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Journal ArticleDOI

Performance Enhancement of a Refrigerator Using Phase Change Material-Based Condenser: An Experimental Investigation

25 Dec 2017-International Journal of Air-conditioning and Refrigeration (World Scientific Publishing Company)-Vol. 25, Iss: 04, pp 1750032
TL;DR: In this article, the authors presented an experimental performance of a domestic refrigerator incorporated with a phase change material (PCM)-based condenser in parallel to the conventional wire-and-tube air-cooled condenser for the climatic conditions of India.
Abstract: Tropical countries like India, the ambient temperature reaches to 45–50∘C in the summer and higher ambient temperature directly impacts the energy required by the household refrigerator. This paper presents an experimental performance of a domestic refrigerator incorporated with a phase change material (PCM)-based condenser in parallel to the conventional wire-and-tube air-cooled condenser for the climatic conditions of India. It is proposed to operate the refrigerator with the PCM-based condenser, while the ambient temperature is higher during the day, otherwise with the air-cooled condenser. Due to large latent heat storage capacity of the PCM, the condenser temperature would not increase significantly. The COP of the PCM-based condenser was 28% higher as compared to air cooled condenser for 60min which reduce to 3% as PCM temperature reached to 33∘C. The energy consumption is lower by ∼15% in 312h of refrigerator experimentation with the proposed modification.
Citations
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Yongseok Jeon1, Dongwoo Kim1, Jongho Jung1, Dong Soo Jang1, Yongchan Kim1 
15 Oct 2018-Energy
TL;DR: In this article, the authors investigated the performance characteristics of an R600a domestic refrigerator-freezer (RF) adopting a condenser outlet split (COS) ejector cycle.
Abstract: The objective of this study is to investigate the performance characteristics of an R600a domestic refrigerator-freezer (RF) adopting a condenser outlet split (COS) ejector cycle. Experiments are conducted to measure the performances of conventional and COS ejector-based domestic RFs using R600a. A test bench is used to analyze the pressure lifting effect, mass flow rate variation, and coefficient of performance (COP) improvement with respect to the entrainment ratio (ER). For entire cycle operation at similar cooling capacity condition, the overall COP improvement of the test bench adopting COS ejector cycle over the baseline cycle is 11.4% at the ER of 0.18. Moreover, the COS ejector-based domestic RF is tested to examine its feasibility in actual applications. The COS ejector-based domestic RF with a compressor speed of 1450 rpm exhibits a temperature profile in the freezer compartment that is similar to that of the baseline domestic RF. At similar cooling capacity condition, the energy consumption of the COS ejector-based domestic RF with the compressor speed of 1450 rpm is 10.9% lower than that of the baseline domestic RF, owing to the pressure lifting effect.

15 citations

Journal ArticleDOI

[...]

TL;DR: In this paper, a new heat pump system is proposed to address the imbalance between power supply and demand solving the electricity soaring problem, which uses thermal energy storage and discharge concept that is capable of continuous heating operation simultaneously.
Abstract: Recently, electricity demand is increasing drastically compared to electric power supply. In particular, this trend is due to the demand for heating in winter, leading to the electricity peak consumption at any time of the day. In this study, a new heat pump system is proposed to address the imbalance between power supply and demand solving the electricity soaring problem. The suggested heat pump system uses thermal energy storage and discharge concept that is capable of continuous heating operation simultaneously. In order to demonstrate the effectiveness of such a system, the dynamic performance change of the system was investigated by experimental study. From the results, it was shown that the performance of heat storage system was varied according to refrigerant mass flow rate branched to the heat storage tank. Furthermore, it was confirmed that the performance was reduced during the heat storage operation process, and it was improved during the discharge operation process. The overall performance is reduced taken as a whole, but it is meaningful that it disperses the electricity peak. As a result of this study, it is expected that the new thermal storage heat pump system can reduce the maximum power load.

10 citations

Journal ArticleDOI

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Sungho Yun1, Sang Hun Lee1, Kang Sub Song1, Wonhee Cho1, Yongchan Kim1 
TL;DR: In this article, the performance improvement of tailored die quenching using material combinations with phase change material over the conventional tailored methods in hot stamping was investigated, and the thermal characteristics of the phase change materials, channel, die, block, and blank were analyzed using thermo-fluid transient simulations with the enthalpy method.
Abstract: The objective of this study is to investigate the performance improvement of tailored die quenching using material combinations with phase change material over the conventional tailored methods in hot stamping. The thermal characteristics of the phase change material, channel, die, block, and blank are analyzed using thermo-fluid transient simulations with the enthalpy method. Four cases of the material combinations with and without the phase change material are adopted as the die and block. A phase change material of lithium nitrate is applied to the soft zone. All cases without the phase change material do not satisfy the soft zone criteria, while all cases with the phase change material satisfy both the soft zone and hard zone criteria, owing to the effects of the heat storage and release in the phase change material. In addition, the martensite finish temperature area ratio increases with increasing the contact pressure, while the martensite start temperature area ratio decreases. The optimum contact pressure is determined to be 15 MPa for H13 and GTCSⓇ with the phase change material to maximize both the strength and ductile area. Overall, the tailored die quenching process using H13 and GTCSⓇ with the phase change material exhibits the best performance for high-quality tailored blanks.

4 citations

References
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TL;DR: In this paper, the authors present the results of experimental tests carried out to investigate the performance of a household refrigerator using a phase change material (PCM) located on the back side of the evaporator in order to improve its efficiency and to provide a storage capacity.
Abstract: This paper presents the results of experimental tests carried out to investigate the performance of a household refrigerator using a phase change material (PCM). The PCM is located on the back side of the evaporator in order to improve its efficiency and to provide a storage capacity allowing several hours of refrigeration without power supply. The system has been tested with water and with a eutectic mixture (freezing point −3 °C) and for a range of operating conditions (PCM thickness, ambient temperature, thermal load). The analysis of the results shows a significant improvement of the performance compared to a conventional system.

121 citations

Journal ArticleDOI

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TL;DR: In this article, a simplified model to assess the energy performance of vapor compression "on-off" controlled refrigerators is presented, which consists of first-principles algebraic equations adjusted with experimental information obtained from the refrigeration system under study.
Abstract: A simplified model to assess the energy performance of vapor compression ‘on–off’ controlled refrigerators is presented herein. The model consists of first-principles algebraic equations adjusted with experimental information obtained from the refrigeration system under study. The experimental work consisted of controlling and measuring the system and component operating conditions in order to gather key information for the development and validation of the model. The methodology showed similar accuracy to that using more sophisticated dynamic simulation codes, but with lower computational costs. When compared to experimental data, the model predicted AHAM energy consumption tests within a ±5% deviation band. A sensitivity analysis considering the number of tube rows in the condenser coil, the number of fins in the evaporator coil and the compressor stroke is also reported. The refrigeration system under study was a top-mount ‘Combi’ 600-l refrigerator, ‘on–off’ controlled by the temperature of the fresh-food compartment.

106 citations

Journal ArticleDOI

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TL;DR: In this paper, a review of the experimental efforts as well as modeling approaches to study the application of phase change materials in domestic refrigerators is presented and, the future and potential promising applications of PCM in domestic refrigerator are discussed.
Abstract: Domestic refrigerators are among the most widely used household appliances and a great portion of energy is used by these systems. Reduction of temperature fluctuation and enhancement of system performance is the main reason of using phase change materials (PCMs) in refrigeration systems. Different approaches have been used to improve the thermal performance of these systems by integration of PCM. A number of studies have focused on the application of PCM at evaporator for cold storage. On the other hand, not much has been done on the condenser side. Despite large number of studies, a comprehensive literature review specifically focusing on the application of PCM in domestic refrigerators is missing. This paper presents a review of the experimental efforts as well as modeling approaches to study the application of PCMs in domestic refrigerators. Moreover, advantages and disadvantages of each type of storage are presented and, the future and potential promising applications of PCMs in domestic refrigerators are discussed.

103 citations

Journal ArticleDOI

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TL;DR: In this article, a first-principles model for simulating the transient behavior of household refrigerators is presented, in which the compressor is on-off controlled by the freezer temperature, while a thermo-mechanical damper is used to set the freshfood compartment temperature.
Abstract: A first-principles model for simulating the transient behavior of household refrigerators is presented in this study. The model was employed to simulate a typical frost-free 440-l top-mount refrigerator, in which the compressor is on–off controlled by the freezer temperature, while a thermo-mechanical damper is used to set the fresh-food compartment temperature. Innovative modeling approaches were introduced for each of the refrigerator components: heat exchangers (condenser and evaporator), non-adiabatic capillary tube, reciprocating compressor, and refrigerated compartments. Numerical predictions were compared to experimental data showing a reasonable level of agreement for the whole range of operating conditions, including the start-up and cycling regimes. The system energy consumption was found to be within ±10% agreement with the experimental data, while the air temperatures of the compartments were predicted with a maximum deviation of ±1 °C.

89 citations

Journal ArticleDOI

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01 Oct 2011-Energy
TL;DR: In this paper, a shape-stabilized phase change material (PCM) was adopted for constructing heat storage condensers, which resulted in a lower condensation temperature, a higher evaporation temperature and a much larger subcooling degree at the condenser outlet.
Abstract: In this study, a kind of shape-stabilized phase change material (PCM) was adopted for constructing heat storage condensers. And a novel household refrigerator equipped with the heat storage condensers was setup based on an ordinary double-door three-star compartment refrigerator. The experimental investigation on the characteristics of the novel refrigerator and an ordinary refrigerator was carried out under the ISO standard test conditions. For the novel refrigerator, part of the condensation heat was stored in the shape-stabilized PCM during the on-time and discharged to the environment while the compressor was off. Therefore, the heat dissipation of the novel refrigerator was continuous during a complete cycle (including a successive on-time and off-time period), different from the intermittent heat dissipation of the ordinary setup. Thus, the overall heat-transfer performances of the condensers could be significantly improved, which resulted in a lower condensation temperature, a higher evaporation temperature and a much larger subcooling degree at the condenser outlet. Compared to the ordinary refrigerator, the total cycle time and the ratio of on-time to the total cycle time of the novel refrigerator were much smaller, which led to more frequent starts of the compressor but lower energy consumption. Experiments demonstrated that the novel refrigerator could increase the energy efficiency by about 12% with only little increase of the cost.

87 citations