTHOR]

As a step towards sustainable energy management systems, energy providers use various demand side management techniques to reduce fluctuations in consumer energy demand. Dynamic pricing schemes encourage consumers to shift their energy usage patterns from peak hours towards off-peak periods, but here usually the active participation of consumers is anticipated. Smart household devices, which can autonomously shift their time of operation, can efficiently support such demand side management techniques. In this paper an adaptive model-based control scheme is proposed to create intelligent cost-aware household appliances, which can change their behaviour to minimize the cost of consumed energy and at the same time provide the required quality of service. The controller utilizes the dynamically changing energy price list, published ahead by the energy provider, thus it cooperatively supports demand side management. The proposed methods are evaluated in a case study, utilizing a household refrigerator. The proposed adaptive model predictive controller can save 5-10% of the energy bill, according to simulation results. [ABSTRACT FROM AUTHOR]

Most of electricity is consumed in either commercial or domestic refrigeration systems. Since the outer volume is determined, inner volume of a refrigeration system is important for a specified energy consumption. Therefore, the optimum distribution of insulation material according to inside and outside conditions for on and off time of a refrigerator is very important. Uniform distribution of insulation material is useful only convection and conduction resistances are the same for all sides and also on and off periods. In this study, a general solution of the optimum distribution of thermal insulation material for a given insulation material volume or given inner volume is suggested for refrigeration systems and also explained by a case study. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study presents a dynamic modulation of voltage excitation angle technology applied to a refrigerator so that the refrigerator operates at optimum energy consumption. This technique utilizes a semiconductor element, Tri-electrode AC switch (TRIAC), as a regulatory element for modulating the voltage excitation angle and the sensing current is taken as the feedback signal to determine the voltage modulation range. Thus, a novel energy saving controller (NESC) was successfully developed. We validated the feasibility of the proposed NESC; tests were performed where the door is closed for one hour and a dynamic simulation of normal use where the door is opened and closed periodically in one hour. The energy-saving rates obtained were 20.48% and 12.88%, respectively. In addition, a long period of one day tests on refrigerator was also conducted with and without NESC, and the best power consumption was measured at 6.597 kWh 24 h −1 . An energy-saving rate of 22.41% was achieved. [ABSTRACT FROM AUTHOR]

Temperature and humidity chambers are used to simulate many thermal-environmental conditions, as well as to observe the effects that a range of temperature and humidity have on a product or material at the manufacturing stage. The energy consumption and accuracy of these test chambers over the last decades have raised concerns for recent researchers. In this study, the energy consumption and stability of a temperature and humidity chamber was investigated under various operating and environmental conditions by adopting a variable speed compressor to the refrigeration unit. The accuracy of temperature and humidity was also investigated. It is found that, for a given surrounding environmental condition, as the dry bulb temperature conditions of the temperature and humidity chambers increased, the cooling capacity of the system increased while the refrigerating unit's power decreased for all operating conditions. However, the total energy consumption of the test unit increased due to an increment in the electric heater output. In maintaining effective stability of temperature and humidity test chambers, it is observed that, varying the refrigeration unit capacity by adjusting compressor speed has the potential for reducing the temperature and relative humidity fluctuations within the chamber for a given operating condition. Adopting a variable speed compressor to the refrigerating unit, have the potential for reducing the energy consumption significantly according to increment of setting temperature of the chamber as well as ensuring system stability for temperature and humidity chambers. [ABSTRACT FROM AUTHOR]

This paper proposes a pseudo bond graph model of thermal transfers by natural convection inside a household refrigerator. It has two inputs: the ambient temperature and the temperature at the level of the evaporator wall. The latter assesses the functioning of the compressor cycles. A performance comparison, with the experimental data, was carried out in order to verify the model, in which, real measurements are used to modulate the evaporator temperature source. The simulation results show the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

This study deals with a frost-free household refrigerator-freezer, in which frosting can be retarded by dehumidifying the air before it enters the evaporator of the refrigerator-freezer via a desiccant-coated heat exchanger. Because the desiccant can be regenerated via the condensation heat of the refrigerant (which is exhausted into ambient air in conventional household refrigerator-freezers), the proposed system can achieve high energy efficiency. Calculations show that the coefficient of performance of this system ( COP ) is within the range 1.5–2.5 at an ambient temperature of 15–35 °C. Moreover, it is found that the relative humidity of the refrigerator air ( RH RA ) and the temperature of freezer air ( T FA ) have a significant effect on COP : COP decreases by about 13% when RH RA varies from 0.4 to 0.8 and by 10% when T FA runs from −18 to −23 °C. [ABSTRACT FROM AUTHOR]

The number and variety of governmental programs designed to promote energy efficiency have increased over time. Examples include mandatory minimum efficiency standards, subsidies for more energy efficient goods and services, and consumer labels, such as the United States Environmental Protection Agency's ENERGY STAR $$^{\textregistered }$$ . While there has been considerable research on the effects of these programs in isolation, there has been less of a focus on joint effects or interactions between programs. This study examines how the offer of a mail-in rebate influences consumer willingness-to-pay for an ENERGY STAR-certified refrigerator. Data used for this study were collected from an online survey containing a hypothetical choice experiment conducted in the United States in 2009. Results suggest that the offer of a rebate induces uncertainty about the quality of ENERGY STAR-certified refrigerators and, thus, could actually reduce willingness-to-pay for such refrigerators. [ABSTRACT FROM AUTHOR]

This paper presents a study on the use of ice to improve the energy efficiency of a domestic refrigerator by applying a pseudo bond graph model that describes the thermal transfers sustained by a quantity of ice introduced inside the cavity of refrigeration. The use of ice resulted in a global energy saving of 4.68%. The effect of ice was found to be more significant during the transitional regime. It reduced the response time to reach the stable average temperature from 15 h to only 3.5 h compared to when not using ice. This achievement did not cost additional electrical power, but rather allowed a saving of electrical energy of 76.73%. However, during the steady state, a reduction in the energy efficiency was noted. An improvement in the cooling by keeping the temperature inside the refrigerator more homogeneous is also proved. The model has two inputs: the outside temperature, and the modulated temperature of the evaporator. This latter determines the functioning of the compressor cycle. The model describes the thermal transfers by natural convection inside the refrigerator. Two experiments were carried out to make a performance comparison and to prove the influence of ice in cooling and energy saving. We used real measurements to modulate the evaporator temperature source in the pseudo bond graph model. The simulation results show the effectiveness of the proposed approach. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The issue of volatile organic compounds (VOCs) is a global concern due to its significant influence on environmental pollution, climate change, and human health. Condensation is an available VOCs recovery method, but it currently has obvious shortcomings in terms of energy consumption, carbon emissions, refrigerants, and emission concentration. In this paper, a novel VOCs condensation system combined with gas turbine was proposed. The heat obtained by burning part of the exhaust gas is employed to drive an absorption refrigerator using ammonia water and a Stirling refrigerator using helium to recover VOCs contained in the remaining exhaust gas, which has the advantages of not requiring an external power supply, low carbon emissions, using natural refrigerant and nearly zero-VOCs emission. In order to obtain the optimal recovery efficiency, a thermodynamic calculation model was established, and related experimental verifications were carried out. The results show that the remaining 93.3% of the VOCs can be recovered by burning 6.7% of the VOCs when the absorption refrigerator (213 K) recovers the waste heat of the gas turbine used to power the Stirling refrigerator (110 K). The carbon emission reduction efficiency is as high as 92.9% and the carbon emission reduction is 16707 tons per year. The effects of the refrigeration temperature, heat source temperature, gas turbine efficiency, refrigerator efficiency and exhaust gas flowrate on the recovery efficiency were also analyzed. • A novel VOCs condensation system without external power supply is proposed. • The carbon emission reduction is 92.9% with recovering waste heat. • Burning 6.7% of the VOCs recovers the remaining 93.3%. [ABSTRACT FROM AUTHOR]

Abstract: Performance of mixed mode helium liquefaction and refrigeration systems based on a number of refrigeration stages has been studied taking compressor discharge pressure, heat exchanger effective UA and expander flow rate as independent parameters. Due to constraints of space and minimum flow rate through expanders (to attain operational reliability), helium plants often have to be designed with heat exchanger UA and number of stages less than the optimum values. It is useful for designers to evaluate the penalty in cold box exergy efficiency when the plant is designed or operated under such constraints. Performance of pure liquefier, pure refrigerator and mixed mode systems when operated at off-design conditions has been evaluated. Exergy efficiency has been used as the tool for the entire analysis of this paper. [Copyright &y& Elsevier]

Abstract: One of the critical areas in the outer shell of household refrigerators is the compressor compartment, which has relatively high temperatures, due to the heat generated while the compressor is running. This implies a larger heat transfer to the interior air volume and, consequently, more energy consumption. One way to decrease this temperature is to ventilate the base of the refrigerator with a small fan. In the research carried out, a decrease of 11 °C in the temperature of the surfaces close to the compressor was recorded, when the fan was running. The implications of this effect can be seen at two levels: changes in the temperature distribution at the bottom of the refrigerator envelope and the resulting dynamic effects, and a decrease in energy consumption of the entire system. Consequently, there are lower CO2 emissions to the environment, making household refrigerators more efficient and sustainable. [Copyright &y& Elsevier]

Field-metered energy use data for 1,467 refrigerators and 185 freezers from seven studies conducted between 1992 and 2010 were used to calculate usage adjustment factors (UAFs), defined as the ratio of measured to tested annual energy use. Multiple regressions of UAFs against several household and climate variables were then performed to obtain separate predictive functions for primary (most-used) refrigerators, secondary (second most-used) refrigerators, and freezers, and residual differences between observed and modeled UAFs were fit to log normal distributions. These UAF functions were used to project energy use in the more than 4,000 households in the 2005 Residential Energy Consumption Survey, a statistical representation of US homes. These energy use projections formed the basis of calculating lifecycle energy savings for more efficient refrigerators and freezers, as well as national energy and cost savings. Results were compared with previous published work by the Department of Energy, demonstrating how UAFs impact energy and cost savings. Such an approach could be further improved with additional data and adapted for other appliances in future analyses. [ABSTRACT FROM AUTHOR]

Abstract: Demand Side Management in power grids has become more and more important in recent years. Continuously growing energy demand both increases the need for distributed generation from renewable energy sources and brings out the topic of Demand Side Management. One of the major application areas of Demand Side Management in smart grids is cooling systems. In this paper, Demand Side Management with control of a refrigerator and its economic effects on consumers are analyzed. With a refrigerator model based on real measurements, several cooling schedules are simulated and annual energy fees for different pricing methods in use in Turkey are calculated and discussed. The results revealed that, 37.9% of refrigerator’s demand in peak period can be shifted to other periods and annual electricity bills for customers can be reduced by 11.4%. [Copyright &y& Elsevier]

Abstract: Solar energy is one of the most efficient, clean and affordable energy alternatives available today. With the current concerns about global warming and ever increasing energy rates, countries are seriously looking for domestic and industrial usage of solar energy. In the present study, a detail review of the application of solar energy for refrigeration systems has been carried out. The utilization of solar energy for refrigeration systems would help in improvement of energy economics, energy consumption and energy efficiency. The review focuses especially on solar panel, desiccant fluid for icemaker and its components. The study also includes thermodynamic equation and material for making component of refrigeration to improve the coefficient of performance. Study around the economic evaluation and solar performance coefficient in the type of refrigerator, modeling and simulation, mathematical equation of heat transfer and type of absorption used are other topics that could be considered. [Copyright &y& Elsevier]

Abstract: The paper introduces the Energy-related Products(ErP)directive and its late evolution. Both the general and the particular eco-design requirements of a refrigerator are presented. The criteria of standby/off are listed as well. The assumptions made for the modeling of the product and source of the database are put forward. There are 11 factors of environmental impacts used in the evaluation software EIME. The environmental impact of manufacturing, distribution, use and the end of life is analyzed according to a certain refrigerator. The results show that three factors are significant, which are electricity consumed by the refrigerator in the use stage, the raw materials of metal and plastics in the manufacturing. The solution to these problems is provided. The introduction of eco-design to development phase of a product is urgent nowadays. [Copyright &y& Elsevier]

Abstract: Given the growing stock of household electrical appliances, China is faced with an urgent challenge of management of household appliances massive disposal. Unfortunately, the majority of waste household appliances are now processed in small workshops mainly by manual disassembly and open incineration which are extremely polluting and health-harming in China. In response to the increasing environmental concerns over household appliance end-oflife treatment, The Regulations on the Administration of the Recovery and Disposal of Waste Electrical and Electronic Products (WEEE Regulations), was promulgated in 2009. To discuss the potential benefits from the implementation of the Regulations, a holistic understanding of the waste appliance recycling business and after-endof –life markets is indispensable. This paper presents a life cycle simulation model to evaluate the potential environmental benefits from the improved end-of-life management. The proposed model provides a mathematical description of close-loop lifecycles and yields quantitative results of energy and raw material consumption and waste generation. Then, as a case study, the environmental benefits of household refrigerator recycling and reuse system compliant to the Regulations is analyzed based on comparison of simulation results of two scenarios respectively representing implementing and not implementing of the Regulations. The proposed model is expected to facilitate policy- and decision-making on product recycling and reuse. [Copyright &y& Elsevier]

Abstract: This paper outlines a simulation model for the cycling behavior of household refrigerators and, therefore, for predicting their energy consumption. The modeling methodology follows a quasi-steady approach, where the refrigeration system and also the refrigerated compartments are modeled following steady-state and transient approaches, respectively. The mass, energy and momentum conservation principles were used to put forward the equation set, whereas experimental data were collected and used to reduce the model closing parameters such as the thermal conductances and capacitances. The experiments were carried out using a controlled temperature and humidity environmental chamber. The model predictions were compared to experimental data, when it was found that the energy consumption is well predicted by the model with a maximum deviation of ±2%. A sensitivity analysis was also carried out to identify opportunities for energy savings. [Copyright &y& Elsevier]

Abstract: In this work, an experimental work was investigated on the nano-refrigerant. TiO2-R600a nano-refrigerants were used in a domestic refrigerator without any system reconstruction. The refrigerator performance was then investigated using energy consumption test and freeze capacity test. The results indicate that TiO2-R600a nano-refrigerants work normally and safely in the refrigerator. The refrigerator performance was better than the pure R600a system, with 9.6% less energy used with 0.5g/L TiO2-R600a nano-refrigerant. Thus, using TiO2-R600a nano-refrigerant in domestic refrigerators is feasible. [ABSTRACT FROM AUTHOR]

Abstract: A pulse tube type stirling machine with warm gas-driven displacer which has a displacer rod is discussed with numerical simulation when it is used as a cryogenic refrigerator, room temperature refrigerator and engine. It has both the advantages of gas-driven-stirling machine with high efficiency and simplicity and the advantages of pulse tube machine with no moving parts at low temperatures. A nodal analysis method that includes the linear motor and the displacer in the machine is introduced. Numerical results show that it has high potential to be used as the cryogenic refrigerator, room temperature refrigerator and engine. In this type of machine, there is an optimum phase angle between displacer and piston, and an optimum swept volume ratio of displacer over compressor for efficiency. The phase angle and swept volume ratio can be adjusted by the natural frequency of the displacer and the diameter of the displacer rod when it is used as a refrigerator. [Copyright &y& Elsevier]

Refrigerator-freezers energy consumption is greatly affected by room temperature, door opening and thermostat setting position. Two frost free household refrigerator freezers of the same capacity were tested in the laboratory to determine the sensitivity of their energy consumption to various usage conditions. The experiments were conducted to investigate the effect of single variables, such as temperature, thermostat setting positions and door opening, and their combined effect on energy consumption. Our investigation reveals that room temperature has the higher effect on energy consumption, followed by door opening. Thermostat setting position has the lower effect on energy consumption. More detailed tests were performed under different room temperature, thermostat setting position and door opening conditions. With the experimental results, a first order mathematical model has been developed to investigate their combined effect on energy consumption. The test results are discussed and presented. [Copyright &y& Elsevier]

• Frost accumulation on an evaporator was measured using meltwater collectors. • Heat distribution of an evaporator was calculated by measuring the heat transfer from the heater. • Power optimization of the defrosting heaters was conducted. • The defrosting performance was improved at the optimum heater power. Power optimization was conducted for the defrosting heaters (conductive and radiant heaters) in a freezer to enhance their performance. The distribution of frost in the evaporator was measured experimentally, and the required defrosting energy corresponding to frost accumulation was calculated. The influence of defrosting heaters on frost was evaluated by measuring the heat quantity of the evaporator. The optimization was carried out such that the two heaters distribute the valid energy to the evaporator minimizing the excessive waste heat. At the optimum heater power, the maximum surface temperature of the evaporator was reduced, and the temperature distribution of the evaporator became uniform. The heater power and defrosting time were reduced through power optimization, thereby increasing the defrosting efficiency up to 6.7%. The effective heater power distribution could be further promoted to other heat exchangers with various heat transfer technologies. [ABSTRACT FROM AUTHOR]

The need for cooling is more and more important in current applications, as environmental constraints become more and more restrictive. Therefore, the optimization of reverse cycle machines is currently required. This optimization could be split in two parts, namely, (1) the design optimization, leading to an optimal dimensioning to fulfill the specific demand (static or nominal steady state optimization); and (2) the dynamic optimization, where the demand fluctuates, and the system must be continuously adapted. Thus, the variability of the system load (with or without storage) implies its careful control-command. The topic of this paper is concerned with part (1) and proposes a novel and more complete modeling of an irreversible Carnot refrigerator that involves the coupling between sink (source) and machine through a heat transfer constraint. Moreover, it induces the choice of a reference heat transfer entropy, which is the heat transfer entropy at the source of a Carnot irreversible refrigerator. The thermodynamic optimization of the refrigerator provides new results regarding the optimal allocation of heat transfer conductances and minimum energy consumption with associated coefficient of performance (COP) when various forms of entropy production owing to internal irreversibility are considered. The reported results and their consequences represent a new fundamental step forward regarding the performance upper bound of Carnot irreversible refrigerator. [ABSTRACT FROM AUTHOR]